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Associazione Studiosi Scienze Eterodosse
di Altra Scienza
L'automobile di Nikola Tesla
Como Construir una Turbina Tesla
Tesla: Un Talento Scomodo
Il Sistema di Nikola Tesla per Trasmettere
Energia Senza Fili In Ogni Parte della Terra
The Earthquake Machine
Tesla's Flying Machine
Experiments with Alternate Currents of High Potential and High Frequency
Tesla's (real) Flying Machine
L'Oscillatore di Tesla
W.B.Carlson L'Inventore di Sogni
Tesla Earthquake Machine
COMO CONSTRUIR UNA TURBINA TESLA
He aquí un gran motor que se ha relegado al olvido: La turbina Tesla. Constituye
un trabajo muy sencillo para el modelista, pues no requiere tolerancias. Y
funciona con aire o vapor
Por Walter E. Burton
Click en la imagen para ver más grande y claro
PARECE PERSEGUIRNOS el fantasma de Nikola Tesla. El año pasado describimos aquí cómo
construir un modelo de la bobina de alta frecuencia de ese gran inventor (septiembre de 1964).
Ahora he aquí su famosa turbina de vapor, la cual siempre se menciona, aunque rara vez puede
verse. Estos dos modelos tienen varias cosas en común: A pesar de que son para fines de diversión
y experimentación, están basados en originales que (1) fueron construidos por razones prácticas; (2)
introdujeron principios revolucionarios; y (3) nunca se produjeron para fines comerciales.
La vista seccional a la izquierda muestra cómo funcionó en realidad un prototipo, construido para
una compañía de fuerza eléctrica. Tenía 25 discos con un espesor de 0.8 milímetros y, a pesar de
que apenas medía 61 x 91 centímetros y que tenía una altura de sólo 61 centímetros, logró producir
una potencia de 200 caballos a una velocidad de 16,000 rpm con un chorro de vapor a una presión
de 8.8 kilogramos por centímetro cuadrado. La trayectoria espiral del vapor llegó a ser de casi 5
metros, y la presión del vapor de escape alcanzó apenas 0.07 kilogramo por centímetro cuadradoprueba de la extraordinaria eficiencia de la turbina.
La manera en que funciona la turbina se muestra en este esquema basado
en informes de ingeniería de 1911 sobre el motor que Tesla construyó para
una compañía de fuerza eléctrica de Nueva York. Cuando el vapor
proveniente de la tobera a la derecha describe una trayectoria espiral entre
los discos, éstos comienzan a girar
La otra característica que dio
origen a un revuelo en aquel
entonces (antes de la Primera
Guerra Mundial) fue la facilidad
con que el motor podía invertirse.
Simplemente se hacía fluir el vapor
a una tobera en el lado opuesto del
eje del rotor. Las turbinas de
norma en aquellos tiempos sólo se
La turbina de Tesla nunca llegó a
producirse comercialmente. Es
posible que fuera demasiado
adelantada para sus tiempos.
Ahora están corriendo rumores de
que ha vuelto a nacer el interés en
ella; el Departamento de Marina,
por ejemplo, de los Estados Unidos
la está sometiendo a serias
consideraciones. Es posible que
todavía se convierta en una
importante unidad de fuerza;
posiblemente en relación con las
plantas atómicas de vapor.
El principio de funcionamiento que estimuló todo este interés en 1911 puede demostrarse en
nuestro modelo. El rotor Tesla consiste en discos montados en posición paralela sobre un eje y
espaciados entre sí a una distancia equivalente a su espesor o ligeramente mayor. En la turbina de
Tesla, estos discos eran de acero endurecido; pero como usted hará funcionar el modelo con
presiones pequeñas solamente, puede utilizar aluminio, el cual es fácil de labrar.
Un chorro de aire (o vapor) aplicado contra el
borde de este conjunto de rotor describe una
trayectoria espiral por los espacios entre los
discos, a fin de encontrar las lumbreras de escape
en el centro. El arrastre del gas contra las
superficies de los discos hace que todo el rotor
Nuestro modelo de 35 onzas (922.25 g) de peso y
3 1/2" (8.89 cm) de altura se halla montado sobre
una plataforma de madera terciada de 3/4" (19.05El eje se labra en tres pasos. En la foto de arriba, la varilla
mm) que mide 5 x 8" (1.27 x 20.32 cm). Si va a de 3/8" ya se ha torneado en un extremo para luego
funcionar con aire, puede construir la turbina deinvertirse por completo con objeto de tornear el otro
casi cualquier metal, utilizando una lata vacía paraextremo; el extremo derecho del centro de espesor mayor
la caja (C) y acero laminado en frío para el eje (S).se rosca después. Foto abajo, se cortan círculos en una
Pero si proyecta utilizar vapor, la caja debe ser decortadora de los discos de aluminio del rotor
aluminio y el eje de acero inoxidable. Todo el
labrado para un modelo de este tamaño se puede
realizar con una herramienta para trabajos de
metal, tal como la Unimat que se muestra en las
La caja cilíndrica para nuestro modelo se cortó de
un viejo extinguidor de fuego hecho de latón. Si el
cilindro que escoge usted tiene un tamaño
excesivo y tiene que quitarle un segmento -o si
tiene usted que construir un cilindro de lámina
plana-una los extremos con una tira de metal
remachada a través de la junta y sellada con
soldadura. Si construye usted la caja de aluminio,
el armado se puede efectuar mediante soportes
remachados, en vez de soldadura. De todos
modos, conviene que una de las placas de
extremo pueda desmontarse, a fin de poder ajustar
el rotor más adelante.
Los extremos de la caja (izquierda) y los discos del rotor (derecha) se rectifican al diámetro exacto con una fresa
partidora. N átese que el diámetro exterior mayor de los extremo exige pivotar el cabezal para dejar el claro necesario.
Los bordes de los discos se redondean con una lima plana y luego se pulen con tela abrasiva de grano fino. A pesar de
que los extremos pueden montarse en el mandril, el agujero central de los discos es demasiado pequeño; por lo tanto, es
necesario hacer un árbol de soporte (centro) con el extremo roscado para dar cabida a un perno
Las lumbreras de escape (izquierda) se perforan can una broca de 1/4", luego se escarían a un diámetro de 3/8". Una
sencilla guía ubica todos los agujeros a la misma distancia del centro (el espaciamiento de 120 grados no es crítico). Las
ranuras para el chorro de aire se cortaron (centro) perforando una serie de agujeros con una broca de guía y luego
utilizando la broca como fresadora para eliminar el metal entre los agujeros. Nótese la abrazadera de ángulo de hierro
para asegurar la caja. A la derecha, puede verse cómo se labran tapas de cojinetes de varillas de latón
El conjunto de la tobera se monta en la
base con una abrazadera en forma de U.
Consiste en (foto abajo) un tubo sobre el
cual se desliza el tubo de caucho del
suministro de aire; una T para el tubo de
cobre que se suelda a un par de grifos; y
las toberas que se sueldan en otros
codos de tubo. Las ranuras para las
toberas en las cajas de aire y la del
motor se liman a ancho suficiente para
dar cabida a la unidad de éstas
La caja se suspende entre dos montantes (parte U) que también sostienen los cojinetes del rotor.
Los montantes deben hacerse de material bastante rígido, tal como latón de calibre 18 (0.0403"). Se
utilizan cuatro cortos tornillos de 2-56 para fijar cada montante a la placa de extremo. En nuestro
modelo, estas piezas se han pulido con una varilla de caucho abrasivo asegurada en un taladro de
banco. La canal entre el montante y la placa permite la salida del escape.
Se utilizaron cojinetes de bolas Fafnir No. 33K5 en el modelo que se muestra; estos cojinetes tienen
un diámetro exterior de 1/2" (1.27 cm), un ancho de 5/32" (3.97 mm) y una perforación de 3/16"
(4.76 mm). Si no hay disponibles cojinetes similares, tendrá usted que alterar las dimensiones
afectadas-o labrar cojinetes de buje de tipo sólido, empleando varilla de bronce de 3/4" (19.05 mm)
Sea cual sea el tipo de cojinetes que escoja usted, fíjelos a los montantes con un par de tornillos de
2-56 introducidos a través de un aro de retén y dentro de agujeros roscados en los montantes. Las
arandelas de presión en el interior evitan que los tornillos se aflojen a causa de las vibraciones. Note
en la vista seccional de la página 72 que los aros de retención se hallan rebajados para dar cabida a
las tapas de los cojinetes, pero que no se hallan ajustados apretadamente contra los montantes.
La ubicación de los cojinetes en relación con el eje del rotor se muestra en la foto inferior derecha
de la página 75. Después de montar los cojinetes en los montantes (centrados sobre los agujeros
de 5/16" (7.94 mm) , coloque el rotor en la caja, tal como se muestra, instale en su lugar la placa de
extremo que se ha quitado y suspenda el eje entre los cojinetes para ubicar los agujeros de montaje
en las placas de extremo. Si el eje no gira libremente cuando se termina el armado, cambie la
alineación de los cojinetes, aflojando o apretando los tornillos del aro de retención o insertando
cuñas entre los montantes y las placas de extremo.
Recuerde también que los discos y arandelas deben ser planos; una manera de aplanarlos consiste
en insertar cada uno de ellos entre placas de acero, antes del armado, y golpear la placa superior
con un martillo.
Las cajas de aire que se muestran arriba se hicieron de tubo de latón de 1/8" (3.17 mm) para
lámparas eléctricas. El extremo se amuescó, se martilló hacia adentro para formar una cúpula
cerrada y luego se selló con soldadura. Puede usted ahorrarse este paso si encuentra trozos de
tubo de 2" (5.08 cm) con un extremo cerrado. La lumbrera de descarga debe consistir en una ranura
con un largo de aproximadamente l 1/8" (2.86 cm) y un ancho de 1/32" (0,75 mm) -o puede ser una
serie de agujeros de 1/32" espaciados a corta distancia entre sí. A continuación, sobre cada
lumbrera de descarga suelde una tobera que se forma atornillando y soldando placas entre sí con
cuñas para formar una ranura, tal como se muestra en el esquema.
Las ranuras en la caja (C) que dan cabida a estas
toberas se deben cortar después de terminar el armado
de las toberas. Se hallan ubicadas en las posiciones de
las 10 y las 2 horas (imagine Que las placas de extremo
son esferas de reloj). La dirección de la rotación
depende de la tobera que se halla conectada, por lo que
se sueldan grifos en las líneas de suministro. Para
simplificar la unidad, puede usted construir una sola
tobera para un funcionamiento en una sola dirección.
Esta se puede soldar directamente a la ranura de la
Este modelo no es para funcionar a altas velocidades
Es fácil doblar los montantes si se tienen bloques
de acero de tamaño adecuado. Antes de doblarlos, con aire o vapor a alta presión. Al someterse a tales
tensiones se producirían problemas con la resistencia de
se perforan agujeros para fijarlos a la base ya la
los discos del rotor y de otras piezas. Pero el modelo
caja y para montar los cojinetes
que se muestra ha funcionado eficientemente durante
meses enteros al conectarse directamente a un
compresor de aire de 1/4 caballo de fuerza; a una
presión comparable, funcionará de manera similar con
El rotor se centra en la caja con cuñas de cartón y
luego se colocan los montantes, con los cojinetes
ya montados, contra las piezas de extremo y se les
marcan los agujeros de montaje
LISTA DE MATERIALES
Extremos de caja
Aro de soldadura;
abrazadera de fleje de "te"
Latón de calibre 18, de 2 7/8" x 3"
Cilindro de 2 3/4" D.I. x 1 3/4"; o latón de calibre 18 de 1 3/4" x
8 3/4" para formar cilindro
Latón de calibre 18, de 3" x 3"
Latón de calibre 18, de 1/4" X 12" para los dos
Discos de rotor
Arandelas de rotor
Tapas de cojinetes
Aro de retención de
Cojinetes de bolas
Varilla de acero laminado en frío de 3/8" x 4" (o una aleacion de
Discos de aluminio de calibre 18, diámetro de 2 1/2"
Discos de aluminio de calibre 18, D.E. de 1/2"
Hexagonal, de latón 1/4"-28
Varilla de latón de 3/4" con longitud de 1" para los dos
Discos de latón de calibre 18 (o más grueso) con D.E. de 1 1/8"
Fafnir 33K5 o equivalente
Pasadores pequeños de latón para placas o equivalentes
Tornillos de máq. de latón, con cabeza red. de 2-56 x 1/4";
cuatro tuercas correspondientes No. 3 x 1/2 para tornillos de
madera de cabeza redonda
Tubo de cobre con D.E. de 1/4", escariado con broca espiral
Cajas de aire
Placas de toberas de aire
Mangas para unir grifos y
olea pequeña de latón o
Tubo de latón 1/8", longitud de 4 1/4"
Pieza de latón de calibre 18 de aproximadamente 1 1/2" X 1
Material de bronce para cuñas de 0.003" x 1/4" x 1"
Cobre de 1/4"
Para dar cabida a tubo anterior; o haga una "T" o "Y" soldando
piezas de tubo entre sí
Pequeños, de latón, tal como se muestra en las fotos
Tubo de cobre de aproximadamente 3/4" con D.I. de 1/4"
Madera natural o madera terciada de 3/4" x 5" x 8"
Bloques de madera de 1/2" x 1/2" x 2 1/2"
Perforación de 3/16"
* Tamaño total de lámina de latón para piezas C, E, U, etc.: 5 1/2" x 12"
**Tamaño total de lámina de aluminio para discos, arandelas: 11 1/2" x 14"
Fuente: Revista Mecánica Popular - Volumen 37 - Diciembre 1965 - Número 6
Notas similares a esta o continuación:
HAGA UNA FANTáSTICA BOBINA TESLA
Comenta esta nota en el foro.: Click Aquí :.
¿Que más te gustaria leer en notas historicas?.: Click Aquí :.
Comenta esta y otras notas en el foro.: Click Aquí :.
Mini Nota Histórica
Es posible que estén tocando a su fin los días del
cantinero. Cierta firma de Alemania ha desarrollado un
bar electrónico que suministra bebidas con sólo oprimir
El cliente escoge una de las bebidas en la lista, oprime
el botón correspondiente, y la bebida cae, totalmente
mezclada, dentro de un vaso colocado de antemano
bajo el tubo de entrega.
No es necesario limitarse a la lista impresa, ya que
puede usted oprimir cualquier combinación de botones
para inventar su propia bebida.
Además, como medida de seguridad, la máquina se
niega a funcionar a no ser que la persona que oprima el
botón tenga el pulso firme. Esto elimina a aquellos que
ya han oprimido un exceso de botones.
Fuente: Revista Mecánica Popular - Volumen 34 - Marzo de 1964 - Número 34
Más Mini-Notas Historicas aquí
Mecánica Popular-Copyright (c) 2006 Hearst Communications, Inc. All Rights Reserved.
Idea original de Mi Mecánica Popular por: Ricardo Cabrera Oettinghaus
TESLA: UN TALENTO SCOMODO
di Mauro Paoletti
Secondo le sacre scritture, all’inizio, il mondo era immerso nelle tenebre quando Dio disse: "Sia la luce.
E la luce fu!" Il fiore di loto si era schiuso e la luce aveva inondato l’intero universo; la divinità si era
Oggi tutti noi ripetiamo quel gesto quando entriamo in una stanza immersa nel buio e premiamo
l’interruttore che permette alla corrente elettrica di correre lungo il filo fino alla lampadina che,
accendendosi, illumina l’ambiente. Abbiamo il difetto di dare molte cose per scontate a causa del loro
uso quotidiano, come fosse sempre stato così, ma avere la luce, dopo che il sole cala dietro l’orizzonte e
le tenebre nascondono il mondo nel buio assoluto, è sempre stato un antico problema dell’uomo.
La pallida luce lunare non era soddisfacente e il fuoco di difficile trasporto e di breve durata; doveva
essere mantenuto acceso e un solo falò, o una sola fiaccola, non fornivano luce a sufficienza. Venne
adottato l’uso di una ciotola piena d’olio o di grasso, dove uno stoppino immerso nel liquido forniva, una
volta acceso, una luce più efficace, trasportabile e duratura.
Col tempo si giunse alla candela di sego o di cera, più comoda e di basso costo; in uso fin dal 3000 a.C..
La svolta importante nel 1892 quando William Murdock scoprì che, bruciando il carbone, veniva
prodotto un gas. Il gas sottoposto a calore generava la luce.
I lampioni a gas rischiararono così alcune città; venivano accesi la sera e spenti all’alba. Il gas però era
molto pericoloso per le frequenti le fughe dovute all’usura e rottura delle tubazioni che servivano per il
suo trasporto. Non tutte le abitazioni erano dotate delle tubazioni per l’erogazione del gas e per molti anni
furono usate ancora le lampade a petrolio.
Nel 1875 molti fabbricati erano illuminati con gas combustibile. Nelle lampade venivano messe delle
reticelle, ideate da Welsbach, che intensificavano la luce.
Alva Edison ricercando un sistema migliore e più sicuro avvalendosi dell’invenzione di Swan, consistente
in ampolle prive dell’aria dove si accendeva una striscia di carta quando veniva attraversata dalla
corrente elettrica, ideò altri tipi di ampolle; usando diversi tipi di gas e altri materiali filiformi al posto
della striscia di carta ottenne lampade più efficaci.
Quando Edison aprì la prima centrale elettrica a corrente continua il buio venne eliminato col semplice
scatto di un interruttore. Il nuovo sistema d’illuminazione aveva molti limiti ma da quel momento l’uomo
poté dire: "sia fatta luce" ed ottenerla.
Ma la lampadina da sola non basta, è necessario che vi sia la corrente elettrica, l’elettricità.
Come e da dove proviene l’elettricità?
Distrattamente e profondamente inseriti nel sistema non lo chiediamo, fa parte delle cose acquisite; è più
facile chiedersi perché d’un tratto viene a mancare perché non può, non deve... Come facciamo senza la
luce; senza elettricità? Tutto si ferma. Non si può lavorare, il computer si spegne; restiamo senza
televisione; diventa difficoltoso anche preparare da mangiare; diveniamo prigionieri degli ascensori; le
comunicazioni si complicano; nelle strade cittadine il caos; un vero incubo.
Per dare forma ad una parte dell’incubo pensiamo al frigorifero, recente invenzione che funziona grazie
all’elettricità. Che fine farebbe la nostra spesa? Fino a pochi decenni fa per la conservazione dei cibi si
faceva uso del sale, delle spezie e del ghiaccio.
Siamo elettro dipendenti, condizionati dall’elettricità, peraltro già conosciuta in un remoto passato.
In Egitto, nel tempio di Hator a Dendera, lo testimoniano le Pietre delle Serpi, bassorilievi che mostrano
enormi bulbi trasparenti con all’interno sinuose serpi, collegati attraverso cavi a treccia al "Djed" che, nel
caso, assumerebbe la funzione di generatore. I bassorilievi ricordano le lampade a luminescenza e le
ampolle in atmosfera rarefatta, create dall’inglese William Crookes nel 1879; lampade che permisero a
Roentgen di scoprire i raggi X nel 1895. Fra i bassorilievi del tempio possiamo vedere rappresentato
anche il procedimento dell’elettrolisi.
Ricordiamo le pile di Bagdad scoperte da Konig.
Un antico documento indiano conosciuto come Agastya Samhita fornisce una serie di istruzioni per
costruire una batteria elettrica.
Cronache antiche di commercianti parlano di un villaggio presso il monte Wilhelmina, in Nuova Guinea,
illuminato da globi di pietra posti su altissimi pali che al tramonto iniziavano a brillare di una strana luce
bianca, simile a quella dei nostri neon, illuminando la notte. Fatto curioso perché sono abbastanza recenti
esperimenti per ottenere una luminescenza da pannelli e oggetti percorsi da correnti deboli senza l’uso di
filamenti e bulbi.
Dopo che Talete di Mileto e Plinio il Vecchio studiarono per primi le proprietà elettriche dell’ambra,
l’uomo si dimenticò come tale energia si poteva ricavare e piombò nel buio per secoli.
Fu William Gilbert, medico della regina Elisabetta, a riscoprire l’elettricità strofinando proprio l’ambra
sulla lana e sulla pelliccia, accorgendosi di poter attirare piccoli oggetti leggeri, come la carta. Chiamò la
strana forza "elettrica" dal nome greco dell’ambra Elektron. Si trattava dell’elettricità statica (1).
Gli elettroni si trasferiscono da un materiale isolante all’altro, quindi i vuoti lasciati dagli elettroni
dell’ambra vengono rimpiazzati dagli elettroni contenuti nella carta. Lo spostamento si chiama carica, ma
se questa avviene in un conduttore la carica in movimento genera una corrente che fluisce nel conduttore
e cessa di essere statica.
Gilbert studiò l’elettricità e il magnetismo, comprese perché l’ago della bussola punta sempre verso il
nord. (2) Scoprì che pezzi di ambra carenti di elettroni si respingevano mentre si attiravano se gli elettroni
erano in eccesso. Benjamin Franklin denominò i due tipi di elettricità positiva, se carente di elettroni, e
negativa, con elettroni in eccesso, enunciando che due cariche uguali si respingono mentre, se diverse, si
Nel 1746 due studiosi dell’Università di Leida inventarono un apparecchio per raccogliere l’elettricità
statica, un condensatore chiamato "bottiglia di Leida".
Venne dedotto che maggiore era la quantità di elettricità accumulata, più lunga la scintilla prodotta dagli
elettroni; l’argomento era la tensione della carica.
Nel 1785 August De Coulomb inventò la bilancia di torsione per misurare il campo elettrico dimostrando
che la carica si distribuisce in modo uniforme sopra una superficie sferica.
Cosa confermata anche da Beccaria con il suo pozzo e da Faraday con la sua gabbia.
Hans Christian Oersted sviluppò la teoria elettromagnetica e nel 1826 Ampère enunciò le leggi
dell’elettromagnetismo inventando lo strumento per misurare il flusso della carica elettrica; George Ohm
declamò la legge sulla resistenza elettrica; Volta diede forma alla prima pila; Faraday al primo generatore
elettrico, la dinamo e l’alternatore; nel 1859 Pacinotti col suo anello trasformò l’energia meccanica in
energia elettrica continua; nel 1866 Heinrich Hertz scoprì le onde elettromagnetiche; nel 1880 Alva
Edison costruì la prima centrale brevettando un sistema di distribuzione. Un anno dopo Edison e Graham
Bell crearono la "Oriental Telephone Co.". Nel 1882 Edison attivò il primo sistema di distribuzione
dell'energia al mondo.
A questo punto compare un personaggio definito "dimenticato benefattore dell’umanità" e che morì
nell’anonimato in assoluta povertà: Nikola Tesla.
Colui che ha inventato la famosa Bobina che porta il suo nome per produrre l’alta tensione necessaria al
tubo catodico del televisore, fornita da un generatore Tesla, attraverso il trasformatore Tesla e trasportata
da un sistema trifase Tesla.
Nikola nacque il 10 luglio 1856 a Smiljan in Croazia, secondo maschio dei cinque figli del reverendo
ortodosso Milutin. Studiò al "Real Gymnasium" di Carlstadt, ingegneria al Politecnico di Graz e
all’Università di Praga. Dopo aver lavorato nella società telefonica di Budapest trovò lavoro a Parigi nella
"Continental Edison" filiale della "Edison Electric Light". La Continental non attraversava un felice
periodo in seguito ad un incidente avvenuto durante l’inaugurazione del nuovo sistema di illuminazione a
Strasburgo, che aveva messo in pericolo la vita dell’imperatore tedesco Guglielmo I.
Edison produceva solo dispositivi a corrente continua, dinamo, motori e sistemi di illuminazione. Gli
investimenti erano cospicui. Tesla, convinto di vedere realizzati i suoi progetti sulla corrente alternata,
parlava con chiunque fosse disposto ad ascoltarlo e, durante una partita a biliardo, il caporeparto, tale
Cunningham, gli propose di creare una società con lui.
Tesla non capiva niente di mercato e commercio e quindi rifiutò; se invece avesse accettato quell’offerta
la sua vita e la nostra sarebbero radicalmente cambiate.
In seguito agli incresciosi fatti di Strasburgo, quale migliore ingegnere della Continental, fu inviato in
quella città allo scopo di realizzare un regolatore automatico delle dinamo, con la promessa di un premio
di 25.000 dollari. Inutile dire che riuscì nell’impresa ma non ottenne il premio promesso.
In quel periodo, nel tempo libero, costruì il primo motore a corrente alternata oltre ad un generatore a due
tempi per alimentarlo.
Alva Edison aveva inviato a Parigi un amico consulente di cui si fidava, Charles Batchellor, il quale
ascoltando le idee di Tesla considerò che era meglio averlo dalla propria parte. Scrisse a Edison una frase
rimasta celebre: "Conosco due grandi uomini, tu sei uno di loro; l’altro è questo giovane…".
Secondo Batchellor, Tesla, avrebbe evitato il costo di numerosi esperimenti, dato che il giovane inventore
prevedeva tutte le conseguenze prima di sperimentare i congegni ideati. Convinse Nikola che a New
York avrebbe coronato i suoi sogni e lo spinse a partire.
Edison stava per ricevere l’aiuto desiderato per le sue dinamo a vapore che non erano sufficienti ad
accendere tutte le lampade dei clienti; non oltre 400. Avrebbe dovuto accoppiarle fra loro, ma non
conosceva la sincronizzazione degli impulsi elettrici. L’arrivo di Tesla fu più che opportuno. Appena
sbarcato aggiustò le bobine dell’Oregon, prima nave con l’illuminazione elettrica, che in seguito ad un
guasto avevano lasciato l’imbarcazione al buio e si presentò a Edison pronto a perfezionare i progetti dei
generatori della sua centrale elettrica. Alva gli promise un compenso di 50.000 dollari a lavoro compiuto.
In un anno sfornò ben ventiquattro tipi diversi di dinamo a corrente continua, capaci di generare
maggiore corrente, semplici da regolare ed accoppiare; il tutto assistito da un sistema che assicurava la
sincronia negli impulsi di corrente.
Edison brevettò le bobine e le sostituì; ma non premiò Tesla. Quando questi si presentò a reclamare il suo
compenso l’americano gli disse: "Tesla, ma lei non capisce l’humor americano..."
Il croato si licenziò.
Fortunatamente per lui, Edison non aveva il controllo dell’industria americana dell’elettricità e trovò altri
finanziatori; ma solo per produrre lampade ad arco destinate all’illuminazione pubblica. Anche in questo
caso fu raggirato e il suo sogno dovette attendere.
Per vendere motori a corrente alternata, occorreva erogare energia alternata a mezzo di idonei cavi,
scatole di raccordo, trasformatori, contatori per le abitazioni. I suoi soci non disponevano di ingenti
capitali per portare avanti un tale progetto ed erano interessati solo alla produzione di lampade ad arco
Tesla compì una nuova impresa, le lampade prodotte all’epoca da Paul Joblochkoff erano composte da
due aste parallele di carbone, separate da gesso e inserite in tubi di ottone collegati alla corrente; all’apice
un filo di carbone che bruciando produceva luce. Duravano solo novanta minuti. Tesla dopo due anni
fornì lampade ad avviamento automatico dotate di un meccanismo di alimentazione che permetteva di
sostituire le aste di carbone quando si consumavano. Il sistema venne adottato per l’illuminazione
pubblica e per le fabbriche.
L’impianto di Edison non avrebbe mai funzionato ai voltaggi di oggi; Tesla aveva scoperto che si poteva
trasformare il voltaggio dell’elettricità a corrente alternata, aumentandolo o diminuendolo a mezzo di un
trasformatore. Avrebbe trasmesso corrente ad alto voltaggio e bassa corrente attraverso cavi sottili.
L’impianto del croato avrebbe messo in pericolo coloro che avevano investito nel sistema a corrente
Quando Edison fondò la "Edison Electric Light" ottenne 2500 azioni; ai capitalisti che finanziarono
l’impresa ne vennero assegnate altre 500: la "Western Union Telegraph", il banchiere J.P. Morgan ne
facevano parte. Ma la società non stava tenendo fede alle promesse di vendita ed Edison non voleva che
la cosa si risapesse. Doveva costruire altre centrali, per ridurre i costi ma i finanziatori non volevano
rischiare altro denaro. Inoltre aveva una causa in corso contro Westinghouse che produceva lampade con
brevetto Edison senza pagare le royalty. L’Oregon aveva fatto richiesta di risarcimento in seguito al
guasto delle bobine, la moglie era gravemente malata. Quando Tesla giunse a New York, Edison aveva il
problema di inviare la corrente oltre gli ottocento metri della sua centrale, i suoi proventi erano
rappresentati solo dalla vendita di impianti d’illuminazione completi a privati o imprese, questo perché
non essendo esperto nel campo dell’elettricità non metteva in pratica la legge di Ohm.
Un filo tende a surriscaldarsi e fondersi se il carico è elevato e, per la nota legge di Ohm, maggiore è la
corrente che passa attraverso il filo, maggiore sarà la caduta di tensione. Quindi si può avere un alto
voltaggio e poca corrente, oppure alta corrente e un basso voltaggio; ossia la capacità dell’elettricità di
correre lungo il filo e portare un numero sufficiente di elettroni che arrivino alla lampadina. Maggiore la
lunghezza del filo, maggiore deve essere il voltaggio, diminuendolo poi quando la corrente entra
nell’abitazione, affinché non rappresenti un pericolo mortale.
Tesla aveva tenuto conto di tutto questo e scoperto che la corrente ad alta frequenza non viaggia
all’interno di un filo, ma al suo esterno. È il famoso effetto pelle o di Kelvin, per questo vengono
utilizzati fili di acciaio rivestiti di rame. L’acciaio rende il filo resistente mentre il rame fornisce una
bassa resistenza dove scorre la corrente. I fulmini che colpiscono un aereo non mettono in pericolo i
passeggeri al suo interno dato che la scarica corre sulla superficie della fusoliera. Per questo Tesla usava
dare spettacolo facendosi passare dalla corrente a 250.000 volt.
Nel frattempo Tesla era stato abbandonato dai suoi finanziatori e costretto a guadagnarsi da vivere
scavando fossi. Nel 1886 presentò un brevetto per un motore elettromagnetico e, parlando
dell’invenzione con il suo caposquadra, ebbe l’occasione di avvicinare l’avvocato Charles Peck, il quale,
coinvolgendo l’amico Alfred Brown sovrintendente della "Western Union Telegraph" a dividere i rischi,
si offrì di fornire un finanziamento. Nacque la "Tesla Electric Company".
Tesla iniziò a lavorare al suo motore a corrente alternata. Poteva produrre un campo magnetico rotante
iniettando due correnti alternate in una coppia di bobine poste ai lati opposti dello statore. Si poteva
modificare il voltaggio e usare fili sottili per portare l’elettricità a lunghe distanze; un trasformatore
riduceva e aumentava la corrente.
Fece domanda all’ufficio brevetti e gli furono concessi ben 30 brevetti diversi. La comunità scientifica lo
invitò a tenere una conferenza. Divenne il padre della moderna elettricità. Peck e Brown decisero di
vendere il brevetto a chi avesse offerto di più.
La conferenza tenuta all’"American Institute of Electrical Enginers" suscitò l’interesse di George
Westinghouse, ingegnere elettronico, il cui padre possedeva una fabbrica che produceva materiale
rotabile per lo stato di New York. George aveva inventato lo scambio di rotaia e il freno ad aria
compressa; secondo Brown era la persona giusta per commercializzare il prodotto di Tesla. Era inoltre la
persona che voleva scalzare il sistema di Edison. Westinghouse offrì a Tesla 25.000 dollari più 50.000 in
azioni e royalty di 2,50 a CV.
Era in corso la "guerra delle correnti". Westinghouse senza pagare le royalty produceva lampade Edison e
questo spinse Edison a intraprendere una campagna denigratoria delle tecnologie utilizzate dal
concorrente. Fece stampare opuscoli dove sottolineò il pericolo derivante dall’uso dell’alto voltaggio
usato nei sistemi ad arco e dimostrò, servendosi di alcuni animali come cavie, quanto poteva essere
pericolosa la corrente alternata. La campagna denigratoria produsse l’interessamento dell’Assemblea
Legislativa che promulgò l’uso della sedia elettrica al posto dell’impiccagione, utilizzando alternatori
La cosa forse influenzò anche la sentenza del tribunale; causa e ricorso furono vinti da Edison nonostante
che Westinghouse dimostrasse che Alva non fosse esperto di elettricità. Ma Edison era in piena crisi, non
sapeva come pagare gli stipendi ai suoi duemila dipendenti e come comprare la materia prima per far
fronte agli ordini che giungevano numerosi, perché incassava solo dopo la consegna. La "Edison Electric"
era stata creata per riscuotere le royalty e i banchieri che la gestivano proposero allo scienziato di
comprare le sue fabbriche e formare una nuova società che si chiamò "Edison General Electric
Il processo aveva messo in crisi anche Westinghouse. Charles Coffin che dirigeva la "Thomson Houston"
concluse un accordo con la "Edison General Electric" divenendo presidente di una nuova società che,
eliminando il nome Edison, si chiamò "General Electric". La fusione fra la "US Electric Company" e la
"Consolidate Electric Light" diede vita alla "Westinghouse Electric Manufacturing Company" e i brevetti
di Tesla furono svenduti ai banchieri.
Tesla parlava di una distribuzione senza fili. Al di là del risparmio del rame, chiunque poteva avere
l’energia elettrica gratuitamente attraverso la collocazione di una semplice antenna; come potevano le
compagnie ricavare profitti? L’energia elettrica veniva fornita a mezzo di un filo, se l’utente non pagava,
i fili venivano recisi e il banchiere tutelato. Come si poteva disconnettere gli utenti morosi se i fili non
esistevano? Le idee del croato andavano contro gli interessi dei banchieri come Morgan. L’elettricità
doveva rimanere in mano alle compagnie, non poteva essere distribuita gratuitamente.
In quel periodo l’inventore effettuò un giro in Europa; prima Londra, poi Parigi, infine al capezzale della
Ritornò in America giusto in tempo per aiutare Westinghouse che finalmente era riuscito a produrre una
lampada senza violare i brevetti della "General Electric". Il primo gennaio del 1893 ben 96.620 lampade
a incandescenza, alimentate dai generatori Tesla, illuminarono i locali della Esposizione Universale di
Chicago dedicata a Colombo. Westinghouse inoltre aveva stipulato un accordo con la "General Electric",
che aveva adottato la nuova tecnologia, cedendo i diritti sui brevetti di Tesla allo scopo di presentare un
offerta congiunta e realizzare una centrale elettrica alle cascate del Niagara. La realizzazione del progetto
venne affidata ad un ingegnere scozzese tale George Forbes; la centrale avrebbe utilizzato tre generatori
Tesla da 5.000 cavalli vapore. Forbes costruì un canale a monte per portare l’acqua alla centrale e alle
turbine attraverso un tubo di due metri di diametro; l’acqua dopo aver percorso un tunnel riaffluiva nel
fiume proprio sotto le cascate. L’apertura avvenne nel 1895; era nata la "Niagara Falls Power and
Conduit Company", definita la più importante opera di ingegneria mai realizzata e Nikola Tesla divenne
il più eminente scienziato e ricavò 500.000 dollari oltre alla libertà di continuare i suoi esperimenti.
In quel periodo cominciò a studiare la velocità di inversione, ossia la frequenza. Costruì trasmettitori
capaci di amplificare i segnali elettrici per giungere a frequenze e voltaggi mai raggiunti, le famose
bobine di Tesla, che generavano scintille lunghe fino a 40 metri. Scoprì che ogni oggetto possiede una
naturale frequenza e, se sollecitato su tale frequenza, iniziava a vibrare fino a raggiungere il punto di
rottura. Nei suoi esperimenti utilizzando correnti di diverse frequenze riuscì a produrre voltaggi altissimi.
Costruì un vibratore senza parti mobili e lo collegò ad un condensatore; insieme risuonavano un milione
di volte al secondo. Ideò un sintonizzatore che divenne la base di tutte le radio e televisori; inventò una
lampadina senza fili, togliendo l’aria da un tubo di vetro, che si illuminava quando veniva messo a
contatto con un campo elettrico ad alta frequenza. In quel periodo costruì le prime lampade a
fluorescenza, i neon; inoltre un tubo che emetteva raggi "X", il circuito di sintonia, il tubo catodico, il
microscopio elettronico, e la famosa "bobina" per generare altissimi voltaggi.
Ideò luci fluorescenti senza fili con le quali illuminò il laboratorio. Aveva installato un filo elettrico
intorno alle pareti esterne dove faceva passare corrente elettrica ad alta frequenza, attraverso un
alternatore speciale; tale circuito radio diffondeva la corrente che veniva raccolta in cuscinetti di filo
collegati ai terminali posti ad ogni lampada fluorescente che funzionavano in tal modo con corrente senza
La bobina altro non è che un trasformatore di risonanza che permette la produzione di corrente alternata
usando sistemi polifase che si basano sull’induzione magnetica con il passaggio di corrente in più fasi.
Due bobine concentriche di filo di rame avvolto con centinaia di spire, un condensatore e uno
spinterometro producono un campo magnetico rotante. Meccanismo alla base degli alti voltaggi dei tubi
catodici delle TV.
Rendendosi conto che una valvola rilevava onde radio descrisse le caratteristiche basilari dell’impianto
radio prima di Marconi: un’antenna, un collegamento a terra, un circuito per la sintonizzazione, un
impianto di ricezione, uno di trasmissione, sintonizzati uno sulla risonanza dell’altro, un detector dei
segnali. Tutto perché aveva scoperto che il passaggio della corrente ad alta frequenza attraverso una
bobina e un condensatore generava un effetto di risonanza a distanza senza bisogno di fili.
Nel 1897 presentò al Madison Square Garden il primo sommergibile radiocomandato. In una gigantesca
vasca girava una barca lunga un metro e mezzo dotata di luci colorate e una antenna; Tesla ne dirigeva a
voce i movimenti e l’immersione. La marina militare non comprese l’importanza di quella invenzione;
sarebbe stata la prima torpediniera silurante senza equipaggio.
A lui si attribuisce anche l’invenzione del telegrafo pluricanale senza fili; altra invenzione non compresa.
Due anni dopo, di nuovo a corto di fondi, trovò un finanziatore in Curtis, l’avvocato che si era occupato
del suo primo brevetto. Leonard Curtis si era ritirato a Colorado Springs divenendo direttore della
"Colorado Springs Power Company". Il sistema Tesla aveva salvato l’industria mineraria locale e Curtis
offrì al croato un lotto di terreno dove costruire un laboratorio. Nel giugno del 1899, nel nuovo
laboratorio costruito a Colorado Springs, Tesla iniziò a studiare i fulmini, i loro effetti e come sfruttare le
loro cariche elettriche.
Oggi Colorado Springs è noto per la vicinanza del NORAD il sistema di difesa missilistico situato sotto i
Il fulmine produceva un tipo di onda radio capace di produrre voltaggi regolari, misurabili allontanandosi
dalla fonte; tale effetto dimostrava che la Terra e l’atmosfera erano cariche elettricamente. La sonda
sovietica Mir accertò, nel 1997, che i temporali appaiono sempre su delle linee a distanze regolari nella
parte scura della Terra dimostrando la possibilità della trasmissione dell’energia elettrica senza l’uso dei
Tesla aveva scoperto che poteva far risuonare elettricamente la Terra come una campana, con un rintocco
ogni due ore. Secondo lo scienziato la frequenza della risonanza elettrica terrestre era di dieci cicli al
secondo; il valore usato oggi è di 7,8 cicli. Lo scopo era studiare le onde radio a bassissima frequenza
capaci di raggiungere qualsiasi luogo, sia sulla superficie, sia sotto il mare.
La struttura del laboratorio di Colorado era alta circa 60 metri; dodici metri misurava la parte inferiore,
simile ad un granaio; al centro del capannone un traliccio e su di esso un’asta di rame che sosteneva una
sfera, anch’essa di rame. L’asta scendeva sopra ad un’enorme bobina situata al centro, sotto il tetto
aperto; il pavimento era di legno circondato da un recinto, sempre di legno, alto due metri e lungo il
perimetro scorreva un grosso cavo elettrico. La recinzione era percorsa da avvolgimenti di filo elettrico.
All’interno della gabbia vari oggetti diversi fra loro, all’esterno del recinto file di condensatori. Il
trasmettitore riceveva impulsi di corrente alternata a basso voltaggio dalla vicina centrale e generava
10.000 watt. Nel corso degli esperimenti si rese conto che diverse velocità di vibrazione producevano
onde stazionarie di diverso tipo, quella che in gergo si chiama "lunghezza d’onda del segnale", e che,
cambiando la lunghezza dell’asta e regolando la sintonizzazione della lunghezza d’onda, poteva ricavare
il massimo voltaggio nella sfera di rame.
Il cellulare che usiamo tutti i giorni è dotato proprio del tipo di antenna di sintonizzazione inventata da
Quando Tesla produsse con il suo apparato il primo fulmine ottenne un lampo di 60 metri e un violento
tuono che venne udito a 42 chilometri di distanza. Le 200 lampade degli apparecchi riceventi che
s’illuminarono furono la prova che l’impianto senza fili funzionava. Il 20 marzo 1900 depositò il brevetto
e nel 1902 tutti gli altri brevetti relativi.
Tesla dimostrò quindi che l’energia elettrica può essere diffusa utilizzando la superficie terrestre,
sfruttando la zona atmosferica dove risiede la risonanza di Schumann e, chiunque, sintonizzandosi con
opportuni apparecchi, può ottenere corrente gratuitamente.
La Terra è in grado di assorbire elettricità e per questo tutti gli strumenti elettrici scaricano a terra. La
corrente che lo scienziato iniettò nel suolo si propagò come un’onda radio alla velocità della luce,
raggiunse l’altra parte e ritornò indietro; il secondo impulso si unì al primo rafforzandolo, e così fece il
terzo, e il quarto, aumentando la potenza smisuratamente. L’obbiettivo di Tesla era scoprire il limite della
risonanza, ma il sovraccarico bruciò il generatore della centrale che gli forniva la corrente e mise al buio
l’intera città di Colorado.
Aveva realizzato il suo sogno e trovato il sistema di produrre plasma elettromagnetico prima ancora che
si coniasse il termine. La miscela di ioni e elettroni scoperta, oggi viene chiamata "Gas ionizzato" ed è in
grado di sprigionare luce e calore. È il funzionamento del Sole.
I brevetti di Tesla sono stati menzionati nella costruzione di armi dotate di proiettili al plasma capaci di
neutralizzare satelliti spia, che fanno parte del progetto "Scudo stellare". Tesla era anche in grado di
produrre la risonanza del campo elettrico terrestre e dominare di conseguenza il tempo meteorologico.
Per capire l’importanza di quanto scoperto dal Nikola pensiamo alla fusione termonucleare, attraverso la
quale otteniamo energia pulita ed economica in seguito alla trasformazione dell’idrogeno in elio; tale
fusione avviene a temperature talmente elevate che non esiste un materiale resistente alla fusione.
L’unica cosa che permette ai materiali di resistere è l’utilizzo di una bolla di plasma come quella che ideò
Tesla per generare il fulmine globulare; scoperta che si è dimostrata importante per lo studio della
Lanciando simili raggi è stato possibile stilare mappe di Venere e della Luna.
In effetti il nostro pianeta è circondato da una particolare carica elettrica, che inizia a 80 km. dalla Terra,
nota come ionosfera. Fra questa e il suolo esiste una zona con un potenziale costante di 220 volt per
metro dentro il quale noi viviamo. Quindi il nostro corpo ha una data quantità di elettricità misurabile,
ma è anche circondato e penetrato da molti campi elettrici, magnetici e gravitazionali generati dalla Terra
e dagli altri pianeti; campi elettromagnetici dovuti agli ultravioletti, campi generati da emittenti radio,
apparecchi televisivi, videoregistratori, telefoni e così via.
Oggi sappiamo che il Sole con la sua energia e la sua attività determina il clima sulla Terra, ne influenza
l'ecosistema e di conseguenza l'esistenza degli esseri viventi su di essa. Sappiamo che l'attività solare si
manifesta nelle macchie solari prodotte dalla differente velocità di rotazione di due campi magnetici:
quello polare e quello equatoriale. Queste eruzioni sprigionano intensi campi magnetici che riducono il
flusso di energia e producono perturbazioni fisiche sulla Terra.
Infatti, attraverso il "vento solare", gli elettroni e l'idrogeno ionizzato si propagano ovunque, interferendo
con il campo magnetico terrestre, contribuendo all'esistenza delle due fasce di Van Allen, ove si
accumulano le particelle elettriche che modificano gli effetti climatici.
Esiste una zona nell’atmosfera carica di elettricità fra la superficie e la ionosfera, conosciuta come
"cavità Shumann"; in pratica un grande condensatore che Tesla riuscì a far vibrare con l’energia elettrica.
Nessuno avrebbe potuto esaurire l’energia trasmessa in quel momento.
Nel 1900 Westinghouse e la "General Electric" avevano il monopolio assoluto dell’erogazione di corrente
alternata e si erano notevolmente arricchite con il suo commercio. Quando Tesla comunicò a
Westinghouse l’esito delle ricerche effettuate a Colorado Spring e i suoi progetti per il futuro, l’uomo
d’affari vide nello scienziato un pericolo per i suoi affari e gli negò ogni ulteriore finanziamento
nell’intento di fermarlo; anzi intraprese una serie di azioni che miravano a denigrarlo davanti all’opinione
pubblica in modo che le sue ricerche non fossero finanziate da altri.
In quel tempo Tesla parlò della possibilità di trasmettere calore al Polo Nord, di formare il ghiaccio ai
tropici; inviare fotografie e trasmettere musica in ogni angolo della Terra; distribuire elettricità gratuita e
Le sue invenzioni lo rendevano un uomo credibile e pericoloso.
La bobina per produrre correnti ad alto voltaggio e alta frequenza, il trasmettitore d’amplificazione, per
generare la risonanza dei campi prodotti con i fulmini con la carica della Terra, il sistema elettrico senza
fili, per trasmettere l’energia elettrica, un sistema per sintonizzare su una determinata lunghezza d’onda
un ricevitore, erano le invenzioni che permettevano la trasmissione della corrente senza fili.
Tesla aveva scoperto che la Terra rispondeva a vibrazioni elettriche di una determinata velocità e se
venivano prodotte onde stazionarie intorno al globo, utilizzando il campo elettrico terrestre, era possibile
trasmettere elettricità senza dispersione di energia.
Si potevano già realizzare in quegli anni alcune delle cose in uso oggi come la trasmissione di messaggi
segreti di stato; la possibilità di scambiare messaggi fra i cittadini in modo rapido e sicuro; telefonare in
ogni luogo e a chiunque, trasmettere le notizie dei quotidiani di tutto il mondo, oltre alla musica,
manoscritti, foto, disegni e documenti; sincronizzare gli orologi con precisione astronomica; creare un
sistema monitorato di navigazione per determinare le rotte delle navi.
L’unica cosa che ancora oggi non possiamo fare, anche se è stato dimostrato nell’ultimo decennio che sia
possibile, è trasmettere energia elettrica in qualunque luogo senza l’uso di fili, ma sappiamo molto bene
il perché. Cosa che Tesla non aveva compreso appieno. Se avesse lavorato come fece Marconi con i
militari e il governo, anziché procedere da solo, oggi sicuramente avremmo un mondo notevolmente
Nikola però non conosceva i meccanismi del mercato, per questo rifiutò anche l’offerta di acquisto dei
Lloyds di Londra per un impianto senza fili da installare su un panfilo. Da quel momento perse notorietà
e divenne per l’opinione pubblica uno scrittore di fantascienza, folle e fuori dal mondo; per questo non
viene ricordato neanche oggi per il grande uomo che è stato e per quello che ha fatto.
Gli unici che lo hanno considerato seriamente, per quello che in effetti era, sono stati Samuel Clemens,
conosciuto come Mark Twain, e J.P. Morgan. Il primo, in qualità di amico e appassionato al tema dei
suoi esperimenti divenne un assiduo frequentatore del laboratorio di Tesla al 35 di South Fifth Avenue. Si
racconta che ebbe l’occasione di sperimentare anche l’effetto delle vibrazioni meccaniche prodotte da un
meccanismo consistente in una piattaforma montata su cuscinetti elastici azionata da aria compressa.
Vibrazioni rivelatesi curative di problemi di digestione ed altri disturbi e con le quali Clemens curò la sua
stipsi. Quando l’inventore ancorò il meccanismo ad una colonna di ferro del suo laboratorio, con
l’aumento della frequenza raggiunse un livello in grado di far vibrare l’intero edificio con il pericolo di
provocare un crollo. Rinunciò così a procedere oltre.
J.P. Morgan, uomo chiave della creazione della "General Electric", per interesse personale, consapevole
che il successo della società si basava sui brevetti di Tesla e che il controllo sui brevetti dava anche il
diritto di sopprimerli o nasconderli, interessato ai lavori dello scienziato per motivi economici, offrì
150.000 dollari per il 51% dei brevetti sviluppati sulla nuova tecnologia senza fili e rese pubblico il
finanziamento iniziale a difesa dei suoi interessi.
Il 23 luglio del 1901 Tesla, ignaro delle vere intenzioni di Morgan, iniziava a Long Island i lavori per
erigere una colossale torre di legno di 60 metri nota col nome di Wardenclyffe, che sosteneva un
elettrodo di rame di 35 metri di diametro, idoneo a raccogliere una carica elettrica. Concepita e costruita
come sistema per le telecomunicazioni senza fili, era il mezzo per dimostrare che era possibile distribuire
l’energia senza utilizzare i fili e continuare quanto iniziato a Colorado Springs.
Tesla dichiarò di svolgere esperimenti tesi a imbrigliare l’energia dei raggi cosmici e costruire un
dispositivo funzionante attraverso l’utilizzo di tale energia. Aggiunse che i raggi cosmici ionizzano l’aria
creando particelle libere come ioni ed elettroni; le cariche vengono catturate in un condensatore che
funziona come scarico per il circuito del motore.
Gli esperimenti erano volti ad utilizzare la Terra come conduttore trasformandola in un gigantesco
trasmettitore elettrico, aprendo la possibilità di comunicare e trasmettere potenza attraverso la crosta
terrestre. Intendeva concepire una stazione trasmittente in grado d'inserire energia elettromagnetica nella
crosta fino a raggiungere la risonanza elettrica della Terra stessa, in modo da utilizzare il pianeta per
intercettare energia, usufruendo delle stazioni riceventi dislocate opportunamente sul globo. Lo scienziato
scoprì, trasmettendo frequenze estremamente basse, che poteva alterare le correnti nell’alta atmosfera e
modificare il clima. Inoltre, utilizzando tali onde, si poteva interagire con l’attività bioelettrica del
cervello e con la naturale vibrazione delle molecole del corpo, manipolando la biofisica umana.
Presso Colorado Springs aveva concepito un nuovo sistema di esplorazione geofisica utilizzando
oscillatori meccanici inventati in precedenza. Gli esperimenti non furono portati a termine perché si
accorse che potevano generare terremoti artificiali di inaudita potenza, modificando le naturali frequenze
di cui sono dotati tutti i corpi e sfruttando quella che chiamò "frequenza risonante", a mezzo della quale
un corpo si mette a vibrare fino alla rottura. Difatti se il trasmettitore avesse inviato una forte energia in
un solo punto si sarebbe verificata una distruzione totale.
Morgan, vedendo nel progetto un pericolo futuro per i suoi interessi, negò allo scienziato altro denaro, ma
nel frattempo Tesla riuscì ad ottenere 10.000 dollari dal Canada per trasmettere l’energia per quello
Stato, costringendo Morgan a dichiarare apertamente che non intendeva finanziare ulteriormente lo
Per il mondo, se Morgan non rischiava i capitali, il progetto non era affidabile e tutti si tirarono indietro.
A 50 anni Tesla si ritrovò senza soldi, solo, come il giorno in cui era sbarcato a New York, mentre
Morgan possedeva tutti i suoi brevetti dell’elettricità senza fili e Westinghouse controllava l’energia a
Tesla, non interessato ai soldi, pieno di fiducia infantile verso un mondo che non lo comprendeva e lo
disprezzava, profondamente ferito, convinto di essere stato abbandonato dagli uomini e da Dio, un uomo
pieno di orgoglio che non si era mai voluto sposare e quindi non aveva avuto modo di provare le gioie di
una famiglia, si mise a scrivere per riuscire a sbarcare il lunario.
Nella scrittura trovò lo sfogo dei suoi risentimenti definendo il mondo "pusillanime e incredulo, la cui
cecità costa cara a tutti"; se la prese con "un’umanità non sufficientemente progredita in un mondo dove
un’idea o un’invenzione viene ostacolata e maltrattata dalla volontà del denaro, dagli interessi egoistici,
dalla pedanteria, dalla stupidità e dall’ignoranza; attaccata e repressa, sottoposta ad amari processi nella
spietata lotta per affermarsi sul mercato".
Negli anni che seguirono, la sua fervida mente partorì altri progetti. Due turbine senza pale da 200 CV
che furono collaudate nella centrale di Waterside a New York e che non trovarono consensi all’epoca;
oggi le turbine a gas si basano sui progetti di Tesla.
Vengono attribuiti a Tesla 700 invenzioni, fra le quali l’illuminazione elettrica, l’energia elettrica a
corrente alternata, il tachimetro, il contagiri meccanico, la diffusione radio, la lampada per flash
fotografici, il motore rotante, la turbina Tesla senza palette, quella per l’accensione dei motori elettrici,
l’auto elettrica senza generatore di corrente, l’uso medico della risonanza magnetica (3), la prima stazione
di energia idroelettrica, la sismologia.
E ancora, negli anni ottanta, uno studio sulla dispersione di energia in un pulsar stellare dimostrò che le
onde gravitazionali esistono e la sua concezione sulla gravità riconsiderata; nel 1896 l’altoparlante,
reclamizzato solo venti anni dopo, a causa della mancanza di un brevetto; l’invenzione delle porte
logiche utilizzate oggi nei computer e nella robotica che Tesla adoperò nel battello radio comandato a
comando vocale; l’iniettore elettrico per auto. Nel 1917 i principi relativi ai livelli di frequenza e potenza
che permisero nel 1934 le prime apparecchiature Radar, onde radio ad alta frequenza che rimbalzano
sugli oggetti tornando indietro alla fonte generatrice. Nel 1928 un apparato di trasporto aereo a decollo
verticale. Parlò inoltre di una macchina "volante, pesante, solida e stabile, in grado di muoversi a volontà
nell’aria in ogni direzione e in perfetta sicurezza, a velocità mai raggiunte, indipendentemente dalle
condizioni atmosferiche; capace di sostare nell’aria anche in presenza di forti venti... ma non è questo il
tempo per parlarne."
Navi che potevano volare utilizzando energia elettromagnetica trasmessa da trasmettitori simili a quelli
concepiti a Colorado Springs. Perfezionò un apparecchio per inviare energia nello spazio interstellare che
in pratica era un prototipo del Laser e di un ordigno al plasma che produceva particelle ad alta energia
nella ionosfera. Nel 1940, in un’intervista sul "New York Times", dichiarò di poter consegnare al governo
il segreto della sua "teleforza" con la quale si poteva distruggere il motore di un aereo: era il famoso
"raggio della morte". Il dipartimento della guerra la considerò la farneticazione di un pazzo.
Il governo jugoslavo concesse a Tesla una piccola pensione di 7.200 dollari l’anno e l’occasione di
trovare una dimora stabile per gli ultimi anni, benché sembra che girovagasse da un albergo all’altro.
L’unico membro della famiglia che gli fu vicino fino alla fine fu il nipote Sava Kosanovich.
Fra la notte del 5 e quella dell’8 gennaio 1943 Tesla morì nella stanza dell’Hotel New Yorker. Il cadavere
venne ritrovato due giorni dopo. La notte dell’8 il nipote ed altri due uomini rovistarono nella sua stanza
in cerca di un testamento, mai trovato, e altri scritti conservati nel Museo a Belgrado. L’FBI che seguiva
Sava confiscò tutto quanto rimaneva dello scienziato.
Un’invenzione risultò depositata nel 1932 presso la cassaforte dell’hotel Grosvoner Clinton, ma l’albergo
rifiutò di consegnarla all’FBI.
Tutto il suo lavoro fu dichiarato Top Secret dall’FBI, dalla marina militare e dal vicepresidente.
Il 12 gennaio 1943 si svolsero i funerali nella cattedrale St. John di New York.
La vicenda Tesla ci spinge ad analizzare più da vicino alcune cose a lui collegate:
Nel laboratorio a Menlo Park, nel New Jersey, Thomas Alva Edison, si dedicò allo studio della dinamo e
produsse una lampada ad incandescenza; nel 1890 nacque la "Edison General Electric Co.".
Nel 1892 dalla fusione fra la "Thomson Houston Co." guidata da Charles Coffin ebbe origine la "General
Nel 1917 fu costituita la "GE Aircraft Enginers" per la fabbricazione dei motori aeronautici; nel 1930 il
primo reparto della "GE Plastics" in seguito agli esperimenti condotti da Edison riguardo ai filamenti
plastici per le lampadine effettuati nel 1893.
Nel 1919 la GE formò la "RCA", "Radio Corporation of America", che nel tempo, a causa della potenza
di trasmissione raggiunta si ripartì in altre due società: il network rosso, la "NBC", "National
Broadcasting Company", e il network blu, la "ABC", "America Broadcasting Company".
Quando scoppiò la seconda guerra mondiale l’RCA era divenuta parte integrante della struttura della
difesa americana, in seguito alla messa a punto di un altimetro di alta precisione per le missioni di
bombardamento ad alta quota. Sempre dell’RCA il trasmettitore portatile indossato dagli agenti segreti
dislocati in territorio nemico, non rilevabile dai tedeschi, con il quale comunicare direttamente, senza
usare codici criptati, con il pilota di un aereo che sorvolava la zona.
Il presidente era il generale David Sarnoff, nato a Minsk, Russia, nel 1891, che aveva lavorato nella
"Marconi Wireless Company". Sembra fosse il telegrafista che ricevette l’S.O.S. dal Titanic nell’Aprile
1912. Reclutato in seguito nell’esercito, divenne direttore della Divisione della guerra psicologica col
grado di generale di brigata, famoso per le dichiarazioni a favore della guerra fredda. Si parla della sua
presenza durante avvistamenti definiti "non convenzionali" (UFO) avvenuti nel 1946 in Svezia e nel 1966
sopra la base militare di Andros nelle Bahamas. Faceva parte di una équipe di esperti militari e in lui
viene indicata la persona che ordinò il sequestro dei filmati e intimò, all’operatore che li aveva eseguiti, il
silenzio. Era considerato un esperto in materia di UFO, cosa risultata molto utile nella conduzione della
Le apparecchiature della base di Andros erano state fabbricate dall’RCA, di conseguenza il generale
Sarnoff viene indicato quale membro di una struttura coperta che si serviva dell’RCA per scopi "occulti"
oltre a quelli ufficiali. La messa in onda di alcune trasmissioni tipo "Dark Skies", nelle quali si parla
liberamente del gruppo "Majestic 12", e di altre trasmissioni riguardanti gli UFO, come la famosa
"Guerra dei Mondi", testimonierebbero che tale uso si è protratto nel tempo e non sia avvenuto per caso.
La progettazione di radar e di altri strumenti molto sofisticati per le forze armate e la commessa militare
di oltre un miliardo di dollari negli anni sessanta aveva conferito all’RCA un posto importante nel
meccanismo bellico statunitense; i suoi affari non erano più solo radiofonici. Nel tempo raggiunse
un'invidiabile posizione nel panorama economico nazionale e mondiale. Il procuratore distrettuale
Garrison, che sosteneva l’ipotesi dell’assassinio di Kennedy da parte dei sostenitori della guerra fredda,
definì il gruppo RCA/NBC, impegnato in una intensa campagna d’informazione ostile al procuratore,
come "la lunga mano del Governo Invisibile".
Da segnalare infine che Guglielmo Marconi credeva negli extraterrestri, secondo le numerose
dichiarazioni rilasciate a riguardo; dopo gli esperimenti eseguiti nel 1933 s’incontrò con David Sarnoff
quando questi era un personaggio di rilievo dell’Intelligence statunitense.
Nel 1993 il dipartimento della difesa americano dichiarò di aver iniziato a costruire un centro ricerche nel
campo delle alte frequenze applicate alle aurore boreali, per esperimenti riguardo alla risonanza della
Terra e dell’atmosfera. Un progetto da 30 milioni di dollari l’anno, che si serve di immense riserve di gas
e petrolio appartenenti alla società ARCO e che, per la sua straordinaria potenza e polivalenza, è
considerato da molti l’arma ultima degli USA. Un sistema tecnologico militare capace di scannerizzare il
sottosuolo alla ricerca di basi segrete sotterranee, o silos di missili, in grado di interrompere tutte le
comunicazioni Hertz, emettere onde ELF in grado di influenzare il comportamento umano, modificare il
tempo atmosferico, provocare terremoti o tsunami e bloccare ogni meccanismo elettronico. Un’arma che
agisce sulla ionosfera con conseguenze imprevedibili e indescrivibili, presentato dal Pentagono come un
innocuo esperimento, un’innocente ricerca sulla ionosfera al fine di migliorare le comunicazioni...
Magda Haalvoet, eurodeputata belga, afferma che questo tipo di armamento implica conseguenze
tecnologiche disastrose e mette in pericolo la democrazia delle Nazioni. La sigla HAARP significa "High
Frequency Active Auroral Research Project": "Metodo ed apparecchiatura per l’alterazione di una regione
dell’atmosfera, ionosfera e/o magnetosfera terrestre".
L’area interessata si trova a Gakona, in un terreno situato a Nord Est di Anchorage in Alaska, nel Golfo
del principe Guglielmo di proprietà del Dipartimento della Difesa USA; consta di 360 antenne alte oltre
20 metri. Doppie antenne a dipoli incrociati, una coppia per la banda bassa da 2,8 a 7 Megahertz e
un’altra per la banda alta da 7 a 10 Megahertz; che trasmettono, a 350 chilometri di distanza, un raggio di
energia ad alta frequenza nella ionosfera; alimentate da sei turbine di 3600 CV che bruciano qualcosa
come 95 tonnellate di diesel al giorno, per generare oltre 1,5 miliardi di Watt. Una zona scelta per la sua
vicinanza al Polo e alla zona di concentrazione delle linee magnetiche del nostro pianeta; per la presenza
di fonti energetiche naturali situate nel sottosuolo e per la distanza dai centri urbani.
La Ionosfera è costituita da particelle ionizzate cariche di energia all’altezza media di 48 chilometri fino a
800 chilometri dalla superficie terrestre; un cuscino ad alta densità energetica che è vitale per il pianeta e
che protegge i suoi abitanti dagli effetti nocivi del sole.
Il sistema HAARP si basa sulle ricerche di Bernard Eastlund, che ha preso spunto dai lavori di Nikola
Tesla; ricerche che dovevano servire ad Eastlund per scoprire vasti giacimenti di gas naturali che la
compagnia petrolifera ARCO stava cercando in Alaska ed hanno fruttato dodici brevetti fra il 1987 e il
1994, la proprietà dei quali è detenuta dalla società APTI-ARCO, un consorzio petrolifero dietro al quale
si celano la Marina, l’Aviazione, e il Dipartimento della Difesa degli Stati Uniti. Anche il fisico nucleare
Edward Teller, noto per essersi dedicato alla costruzione della bomba all’idrogeno ed ha contribuito al
sistema "Guerre Stellari", ha collaborato al progetto.
I brevetti di Tesla riguardavano il metodo e il dispositivo per alterare uno strato dell’atmosfera terrestre,
ionosfera e magnetosfera e creare un ciclotrone artificiale per riscaldare una zona di plasma e produrre
uno scudo di particelle relativistiche ad un’altezza superiore della superficie terrestre.
Collegati al progetto vi sono oltre 400 brevetti, per la maggior parte armi offensive che sfruttano il
sistema d’irraggiamento a fascio diretto dalla Terra verso lo spazio. Si può dirigere l’energia ad alta
frequenza verso un’antenna ricevente, ovunque, anche in centri urbani. Si può interferire con ampie zone
dell’atmosfera per abbattere qualsiasi tipo di oggetto volante.
Anche la Russia si è dedicata ad una simile ricerca prima della divisione del suo territorio.
Vi sono altre installazioni simili in varie parti del pianeta: ad Arecibo, a Fairbanks in Alaska, a Tromso in
Norvegia, a Pine Bush in Australia ed a Steeplebush in Inghilterra. Sicuramente se ne stanno costruendo
Si è saputo che l’impianto pilota di Gakona è in grado di irradiare 1.700.000.000 Watt nell’atmosfera. Il
progetto HAARP rappresenta lo sviluppo negativo dell’invenzione di Tesla. Egli odiava la guerra e, a tal
proposito, dichiarò: "Non si può abolire la guerra mettendola fuori legge. Non vi si può porre fine
disarmando i forti. Ma si può fermarla rendendo tutti i paesi in grado di difendersi. Ho appena scoperto
una nuova arma di difesa che, se verrà adottata, trasformerà completamente i rapporti tra le nazioni. Le
renderà tutte, grandi e piccole che siano, invulnerabili a qualsiasi attacco proveniente da terra, dal mare o
dall’aria. Bisognerà, in primo luogo, costruire una grande officina per fabbricare quest’arma, ma quando
sarà completata, sarà possibile distruggere uomini e macchine in un raggio di 320 Km."
Nel 1934 Tesla descrisse in un articolo un’apparecchiatura simile al laser, affermando: "Questo
strumento proietta particelle che possono essere relativamente grandi o microscopiche, che permettono di
trasmettere a gran distanza un’energia milioni di volte più forte di quella ottenibile con qualsiasi altro
raggio. Così una corrente più sottile di un filo può trasmettere migliaia di cavalli vapore. E nulla le può
Le onde a bassa frequenza, ELF, generate dal sistema, possono influenzare le attività cerebrali. Nel 1952
il Dr. Jose Delgado, professore dell'Università di Yale, scoprì che si poteva modificare il comportamento
emozionale del pensiero. Il Dr. Robert Becker dimostrò che tali onde potevano provocare paura,
Nel 1970 Zbignieu Brezinski, fondatore della commissione trilaterale David Rockfeller’s pubblicò un
libro sulla possibilità di controllare il clima per produrre periodi di prolungata siccità o inondazioni. Da
segnalare che Brezinski era anche direttore della sicurezza nazionale del presidente Carter e fondatore
della "Federal Emergency Management Agency".
Cinesi e russi denunciano da tempo la possibilità che un paese, nello specifico gli Stati Uniti, possa
alterare le forze della natura sconvolgendo il regime delle piogge. Dichiarano di avere forti
preoccupazioni per gli esperimenti americani in Alaska, definendo il progetto HAARP un’arma geofisica
con la quale condizionare il clima alterando attraverso l’emissione di microonde la temperatura e
L’intensità e la frequenza dei disastri che si sono registrati in questi ultimi anni sarebbero da imputare ai
test del progetto HAARP, in quanto in tale progetto verrebbero usati metodi in grado di provocare
terremoti e modificare le precipitazioni, la temperatura, il livello del mare, la caratteristica della luce
Nel 2002 ben 220 deputati della Duma firmarono un appello indirizzato all’ONU per chiedere la messa al
bando degli esperimenti elettromagnetici dell’HAARP ritenuti una nuova arma in grado di influenzare gli
elementi naturali con le onde ad alta frequenza. Il progetto è tuttora in opera.
Nel 1914 Harry Grindell Matthews dichiarò di aver inventato un raggio invisibile, conosciuto come il
"raggio della morte", capace di bloccare qualsiasi motore, riprendendo un vecchio un progetto di Tesla
per teletrasportare energia elettrica. Durante una dimostrazione sarebbe riuscito a bloccare il motore a
scoppio di una moto, a far esplodere polveri a distanza ed accendere una lampada senza fare uso di
Il Ministero dell’Aviazione inglese non fu convinto dalla prova, in quanto il suo raggio di azione era
attivo entro diciotto metri.
Nel 1925 Grindell si recò in America e al suo ritorno in patria dichiarò di aver venduto il brevetto agli
USA. Da quel momento lo scienziato venne dimenticato; morì nel 1941. La sua tecnologia fu impiegata
per proiettare in cielo immagini pubblicitarie. Non fu l’unico a costruire un sistema per generare un
raggio simile, in tale impresa si cimentò, e sembra con esiti positivi, anche Guglielmo Marconi. A
convalidare tale impresa, pur in modo indiretto, un testimone di tutto rilievo: Rachele Mussolini. Nel suo
libro "Mussolini privato", descrive cosa le accadde una mattina del 1936 mentre percorreva con l’auto la
Roma-Ostia: "Un giorno, alla fine di giugno del 1936, a pranzo, avevo detto a Benito che nel pomeriggio
mi sarei recata ad Ostia a controllare alcuni lavori in una proprietà agricola. Mio marito sorrise e mi
disse: Trovati sull’autostrada fra le tre e le tre e mezza. Qualcosa ti sorprenderà."
Secondo quanto riportato nel libro, a metà strada l’auto si fermò e nonostante che l’autista facesse di tutto
per rimetterla in moto, la macchina non ne volle sapere. Accadde lo stesso a tutte le auto che si trovarono
in zona, sia quelle che viaggiano verso Ostia, sia quelle dirette verso Roma. Rachele guardò l’orologio:
erano le 3,10. All’autista disse di aspettare fino alle 3,30. L’uomo chiese perché aspettare tanto, ma dopo
aver visto inutili i suoi tentativi di far ripartire il motore, alla fine si arrese. Alla 3,35 Rachele Mussolini
disse all’autista di riprovare a far ripartire l’auto. Inutile dirlo l’auto si rimise in moto.
La sera a cena narrò l’accaduto a tavola e Mussolini confermò che era stato fatto un esperimento
segretissimo in quel punto dell’autostrada. "Un’invenzione di Marconi che può dare all’Italia una potenza
superiore a quella di tutti gli altri paesi del mondo. Marconi sta continuando le ricerche."
Mussolini spiegò alla moglie che Marconi utilizzando un raggio misterioso poteva interrompere il
circuito elettrico dei motori di qualsiasi tipo.
Purtroppo Marconi era devotissimo alla chiesa, causa l’annullamento del matrimonio dalla sacra rota, e
papa Pio XI, saputo della cosa, si allarmò e chiese allo scienziato di non proseguire le ricerche.
Da Donna Rachele sappiamo che Marconi riferì tutto a Mussolini che, non volendo inimicarsi il Papa,
lasciò libertà di scelta allo studioso, il quale sospese le ricerche ma non distrusse la documentazione e la
scoperta stessa. L’anno dopo, il 1937, Marconi morì.
La cosa è più che certa, dato che lo stesso duce lo confermerà a Ivanoe Fossati, il 20 Marzo 1945, in una
intervista. "È vero sulla strada di Ostia, ad Acilia Marconi ha fermato i motori delle automobili, delle
moto. L’esperimento fu ripetuto sulla strada di Anzio; a Orbetello aerei radiocomandati furono incendiati
a duemila metri di altezza." Al giornalista Mussolini disse che Marconi ebbe degli scrupoli e chiese
consiglio al Papa che gli disse di nascondere la scoperta. Disse anche che non si sentì di obbligarlo nella
scelta, pur facendogli presente che la scoperta poteva essere fatta da altri e utilizzata contro l’Italia, ma lo
studioso morì improvvisamente poco tempo dopo.
Vi sono inoltre due fatti da registrare.
Primo: sembra che nel 1939 nella città di Essen, nell’ora di punta del traffico, tutto quanto era elettrico e
meccanico si bloccò per dieci minuti: auto, camion, moto, orologi. I giornali non menzionarono
l’accaduto. Era stato sottratto ai fascisti il progetto del raggio della morte?
Secondo: il segreto di Marconi lo conosceva un certo Pier Luigi Ighina, suo collaboratore, un radiotecnico
milanese che per dieci anni fu aiutante dell’inventore; fu lui a scoprire l’"atomo magnetico" che si trova
in mezzo agli altri atomi e fornisce loro il movimento continuo. Dividendolo scoprì il "monopolo
Isolando gli atomi della materia dagli atomi magnetici i primi non hanno la possibilità di muoversi e la
materia non si trasforma, quindi l’atomo magnetico produce anche le variazioni degli atomi della
materia. Secondo quanto dichiarato da Ighina il monopolo è il principio positivo o negativo dell’energia
solare che giunge sulla Terra; viene bloccata e riflessa divenendo energia terrestre. Dall’interazione
dell’energia solare con quella terrestre si produce materia.
Ighina aveva inventato una macchina capace di controllare le nuvole con la quale liberava il cielo dalla
loro presenza. Per riuscire a fare questo aveva sepolto quintali di polvere di alluminio sotto il prato del
suo giardino trasformandolo in un monopolo magnetico.
Durante il Primo Congresso Internazionale di Medicina Ufficiale e Naturale di Milano venne proiettata
una videocassetta del filmato inerente al dissolvimento dell’agglomerato nuvoloso sul cielo di Imola, con
la ricomparsa del sereno nella zona interessata e trattata da Ighina con monopoli magnetici. Una scoperta
che poteva risolvere il problema delle siccità e delle alluvioni nel mondo.
L’atomo magnetico è più piccolo degli altri atomi e pulsa più velocemente. Ighina costruì
un’apparecchiatura per regolare le vibrazioni atomiche magnetiche basata sull’energia dell’atomo
magnetico; con tale energia secondo l’inventore si poteva guarire qualsiasi malattia, fondere metalli a
distanza, produrre energia elettrica, investigare nel sotto suolo alla ricerca di giacimenti petroliferi e falde
acquifere, aumentare la produzione agricola. (Il progetto Haarp?)
Da quanto dichiarato da Ighina sembra che Marconi sia rimasto ucciso dal suo stesso esperimento durante
il quale aveva provocato l’interruzione della circolazione del sangue; perché come spiegò il radiotecnico i
monopoli scompongono la materia sulla stessa materia. Se ne accorse quando vide la salma e osservò
sotto la pelle alcuni "gnocchetti neri". I medici diagnosticarono la morte in seguito ad un attacco di
In merito a questo "raggio invisibile", o "della morte", negli anni '90 giornali e TV diffusero la notizia che
la polizia statunitense sarebbe stata dotata di un meccanismo capace di bloccare il motore dell’auto usata
dai malviventi per darsi alla fuga. Tutto questo porta a pensare alla tecnologia in possesso degli UFO,
dato che in molti casi di avvistamenti i motori delle auto si bloccano, la luce elettrica viene a mancare,
ogni meccanismo si ferma. Fenomeni riscontrati anche nelle vicende riguardanti il famoso Triangolo
delle Bermuda, fenomeni che interessano campi elettromagnetici. Sembra però che tale progetto sia stato
abbandonato perché in virtù del suo ampio raggio d’azione, fermerebbe anche i pacemakers e interrompe
la corrente nelle abitazioni circostanti al luogo di azione.
L’apparato costruito da Tesla proiettava particelle, grandi o microscopiche, in modo da concentrarle in
una piccola area e inviarle a grandi distanze utilizzando energie "trilioni di volte" più potenti di quelle
attualmente in uso. Un fascio più sottile di un capello a cui niente resiste. Una tecnologia che può
diventare un’arma capace di abbattere migliaia di aerei a 400 chilometri di distanza, un acceleratore di
particelle oggi in uso nei laboratori nucleari e nello scudo spaziale. Atto a produrre un’arma al plasma.
In virtù di questo, qualcuno lo ha indicato come l’autore involontario dell’esplosione del 30 giugno 1908
nella Tunguska, in Siberia. Esiste la strana coincidenza che lo stesso giorno in si manifestò il fenomeno
in Russia, l’inventore, stava eseguendo un esperimento con lo scopo di inviare un’onda di immensa
energia e stabilire la comunicazione con una spedizione artica, localizzata nella linea retta compresa fra il
laboratorio e il luogo dell’esplosione. Dato che il suo trasmettitore poteva generare una forza distruttiva
pari a una bomba all’idrogeno di 10 megatoni, è stato fatto due più due. Non esistono però prove a
conferma, nonostante che l’esplosione della Tunguska non abbia lasciato crateri prodotti da meteoriti o
comete, caduta di UFO; non ci furono segnalazioni in merito a tali fenomeni. L’unico effetto prodotto
alcuni giorni dopo, una luce aurorale anomala che potrebbe far pensare all’uso di apparecchiature da
parte di Tesla; apparecchiature che oggi farebbero parte del progetto HAARP. Nonostante questo
rimangono molti interrogativi: doveva avere una potenza di 30 megatoni e per raggiungerla doveva
coinvolgere più centrali, quindi non si poteva nascondere il fatto; inoltre risultano testimonianze
contraddittorie riguardo alla traiettoria. L’unico che poteva far luce sull’evento era proprio Tesla, ma
mantenne il riserbo più assoluto in merito ai progetti che potevano produrre armi ad energia distruttiva.
A Tesla è legata una storia riguardo ad un’auto elettrica. Si racconta che nell’estate del 1931 le strade
della cittadina di Buffalo fossero percorse da una Pierce Arrow che non presentava emissione di fumi dal
tubo di scarico in quanto avrebbe avuto uno motore elettrico e non combustione interna. Era guidata da
tale Petar Savo indicato come un giovane parente di Tesla, un personaggio che parlando dello scienziato
si riferiva a lui come "zio". Noi sappiamo che il nome del nipote controllato dall’FBI era diverso.
Sembra che nei primi del novecento le auto elettriche avessero buone prospettive; in molti avevano
anticipato veicoli alimentati da batterie.
L’auto a benzina necessitava di una valvola a farfalla, una manovella per far girare il motore, acqua per
un radiatore, quando proprio a quel tempo vi erano poche officine per auto e un normale elettricista
poteva eseguire la manutenzione del semplice motore a corrente continua.
Nessun inquinamento, velocità contenuta e meno incidenti mortali, costi ribassati anche a livello
produzione, non ci sarebbe stato bisogno di un accordo di Kyoto che nessuno rispetta, non avremmo
avuto, come lo abbiamo oggi, un problema con i paesi islamici e non avremmo alimentato e finanziato di
conseguenza il terrorismo.
I grandi magazzini impiegavano camion elettrici, così i medici e le donne perché tali auto erano più facili
da guidare, ma questo solo in città; le strade americane venivano percorse da veicoli con motore a
combustione interna, più veloci e con maggiore autonomia. "Detroit Electric", "Columbia", "Baker",
"Rauch & Lang" e "Woods" furono le principali aziende tra quelle che producevano questo tipo di veicoli
Le batterie erano però scarse, pesanti, ingombranti, al piombo, le auto avevano prestazioni limitate, oltre
gli 80 Km/h la batteria si poteva deteriorare. Richiedevano molto tempo per la ricarica per un’autonomia
massima di 160 chilometri. Quindi quando l’affidabilità e la velocità delle auto a benzina migliorò le
auto elettriche sparirono.
Petar Savo era stato nell'esercito austriaco ed era un esperto pilota; intervistato nel 1967, raccontò
l’episodio dell’auto elettrica che collaudò per conto di Tesla. "La Westinghouse Electric" e la "Pierce-
Arrow" avevano preparato un’auto sperimentale seguendo le indicazioni di Tesla con finanziamenti della
"Studebacker Corporation". Aveva un motore elettrico a corrente che poteva raggiungere 1.800 giri al
minuto, senza spazzole, raffreddato da una ventola frontale e due terminali di alimentazione sotto il
cruscotto. Savo racconta che Tesla sollevò il cofano, fece qualche regolazione, posizionò 12 valvole
termoioniche in un dispositivo all’interno di una scatola di circa sessanta centimetri per trenta e alta
quindici. Poi eseguì la connessione al motore. L’auto percorse circa 80 chilometri attorno a Buffalo,
raggiungendo i 145 km/h in perfetto silenzio.
A detta di Tesla il dispositivo che alimentava l’auto era in grado di alimentarlo per sempre e soddisfare il
fabbisogno energetico di un'abitazione; l’inventore affermò che sfruttava una "misteriosa radiazione
proveniente dall'etere, disponibile in quantità illimitata".
L’auto aveva una batteria ricaricata da una antenna che entrava in sintonia con la risonanza di Schumann
intorno ai 7,83 Hz. Una valigia come quelle dei ricevitori a bassa frequenza rimodulava la corrente
alternata del campo magnetico terrestre in corrente continua necessaria alla batteria fornendo una
quantità illimitata di energia.
Considerando tutto questo non possiamo fare a meno di pensare che la Grande Piramide potesse
assumere la funzione di quella valigetta, assorbendo dalla Terra energia elettrica per distribuirla senza
l’uso dei fili, sfruttando proprio la risonanza di Schumann sulle frequenze di 30 Hz riscontrata nella
Gli esperimenti durarono una settimana, l’auto percorse vari tipi di strade alla velocità di 150 chilometri
orari, dopodiché venne consegnata in tutta segretezza in una fattoria vicina a Buffalo e Tesla si portò via
il suo dispositivo. Nel 1933 per problemi amministrativi la "Pierce Arrow" venne liquidata e la storia si
Nel New York Daily News del 2 aprile 1934 un articolo intitolato "Il sogno di Tesla di un'energia senza
fili vicino alla realtà", si parlava di un "esperimento programmato per spingere un'automobile utilizzando
la trasmissione senza fili di energia elettrica".
Nello stesso periodo la "Westinghouse Corporation" pagò per la sistemazione di Tesla al "New Yorker
Hotel" di New York , dove visse per tutto il resto della sua vita.
Tesla venne anche reclutato dalla Westinghouse per ricerche non ben specificate sulle trasmissioni
senza fili ed egli interruppe le sue dichiarazioni pubbliche sui raggi cosmici.
Leggende metropolitane, o studiati cover p su invenzioni che potevano danneggiare il potere di
Su tutta la storia non vi sono molti riscontri.
Riguardo le auto all’Idrogeno, oggi parliamo di auto con motore a celle di combustibile, a idrogeno.
Una nuova frontiera già disponibile che viene ostacolata esclusivamente da problemi politici visto che
quelli economici potranno essere risolti nel momento in cui si passerà ad una produzione industriale
con l’abbattimento dei relativi costi. In soli cinque anni, massimo sette, si potrebbe riconvertire l’intero
parco auto, azzerare il tasso d’inquinamento mettendosi in regola con l’accordo di Kyoto e sganciarsi
dal petrolio e da tutti i problemi che dal suo uso derivano.
Ironia della sorte la cella a combustibile (4), o pila a gas, fu ideata nel 1839 da William Grove, un
curioso avvocato del Galles con l'hobby della chimica. Durante un esperimento di elettrolisi,
procedimento attraverso il quale si può separare idrogeno e ossigeno dall’acqua, si accorse che, nel
momento in cui le batterie che alimentavano le celle elettrolitiche venivano escluse, il processo
riprendeva al contrario; cioè l’idrogeno e l’ossigeno si riunivano generando elettricità. La comunità
scientifica pur interessata inizialmente preferì optare per la dinamo, scoperta poco tempo dopo da
Passarono 120 anni prima che la NASA adottasse le "fuell cells" per il progetto Apollo e invogliasse il
loro uso a livello industriale. Infatti, a partire dagli anni ’60, le pile a combustibile sono state utilizzate
per tutte le missioni spaziali sia Apollo, sia Shuttle, al fine di produrre acqua ed energia elettrica nello
La cella, in pratica, si comporta come un generatore di energia elettrica prodotta attraverso la reazione
chimica controllata tra idrogeno e ossigeno grazie a un catalizzatore di platino. Si verifica il consumo
di un combustibile, nel caso idrogeno e ossigeno, con emissione di vapore acqueo. Non più camere di
scoppio, pistoni, combustione.
Fra i cinque tipi di celle a combustibile, le più interessanti sono quelle ad acido fosforico e a membrana
scambiatrice di protoni detta anche Pem. Le prime usate negli impianti di potenza, le seconde nella
locomozione dei veicoli.
Le pile Pem sono state sviluppate alla fine degli anni Cinquanta negli Usa, dalla "General Electric", e
grazie alla collaborazione con la "Ballard Power Systems", società canadese di alta tecnologia, e con
l’inglese "Johnson Matthey", specializzata in catalizzatori, il costo del platino in una cella Pem è sceso
Oltre al settore dell'autotrazione, i campi di applicazione delle "fuel cells" sono la produzione di
energia, apparecchiature per telecomunicazioni, sistemi di alimentazione per cellulari, personal
computer e fabbisogni domestici.
Il metodo più economico per disporre di idrogeno è estrarlo dal gas naturale ma, con tale
procedimento, noto come "Steam Reforming", viene liberata come sottoprodotto anidride carbonica; un
secondo sistema è produrlo partendo dall’acqua, separandolo dall’ossigeno attraverso l’elettrolisi.
La scelta vincente è rappresentata dalle celle a combustibile alimentate da idrogeno se ottenuto
dall’acqua attraverso l’energia elettrica prodotta da fonti rinnovabili. L’acqua generata dalle "Fuel
Cell" è così pura che viene bevuta dagli astronauti sullo Shuttle.
In occasione della rassegna IFA, la più grande Fiera dell’Elettronica del mondo, tenutasi a Berlino nel
settembre del 2005, è stata presentata, dalla Toshiba una piccolissima centrale, costituita da una mini
cella a combustibile alimentata da un’alta concentrazione di metanolo (99,5%) come combustibile.
Uno strumento idoneo e alternativo per ricaricare le batterie di Notebook, audio digitali, dvd portatili,
telefoni cellulari. Pesa 8,5 grammi e produce 100 milliwatt di energia in un compatto che misura
appena 22x56x4,5 mm. Per il suo funzionamento necessita solo di 2 millilitri di combustibile per
assicurare 20 ore di autonomia in un riproduttore di MP3 audio.
Le Piramidi potevano essere state immense celle a combustibile per fornire energia al popolo che
occupava le terre tredicimila anni fa.
Secondo Alan Alford la Camera della Regina nella Grande Piramide di Giza, sarebbe stata il punto
dove si doveva trovare la cella energetica idonea a produrre la separazione fra l’ossigeno e l’idrogeno;
il sarcofago nella camera del Re il recipiente dove avveniva la combustone controllata dell’idrogeno; le
cinque stanze sopra tale camera, ossia il Ded, il dispositivo di raffreddamento.
Alford ipotizza che nelle 27 nicchie allineate nella Grande Galleria e adesso vuote, si trovavano
cristalli capaci di risuonare a diverse frequenze e impiegati per comunicare.
Questo ci porta a fantasticare ancora un po' e a compiere un viaggio fino ad Atlantide.
Secondo quanto riportato riguardo alle dichiarazioni del veggente Cayce, la civiltà Atlantidea
disponeva di una avanzata tecnologia, comprendente anche "i raggi distruttivi"; Cayce parlò di
televisione, aeromobili, quando ancora non esistevano; dichiarò che quel popolo era capace di alterare
la struttura atomica dei cristalli per ricavare enormi quantità di energia, attraverso un sistema che
ricorda quelli descritti da Tesla. I cristalli sarebbero stati isolati in un edificio "foderato di pietra non
La descrizione ricorda le torri di vetro girevoli di cui disponevano i Thuata de Danan, protagonisti delle
saghe irlandesi, rivestite appunto di un materiale isolante a protezione delle radiazioni emanate dalle
I documenti con le descrizioni per costruire tali "pietre" verrebbero custoditi in tre posti diversi: nei
templi di Atlantide sommersi a Bimini, in un tempio in Egitto e nel tempio di Itlar nello Yucatan.
Cayce parlò anche di Faser e Maser, l'energia derivante dalla luce polarizzata, dicendo che proprio il
cattivo uso di tale energia scatenò forze incontrollabili che causarono la distruzione del continente.
Nel 1970 il Dottor Ray Brown durante un’immersione con alcuni suoi amici nelle acque del triangolo
delle Bermuda, vicino alle isole Bari, Bahamas, vide, a quaranta metri di profondità, una vasta città
sommersa e una piramide con un'apertura sulla sua sommità. Ecco la sua testimonianza:
"La costruzione era in pietra liscia, le giunzioni fra i blocchi si distinguevano appena. L'apertura era
una specie di pozzo che immetteva in una stanza interna rettangolare. Completamente priva di alghe e
coralli e stranamente ben illuminata senza che ci fosse nessuna luce diretta. Vidi qualcosa che riluceva.
Dal soffitto pendeva un’asta metallica con incastonata una pietra rossa sfaccettata e affusolata in punta.
Sotto di essa un basamento in pietra sono sopra una piastra sempre di pietra, sulla quale due mani di
bronzo, annerite da evidenti bruciature, sorreggevano una sfera di cristallo. Non riuscendo a smuovere
l’asta e la pietra rossa, afferrai il cristallo e venni via. Mentre uscivo da quel luogo mi parve di
avvertire una presenza. All'interno di questo cristallo rotondo vi era una serie di forme piramidali, tre
per l’esattezza e tenendolo in mano si avvertiva una vibrazione."
Pervaso dal timore che la sfera gli fosse confiscata non ne ha rivelata l’esistenza fino al 1975, nel corso
di una conferenza a Phoenix, né il punto esatto del suo ritrovamento e cosa ne è stato del cristallo.
Il particolare delle mani metalliche che sorreggono un cristallo, rammentano le mani degli isolatori che
sostengono le "lampade" rappresentate sulle pareti di Dendera. Il fatto che siano state viste annerite e
bruciate significa che erano state sottoposte ad un fortissimo calore, quindi la piramide catalizzava una
sorta d’energia indirizzandola, attraverso l’asta, nella sfera di cristallo. La pietra rossa poteva essere un
rubino, pietra solitamente usata nei laser per concentrare e proiettare l’energia. In quanto alla sfera vi
sono testimonianze che parlano di fenomeni paranormali; di metalli che in contatto con essa si
magnetizzano temporaneamente; l’ago della bussola girerebbe prima in senso orario e poi in senso
opposto. Si è parlato di casi di guarigione dopo averla toccata.
Un collegamento al teschio di cristallo? Speculazioni?
Fatto che non si può negare. Il cristallo della sfera testimonia l’esistenza di civiltà in possesso di una
tecnologia avanzatissima perché perfino gli esperti dell’Istituto Smithsoniano di Washington hanno
dichiarato che, solo dopo il 1900 siamo entrati in possesso di una tecnologia con la quale poter tagliare
il quarzo e ricavarne una sfera perfetta.
Dal passato saltiamo al futuro in quanto Tesla non era in accordo con Einstein riguardo alla curvatura
dello spazio per lui impossibile: "Se esistesse non si spiegherebbe il moto dei corpi come li osserviamo.
Solo un campo di forza può spiegarlo e la sua assunzione dispensa la curvatura spaziale dell’esistere."
Tesla condivideva la visione della luce intesa come particella e come onda; lavorava ad un progetto
relativo ad una "barriera di luce" in grado di alterare tempo, spazio, gravità e materia. Voci dal sapore
di leggenda abbinano il suo nome al "Progetto Filadelfia" riguardante la sparizione di una nave e il suo
equipaggio dopo averla esposta ad un forte campo magnetico.
Qualcosa che potrebbe fornire la spiegazione delle strane sparizioni nel famoso triangolo delle
Oggetto dell’esperimento il cacciatorpediniere Eldridge D173 che finì avvolto da una strana nebbia
luminescente e verdastra appena i generatori magnetici furono messi in funzione. La nave sparì davanti
agli occhi degli osservatori rimasti a bordo della SS Furuseth e della SS Malay, lasciando ben visibile
la sua impronta nell’acqua, all’interno di un campo di forza di forma sferica di circa cento metri
L’Eldridge fu vista apparire e scomparire a Norfolk in Virginia e l’equipaggio subì conseguenze
sconvolgenti devastanti. Uomini che apparivano e sparivano in ogni luogo si trovassero.
La storia venne rivelata da un non ben identificato Carl Allen in corrispondenza epistolare con il dottor
Morris Jessup, astronomo e ricercatore, autore di un libro collegato alla storia, "The case for the Ufo".
Jessup morì in circostanze misteriose e sospette. La vicenda è stata divulgata da Manson Valentin con
il quale Jessup era in contatto e, successivamente, da Charles Berlitz che intervistò Valentin.
Queste le vicende collegate a Tesla, un personaggio scomodo all’epoca e sicuramente lo sarebbe anche
ai nostri tempi, ma riconosciuto come l’inventore del mondo che noi conosciamo; senza di lui non
saremo giunti a questo grado di sviluppo tecnologico.
150.000 documenti custoditi nel Museo a lui intestato a Belgrado testimoniano la sua grande
conoscenza dell’elettromagnetismo, la sua capacità di visualizzare nella mente il problema e passare
alla soluzione senza dover stilare disegni ed effettuare calcoli. La sua mania di perfezionismo, l’enorme
serietà, le doti di eloquenza; l’amore per la natura che lo spingeva a compiere lunghe passeggiate.
Appare come un uomo che desiderava una società sana e giusta, retta da principi egualitari, "non
dominata dagli interessi egoistici di oscuri manovratori dell’economia e della politica; individui privi
di coscienza che perseguono i propri interessi non tenendo conto dei danni provocati all’umanità."
Consapevole che il mondo è governato da pochi furbi e facoltosi, come lui li definiva, nascosti nelle
stanze del comando, intenti a raggirare una massa di illusi, poveri, indifesi ignoranti. Sapeva come
cambiare gli equilibri mondiali ponendo a "disposizione di tutti illimitate e smisurate sorgenti di
energie che avrebbero diffuso il benessere, creato cultura, conoscenza e consapevolezza; portando il
mondo ad un autocontrollo; togliendo ai gruppi di potere l’opportunità di manipolare la massa per
conseguire il loro egoistico interesse".
Utopia. Per queste sue idee Tesla fu contrastato.
Nell’elite militare e industriale del tempo figuravano uomini come John Rockefeller Jr., Julius
Rosenwald, Henry Ford, Harvey Firestone, Herbert Hoover, il generale Pershing (5); ben consapevoli
che le invenzioni di Edison non avevano un futuro, ma Edison era asservito al sistema, Tesla, al
contrario, lo combatteva.
Per questo vennero tagliati i fondi all’inventore; le sue invenzioni non dovevano modificare lo status
quo raggiunto, non in quel momento, il cambiamento richiedeva tempo. Il genio invece innesca salti
quantici nello sviluppo tecnologico che costringono a cambiamenti repentini degli equilibri; quindi chi
gestisce il potere deve bloccarli o rallentarli con ogni mezzo.
Lo fecero passare per pazzo; lo fu quando scoprì le frequenza di risonanza della Terra; ma cinquanta
anni dopo Shumann disse che aveva ragione.
Lo dotarono di poteri extraterrestri quando pilotò il battello col radiocomando; ma i tedeschi in guerra
fecero lo stesso con i missili ed oggi si fa uso delle "smart bombs" guidate da Laser e GPS.
L’unità di misura del flusso magnetico porta il suo nome, un onore concesso a pochi, a riconoscimento
del suo enorme e indiscusso talento; ma non fu premiato con il premio Nobel come avrebbe meritato;
gli fu conferita solo la Edison Medal. La cerimonia avvenne il 18 maggio 1917. Nell’occasione, uno
dei membri della "Enginering Society Building" chiuse il suo discorso, nel quale elogiava i meriti
dell’inventore croato, dicendo:
E alla fine Dio disse "Sia Tesla e la luce fu".
1. L’elettricità statica varia dai 20.000 ai 50.000 volt. Il corpo umano tende ad immagazzinare tale
2. Considerando il principio dell’attrazione dei poli opposti, qualsiasi magnete libero di ruotare tende a
orientare il proprio polo sud verso quello nord terrestre; ed è quello che fa l’ago di una bussola perché è
un piccolo magnete i cui poli si orientano parallelamente alle linee dello spettro magnetico terrestre.
Fenomeno possibile in quanto la Terra è una gigantesca calamita.
3. Tutte le macchine per la risonanza magnetica nucleare sono calibrate con l’unità di Tesla, da 2 a 9.
Un Tesla equivale a 1000 Gauss (unita di misura del flusso magnetico). Estremamente importante per
la diagnosi degli organi interni del corpo umano specie in caso di tumori e processi degenerativi del
cervello e della colonna vertebrale. Più forte è il campo magnetico più forte la quantità dei segnali
radiofonici tratti dagli atomi del corpo e quindi più alta la qualità delle immagini. I nuclei atomici
mostrano la loro presenza assorbendo o emettendo onde radio una volta esposti ad un campo magnetico
sufficientemente forte. Il segnale dell’idrogeno nel tessuto canceroso è diverso da quello di un tessuto
sano perché i tumori contengono più acqua e quindi più atomi di idrogeno. La preparazione all’esame è
insolita in quanto è necessario lasciare fuori della stanza ogni oggetto metallico smontabile, comprese
protesi dentarie, acustiche e di altro tipo.
4. La Cella a combustibile è come un piccolo generatore che produce energia da combustibili quali
l’idrogeno o l’alcool per generare una reazione chimica senza combustione o uso di parti mobili come
5. Pershimg John Joseph generale statunitense (1860-1948) che durante la prima guerra mondiale
venne nominato comandante capo delle forze nordamericane in Europa e che sotto la sua direzione
costituirono uno dei principali fattori della vittoria alleata.
Home ~ Catalog ~ Links
Nikola Tesla: Mechanical Oscillator
L. Anderson: Tesla's Teleforce & Tele-Geodynamics Proposals
D. Pond & W. Baumgartner: Nikola Tesla's Earthquake Machine
J. O'Neill: Prodigal Genius: The Life and Times of Nicola Tesla
M. Cheney: Tesla: Man Out of Time
N. Tesla: US Patent # 514,169 ~ Reciprocating Engine
N. Tesla: US Patent # 517,900 ~ Steam Engine
Nikola Tesla's Teleforce & Telegeodynamics Proposals
"Two important papers, hidden for more than 60 years, are presented for the first time. The
principles behind teleforce -- the particle-beam weapon, and telegeodynamics -- the
mechanical earth-resonance concept for seismic exploration, are fully addressed. In addition
to copies of the original documents, typed on Tesla's official stationery, this work also
includes two Reader's Aid sections that guide the reader through the more technical aspects of
each paper. The papers are followed by Commentary sections which provide historical
background and functional explanations of the two devices. Significant newspaper articles
and headline accounts are provided to document the first mention of these proposals. A large
Appendix provides a wealth of related material and background information, followed by a
Bibliography section and Index.
"This book contains the original texts of two unique proposals that Nikola Tesla offered up
during his later years. In both cases, the technologies described trace their roots back to an
earlier and tremendously productive decade in Tesla's life beginning in the early 1890s. At
the time of the proposals' unveiling, "teleforce," the particle beam concept, and
"telegeodynamics," the mechanical earth-resonance concept, received significant press
"On the occasion of his annual birthday celebration interview by the press on July 10, 1935 in
his suite at the Hotel New Yorker, Tesla announced a method of transmitting mechanical
energy accurately with minimal loss over any terrestrial distance, including a related new
means of communication and a method, he claimed, which would facilitate the unerring
location of underground mineral deposits. At that time he recalled the earth-trembling
"quake" that brought police and ambulances rushing to the scene of his Houston Street
laboratory while an experiment was in progress with one of his mechanical oscillators..."
Reactive Forces Obtainable by Tesla's Isochronous Oscillators ~
"These are generated by Tele-Geo-Dynamic transmitters which are reciprocating engines of
extreme simplicity adapted to impress isochronous vibrations upon the earth, thereby causing
the propagation of corresponding rhythmical disturbances through the same which are,
essentially, sound waves like those conveyed through the air and ether. . . . With a machine of
this kind it will be practicable, in the differentiation of densities and aggregate states of
subterranean strata and tracing their outlines on the earth's surface, to reach a precision
approximating that which is secured in the investigation of the internal structure of bodies by
penetrative rays. For just as the vacuum tube projects Roentgen shadows on a fluorescent
screen, so the transmitter produces on the earth's surface shadows which can be detected by
acoustic devices or rendered visible by optical instruments. The receiver can be made so
sensitive that prospecting may be accomplished while riding in a car and without limit of
distance from the transmitter."
Table of Contents
Nikola Tesla's Teleforce Proposal
New Art of Projecting Concentrated Non-Dispersive Energy Through Natural Media. By
New York Times, September 22, 1940, "'Death Ray' for Planes"
Nikola Tesla's Telegeodynamics Proposal
Relative Merits of the Lucas Method of Prospecting by Detonations of Explosive
Compounds and of The Tesla Method of Prospecting by Isochronous Oscillations
Theoretically Considered. By Nikola Tesla
Tesla correspondence from George Scherff, June 17, 1937
New York Times, July 11, 1935, "Tesla, 79, Promises to Transmit Force"
Possibilities of Electrostatic Generators. By Nikola Tesla
Tesla Correspondence to J. P. Morgan, Jr., November 29, 1934
Tesla correspondence from George Scherff, April 19, 1918
Address Before The New York Electrical Society, "Mechanical and Electrical Oscillators"
by Nikola Tesla
Electric Generator ~ U.S. Patent No. 511,916
Reciprocating Engine ~ U.S. Patent No. 514,169
Steam Engine ~ U.S. Patent No. 517,900
Mechanical Therapy by Nikola Tesla
Detroit Free Press, Jan. 18, 1896, "Tesla's Health Giver"
Nikola Tesla's Earthquake Machine
Dale Pond & Walter Baumgartner
Available from: http://www.tfcbooks.com/
"Much of the material presented in this book is related to the construction of a class of
machine invented by Tesla and known as the reciprocating Mechanical Oscillator. Serious
students of Tesla's work may recognize this machine as the basis of his system for producing
electrical vibrations of a very constant period. In 1898 another variation was used to create a
small earthquake in the neighborhood surrounding his Houston Street lab. Tesla called this
method of transmitting mechanical energy "telegeodynamics." Included are mechanical
drawings that will guide you through the construction of a working model of the Tele-GeoDynamic Oscillator, plus a comprehensive description of the machine in Tesla's own words."
Prodigal Genius: The Life and Times of Nicola Tesla
Tele-Geo-Dynamics is the transmission of sonic or acoustic vibrations, which can be
produced with comparatively simple apparatus. There is of course much sonic equipment
available now for different applications, but this has little or nothing to do with Nikola Tesla's
oscillator-generator. What Tesla proposed represents a new technology in sonic transmission
In Tesla's oscillator-generator, a Resonance effect can be observed. Since resonance seems to
be an ever increasing effect with this oscillator-generator, it can be deduced that there must
be a great source of energy available through it.
Why can a resonance be created in the oscillator-generator when it cannot in a ordinary
reciprocating engine? With the oscillator-generator, all governing mechanisms are eliminated.
On the other hand, consider the car engine. Starting with the cylinder, a reciprocating motion
is converted into rotary motion by a means of shafts, cranks, gears, drivetrains, transmissions,
These parts all consume work by friction, but the greatest loss occurs in the change from
reciprocating to rotary motion. At each point every varying inclination of the crank and
pistons work at a disadvantage and result in loss of efficiency.
In Tesla's oscillator-generator, the piston is entirely free to move as the medium impels it
without having to encounter and overcome the inertia of a moving system and in this respect
the two types of engines differ radically and essentially.
This type of engine, under the influence of an applied force such as the tension of compressed
air, steam, or other gases under pressure, yields an oscillation of a constant period.
The objective of the Tesla oscillator-generator is to provide a mechanism capable of
converting the energy of compressed gas or steam into mechanical power. Since the
oscillator-generator is denuded of all governing devices, friction is almost non-existent. In
other words, the piston floats freely in air and is capable of converting all pressure into
Our objective in building the engine is to provide an oscillator which under the influence of
an applied force such as the elastic tension of a gas under pressure will yeild an oscillating
movement which within very wide limits, will be of constant period, irrespective of variation
of load, frictional losses, and other factors which in ordinary engines change in the rate of
It is a well-known priciple that if a spring possessing a sensible inertia is brought under
tension, i.e., being stretched, and then freed, it will perform vibrations which are isochronous.
As far as the period in general is concerned, it will depend on the rigidity of the spring, and its
own inertia or that of the system of which it may form an immediate part. This is known as
Simple Harmonic Motion.
This simple harmonic motion in the form of isochronous sound vibrations can be impressed
upon the earth, causing the propagation of corresponding rhythmical disturbances through the
same which pass through its remotest boundaries without attenuation so that the transmission
is affected with an efficiency of one hundred percent.
Tesla: Man Out of Time
He attached an oscillator no larger than an alarm clock to a steel link 2' long and 2" thick.
"For a long time nothing happened, but at last the great steel link began to tremble, increased
its trembling until it dilated and contracted like a beating heart, and finally broke.
Sledgehammers could not have done it", he told a reporter, "crowbars could not have done it,
but a fusillade of taps, no one of which would have harmed a baby, did it."
Pleased with this beginning, he put the little oscillator in his coat pocket. Finding a half-built
steel building in the Wall Street district, 10 stories high with nothing up but the steelwork, he
clamped the oscillator to one of the beams.
"In a few minutes I could feel the beam trembling. Gradually the trembling increased in
intensity and extended throughout the whole great mass of steel. Finally the structure began to
creak and weave, and the steelworkers came to the ground panic-stricken, believing that there
had been an earthquake. Before anything serious happened, I took off the oscillator, put it in
my pocket, and went away. But if I had kept on 10 minutes more, I could have laid that
building flat in the street. And with the same oscillator I could drop Brooklyn Bridge in less
than an hour."
Sparling, Earl: N. Y. World-Telegram (July 11, 1935), "Nikola Tesla, at 79, Uses Earth to
Transmit Signals; Expects to have $100,000,000 Within Two Years" ~ Here Tesla tells the
story of the earthquake generated by the mechanical oscillator in his NYC laboratory in 1898,
which brought the police there to stop him. They entered the lab just in time to see Tesla
swing a slegehammer and smash the tiny device, which was mounted on a girder:
Nikola Tesla revealed that an earthquake which drew police and ambulances to the region of
his laboratory at 48 E. Houston St., New York, in 1898, was the result of a little machine he
was experimenting with at the time which "you could put in your overcoat pocket."
The bewildered newspapermen pounced upon this as at least one thing they could understand
and "the father of modern electricity" told what had happened as follows:
"I was experimenting with vibrations. I had one of my machines going and I wanted to see if I
could get it in tune with the vibration of the building. I put it up notch after notch. There was
a peculiar cracking sound.
"I asked my assistants where did the sound come from. They did not know. I put the machine
up a few more notches. There was a louder cracking sound. I knew I was approaching the
vibration of the steel building. I pushed the machine a little higher. "Suddenly all the heavy
machinery in the place was flying around. I grabbed a hammer and broke the machine. The
building would have been about our ears in another few minutes. Outside in the street there
"The police and ambulances arrived. I told my assistants to say nothing. We told the police it
must have been an earthquake. That's all they ever knew about it."
Some shrewd reporter asked Dr. Tesla at this point what he would need to destroy the Empire
State Building and the doctor replied: "Vibration will do anything. It would only be necessary
to step up the vibrations of the machine to fit the natural vibration of the building and the
building would come crashing down. That's why soldiers break step crossing a bridge."
In another interview, he boasted that, "With this principle one could split the earth in half like
Century Magazine, p. 921, Figure 2 (April 1895) ~ In 1893 Tesla constructed a preferred
embodiment of the mechanical oscillator which he described as a "double compound
mechanical and electrical oscillator for generating current of perfect, constant, dynamo
frequency of 10 horsepower."
Allan L. Benson: World Today (Feb. 1912); "Nikola Tesla, Dreamer" ~ An illustration for the
article shows an artist's conception of the planet splitting in two. The caption reads: "Tesla
claims that in a few weeks he could set the earth's crust into such a state of vibration that it
would rise and fall hundreds of feet and practically destroy civilization. A continuation of
this process would, he says, eventually split the earth in two."
New York Sun (July 10, 1935); "New Apparatus Transmits Energy - Tesla Announces Method
of Remote Control," .
N. Y. American (July 11, 1935), Section 2; "Tesla's Controlled Earth Quakes Power Through
the Earth, A Startling Discovery".
New York Herald Tribune (July 11, 1935), pp. 1, 8; "Tesla, at 79, Discovers New Message
Wave - At Birthday Luncheon He Announces Machine for 1-Way Communication"
New York Sun (July 11, 1935); "Nikola Tesla Describes New Invention - Art of TeleGeodynamics"
New York Times (July 11, 1935), p. 23, col. 8; "Tesla, 79, Promises to Transmit Force Transmission of Energy Over World,"
US Patent # 514,169
To all whom it may concern:
Be it known that I, Nikola Tesla, a citizen of the United States, residing at New York, in the
county and State of New York, have invented certain new and useful Improvements in
Reciprocating Engines, of which the following is a specification, reference being had to the
drawing accompanying and forming a part of the same.
In the invention which forms the subject of my present application, my object has been,
primarily to provide an engine, which under the influence of an applied force such as the
elastic tension of steam or gas under pressure will yield an oscillatory movement which,
within very wide limits, will be of constant period, irrespective of variations of load,
frictional losses and other factors which in all ordinary engines produce change in the rate of
The further objects of the invention are to provide a mechanism, capable of converting the
energy of steam or gas under pressure into mechanical power more economically than the
forms of engine heretofore used, chiefly by overcoming the losses which result in these by the
combination with rotating parts possessing great inertia of a reciprocating system; which also,
is better adapted for use at higher temperatures and pressures, and which is capable of useful
and practical application to general industrial purposes, particularly in small units.
The invention is based upon certain well known mechanical principles a statement of which
will assist in a better understanding of the nature and purposes of the objects sought and
results obtained. Heretofore, where the pressure of steam or any gas has been utilized and
applied for the production of mechanical motion it has been customary to connect with the
reciprocating or moving parts of the engine a fly-wheel or some rotary system equivalent in
its effect and possessing relatively great mechanical inertia, upon which dependence was
mainly placed for the maintenance of constant speed. This, while securing in a measure this
object, renders impossible the attainment of the result at which I have arrived, and is attended
by disadvantages which by my invention are entirely obviated. On the other hand, in certain
cases, where reciprocating engines or tools have been used without a rotating system of great
inertia, no attempt, so far as I know, has been made to secure conditions which would
necessarily yield such results as I have reached.
It is a well known principle that if a spring possessing a sensible inertia be brought under
tension, as by being stretched, and then freed it will perform vibrations which are isochronous
and, as to period, in the main dependent upon the rigidity of the spring, and its own inertia or
that of the system of which it may form an immediate part. This is known to be true in all
cases where the force which tends to bring the spring or movable system into a given position
is proportionate to the displacement.
In carrying out my invention and for securing the objects in general terms stated above, I
employ the energy of steam or gas under pressure, acting through proper mechanism, to
maintain in oscillation a piston, and, taking advantage of the law above stated, I connect with
said piston, or cause to act upon it, a spring, under such conditions as to automatically
regulate the period of the vibration, so that the alternate impulses of the power impelled
piston, and the natural vibrations of the spring shall always correspond in direction and
coincide in time.
While, in the practice of the invention I may employ any kind of spring or elastic body of
which the law or principle of operation above defined holds true, I prefer to use an air spring,
or generally speaking a confined body or cushion of elastic fluid, as the mechanical
difficulties in the use of metallic springs are serious, owing mainly, to the tendency to break.
Moreover, instead of permitting the piston to impinge directly upon such cushions within its
own cylinder, I prefer, in order to avoid the influence of the varying pressure of the steam or
gas that acts upon the piston and which might disturb the relations necessary for the
maintenance of isochronous vibration, and also to better utilize the heat generated by the
compression, to employ an independent plunder connected with the main piston, and a
chamber or cylinder therefore, containing air which is normally, at the same pressure as the
external atmosphere, for thus a spring of practically constant rigidity is obtained, but the air or
gas within the cylinder may be maintained at any pressure.
In order to describe the best manner of which I am aware in which the invention is or may be
carried into effect, I refer now to the accompanying drawing which represents in central
cross-section an engine embodying my improvements.
A is the main cylinder in which works a piston B. Inlet ports CC pass through the sides of the
cylinder, opening at the middle portion thereof and on opposite sides. Exhaust ports DD
extend through the wall of the cylinder and are formed with branches that open into the
interior of the cylinder on each side of the inlet ports and on opposite sides of the cylinder.
The piston B is formed with two circumferential grooves EF, which communicate through
openings G in the piston with the cylinder on opposite sides of said piston respectively.
I do not consider as of special importance the particular construction and arrangement of the
cylinder, the piston and the ports for controlling it, except that it is desirable that all the ports,
and more especially, the exhaust ports should be made very much larger than is usually the
case, so that no force due to the action of the steam or compressed air will tend to retard of
affect the return of the piston in either direction.
The piston B is secured to a piston rod H, which works in suitable stuffing boxes in the heads
of the cylinder A. This rod is prolonged on one side and extends through bearings V in a
cylinder I suitably mounted or supported in line with the first, and within which is a disk or
plunger J carried by the rod H.
The cylinder I is without ports of any kind and is air-tight except as a small leakage my occur
through the bearings V, which experience has shown need not be fitted with any very
considerable accuracy. The cylinder I is surrounded by a jacket K which leaves an open space
or chamber around it. The bearings V in the cylinder I, extend through the jacket K which
leaves an open space or chamber around it. The bearings V in the cylinder I, extend through
the jacket K to the outside air and the chamber between the cylinder and jacket is made steam
or air tight as by suitable packing. The main supply line L for steam or compressed air leads
into this chamber, and the two pipes that lead to the cylinder A run from the said chamber, oil
cups M being conveniently arranged to deliver oil into the said pipes for lubricating the
In the particular form of engine shown the jacket K which contains the cylinder I is provided
with a flange N by which it is screwed to the end of cylinder A. A small channel O is thus
formed which has air vents P in its sides and drip pipes Q leading out from it through which
the oil which collects in it is carried off.
To explain now the operation of the device above described. In the position of the parts
shown, or when the piston is at the middle point of its stroke, the plunger J is at the center of
the cylinder I and the air on both sides of the same is at the normal pressure of the outside
atmosphere. If a source of steam or compressed air be then connected to the inlet ports CC of
the cylinder A and a movement be imparted to the piston as by a sudden blow, the latter is
caused to reciprocate in a manner well understood. The movement of the piston in either
direction ceases when the force tending to impel it and the momentum which it has acquired
are counterbalanced by the increasing pressure of the steam or compressed air in that end of
the cylinder toward which it is moving and as in its movement the piston has shut off at a
given point, the pressure that impelled it and established the pressure that tends to return it, it
is then impelled in the opposite direction, and this action is continued as long as the requisite
pressure is applied. The movements of the piston compress and rarify the air in the cylinder I
at opposite ends of the same alternately. A forward stroke compresses the air ahead of the
plunger J and tends to drive it forward. This action of the plunger upon the air contained in
the opposite ends of the cylinder is exactly the same in principle as though a piston rod were
connected to the middle point of a coiled spring, the ends of which are connected to fixed
supports. Consequently the two chambers may be considered as a single spring. The
compressions of the air in the cylinder I and the consequent loss of energy due mainly to the
imperfect elasticity of the air, give rise to a very considerable amount of heat. This heat I
utilize by conducting the steam or compressed air to the engine cylinder through the chamber
formed by the jacket surrounding the air-spring cylinder. The heat thus taken up and used to
raise the temperature of the steam or air acting upon the piston is availed of to increase the
efficiency of the engine. In any given engine of this kind the normal pressure will produce a
stroke of determined length, and this will be increased or diminished according to the
increase of pressure above or the reduction of pressure below the normal.
In constructing the apparatus I allow for a variation in the length of stroke by giving to the
confining cylinder I of the air spring properly determined dimensions. The greater the
pressure upon the piston, the higher will be the degree of compression of the air-spring, and
the consequent counteracting force upon the plunger. The rate or period of reciprocation of
the piston, however, is no more dependent upon the pressure applied to drive it, than would
be the period of oscillation of a pendulum permanently maintained in vibration, upon the
force which periodically impels it, the effect of variations in such force being merely to
produce corresponding variations in the length of stroke or amplitude of vibration
respectively. The period is mainly determined by the rigidity of the air spring and the inertia
of the moving system, and I may therefore secure any period of oscillation within very wide
limits by properly portioning these factors, as by varying the dimensions of the air chamber
which is equivalent to varying the rigidity of the spring, or by adjusting the weight of the
moving parts. These conditions are all readily determinable, and an engine constructed as
herein described my be made to follow the principle of operation above stated and maintain a
perfectly uniform period through very much wider limits of pressure than in ordinary use it is
ever likely to be subjected to, and it may be successfully used as a prime mover wherever a
constant rate of oscillation or speed is required, provided the limits within which the forces
tending to bring the moving system to a given position are proportionate to the displacements,
are not materially exceeded. The pressure of the air confined in the cylinder when the plunger
J is in its central position will always be practically that of the surrounding atmosphere, for
while the cylinder is so constructed as not to permit such sudden escape of air as to sensibly
impair or modify the action of the air spring there will be a slow leakage of air into or out of
it around the piston rod according to the pressure therein, so that the pressure of the air on
opposite sides of the plunger will always tend to remain at that of the outside atmosphere.
As an instance of the uses to which this engine may be applied I have shown its piston rod
connected with a pawl R the oscillation of which drives a train of wheels. These may
constitute the train of a clock or of any other mechanism. The pawl R is pivoted at R’ and its
bifurcated end engages with the teeth of the ratchet wheel alternately on opposite sides of the
same, one end of the pawl at each half oscillation acting to propel the wheel forward through
the space of one tooth when it is engaged and locked by the other end on the last half of the
oscillation which brings the first end of the oscillation into position to engage with another
Another application of the invention is to move a conductor in a magnetic field for generating
electric currents, and in these and similar uses it is obvious that the characteristics of the
engine render it especially adapted for use in small sizes or units.
Having now described my invention, what I claim is: [ Claims not included here ]
US Patent # 517,900
To all whom it may concern:
Be it known that I, Nikola Tesla, a citizen of the United States, residing at New York, in the
county and State of New York, have invented certain new and useful Improvements in Steam
Engines, of which the following is a specification, reference being had to the drawing
accompanying and forming a part of the same.
Heretofore, engines, operated by the application of a force such as the elastic tension of steam
or a gas under pressure, have been provided with a flywheel, or some rotary system equivalent
in its effect and possessing relatively great mechanical inertia, which was relied upon for
maintaining a uniform speed. I have produced, however, an engine which without such
appurtenances produces, under very wide variations of pressure, load, and other disturbing
causes, an oscillating movement of constant period, and have shown and described the same
in [ US Patent # 514,169 ]. A description of the principle of the construction and mode of
operation of this device is necessary to an understanding of my present invention. When a
spring which possess a sensible inertia is brought under tension as by being stretched and then
freed it will perform vibrations which are isochronous and, as to period, in the main
dependent upon the rigidity of the spring, and its own inertia or that of the system of which it
may form an immediate part. This is known to be true in all cases where the force which
tends to bring the spring or movable system into a given position is proportionate to the
displacement. In utilizing this principle for the purpose of producing reciprocating movement
of a constant period, I employ the energy of steam or gas under pressure, acting through
proper mechanism, to maintain in oscillation a piston, and connect with it or cause to act
upon such piston a spring, preferably an air spring, under such conditions as to automatically
regulate the period of the vibration, so that the alternate impulses of the power impelled
piston and the natural vibrations of the spring shall always correspond in direction and
coincide in time. In such an apparatus it being essential that the inertia of the moving system
and the rigidity of the spring should bear certain definite relations, it is obvious that the
practicable amount of work performed by the engine, when this involves the overcoming of
inertia is a limitation to the applicability of the engine. I therefore propose, in order to secure
all the advantages of such performances as this engine is capable of, to utilize it as the means
of controlling the admission and exhaust of steam or gas under pressure in other engines
generally, but more especially those forms of engine in which the piston is free to reciprocate,
or in other words, is not connected with a flywheel or other like device for regulating or
controlling its speed.
The drawings hereto annexed illustrate devices by means of which the invention may be
carried out, Figure 1 being a central vertical section of an engine embodying my invention,
and Figure 2 a similar view of a modification of the same.
Referring to Figure 1, A designates a cylinder containing a reciprocating piston B secured to a
rod C extending through on or both cylinder heads.
DD; are steam ducts communicating with the cylinder at or near its ends and E is the exhaust
chamber or passage located between the steam ports. The piston B is provided with the usual
passages FF’ which by the movements of the piston are brought alternately into
communication with the exhaust port.
G designates a slide valve which when reciprocated admits the steam or the gas by which the
engine is driven, from the pipe G’ through the ducts DD’ to the ends of the cylinder.
The parts thus described may be considered as exemplifying any cylinder, piston and slide
valve with the proper ports controlled thereby, but the slide valve instead of being dependent
for its movement upon the piston B is connected in any manner so as to be reciprocated by the
piston rod of a small engine of constant period, constructed substantially as follows: a is the
cylinder, in which works the piston b. An inlet pipe c passes through the side of the cylinder
at the middle portion of the same. The cylinder exhausts through ports dd into a chamber d’
provided with an opening d". the piston b is provided with two circumferential grooves e,f
which communicate through openings g in the same with the cylinder chambers on opposite
sides of the piston. The special construction of this device may be varied considerably, but it
is desirable that all the ports, and more particularly, the exhaust ports be made larger than is
usually done, so that no force due to the action of the steam or compressed air in the
chambers will tend to retard or accelerate the movement of the piston in either direction. The
piston b is ecured to a rod h which extends through the cylinder heads, the lower end carrying
the slide valve above described and the upper end having secured to it a plunger j in a
cylinder I fixed to the cylinder a and in line with it. The cylinder I is without ports of any kind
and is air-tight except that leakage may occur around the piston rod which does not require to
be very close fitting, and constitutes an ordinary form of air spring.
If steam or a gas under pressure be admitted through the port c to either side of the piston b,
the latter, as will be understood, may be maintained in reciprocation, and it is free to move, in
the sense that its movement in either direction ceases only when the force tending to impel it
and the momentum which it has acquired are counterbalanced by the increasing pressure of
the steam in that end of the cylinder toward which it is moving, and as in its movement the
piston has shut off at a given point, the pressure that impelled it and established the pressure
that tends to return it, it is then impelled in the opposite direction, and this action is continued
as long as the requisite pressure is applied. The movements of the piston compress and rarify
the air in the cylinder I at opposite ends of the same alternately, and this results in the
heqating of the cylinder. But since a variation of the temperature of the air in the chamber
would affect the rigidity of the air spring, I maintain the temperature uniform as by
surrounding the cylinder I with a jacket a’ which is open to the air and filled with water.
In such an engine as that just described the normal pressure will produce a stroke of
determined length, which may be increased or diminished according to the increase of
pressure above or the reduction of pressure below the normal and due allowance is made in
constructing the engine for a variation in the length of stroke or amplitude of vibration
respectively. The period is mainly determined by the rigidity of the air spring and the inertia
of the moving system and I may therefore secure any period of oscillation within very wide
limits by properly adjusting these factors, as by varying the dimensions of the air chamber
which may be equivalent to varying the rigidity of the spring, or by adjusting the weight of the
moving parts. This latter is readily accomplished by making provision for the attachment to
the piston rod of one or more weights h’. Since the only work which the small engine has to
perform is the reciprocation of the valve attached to the piston rod, its load is substantially
uniform and its period by reason of its construction will be constant. Whatever may be the
load on the main engine therefore the steam is admitted to the cylinder at defined intervals,
and thus any tendency to a change of the period of vibration in the main engine is overcome.
The control of the main engine by the engine of constant period may be effected in other
ways --- of which Figure 2 will serve as an illustration. In this case the piston of the
controlling engine constitutes the slide valve of the main engine, so that the latter may be
considered as operated by the exhaust of the former. In the figure I have shown two cylinders
AA’ placed end to end with a piston B and B’ in each. The cylinder of the controlling engine
is formed by or in the casing intermediate to the two main cylinders but in all other essential
respects the construction and mode of operation of the controlling engine remains as
described in connection with Figure 1. The exhaust ports dd, however, constitute the inlet
ports of the cylinders AA’ and the exhaust of the latter is effected through the ports m,m
which are controlled by the pistons B and B’ respectively. The inlet port for the admission of
the steam to the controlling engine is similar to that in Figure 1 and is indicated by the dotted
circle at the center of the piston b.
An engine of the kind described possess many and important advantages. A much more
perfect regulation and uniformity of action is secured, while the engine is simple and its
weights for a given capacity is very greatly reduced. The reciprocating movement of the
piston may be converted into rotary motion or it may be utilized and applied in any other
manner desired, either directly or indirectly.
In [ US Patent # 514,169 ] I have shown and described two reciprocating engines combined in
such manner that the movement or operation of one is dependent upon and controlled by the
other. In the present case, however, the controlling engine is not designed nor adapted to
perform other work than the regulation of the period of the other, and it is moreover an engine
of defined character which has the capability of an oscillating movement of constant period.
What I claim is: [ Claims not included here ]
Top ~ Home ~ Catalog ~ Links
Nikola Tesla's Inventions
The Earthquake Machine
Apart from his work on electricity Tesla also experimented
with mechanical oscillations and invented devices that
could produce mechanical oscillations of desired
frequency. These devices became famous as "earthquake
machines", because of their ability to resonate with a
building or a large construction and produce earthquakelike effects. Resonance, either electrical or mechanical, is
a fundamental principle in Tesla's work.
Mechanical resonance is a well known physical
phenomenon. Each construction has an oscillation
frequency (also called resonant frequency), which is the
frequency the construction freely vibrates and depends on
physical parameters. An external vibration produces
driven oscillations, and when the external source frequency equals the resonant
frequency the oscillation amplitude becomes maximum, usually resulting to a
Tesla himself described an incident of
experimenting with one such device in 1887, when
he tuned to the building's frequency and a
cracking sound was heard. As he changed the
frequency the sound became more intense until
everything in his laboratory started "flying
around" and people nearby were terrified. When
he realized what was happening, and that the
police was on the way, he destroyed the device
with a hammer.
Later on, Tesla claimed that with such a device he
could split the planet, or on the other hand relieve
the stress is tectonic plates and thus avoid
There are two related patents registered by Tesla:
Patent No. 511,916 (Jan. 2, 1894) titled "Electric
Generator" and Patent No. 514,169 (Feb. 6, 1894)
titled "Reciprocating Engine".
Related interesting web sites
The Collapse of the Tacoma Narrows Bridge by Rachel Martin. A bridge
that collapsed in 1940 probably due to resonance with a light breeze.
Flying Machine | Part 2, Photos | Biography | US patents | Tesla's Ele. Car (FEVj)
Tesla's Flying Machine
"Not the airplane, the flying machine," responded Dr. Tesla.
A Tesla force field generator
the flying stove
"I am now planning aerial machines devoid of
sustaining planes, ailerons, propellers, and other
external attachments, which will be capable of
immense speeds" - Tesla's autobiography
"To a Westinghouse manager, Tesla wrote 'You
should not be at all surprised, if some day you
see me fly from New York to Colorado Springs
in a contrivance which will resemble a gas
stove and weigh as much. ... and could, if
necessary enter and depart through a window.'"
- TESLA: Man Out of Time, pg.198
Tesla Memorial Society of N.Y.
a short biography page
Tesla's Autobography on-line
Tesla intended the world to have a free,
wireless, source of power "My power generator
will be of the simplest kind -- just a big mass of
steel, copper and aluminum comprising a
stationary and rotating part, peculiarly
According to museum officials at The Nikola
Tesla museum in Belgrade, "he left sketches of
interplanetary ships. This information, however,
has not been made available to western
scholars." pg. 203
How Tesla intended to power his flying machine
"Not the airplane, the flying machine," responded Dr. Tesla." Now you have struck the
point in which I am most deeply interested--the object toward which I have been devoting
my energies for more than twenty years--the dream of my life. It was in seeking the means
of making the perfect flying machine that I developed this engine."
"Twenty years ago I believed that I would be the first man to fly; that I was on the track of
accomplishing what no one else was anywhere near reaching. I was working entirely in
electricity then and did not realize that the gasoline engine was approaching a perfection
that was going to make the airplane feasible. There is nothing new about the airplane but
its engine, you know. What I was working on twenty years ago was the wireless
transmission of electric power. My idea was a flying machine propelled by an electric
motor, with power supplied from stations on the earth. I have not accomplished this as
yet, but am confident that I will in time. [However] When I found that I had been
anticipated as to the flying machine, by men working in a different field, I began to study
the problem from other angles, to regard it as a mechanical rather than an electrical
problem. I felt certain there must be some means of obtaining power that was better than
any now in use, and by vigorous use of my gray matter for a number of years I grasped the
possibilities of the principle of the viscosity and adhesion of fluids and conceived the
mechanism of my engine."
"With a thousand horse power engine, weighing only one hundred pounds, imagine the
possibilities in automobiles, locomotives and steamships. In the space now occupied by
the engines of the Lusitania twenty-five times her 80,000 horse power could be developed,
were it possible to provide boiler capacity sufficient to furnish the necessary steam."
There is the "rub". some source of power needed to drive it.
"The flying machine of the future -- my flying machine -- will be heavier than air,
but it will not be an airplane. It will have no wings. It will be substantial, solid, stable.
You cannot have a stable airplane. The gyroscope can never be successfully applied to the
airplane, for it would give a stability that would result in the machine being torn to pieces
by the wind, just as the unprotected airplane on the ground is torn to pieces by a high
wind. My flying machine will have neither wings nor propellers. You might see it on the
ground and you would never guess that it was a flying machine. Yet it will be able to
move at will through the air in any direction with perfect safety, higher speeds than have
yet been reached, regardless of weather and oblivious of 'holes in the air' or downward
currents. It will ascend in such currents if desired. It can remain absolutely stationary in
the air even in a wind for great length of time. Its lifting power will not depend upon any
such delicate devices as the bird has to employ, but upon positive mechanical action."
"You will get stability through gyroscopes?" I asked." Through gyroscopic action
of my engine, assisted by some devices I am not yet prepared to talk about," he replied.
Dr. Tesla smiled an inscrutable smile. "All I have to say on that point is that my airship
will have neither gas bag, wings nor propellers," he said. "It is the child of my dreams,
the product of years of intense and painful toil and research. I am not going to talk about it
any further. But whatever my airship may be, here at least is an engine that will do
things that no other engine ever has done, and that is something tangible."
from the book Tesla's Engine -- A New Dimension For Power
and from "PART I" of the Tesla Turbine And Pump
chapter 20: "Flying Stove" - Margaret Cheney
"At the tremendously high speeds at which the turbine operated, averaging 35,000 rpm,
the centrifugal force was so great that it stretched the metal...
"When the manager of Westinghouse's railway and lighting division wrote asking for
details on the turbine, Tesla replid confidently that it was superior to anything in the
competition in terms of extreme lightness and high performance. Indeed, he said, he was
planning to use it in a boxlike flivver airplane."
We know that Tesla invented many things which no one else has been able
to duplicate since. He spoke of even more which he intended to do but
never got around to. There are many books written by people claiming to
have some of this, and or other, information. (And, there is a wealth of it locked
up where no one can get to it - in Belgrade, in the FBI, in the US military -- it is hard to
know. They are all very secretive about it.)
Tesla, Man of Mystery is one of those books. Along with general info. on
Tesla and a few fables, there is one diagram and enough information about
it, for us to duplicate the device. They call it the "Tesla space Drive". It may
be the heart of what Tesla said would look like flying on "a gas stove" and
is "peculiarly assembled." (above) So, here it is:
The Tesla Space Drive
The Flying Stove - Aerial Machine
Diagram from page 31 of Tesla, Man of Mystery © 1992
Chapter 4: "The Tesla Space Drive"
"The first step in developing this system is to cause
a counter-clockwise (sense chosen arbitrarily)
acceleration of the center of mass of the four
eccentrics (refer to diagram) in a circular orbit
about the X axis.
"... there is a common point about which the center
of mass of the eccentrics and the center of mass of
the device as a whole gyrate." pg.32
"The reaction to this angular acceleration is a linear
acceleration along the system axis (X) and directed
outward from the page. ... this system functions in
accordance with the right-hand rule.
... [ It will ] wobble noticeably at low thrust levels. This effect fades out, however, as the
thrust is increased."
My first observation is that it is a set of 4 spinning weights arranged on a frame "peculiarly
assembled" as Tesla said. Interesting! - It is so simple (easy & cheap!) to build, and yet, it
does something Phenomenal! The object is not spinning nor do any one of the spinning weights
match the orbit of the object (frame) and yet, the mass of the object is in orbit. Like electrons in
orbit in a stationary coil - an area in which Tesla is already famous. Instead of acceleration by
the left hand rule, now it is by the right hand rule. Even that makes sense. No one seriously
interested in a new, cheap, source of propulsion need question or dispute anything, just build it
and see if you can get it to rise up - if you can get the spinning weights, eccentrics, going fast
I have heard of 2 people working on this; one in Calif. (San Jose),
and the other in Australia (Melbourne). What they may not know is
the weight and speed needed to achieve success - see below. I found
the machine easy to build but, just guessing at the rotational speed
needed for the weights ("eccentrics") did't work for me and, just
applying whatever motors are handy hasn't worked for me yet
either. ( motors A and B above, of course ) I tried 3 or 4 before I finally
got to the current air motors and I am not sure about them) From
the information we can put together on Tesla, it looks like he
intended to use a turbine, in some way, to drive it. A turbine that
might weigh 100 lbs and produce 1,000 hp.
Well, on my most recent frame, I put 1/2 hp air motors and that may
be just barely enough, if I am lucky. I hope that if I reduce the
weights, the same motors will be able to increase in speed enough
to reach the new required speed which will now be higher.
Otherwise, I will have to find stronger motors. Like I say, guessing
is not very helpful.
Collectively, the center of orbit of the four "eccentrics" defines a circle for which
the center point is the center of mass for the frame the eccentrics are built on. The
direct approach is to build the device symmetrically about the center point: with a
top as well as a bottom. Nothing is mounted on the base. The 4 eccentrics must be
able to spin. They are mounted above the base. Everything is mounted between the
top and base plates: "...there is a common point..." which won't exist unless the unit
is symetrical. It needs a top plate to keep it as rigid and as light weight as possible
as well as symetrical. I believe whoever wrote this chapter in this book, did not
have a clear picture of Tesla's intentions, directions, for the building of this devicemotor and, who but Tesla would think of this novel, phenomenal, assembly.
An issue not mentioned is the speed requirement (of the eccentrics). The speed
needed makes things difficult. A significant motor (always a pair) will be required.
I started out using a 1,000 rpm, ele. motor, upgraded to a 1/4th hp 10,000 rpm ele.
motor, then, lastly, to a 1/2hp 22,000rpm air motor. It was not till the 2nd set of
motors that I figured out the required speed and only with the last motors that I
realized just how far short I was from producing enough power to get there.
However, just for demonstration purposes, I may not have been too far short. The
air motors were light-weight enough and powerful enough to see a reaction
occurring (more than "normal" vibrations) at only 300 to 400 rpm) but, no forward,
up, motion. None of the motors would get the system "up to speed" which I thought
was in the neighborhood of 2,000 to 10,000 rpm - depending on the amount of
weight I put on the eccentrics (see below). Because the motors did not have the
power to handle the inertia and weight of the eccentrics. I started looking at some
hydraulic motors, one of which, I believe, only weighed 2 or 3 pounds and
developed 25 hp. That I believe will be more than enough to demonstrate the
system but, a that time, my job situation changed, I moved from Phoenix to Omaha,
and all my experimenting came to a halt. I now live in Florida, near Fort
Lauderdale, and am getting restarted.
Then as now, I believe Tesla knew that turbine blades would be needed - not
angled to catch or create any air or wind - but parallel and flat so as to pass through
the air with the least resistance possible.
"We recently received a set of plans from a
former pupil * of Nikola Tesla who believes that
a space ship, ... can actually be constructed.
"He bases his plans, he told us, upon existing
files he secretly obtained shortly before Tesla's
death, and before these could be seized by the
authorities. He and Tesla had been very close
friends and had worked together on a number of
* Bloyce D. Fitzgerald is virtually the only person that this could refer to. He was
the one of two who worked with Tesla daily during the few weeks before his death.
He studied Tesla's papers, carrying them home to study every night and took them
back the next day. He had never met Tesla before and he was the one who called
the authorities upon Tesla's death and then tried to view the sealed papers two
years later. See TESLA: Man Out of Time by Margaret Cheney; pages 270-277.
Bloyce must now be 70+ (or more) years old and among the few surviving to have
studied under Tesla - over 50 years ago. Surely he did not want his name given out
because he is an old man and wants to be left alone.
In any case, anything that has been dormant for 50 years is not likely to change
now, unless it changes hands. It is likely that he realizes it will go with him to his
grave if he does not "give it to the public" before it is too late, which he has just
done. If he no longer felt any reason to hide anything, then, what is not mentioned,
is not known.
Explanation of ... what it IS, what it DOES, how it WORKS:
By Greg Smith
FORCE FIELD GENERATOR / MOTOR
The Tesla Drive
This device converts inertial energy into centrifugal acceleration which, according
to the right-hand rule, generates linear acceleration. The principal is the same for
the way that the centrifugal acceleration of electrons, in a coil, exert linear
acceleration on a metal rod placed in the center of the coil. Here, the acceleration is
exerted on the frame. An electric motor is the result of electrons in orbit; this
(protonian) motor is the result of protons, entire atoms, the entire device, in orbit.
The rotation (rpm) necessary to generate acceleration depends upon:
1. the mass of the entire device
2. the mass of the 4 rotating inertial loads, (4 masses),
3. the radius of those 4 loads (aka 4 eccentrics, 4 masses)
4. and, gravity
1. If the mass of the 4 inertial loads totals 1/10th the total mass of the entire
device, then the radius of rotation of the center of mass of the system (the
entire device) is 1/20th that of the radius of any one of the rotating loads.
(not 1/10th. This is just geometry but, I overlooked it for a time) (only 2 of
4 weights going left to right and only 2 of 4 going front to back)
2. It is the rotation of the entire system (device) that must get up enough
centrifugal acceleration to defeat gravity.
3. Examples of that acceleration are: On a 50 inch radius, something greater
than 26.5 rpm. (28+ rpm)
This can be observed with a weight on a string. With a 50" string, just swinging the weight
back and forth like a pendulum, gives the same rate of oscillation with very little, almost no,
arc as it does with significantly more - about 26.5 cycles per minute (cpm). Since there is no
energy being applied to the pendulum and it will eventually come to a rest, it is intuitive that
if there is any (constant) energy entered into the system to maintain spin, it will, be spinning
at a rate greater than 26.5 rpm, in this example, at sea level, in south Florida (where I
in my continued experimenting, I found it took about 28 rpm actually, to keep it spinning
around, not just back and forth. Keeping in mind that these results will vary, though only
very slightly, with altitude and latitude, I will say that I first performed this test in Phoenix,
Arizona and most recently at sea level - living near the beach (Atlantic ocean) in Pompano
Beach, Florida. (if you are enough closer to the poles or at a high altitude (Colorado?) do
this same experiment and compare)
if a 50" radius requires more than 26.5 rpm ( & 26.5 x 26.5 = 702 (700) )
then a 25" radius requires more than 1400^½ rpm = more than 37.44 rpm (1402)
or, in my (50") experimenting, about 28 rpm ( & 28 x 28 = 784 ) ( 784 x 2 = 1568 )
and about a 40 rpm minimum at 25" (40= 39.7 x 39.7 = 1576 ) ( 39.6 x 39.6 = 1568 )
and about a 400 rpm minimum at .25" ( 400 x 400 = 1600 ) ( 396 x 396 = 156,800 )
and about a 900 rpm minimum at .05" ( 900= 885 X 885 = 784,000 )
and about a 625 rpm minimum at .1" ( 626 X 626 = 392,000 )
and about a 2,000 rpm minimum at .01" ( 1,979 X 1,979 = 3,920,000 )
and about a 2,800 rpm minimum at .005" ( 2800 X 2800 = 7,840,000 )
Example system: If the mass of the 4 inertial loads totals about 20 oz, the total mass of the
entire device (including the moving weights) about 10 lbs, and the center of mass of each of
the 4 masses is out about 4" from its shaft, then the net radius for the system is 1/4" and the
needed speed is about 400+ rpm.
(10/16)/10 x 4" = 5/80 x 4 = 5/20 = .25"
This example is about what I have had with my most recent frame and 1/2 hp air motors.
So, I only needed about 400+ rpm
In any case, I thought we were close to 400 and maybe we were. A friend said "Something is
happening here" when it started shaking more than we thought it should have - as it got up
as much speed as we could give it.
If the same 1/2 hp motors can get up over 625rpm (.12 -> .1) by cutting the arms down
from 4" to 2", or if we can get more air pressure into the 2 air motors, which we had trouble
with, to get more power out of them, then maybe we could get it off the ground with the
equipment we have now.
Another example system: If the mass of the 4 inertial loads totals about 8 oz, the
total mass of the entire device about 10 lbs, and the center of mass of each of the
4 masses is out about 2" from its shaft, then the net radius for the system is 1/20"
and the needed speed is about 900+ rpm.
Note: the force exerted by each mass on each shaft (in pounds) is: the rotating mass (in
pounds) times the radius in inches times the RPM's squared ( rpm x rpm ) times 0.0000284
= "X" pounds of force exerted on each shaft.
my best drawing, "blueprint", of the Force Field Motor - Greg
I admit, I left out the motors in this diagram (see 1st diagram above), since there is no design specificiation for
them. They can be anything you can get ahold of. The only requirement is that they be able to get your weights
up to your needed speed.
Some information here is temporarily suspended while being enhanced. Please check back
in few weeks.
Third model, with 10,000 rpm ele. motors: Sept. 4th, 1993
The shafts and pillow blocks are also, now, aluminum alloy.
This model was fine but, the frame was just a little flimsy
( the top was removed for the purpose of the photo )
Watch 2 that are opposite each other, then the other two.
photographed on Fri., March 24th, 2006
the frame is rigid and the motors are very light weight
I made the frame taller to accomodate longer arms
and, slower speed requirements but, that was not necessary.
There is an increased strength and reduced stress benefit
to the double arms.
The radius of the earth varies from about 6357 (polar) to 6378 (equatorial)
The acceleration of gravity can be found by using a pendulum or, more
precisely, by laser timing of an object falling freely in a vacuum. The result
is about 9.8 m/s^2. It varies with latitude and elevation (and, perhaps, with
density of local rocks ex: Colorado vs. Florida).
For small amplitude oscillations, the period of the pendulum is
proportional to the square root of the length (radius) and is inversely
proportional to the square root of the acceleration of gravity.
Newton's law of universal gravitation
About fifty years after Kepler announced the laws now named after him,
Isaac Newton showed that every particle in the Universe attracts every
other with a force which is proportional to the products of their masses and
inversely proportional to the square of their separation.
If F is the force due to gravity, g the acceleration due to gravity, G the
Universal Gravitational Constant (6.67x10-11 N.m2/kg2), m the mass and r
the distance between two objects. Then
F = G m 1 m 2 / r2
Acceleration due to gravity outside the Earth
It can be shown that the acceleration due to gravity outside of a spherical
shell of uniform density is the same as it would be if the entire mass of the
shell were to be concentrated at its center.
Using this we can express the acceleration due to gravity (g') at a radius (r)
outside the earth in terms of the Earth's radius (re) and the acceleration due
to gravity at the Earth's surface (g)
g' = (re2 / r2) g
Acceleration due to gravity inside the Earth
Here let r represent the radius of the point inside the earth. The formula for
finding out the acceleration due to gravity at this point becomes:
g' = ( r / re )g
In both the above formulas, as expected, g' becomes equal to g when r = re.
a satellite orbiting at an altitude of 22,300 miles would require exactly 24 hours to orbit the
Earth's Equatorial radius = 3963 miles
so the difference in gravity at 22,300 + 3963 (r) miles is
39632 / 26,2632 = 15,705,369 / 689,745,000 = .0227692
= 2.3% of our gravity = 1/44 of our gravity here at the surface
One must get up at least about 4000 mi. just to get to where the gravity is 1/4th of our surface
gravity. Or about 9,000 mi above the surface to get to 1/10th our gravity.
Here is a July 14th 2003 depiction of many of our satelites in orbit.
The ring being those at the 22,300 mi, geostationary, distance.
— Experiments with Alternate Currents of High Potential and High Frequency —
Lecture delivered before the I.E.E., London, February, 1892.
I cannot find words to express how deeply I feel the honor of addressing some of the foremost thinkers of the
present time, and so many able scientific men, engineers and electricians, of the country greatest in scientific
The results which I have the honor to present before such a gathering I cannot call my own. There are among you
not a few who can lay better claim than myself on any feature of merit which this work may contain. I need not
mention many names which are world-known -- names of those among you who are recognized as the leaders in
this enchanting science; but one, at least, I must mention -- a name which could not bc omitted in a demonstration
of this kind. It is a name associated with the most beautiful invention ever made: it is Crookes!
When I was at college, a good time ago; I read, in a translation (for then I was not familiar with you magnificent
language), the description of his experiments on radiant matter. I read it only once in my life -- that time -- yet
every detail about that charming work I can remember this day. Few are the books, let me say, which can make
such an impression upon the mind of a student.
But if, on the present occasion, I mention this name as one of many your institution can boast of, it is because I
have more than one reason to do so. For what I have to tell you and to show you this evening concerns, in a large
measure, that same vague world which Professor Crookes has so ably explored; and, more than this, when I trace
back the mental process which led me to these advances -- which even by myself cannot be considered trifling,
since they are so appreciated by you -- I believe that their real origin, that which started me to work in this
direction, and brought me to them, after a long period of constant thought, was that fascinating little book which I
read many years ago.
And now that I have made a feeble effort to express my homage and acknowledge my indebtedness to him and
others among you, I will make a second effort, which I hope you will not find so feeble as the first, to entertain you.
Give me leave to introduce the subject in a few words.
A short time ago I had the honor to bring before our American Institute of Electrical Engineers some results then
arrived at by me in a novel line of work. I need not assure you that the many evidences which I have received that
English scientific men and engineers were interested in this work have been for me a great reward and
encouragement. I will not dwell upon the experiments already described, except with the view of completing, or
more clearly expressing, some ideas advanced by me before, and also with the view of rendering the study here
presented self-contained, and my remarks on the subject of this evening's lecture consistent.
This investigation, then, it goes without saying, deals with alternating currents, and, to be more precise, with
alternating currents of high potential and high frequency. Just in how much a very high frequency is essential for
the production of the results presented is a question which, even with my present experience, would embarrass
me to answer. Some of the experiments may be performed with low frequencies; but very high frequencies are
desirable, not only on account of the many effects secured by their use, but also as a convenient means of
obtaining, in the induction apparatus employed, the high potentials, which in their turn are necessary to the
demonstration of most of the experiments here contemplated.
Of the various branches of electrical investigation, perhaps the most interesting and immediately the most
promising is that dealing with alternating currents. The progress in this branch of applied science has been so
great in recent years that it justifies the most sanguine hopes. Hardly have we become familiar with one fact, when
novel experiences are met with and new avenues of research are opened. Even at this hour possibilities not
dreamed of before are, by the use of these currents, partly realized. As In nature all is ebb and tide, all is wave
motion, so it seems that in all branches of industry alternating currents -- electric wave motion -- will have the
One reason, perhaps, why this brand of science is being so rapidly developed is to be found in the interest which
is attached to its experimental study. We wind a simple ring of iron with coils; we establish the connections to the
generator, and with wonder and delight we note the effects of strange forces which we bring into play, which allow
us to transform, to transmit and direct energy at will. We arrange the circuits properly, and we see the mass of iron
and wires behave as though it were endowed with life, spinning a heavy armature, through invisible connections,
with great speed and power with the energy possibly conveyed from a great distance. We observe how the energy
of an alternating current traversing the wire manifests itself -- not so much in the wire as in the surrounding space
-- in the most surprising manner, taking the forms of heat, light, mechanical energy, and, most surprising of all,
even chemical affinity. All these observations fascinate us, and fill us with an intense desire to know more about
the nature of these phenomena. Each day we go to our work in the hope of discovering -- in the hope that some
one, no matter who, may find a solution of one of the pending great problems, -- and each succeeding day we
return to our task with renewed ardor; and even if we are unsuccessful, our work has not been in vain, for in these
strivings, in these efforts, we have hours of untold pleasure, and we have directed our energies to the benefit of
We may take -- at random, if you choose -- any of the many experiments which may be performed with alternating
currents; a few of which only, and by no means the mast striking, form the subject of this evening's demonstration;
they are all equally interesting, equally inciting to thought.
Here is a simple glass tube from which the air has been partially exhausted. I take hold of it; I bring my body in
contact with a wire conveying alternating currents of high potential, and the tube in my hand is brilliantly lighted. In
whatever position I may put it, wherever I may move it in space, as far as I can reach, its soft, pleasing light
persists with undiminished brightness.
Here is an exhausted bulb suspended from a single wire. Standing on an insulated support, I grasp it, and a
platinum button mounted in it is brought to vivid incandescence.
Here, attached to a leading wire is another bulb, which, as I touch its metallic socket, is filled with magnificent
colors of phosphorescent light.
Here still another, which by my fingers' touch casts a shadow-- the Crookes shadow, of the stem inside of it.
Here, again, insulated as I stand on this platform, I bring my body in contact with one of the terminals of the
secondary of this induction coil -- with the end of s wire many miles long -- and you see streams of light break forth
from its distant end, which is set in violent vibration.
Here, once more, attach these two plates of wire gauze to the terminals of the coil, I set them a distance apart, and
I set the coil to work. You may see a small spark pass between the plates. I insert a thick plate of one of the best
dielectrics between them, and instead of rendering altogether impossible, as we are used to expect, I aid the
passage of the discharge, which, as I insert the plate, merely changes in appearance and assumes the form of
Is there, I ask, can there be, a more interesting study than that of alternating currents?
In all these investigations, in all these experiments, which ate so very, very interesting, for many years past -- ever
since the greatest experimenter who lectured in this hall discovered its principle -- we have had a steady
companion, an appliance familiar to every one, a plaything once, a thing of momentous importance now -- the
induction coil. There is no dearer appliance to the electrician. From the ablest among you, I dare say, down to the
inexperienced student, to your lecturer, we all have passed many delightful hours in experimenting with the
induction coil. We have watched its play, and thought and pondered over the beautiful phenomena which it
disclosed to our ravished eyes. So well known is this apparatus, so familiar are these phenomena to every one,
that my courage nearly fails me when I think that I have ventured to address so able an audience, that I have
ventured to entertain you with that same old subject. Here in reality is the same apparatus, and here are the same
phenomena, only the apparatus is operated somewhat differently, the phenomena are presented in n different
aspect. Some of the results we find as expected, others surprise us, but all captivate our attention, for in scientific
investigation each novel result achieved may be the centre of a new departure, each novel fact learned may lead
to important developments.
Usually in operating an induction foil we have set up a vibration of moderate frequency in the primary, either by
means of an interrupter or break, or by the use of an alternator. Earlier English investigators, to mention only
Spottiswoode and J. E. H. Gordon, have used a rapid break in connection with the coil. Our knowledge and
experience of to-day enables us to see clearly why these coils under the conditions of the tests did not disclose
any remarkable phenomena, and why able experimenters failed to perceive many of the curious effects which
have since been observed.
In the experiments such as performed this evening, we operate the coil either from a specially constructed
alternator capable of giving many thousands of reversals of current per second, or, by disruptively discharging a
condenser through the primary, we set up a vibration in the secondary circuit of a frequency of many hundred
thousand or millions per second, if we so desire; and in using either of these means we enter a field as yet
It is impossible to pursue an investigation in any novel line without finally making some interesting observation or
learning some useful fact. That this statement is applicable to the subject of this lecture the many curious and
unexpected phenomena which we observe afford a convincing proof. By way of illustration, take for instance the
most obvious phenomena, those of the discharge of the induction coil.
Here is a coil which is operated by currents vibrating with extreme rapidity, obtained by disruptively discharging a
Leyden jar. It would not surprise a student were the lecturer to say that the secondary of this coil consists of a
small length of comparatively stout wire; it would not surprise him were the lecturer to state that, in spite of this, the
coil is capable of giving any potential which the best insulation of the turns is able to withstand; but although he
may be prepared, and even be indifferent as to the anticipated result, yet the aspect of the discharge of the coil
will surprise and interest him. Every one is familiar with the discharge of an ordinary coil; it need not be
reproduced here. But, by way of contrast, here is a form of discharge of a coil, the primary current of which is
vibrating several hundred thousand times per second. The discharge of an ordinary coil appears as a simple line
or band of light. The discharge of this coil appears in the form of powerful brushes and luminous streams issuing
from all points of the two straight wires attached to the terminals of the secondary (Fig. 1.) Now compare this
phenomenon which you have just witnessed with the discharge of a Holtz or Wimshurst machine -- that other
interesting appliance, so dear to the experimenter. What a difference there is between these phenomena! And yet,
had I made the necessary arrangements -- which could have been made easily, were it not that they would
interfere with other experiments -- I could have produced with this coil sparks which, had I the coil hidden from
your view and only two knobs exposed, even the keenest observer among you would find it difficult, if not
impossible, to distinguish from those of an influence or friction machine. This may be done in many ways -- for
instance, by operating the induction coil which charges the condenser from an alternating-current machine of very
low frequency, and preferably adjusting the discharge circuit so that there are no oscillations set up in it. We then
obtain in the secondary circuit, if the knobs are of the required size and properly set, a more or less rapid
succession of sparks of great intensity and small quantity, which possess the same brilliancy, and are
accompanied by the same sharp crackling sound, as those obtained from a friction or influence machine.
Another way is to pass through two primary circuits, having a common secondary, two currents of a slightly
different period, which produce in the secondary circuit sparks occurring at comparatively long intervals. But, even
with the means at hand this evening, I may succeed in imitating the spark of a Holtz machine. For this purpose I
establish between the terminals of the coil which charges the condenser a long, unsteady arc, which is periodically
interrupted by the upward current of air produced by it. To increase the current of air I place on each side of the
arc, and close to it, a large plate of mica. The condenser charged from this coil discharge into the primary circuit of
a second coil through a small air gap, which is necessary to produce a sudden rush of current through the primary.
The scheme of connections in the present experiment is indicated in Fig. 2.
G is an ordinarily constructed alternator, supplying the primary P of an induction coil, the secondary S of which
charges the condensers or jars C C. The terminals of the secondary are connected to the inside coatings of the
jars, the outer coatings being connected to the ends of the primary p p of a second induction coil. This primary p p
has a small air gap a b.
The secondary s of this coil is provided with knobs or spheres K K of the proper size and set at a distance suitable
for the experiment.
A long arc is established between the terminals A B of the first induction coil. M M are the mica plates.
Each time the arc is broken between A and B the jars are quickly charged and
discharged through the Primary p p, producing a snapping spark between the knobs K K. Upon the arc forming
between A and B the potential falls, and the jars cannot be charged to such high potential as to break through the
air gap a b until the arc is again broken by the draught.
In this manner sudden impulses, at long intervals, are produced in the primary P P, which in the secondary s give
n corresponding number of impulses of great intensity. If the secondary knobs or spheres K K are of the proper
size, the sparks show much resemblance to those of a Holtz machine. But these two effects, which to the eye
appear so very different, are only two of the many discharge phenomena. We only need to change the conditions
of the test, and again we make other observations of interest.
When, instead of operating the induction coil as in the last two experiments, we operate it from a high frequency
alternator, as in the next experiment, a systematic study of the phenomena is rendered mud•1 more easy. In such
case, in varying the strength and frequency of the currents through the primary, we may observe five distinct forms
of discharge, which I have described in my former paper on the subject* before the American Institute of Electrical
Engineers, May 20, 1891.
It would take too much time, and it would lead us too far from the subject presented this evening, to reproduce all
these forms, but it seems to me desirable to show you one of them. It is a brush discharge, which is interesting in
more than one respect. Viewed from a near position it resembles much a jet of gas escaping under great pressure.
We know that the phenomenon is due to the agitation of the molecules near the terminal, and we anticipate that
some heat must be developed by the impact of the molecules against the terminal or against each other. Indeed,
we find that the brush is hot, and only a little thought leads us to the conclusion that, could we but reach
sufficiently high frequencies, we could produce a brush which would give intense light and heat, and which would
resemble in every particular an ordinary flame, save, perhaps, that both phenomena might not be due to the same
agent -- save, perhaps, that chemical affinity might not be electrical in its nature.
As the production of heat and light is here due to the impact of the molecules, or atoms of air, or something else
besides, and, as we can augment the energy simply by raising the potential, we might, even with frequencies
obtained from a dynamo machine, intensify the action to such a degree as to bring the terminal to melting heat.
But with such low frequencies we would have to deal always with something of the nature of an electric current. If I
approach a conducting object to the brush, a thin little spark passes, yet, even with the frequencies used this
evening, the tendency to spark is not very great. So, for instance, if I hold a metallic sphere at some distance
above the terminal you may see the whole space between the terminal and sphere illuminated by the streams
without the spark passing; and with the much higher frequencies obtainable by the disruptive discharge of a
condenser, were it not for the sudden impulses, which are comparatively few in number, sparking would not occur
even at very small distances. However, with incomparably higher frequencies, which we may yet find means to
produce efficiently, and provided that electric impulses of such high frequencies could be transmitted through a
conductor, the electrical characteristics of the brush discharge would completely vanish -- no spark would pass, no
shock would be felt -- yet we would still have to deal with an electric phenomenon, but in the broad, modern
interpretation of the word. In my first paper before referred to I have pointed out the curious properties of the
brush, and described the best manner of producing it, but I have thought it worth while to endeavor to express
myself more clearly in regard to this phenomenon, because of its absorbing interest.
* See The Electrical World, July 11, 1891.
When a coil is operated with currents of very high frequency, beautiful brush effects may be produced, even if the
coil be of comparatively small dimensions. The experimenter may vary them in many ways, and, if it were nothing
else, they afford a pleasing sight. What adds to their interest is that they may be produced with one single terminal
as well as with two -- in fact, often better with one than with two.
But of all the discharge phenomena observed, the most pleasing to the eye, and the most instructive, are those
observed with a coil which is operated by means of the disruptive discharge of a condenser. The power of the
brushes, the abundance of the sparks, when the conditions are patiently adjusted, is often amazing. With even a
very small coil, if it be so well insulated as to stand a difference of potential of several thousand volts per turn, the
sparks may be so abundant that the whole coil may appear a complete mass of fire.
Curiously enough the sparks, when the terminals of the coil are set at a considerable distance, seem to dart in
every possible direction as though the terminals were perfectly independent of each other. As the sparks would
soon destroy the insulation it is necessary to prevent them. This is best done by immersing the coil in a good liquid
insulator, such as boiled-out oil. Immersion in a liquid may be considered almost an absolute necessity for the
continued and successful working of such a coil.
It is, of course, out of the question, in an experimental lecture, with only a few minutes at disposal for the
performance of each experiment, to show these discharge phenomena to advantage, as to produce each
phenomenon at its best a very careful adjustment is required. But even if imperfectly produced, as they are likely
to be this evening, they are sufficiently striking to interest an intelligent audience.
Before showing some of these curious effects I must, for the sake of completeness, give a short description of the
coil and other apparatus used in the experiments with the disruptive discharge this evening.
It is contained in a box B (Fig. 3) of thick boards of hard wood, coveted on the outside with zinc sheet Z, which is
carefully soldered all around. It might be advisable, in a strictly scientific investigation, when accuracy is of great
importance, ~o do away with the metal covet, as it might introduce many errors, principally on account of its
complex action upon the coil, as a condenser of very small capacity and as an electrostatic and electromagnetic
screen. When the coil is used for such experiments as are here contemplated, the employment of the metal cover
offers some practical advantages, but these are not of sufficient importance to be dwelt upon.
The coil should be placed symmetrically to the metal cover, and the space between should, of course, not be too
small, certainly not less than, say, five centimeters, but much more if possible; especially the two sides of the zinc
box, which are at right angles to the axis of the coil, should be sufficiently remote from the latter, as otherwise they
might impair its action and be a source of loss.
The coil consists of two spools of hard rubber R R held apart at a distance of 10 centimetres by bolts c and nuts n,
likewise of hard rubber. Each spool comprises a tube T of approximately 8 centimetres inside diameter, and 3
millimetres thick, upon which are screwed two flanges F F, 24 centimetres square, the space between the flanges
being about 3 centimetres. The secondary, S S, of the best gutta percha-covered wire, has 26 layers, 10 turns in
each, giving for each half a total of 260 turns. The two halves are wound oppositely and connected in series, the
connection between both being made over the primary. This disposition besides being convenient, has the
advantage that when the coil is well balanced -- that is, when both of its terminals T1 T1 are connected to bodies
or devices of equal capacity -- there is not much danger of breaking through to the primary, and the insulation
between the primary and the secondary need not be thick. In using the coil it is advisable to attach to both
terminals devices of nearly equal capacity, as, when the capacity of the terminals is not equal, sparks will be apt to
pass to the primary. To avoid this, the middle point of the secondary may be connected to the primary, but this is
not always practicable.
The primary P P is wound in two parts, and oppositely, upon a wooden spool W, and the four ends are led out of
the oil through hard rubber tubes t t. The ends of the secondary T1 T1 are also led out of the oil through rubber
tubes tl tl of great thickness. The primary and secondary layers are insulated by cotton cloth, the thickness of the
insulation, of course, bearing some proportion to the difference of potential between the turns of the different
layers. Each half of the primary has four layers, 24 turns in each, this giving a total of 96 turns. When both the
parts are connected in series, this gives a ratio of conversion of about 1:2.7, and with the primaries in multiple,
1:5,4 but in operating with very rapidly alternating currents this ratio does not convey even an approximate idea of
the ratio of the E.M.Fs. in the primary and secondary circuits. The coil is held in position in the oil on wooden
supports, there being about 5 centimetres thickness of oil all round. Where the oil is not specially needed, the
space is filled with pieces of wood, and for this purpose principally the wooden box B surrounding the whole is
The construction here shown is, of course, not the best on general principles, but I believe it is a good and
convenient one for the production of effects in which are excessive potential and a very small current are needed.
In connection with the coil I use either the ordinary form of discharger or a modified form. In the former I have
introduced two changes which secure some advantages, and which are obvious. If they are mentioned, it is only in
the hope that some experimenter may find them of use.
One of the changes is that the adjustable knobs A and B (Fig. 4), of the discharger are held in jaws of brass, J J,
by spring pressure, this allowing of turning them successively into different positions, and so doing away with the
tedious process or frequent polishing up.
The other change consists in the employment of a strong electromagnet N S, which is placed with its axis at right
angles to the line joining the knobs A and B, and produces a strong magnetic field between them. The pole pieces
of the magnet are movable and properly formed so as to protrude between the brass knobs, in order to make the
as intense as possible; but to prevent the discharge from jumping to thc magnet the pole pieces are protected by a
layer of mica, M M, of sufficient thickness. sl sl and s2 s2 are screws for fastening the wires. On each side one of
the screws is for large and the other for small wires. L L are screws for fixing in position the rods R R, which
support the knobs.
In another arrangement with the magnet I take the discharge between the rounded pole pieces themselves, which
in such case are insulated and preferably provided with polished brass caps.
The employment of an intense magnetic field is of advantage principally when the induction coil or transformer
which charges the condenser is operated by currents of very low frequency. In such a case the number of the
fundamental discharges between the knobs may be so small as to render the currents produced in the secondary
unsuitable for many experiments. The intense magnetic field than serves to blow out the arc between the knobs as
soon as it is formed, and the fundamental discharges occur in quicker succession.
Instead of the magnet, a draught or blast of air may be employed with some advantage. In this case the arc is
preferably established between the knobs A B, in Fig. 2 (the knobs a b being generally joined, or entirely done
away with), as in this disposition the arc is long and unsteady, and is easily affected by the draught.
When a magnet is employed to break the arc, it is better to choose the connection indicated diagrammatically in
Fig 5, as in this case the currents forming the arc are much more powerful, and the magnetic field exercises a
greater influence. The use of the magnet permits, however, of the arc being replaced by a vacuum tube, but I have
encountered great difficulties in working with an exhausted tube.
The other form of discharger used in these and similar experiments is indicated in Figs. 6 and 7. It consists of a
number of brass pieces c c (Fig. 6), each of which comprises a spherical middle portion m with an extension e
below -- which is merely used to fasten the piece in a lathe when polishing up the discharging surface -- and a
column above, which consists of a knurled flange f surmounted by a threaded stem I carrying a nut n, by means of
which a wire is fastened to the column. The flange f
conveniently serves for holding the brass piece when fastening the wire, and also for turning it in any position
when it becomes necessary to present a fresh discharging surface. Two stout strips of hard rubber R R, with
g g (Fig. 7) to fit the middle portion of the pieces c c, serve to clamp the latter and hold them firmly in position by
means of two bolts C C (of which only one is shown) passing through the ends of the strips.
In the use of this kind of discharger I have found three principal advantages over the ordinary form. First, the
dielectric strength of a given total width of air space is greater when a great many small air gaps are used instead
of one, which permits of working with a smaller length of air gap, and that means smaller loss and less
deterioration of the metal; secondly by reason of splitting the arc up into smaller arcs, the Polished surfaces are
made to last much longer; and, thirdly, the apparatus affords some gauge in the experiments. I usually set the
pieces by putting between them sheets of uniform thickness at a certain very small distance which is known from
the experiments of Sir William Thomson to require a certain electromotive force to be bridged by the spark.
It should, of course, be remembered that the sparking distance is much diminished as the frequency is increased.
By taking any number of spaces the experimenter has a rough idea of the electromotive force, and he finds it
easier to repeat an experiment, as he has not the trouble of setting the knobs again and again. With this kind of
discharger I have been able to maintain an oscillating motion without any spark being visible with the naked eye
between the knobs, and they would not show a very appreciable rise in temperature. This form of discharge also
lends itself to many arrangements of condensers and circuits which are often very convenient and timesaving. I
have used it preferably in a disposition similar to that indicated in Fig. 2, when the currents forming the arcs are
I may here mention that I have also used dischargers with single or multiple air gaps, in which the discharge
surfaces were rotated with great speed. No particular advantage was, however, gained by this method, except in
cases where the currents from the condenser were large and the keeping cool of the surfaces was necessary, and
in cases when, the discharge not being oscillating of itself, the arc as soon as established was broken by the air
current, thus starting the vibration at intervals in rapid succession. I have also used mechanical interrupters in
many ways. To avoid the difficulties with frictional contacts, the Preferred plan adopted was to establish the arc
and rotate through it at great speed a rim of mica provided with many holes and fastened to a steel plate.
It is understood, of course, that the employment of a magnet, air current, or other interrupter, produces an effect
worth noticing, unless the self-induction, capacity and resistance are so related that there are oscillations set up
upon each interruption.
I will now endeavor to show you some of the most noteworthy of these discharge phenomena.
I have stretched across the room two ordinary cotton covered wires, each about 7 metres in length. They are
supported on insulating cords at a distance of about 30 centimetres. I attach now to each of the terminals of the
coil one of the wires and set the coil in action. Upon turning the lights off in the room you see the wires strongly
illuminated by the streams issuing abundantly from their whole surface in spite of the cotton covering, which may
even be very thick. When the experiment is performed under good conditions, the light from the wires is
sufficiently intense to allow distinguishing the objects in a room. To produce the best result it is, of course,
necessary to adjust carefully the capacity of the jars, the arc between the knobs and the length of the wires. My
experience is that calculation of the length of the wires leads, in such case, to no result whatever. The
experimenter will do best to take the wires at the start very long, and then adjust by cutting off first long pieces,
and then smaller and smaller ones as he approaches the right length.
A convenient way is to use an oil condenser of very small capacity, consisting of two small adjustable metal plates,
in connection with this and similar experiments. In such case I take wires rather short and set at the beginning the
condenser plates at maximum distance. If the streams for the wires increase by approach of the plates, the length
of the wires is about right; if they diminish the wires are too long for that frequency and potential. When a
condenser is used in connection with experiments with such a coil, it should be an oil condenser by all means, as
in using an air condenser considerable energy might be wasted. The wires leading to the plates in the oil should
be very thin, heavily coated with some insulating compound, and provided with n conducting covering -- this
preferably extending under the surface of the oil. The conducting cover should not be too near the terminals, or
ends, of the wire, as a spark would be apt to jump from the wire to it. The conducting coating is used to diminish
the air losses, in virtue of its action as an electrostatic screen. As to the size of the vessel containing the oil and
the site of the plates, the experimenter gains at once an idea from a rough trial. The size of the plates in oil is,
however, calculable, as the dielectric losses are very small.
In the preceding experiment it is of considerable interest to know what relation the quantity of the light emitted
bears to the frequency and potential of the electric impulses. My opinion is that the heat as well as light effects
produced should be proportionate, under otherwise equal conditions of test, to the product of frequency and
square of potential, but the experimental verification of the law, whatever it may be, would be exceedingly difficult.
One thing is certain, at any rate, and that is, that in augmenting the potential and frequency we rapidly intensify
the streams; and, though it may be very sanguine, it is surely not altogether hopeless to expect that we may
succeed in producing a practical illuminant on these lines. We would then be simply using burners or flames, in
which there would be no chemical process, no consumption of material, but merely a transfer of energy, and which
would, in all probability emit more light and less heat than ordinary flames.
The luminous intensity of the streams is, of course, considerably increased when they are focused upon a small
surface. This may be shown by the following experiment:
I attach to one of the terminals of the coil a wire w (Fig. 8), bent in a circle of about 30 centimetres in diameter, and
to the other terminal I fasten a small brass sphere s, the surface of the wire being preferably equal to the surface
of the sphere, and the centre of the latter being in a line at right angles to the plane of the wire circle and passing
through its centre. When the discharge is established under proper conditions, a luminous hollow cone is formed,
and in the dark one-half of the brass sphere is strongly illuminated, as shown in the cut.
By some artifice or other, it is easy to concentrate the streams upon small surfaces and to produce very strong
light effects. Two thin wires may thus be rendered intensely luminous. In order to intensify the streams, the wires
should be very thin and short; but as in this case their capacity would be generally too small for the coil - at least,
for such a one as the present -- it is necessary to augment the capacity to the required value, while, al the same
time, the surface of the wires remains very small. This may be done in many ways.
Here, for instance, I have two plates R R, of hard rubber (Fig. 9), upon which I have glued two very thin wires w w,
so as to form a name. The wires may be bare or covered with the best insulation -- it is immaterial for the success
of the experiment. Well-insulated wires, if anything, are preferable. On the back of each plate, indicated by the
shaded portion, is a tinfoil coating t t. The plates are placed in line at a sufficient distance to prevent a spark
passing from one to the other wire. The two tinfoil coatings I have joined by a conductor C, and the two wires I
presently connect to the terminals of the coil. It is now easy, by varying the strength and frequency of the currents
through the primary, to find a point at which the capacity of the system is best suited to the conditions, and the
wires become so strongly luminous that, when the light in the room is turned off the name formed by them appears
in brilliant letters.
It is perhaps preferable to perform this experiment with a coil operated from an alternator of high frequency, as
then, owing to the harmonic rise and fall, the streams are very uniform, though they are less abundant than when
produced with such a coil as the present. This experiment, however, may be performed with low frequencies, but
much less satisfactorily.
When two wires, attached to the terminals of the coil, are set at the proper distance, the streams between them
may be so intense as to produce a continuous luminous sheet. To show this phenomenon I have here two circles,
C and c (Fig. 10), of rather stout wire, one being about 80 centimetres and the other 30 centimetres in diameter.
To each of the terminals of the coil I attach one of the circles. The supporting wires are so bent that the circles
may be placed in the same plane, coinciding as nearly as possible. When the light in the room is turned off and
the coil set to work, you see the whole space between the wires uniformly filled with streams, forming a luminous
disc, which could be seen from a considerable distance, such is the intensity of the streams. The outer circle could
have been much larger than the present one; in fact, with this coil I have used much larger circles, and I have
been able to produce a strongly luminous sheet, covering an area of more than one square metre, which is a
remarkable effect with this very small coil. To avoid uncertainty, the circle has been taken smaller, and the area is
how about 0,43 square metre.
The frequency of the vibration, and the quickness of succession of the sparks between the knobs, affect to a
marked degree the appearance of the streams. When the frequency is very low, the air gives way in more or less
the same manner, as by a steady difference of potential, and the streams consist of distinct threads, generally
mingled with thin sparks, which probably correspond to the successive discharges occurring between the knobs.
But when the frequency is extremely high, and the arc of the discharge produces a very loud but smooth sound -showing both that oscillation takes place and that the sparks succeed each other with great rapidity -- then the
luminous streams formed are perfectly uniform. To reach this result very small coils and jars of small capacity
should be used. I take two tubes of thick Bohemian glass, about 5 centimetres in diameter and 20 centimetres
long. In each of the tubes I slip a primary of very thick copper wire. On the top of each tube I wind a secondary of
much thinner gutta-percha covered wire. The two secondaries I connect in series, the primaries preferably in
multiple arc. The tubes are then placed in a large glass vessel, at a distance of l0 to 15 centimetres from each
other, on insulating supports, and the vessel is filled with boiled out oil, the oil reaching about an inch above the
tubes. The free ends of the secondary are lifted out of the oil and placed parallel to each other at a distance of
about 10 centimetres. The ends which are scraped should be dipped in the oil. Two four-pint jars joined in series
may be used to discharge through the primary. When the necessary adjustments in the length and distance of the
wires above the oil and in the arc of discharge are made, a luminous sheet is produced between the wires, which
is perfectly smooth and textureless, like the ordinary discharge through a moderately exhausted tube.
I have purposely dwelt upon this apparently insignificant experiment. In trials of this kind the experimenter arrives
at the startling conclusion that, to pass ordinary luminous discharges through gases, no particular degree of
exhaustion is needed, but that the gas may be at ordinary or even greater pressure. To accomplish this, a very
high frequency is essential; a high potential is likewise required, but this is a merely incidental necessity. These
experiments teach us that, in endeavoring to discover novel methods of producing light by the agitation of atoms,
or molecules, of a gas, we need not limit our research to the vacuum tube, but may look forward quite seriously to
the possibility of obtaining the light effects without the use of any vessel whatever, with air at ordinary pressure.
Such discharges of very high frequency, which render luminous the air at ordinary pressures, we have probably
often occasion to witness in Nature. I have no doubt that if, as many believe, the aurora borealis is produced by
sudden cosmic disturbances, such as eruptions at the sun's surface, which set the electrostatic charge of the earth
in an extremely rapid vibration the red glow observed is not confined to the upper rarefied strata of the air, but the
discharge traverses, by reason of its very high frequency, also the dense - atmosphere in the form of a glow, such
as we ordinarily produce in a slightly exhausted tube. If the frequency were very low or even more so, if the charge
were not at all vibrating, the dense air would break down as in a lightning discharge. Indications of such breaking
down of the lower dense strata of the air have been repeatedly observed at the occurrence of this marvelous
phenomenon; but if it does occur; it can only be attributed to thc fundamental disturbances, which are few in
number, for the vibration produced by them would be far too rapid to allow a disruptive break. It is the original and
irregular impulses which affect the instruments; the superimposed vibrations probably pass unnoticed.
When an ordinary low frequency discharge is passed through moderately rarefied air, the air assumes a purplish
hue. If by some means or other we increase the intensity of the molecular, or atomic, vibration, the gas changes to
a white color. A similar change occurs at ordinary pressures with electric impulses of very high frequency. If the
molecules of the air around a wire are moderately agitated, the brush formed is reddish or violet; if the vibration is
rendered sufficiently intense, the streams become white. We may accomplish this in various ways. In the
experiment before shown with the two wires across the room, I have endeavored to secure the result by pushing to
a high value both the frequency and potential; in the experiment with the thin wires glued on the rubber plate I
have concentrated the action upon a very small surface -- in other words, I have worked with a great electric
A most curious form of discharge is observed with such a coil when the frequency and potential are pushed to the
extreme limit. To perform the experiment, every part of the coil should be heavily insulated, and only two small
spheres -- or, better still, two sharp-edged metal discs (d d, Fig. 11) of no mote than a few centimetres in diameter
-- should be exposed to the air. The coil here used immersed in oil, and the ends of the secondary reaching out of
the oil are covered with an airtight cover of hard rubber of great thickness. All cracks, if there are any, should be
carefully stopped up, so that the brush discharge cannot form anywhere except on the small spheres or plates
which are exposed to the air. In this case, since there are no large plates or other bodies of capacity attached to
the terminals, the coil is capable of an extremely rapid vibration. The potential may be raised by increasing, as far
as the experimenter judges proper, the rate of change of the primary current. With a coil not widely differing from
the present, it is best to connect the two primaries in multiple arc; but if the secondary should have a much greater
number of turns the primaries should preferably be used in series, as otherwise the vibration might be too fast for
the secondary. It occurs under these conditions that misty white streams break forth from the edges of the discs
and spread out phantom-like into space. With this coil, when fairly well produced, they are about 25 to 30
centimetres long. When the hand is held against them no sensation is produced, and a spark, causing a shock,
jumps from the terminal only upon the hand being brought much nearer. If the oscillation of the primary current is
rendered intermittent by some means or other, there is a corresponding throbbing of the streams, and now the
hand or other conducting object may be brought in still greater proximity to the terminal without a spark being
caused to jump.
Among the many beautiful phenomena which may be produced with such a coil I have here selected only those
which appear to possess some features of novelty, and lead us to some conclusions of interest. One will not find it
at all difficult to produce in the laboratory, by means of it, many other phenomena which appeal to the eye even
more than these here shown, but present no particular feature of novelty.
Early experimenters describe the display of sparks produced by an ordinary large induction coil upon an insulating
plate separating the terminals. Quite recently Siemens performed some experiments in which fine effects were
obtained, which were seen by many with interest. No doubt large coils, even if operated with currents of low
frequencies, are capable of producing beautiful effects. But the largest coil ever made could not, by far, equal the
magnificent display of streams and sparks obtained from such a disruptive discharge coil when properly adjusted.
To give an idea, a coil such as the present one will cover easily a plate of 1 metre in diameter completely with the
streams. The best way to perform such experiments is to take a very thin rubber or a glass plate and glue on one
side of it a narrow ring of tinfoil of very large diameter, and on the other a circular washer, the centre of the latter
coinciding with that of the ring, and the surfaces of both being preferably equal, so as to keep the coil well
balanced. The washer and ring should be connected to the terminals by heavily insulated thin wires. It is easy in
observing the effect of the capacity to produce a sheet of uniform streams, or a fine network of thin silvery threads,
or a mass of loud brilliant sparks, which completely cover the plate.
Since I have advanced the idea of the conversion by means of the disruptive discharge, in my paper before the
American Institute of Electrical Engineers at the beginning of the past year, the interest excited in it has been
considerable. It affords us a means for producing any potentials by the aid of inexpensive coils operated from
ordinary systems of distribution, and -- what is perhaps more appreciated-- it enables us to convert currents of any
frequency into currents of any other lower or higher frequency. But its chief value will perhaps be found in the help
which it will afford us in the investigations of the phenomena of phosphorescence, which a disruptive discharge
coil is capable of exciting in innumerable cases where ordinary coils, even the largest, would utterly fail.
Considering its probable uses for many practical purposes, and its possible
introduction into laboratories for scientific research, a few additional remarks as to the construction of such a coil
will perhaps not be found superfluous.
It is, of course, absolutely necessary to employ in such a coil wires provided with the best insulation.
Good coils may be produced by employing wires covered with several layers of cotton, boiling the coil a long time
in pure wax, and cooling under moderate pressure. The advantage of such a coil is that it can be easily handled,
but it cannot probably give as satisfactory results as a coil immersed in pure oil. Besides, it seems that the
presence of a large body of wax affects the coil disadvantageously, whereas this does not seem to be the case
with oil. Perhaps it is because the dielectric losses in the liquid are smaller.
I have tried at first silk and cotton covered wires with oil immersion; but I have been gradually led to use guttapercha covered wires, which proved most satisfactory. Gutta-percha insulation adds, of course, to the capacity of
the coil, and this, especially if the coil be large, is a great disadvantage when extreme frequencies are desired;
but, on the other hand, gutta-percha will withstand much more than an equal thickness of oil, and this advantage
should be secured at any price. Once the coil has been immersed, it should never be taken out of the oil for more
than a few hours, else the gutta-percha will crack up and the coil will not be worth half as much as before. Guttapercha is probably slowly attacked by the oil, but after an immersion of eight to nine months I have found no ill
I have obtained in commerce two kinds of gutta-percha wire: in one the insulation sticks tightly to the metal, in the
other it does not. Unless a special method is followed to expel all air, it is much safer to use the first kind. I wind
the coil within an oil tank so that all interstices are filled up with the oil. Between the layers I use cloth boiled out
thoroughly in oil, calculating the thickness according to the difference of potential between the turns. There seems
not to be a very great difference whatever kind of oil is used; I use paraffin or linseed oil.
To exclude more perfectly the air, an excellent way to proceed, and easily practicable with small coils, is the
following: Construct a box of hard wood of very thick boards which have been for a long time boiled in oil. The
boards should be so joined as to safely withstand the external air pressure. The coil being placed and fastened in
position within the box, the latter is closed with a strong lid, and covered with closely fitting metal sheets, the joints
of which are soldered very carefully. On the top two small holes are drilled, passing through the metal sheet and
the wood, and in these holes two small glass tubes are inserted and the joints made air-tight. One of the tubes is
connected to a vacuum pump and the other with a vessel containing a sufficient quantity of boiled-out oil. The
latter tube has a very small hole at the bottom, and is provided with a stopcock. When a fairly good vacuum has
been obtained, the stopcock is opened and the oil slowly fed in. Proceeding in this manner, it is impossible that
any big bubbles, which are the principal danger, should remain between the turns. The air is most completely
excluded, probably better than by boiling out, which, however, when gutta-percha coated wires are used, is not
For the primaries I use ordinary line wire with thick cotton coating. Strands of very thin insulated wires properly
interlaced would, of course, be the best to employ for the primaries, but they are not to be had.
In an experimental coil the size of the wires is not of great importance. In the coil here used the primary is No, 12
and the secondary No. 24 Brown & Sharpe gauge wire; but the sections maybe varied considerably. I would only
imply different adjustments; the results aimed at would not be materially affected.
I have dwelt at some length upon the various forms of brush discharge because, in studying them, we not only
observe phenomena which please our eye, but also afford us food for thought, and lead us to conclusions of
practical importance. In the use of alternating currents of very high tension, too much precaution cannot be taken
to prevent the brush discharge. In a main conveying such currents, in an induction coil or transformer, or in a
condenser, the brush discharge is a source of great danger to the insulation. In a condenser especially the
gaseous matter must be most carefully expelled, for in it the charged surfaces are near each other, and if the
potentials are high, just as sure as a weight will fall if let go, so the insulation will give way if a single gaseous
bubble of some site be present, whereas, if all gaseous matter were carefully excluded, the condenser would
safely withstand a much higher difference of potential. A main conveying alternating currents of very high tension
may be injured merely by a blowhole or small crack in the insulation, the more so as a blowhole is apt to contain
gas at low pressure; and as it appears almost impossible to completely obviate such little imperfections, I am led
to believe that in our future distribution of electrical energy by currents of very high tension liquid insulation will be
used. The cost is a great drawback, but if we employ an oil as an insulator the distribution of electrical energy with
something like 100,000 volts, and even more, become, at least with higher frequencies, so easy that they could be
hardly called engineering feats. With oil insulation and alternate current motors transmissions of power can be
effected with safety and upon an industrial basis at distances of as much as a thousand miles.
A peculiar property of oils, and liquid insulation in general, when subjected to rapidly changing electric stresses, is
to disperse any gaseous bubbles whid•1 may be present, and diffuse them through its mass, generally long before
any injurious break can occur. This feature may be easily observed with an ordinary induction coil by taking the
primary out, plugging up the end of the tube upon which the secondary is wound, and fining it with some fairly
transparent insulator, such as paraffin oil. A primary of s diameter something like six millimetres smaller than the
inside of the tube may be inserted in the oil. When the coil is set to work one may see, looking from the top
through the oil, many luminous points -- air bubbles which are caught by inserting the primary, and which ate
rendered luminous in consequence of the violent bombardment. The occluded air, by its impact against the oil,
beats it; the oil begins to circulate, carrying some of the air along with it, until the bubbles are dispersed and the
luminous points disappear. In this manner, unless large bubbles are occluded in such way that circulation is
rendered impossible, a damaging break is averted, the only effect being a moderate warming up of the oil. If,
instead of the liquid, a solid insulation, no matter how thick, were used, a breaking through and injury of the
apparatus would be inevitable.
The exclusion of gaseous matter from any apparatus in which the dielectric is subjected to more or less rapidly
changing electric forces is, however, not only desirable in order to avoid a possible injury of the apparatus, but
also on account of economy. In a condenser, for instance, as long as only a solid or only a liquid dielectric is used,
the loss is small; but if a gas under ordinary or small pressure be present the loss may be very great. Whatever
the nature of the force acting in the dielectric may be, it seems that in a solid or liquid the molecular displacement
produced by the force is small: hence the product of force and displacement is insignificant, unless the force be
very great; but in a gas the displacement, and, therefore, this product is considerable; the molecules are free to
move, they reach high speeds, and the energy of their impact is lost in heat or otherwise. If the gas be strongly
compressed, the displacement due to the force is made smaller, and the losses are reduced.
In most of the succeeding experiments I prefer, chiefly on account of the regular and positive action, to employ the
alternator before referred to. This is one of the several machines constructed by me for the purposes of these
investigations. It has 384 pole projections, and is capable of giving currents of a frequency of about 10,000 per
second. This machine has been illustrated and briefly described in my first paper before the American Institute of
Electrical Engineers, May 20, 1831, to which I have already referred. A more detailed description, sufficient to
enable any engineer to build a similar machine, will be found in several electrical journals of that period.
The induction coils operated from the machine are rather small, containing from 5,000 to 15,000 turns in the
secondary. They are immersed in boiled-out linseed oil, contained in wooden boxes covered with zinc sheet.
I have found it advantageous to reverse the usual position of the wires, and to wind, in these coils, the primaries
on the top; this allowing the use of a much bigger primary, which, of course, reduces the danger of overheating
and increases the output of the coil. I make the primary on each side at least one centimetre shorter than the
secondary, to prevent the breaking through on the ends, which would surely occur unless the insulation on the top
of the secondary be very thick, and this, of course, would be disadvantageous.
When the primary is made movable, which is necessary in some experiments, and many times convenient for the
purposes of adjustment, I cover the secondary with wax, and turn it off in a lathe to a diameter slightly smaller than
the inside of the primary coil. The latter I provide with a handle reaching out of the oil, which serves to shift it in
any position along the secondary.
I will now venture to make, in regard to the general manipulation of induction coils, a few observations bearing
upon points which have not been fully appreciated in earlier experiments with such coils, and are even now often
The secondary of the coil possesses usually such a high self-induction that the current through the wire is
inappreciable, and may be so even when the terminals ate joined by a conductor of small resistance. If capacity is
added to the terminals, the self-induction is counteracted, and a stronger current is made to flow through the
secondary, though its terminals are insulated from each other. To one entirely unacquainted with the properties of
alternating currents nothing will look more puzzling. This feature was illustrated in the experiment performed at the
beginning with the top plates of wire gauze attached to the terminals and the rubber plate. When the plates of wire
gauze were close together, and a small arc passed between them, the arc prevented a strong current from passing
through the secondary, because it did away with the capacity on the terminals; when the rubber plate was inserted
between, the capacity of the condenser formed counteracted the self-induction of the secondary, a stronger
current passed now, the coil performed more work, and the discharge was by far more powerful.
The first thing, then, in operating the induction coil is to combine capacity with the secondary to overcome the selfinduction. If the frequencies and potentials are very high gaseous matter should be carefully kept away from the
charged surfaces. If Leyden jars are used, they should be immersed in oil, as otherwise considerable dissipation
may occur if the jars are greatly strained. When high frequencies are used, it is of equal importance to combine a
condenser with the primary. One may use a condenser connected to the ends of the primary or to the terminals of
the alternator, but the latter is not to be recommended, as the machine might be injured. The best way is
undoubtedly to use the condenser in series with the primary and with the alternator, and to adjust its capacity so
as to annul the self-induction of both the latter. The condenser should be adjustable by very small steps, and for a
finer adjustment a small oil condenser with movable plates may be used conveniently.
I think it best at this juncture to bring before you a phenomenon, observed by me some time ago, which to the
purely scientific investigator may perhaps appear more interesting than any of the results which I have the
privilege to present to you this evening.
It may be quite properly ranked among the brush phenomena -- in fact, it is a brush, formed at, or near, a single
terminal in high vacuum.
In bulbs provided with a conducting terminal, though it be of aluminium, the brush has but an ephemeral existence,
and cannot, unfortunately, be indefinitely preserved in its most sensitive state, even in a bulb devoid of any
conducting electrode. In studying one phenomenon, by all means a bulb having no leading-in wire should be used.
I have found it best to use bulbs constructed as indicated in Figs. 12 and 13.
In Fig. 12 the bulb comprises an incandescent lamp globe L, in the neck of which is sealed a barometer tube 6, the
end of which is blown out to form a small sphere s. This sphere should be sealed as closely as possible in the
centre of the large globe. Before sealing, a thin tube t, of aluminium sheet, may be slipped in the barometer tube,
but it is not important to employ it.
The small hollow sphere s is filled with some conducting powder, and a wire w is cemented in the neck for the
purpose of connecting the conducting powder with the generator.
The construction shown in Fig. 13 was chosen in order to remove from the brush any conducting body which might
possibly affect it. The bulb consists in this case of a lamp globe L, which has a neck n, provided with a tube b and
small sphere s, sealed to it, so that two entirely independent compartments are formed, as indicated in the
drawing. When the bulb is in use, the neck n is provided with a tinfoil coating, which is connected to the generator
and acts inductively upon the moderately rarefied and highly conducting gas enclosed in the neck. From there the
current passes through the tube b into the small sphere s, to act by induction upon the gas contained in the globe
It is of advantage to make the tube t very thick, the hole through it very small, and to blow the sphere s very thin. It
is of the greatest importance that the sphere J be placed in the centre of the globe L.
Figs. 14, 15 and 16 indicate different forms, or stages, of the brush. Fig. 14 shows the brush as it first appears in a
bulb provided with a conducting terminal: but, as in such a bulb it very soon disappears -- often after a few minutes
-- I will confine myself to the description of the phenomenon as seen in a bulb without conducting electrode. It is
observed under the following conditions:
When the globe L (Figs. 12 and 13) is exhausted to a very high degree, generally the bulb is not excited upon
connecting the wire w (Fig. 12) or the tinfoil coating of the bulb (Fig. 13) to the terminal of the induction coil. To
excite it, it is usually sufficient to grasp the globe L with the hand. An intense phosphorescence then spreads at
first over the globe, but soon gives place to a white, misty light. Shortly afterward one may notice that the
luminosity is unevenly distributed in the globe, and after passing the current for some time the bulb appears as in
Fig. 15. From this stage the phenomenon will gradually pass to that indicated in Fig. 16, after some minutes,
hours, days or weeks, according as the bulb is worked. Warming the bulb or increasing the potential hastens the
When the brush assumes the form indicated in Fig. 16, it may be brought to a state of extreme sensitiveness to
electrostatic and magnetic influence. The bulb hanging straight down from a wire, and all objects being remote
from it, the approach of the observer at a few paces from the bulb will cause the brush to fly to the opposite side,
and if he walks around the bulb it will always keep on the opposite side. It may begin to spin around the terminal
long before it reaches that sensitive stage. When it begins to turn around principally, but also before, it is affected
by a magnet and at a certain stage it is susceptible to magnetic influence to an astonishing degree. A small
permanent magnet, with its poles at a distance of no more than two centimetres, will affect it visibly at a distance of
two metres, slowing down or accelerating the rotation according to how it is held relatively to the brush. I think I
have observed that at the stage when it is most sensitive to magnetic, it is not most sensitive to electrostatic,
influence. My explanation is, that the electrostatic attraction between the brush and the glass of the bulb, which
retards the rotation, grows much quicker than the magnetic influence when the intensity of the stream is increased.
When the bulb hangs with the globe L down, the rotation is always clockwise. In the southern hemisphere it would
occur in the opposite direction and on the equator the brush should not turn at all. The rotation may be reversed
by a magnet kept at some distance. The brush rotates best, seemingly, when it is at right angles to the lines of
force of the earth. It very likely rotates, when at its maximum speed, in synchronism with the alternations, say
10,000 times a second. The rotation can be slowed down or accelerated by the approach or receding of the
observer or any conducting body, but it cannot be reversed by putting the bulb in any position. When it is in the
state of the highest sensitiveness and the potential or frequency be varied the sensitiveness is rapidly diminished.
Changing either of these but little will generally stop the rotation. The sensitiveness is likewise affected by the
variations of temperature. To attain great sensitiveness it is necessary to have the small sphere s in the centre of
the globe L, as otherwise the electrostatic action of the glass of the globe will tend to stop the rotation. The sphere
s should be small and of uniform thickness; any dissymmetry of course has the effect to diminish the
The fact that the brush rotates in a definite direction in a permanent magnetic field seems to show that in
alternating currents of very high frequency the positive and negative impulses are not equal, but that one always
preponderates over the other.
Of course, this rotation in one direction may be due to the action of two elements of the same current upon each
other, or to the action of the field produced by one of the elements upon the other, as in a series motor, without
necessarily one impulse being stronger than the other. The fact that the brush turns, as far as I could observe, in
any position, would speak for this view. In such case it would turn at any point of the earth's surface. But, on the
other hand, it is then hard to explain why a permanent magnet should reverse the rotation, and one must assume
the preponderance of impulses of one kind.
As to the causes of the formation of the brush or stream, I think it is due to thc electrostatic action of the globe and
the dissymmetry of the parts. If the small bulb s and the globe L were perfect concentric spheres, and the glass
throughout of the same thickness and quality, I think the brush would not form, as the tendency to pass would be
equal on all sides. That the formation of the stream is due to an irregularity is apparent from the fact that it has the
tendency to remain in one position, and rotation occurs most generally only when it is brought out of this position
by electrostatic or magnetic influence. When in an extremely sensitive state it rests in one position, most curious
experiments may be performed with it. For instance, the experimenter may, try selecting a proper position,
approach the hand at a certain considerable distance to the bulb, and he may cause the brush to pass off by
merely stiffening the muscles of the arm. When it begins to rotate slowly, and the hands are held at a proper
distance, it is impossible to make even the slightest motion without producing a visible effect upon the brush. A
metal plate connected to the other terminal of the coil affects it at a great distance, slowing down the rotation often
to one turn a second.
I am firmly convinced that such a brush, when we learn how to produce it properly, will prove a valuable aid in the
investigation' of the nature of the forces acting in 2n electrostatic or magnetic field. If there is any motion which is
measurable going on in the space, such a brush ought to reveal it. It is, so to speak, a beam of light, frictionless,
devoid of inertia.
I think that it may find practical applications in telegraphy. With such a brush it would be possible to send
dispatches across the Atlantic, for instance, with any speed, since its sensitiveness may be so great that the
slightest changes will affect it. If it were possible to make the stream more intense and very narrow, its deflections
could be easily photographed.
I have been interested to find whether there is a rotation of the stream itself, or whether there is simply a stress
traveling around in the bulb. For this purpose I mounted a light mica fan so that its vanes were in the path of the
brush. If the stream itself was rotating the fan would be spun around. I could produce no distinct rotation of the fan,
although I tried the experiment repeatedly; but as the fan exerted a noticeable influence on the stream, and the
apparent rotation of the latter was, in this case, never quite satisfactory, the experiment did not appear to be
I have been unable to produce the phenomenon with the disruptive discharge coil, although every other of these
phenomena can be tell produced by it -- many, in fact, much better than with coils operated from an alternator.
It may be possible to produce the brush by impulses of one direction, or even by a steady potential, in which case
it would be still more sensitive to magnetic influence.
In operating an induction coil with rapidly alternating currents, we realize with astonishment, for the first time, the
great importance of the relation of capacity, self-induction and frequency as regards the general result. The effects
of capacity are the most striking, for in these experiments, since the self-induction and frequency both are high,
the critical capacity is very small, and need be but slightly varied to produce a very considerable change. The
experimenter may bring his body in contact with the terminals of the secondary of the coil, or attach to one or both
terminals insulated bodies of very small bulk, such as bulbs, and he may produce a considerable rise or fall of
potential, and greatly affect the flow of the current through the primary. In the experiment before shown, in which a
brush appears at a wire attached to one terminal, and the wire is vibrated when the experimenter brings his
insulated body in contact with the other terminal of the coil, the sudden rise of potential was made evident.
I may show you the behavior of the coil in another manner which possesses a feature of some interest. I have here
a little light fan of aluminium sheet, fastened to a needle and arranged to rotate freely in a metal piece screwed to
one of the terminals of the coil. When the coil is set to work, the molecules of the air are rhythmicallv attracted and
repelled. As the force with which they are repelled is greater than that with which they are attracted, it results that
there is repulsion exerted on the surfaces of the fan. If the fan were made simply of a metal sheet, the repulsion
would be equal on the opposite sides, and would produce no effect. But if one of the opposite surfaces is
screened, or if, generally speaking, the bombardment on this side is weakened in some wag or other, there
remains the repulsion exerted upon the other, and the fan is set in rotation. The screening is best effected by
fastening upon one of the opposing sides of the fan insulated conducting coatings, or, if the fan is made in the
shape of an ordinary propeller screw. by fastening on one side, and close to it, an insulated metal plate. The static
screen may however, be omitted and simply a thickness of insulating material fastened to one of the sides of the
To show the behavior of the coil, the fan may be placed upon the terminal and it will readily rotate when the coil is
operated by currents of very high frequency. With a steady potential, of course, and even with alternating currents
of very low frequency, it would not turn, because of the very slow exchange of air and, consequently, smaller
bombardment; but in the latter case it might turn if the potential were excessive. With a pin wheel, quite the
opposite rule holds good; it rotates best with a steady potential, and the effort is the smaller the higher the
frequency. Now, it is very easy to adjust the conditions so that the potential is normally not sufficient to turn the
fan, but that by connecting the other terminal of the coil with an insulated body it rises to a much greater value, so
as to rotate the fan, and it is likewise possible to stop the rotation by connecting to the terminal a body of different
size, thereby diminishing the potential.
Instead of using the fan in this experiment, we may use the "electric" radiometer with similar effect. But in this case
it will be found that the vanes will rotate only at high exhaustion or at ordinary pressures; they will not rotate at
moderate pressures, when the air is highly conducting. This curious observation was made conjointly by Professor
Crookes and myself. I attribute the result to the high conductivity of the air, the molecules of which then do not act
as independent carriers of electric charges, but act all together as a single conducting body. In such case, of
course, if there is any repulsion at all of the molecules from the vanes, it must be very small. It is possible,
however, that the result is in part due to the fact that the greater part of the discharge passes from the leading-in
wire through the highly conducting gas, instead of passing off from the conducting vanes.
In trying the preceding experiment with the electric radiometer the potential should not exceed a certain limit, as
then the electrostatic attraction between the vanes and the glass of the bulb may be so great as to stop the
A most curious feature of alternate currents of high frequencies and potentials is that they enable us to perform
many experiments by the use of one wire only. In many respects this feature is of great interest.
In a type of alternate current motor invented by me some years ago I produced rotation by inducing, by means of a
single alternating current passed through a motor circuit, in the mass or other circuits of the motor, secondary
currents, which, jointly with the primary or inducing current, created n moving field of force. A simple but crude
form of such a motor is obtained by winding upon an iron core a primary, and close to it a secondary coil, joining
the ends of the latter and placing a freely movable metal disc within the influence of the field produced by both.
The iron core is employed for obvious reasons, but it is not essential to the operation. To improve the motor, the
iron core is made to encircle the armature. Again to improve, the secondary coil is made to overlap partly the
primary, so that it cannot free itself from a strong inductive action of thc latter, repel its lines as it may. Once more
to improve, the proper difference of phase is obtained between the primary and secondary currents by a
condenser, self-induction, resistance or equivalent windings.
I had discovered, however, that rotation is produced by means of a single coil and cote; my explanation of the
phenomenon, and leading thought in trying the experiment, being that there must be a true time lag in the
magnetization of the core. I remember the pleasure I had when, in the writings of Professor Ayrton, which came
later to my hand, I found the idea of the time lag advocated. Whether there is a true time lag, whether the
retardation is due to eddy currents circulating in minute paths, must remain an open question, but the fact is that a
coil wound upon an iron core and traversed by an alternating current creates a moving field of force, capable of
setting an armature: in rotation- It is of some interest, in conjunction with the historical Arago experiment, to
mention that in lag or phase motors I have produced rotation in the opposite direction to the moving field, which
means that in that experiment the magnet may not rotate, or may even rotate in the opposite direction to the
moving disc. Here, then, is a motor (diagrammatically illustrated in Fig. 17), comprising a coil and iron core, and a
freely movable copper disc in proximity to the latter.
To demonstrate a novel and interesting feature, I have, for a reason which I will explain, selected this type of
motor. When the ends of the coil are connected to the terminals of an alternator the disc is set in rotation. But it is
not this experiment, now well known, which I desire to perform. What I wish to show you is that this motor rotates
with one single connection between it and the generator; that is to say, one terminal of the motor is connected to
one terminal of the generator -- in this case the secondary of a high-tension induction coil -- the other terminals of
motor and generator being insulated in space. To produce rotation it is generally (but not absolutely) necessary to
connect the free end of the motor coil to an insulated body of some size. The experimenter's body is more than
sufficient. If he touches the free terminal with an object held in the
hand, a current passes through the coil and the copper disc is set in rotation. If an exhausted tube is put in series
with the coil, the tube lights brilliantly, showing the passage of a strong current. Instead of the experimenter's
body, a small metal sheet suspended on a cord may be used with the same result. In this case the plate acts as a
condenser in series with the coil. It counteracts the self-induction of the latter and allows a strong current to pass.
In such a combination, the greater the self-induction of the coil the smaller need be the plate, and this means that
a lower frequency, or eventually a lower potential, is required to operate the motor. A single coil wound upon a
core has a high self-induction; for this reason principally, this type of motor was chosen to perform the experiment.
Were a secondary closed coil wound upon the core, it would tend to diminish the self-induction, and then it would
be necessary to employ a much higher frequency and potential. Neither would be advisable, for a higher potential
would endanger the insulation of the small primary coil, and a higher frequency would result in a materially
It should be remarked that when such a motor with a closed secondary is used, it is not at all easy to obtain
rotation with excessive frequencies, as the secondary cuts off almost completely the lines of the primary -- and
this, of course, the more, the higher the frequency -- and allows the passage of but a minute current. In such a
case, unless the secondary is closed through a condenser, it is almost essential, in order to produce rotation, to
make the primary and secondary coils overlap each other more or less.
But there is an additional feature of interest about this motor, namely, it is not necessary to have even a single
connection between the motor and generator, except, perhaps, through the ground; for not only is an insulated
plate capable of giving off energy into space, but it likewise capable of deriving it from an alternating electrostatic
field, though in the latter case the available energy is much smaller. In this instance one of the motor terminals is
connected to the insulated plate or body located within the alternating electrostatic field, and the other terminal
preferably to the ground.
It is quite possible, however, that such "no-wire" motors, as they might be called, could be operated by conduction
through the rarefied air at considerable distances. Alternate currents, especially of high frequencies, pass with
astonishing freedom through even slightly rarefied gases. The upper strata of the air are rarefied. To reach a
number of miles out into space requires the overcoming of difficulties of a merely mechanical nature. There is no
doubt that with the enormous potentials obtainable by the Use of high frequencies and oil insulation luminous
discharges might be passed through many miles of rarefied air, and that, by thus directing the energy of many
hundreds or thousands of horse-power, motors or lamps might be operated at considerable distances from
stationary sources. But such schemes are mentioned merely as possibilities. We shall have no need to transmit
power at all. Ere many generations pass, our machinery will be driven by a power obtainable at any point of the
universe. This idea is not novel. Men have been led to it long ago by instinct or reason; it has been expressed in
many ways, and in many places, in the history of old and new. We find it in the delightful myth of Antheus, who
derives power from the earth; we find it among the subtile speculations of one of your splendid mathematicians
and in many hints and statements of thinkers of the present time. Throughout space there is energy. Is this energy
static or kinetic! If static our hopes are in vain; if kinetic -- and this we know it is, for certain - then it is a mere
question of time when men will succeed in attaching their machinery to the very wheelwork of nature. Of all, living
or dead, Crookes came nearest to doing it. His radiometer will turn in the light of day and in the darkness of the
night; it will turn everywhere where there is heat, and heat is everywhere. But, unfortunately, this beautiful little
machine, while it goes down to posterity as the most interesting, must likewise be put on record as the most
inefficient machine ever invented!
The preceding experiment is only one of many equally interesting experiments which may be performed by the use
of only one wire with alternate currents of high potential and frequency. We may connect an insulated line to a
source of such currents, we may pass an inappreciable current over the line, and on any point of the same we are
able to obtain a heavy current, capable of fusing a thick copper wire. Or we may, by the help of some artifice,
decompose a solutic4n in any electrolytic cell by connecting only one pole of the cell to the line or source of
energy. Or we may, by attaching to the line, or only bringing into its vicinity, light up an incandescent lamp, an
exhausted tube, or ~ phosphorescent bulb.
However impracticable this plan of working may appear in many cases, it certainly seems practicable, and even
recommendable, in the production of light. A perfected lamp would require but little energy, and if wires were used
at all we ought to be able to supply that energy without a return wire.
It is now a fact that a body may be rendered incandescent or phosphorescent b) bringing it either in single contact
or merely in the vicinity of a source of electric impulses of the proper character, and that in this manner a quantity
of light sufficient to afford a practical illuminant may be produced. It is, therefore, to say the least, worth while to
attempt to determine the best conditions and to invent the best appliances for attaining this object.
Some experiences have already been gained in this direction, and I will dwell on them briefly, in the hope that they
might prove useful.
The heating of a conducting body inclosed in a bulb, and connected to a source of rapidly alternating electric
impulses, is dependent on so many things of a different nature, that it would be difficult to give a generally
applicable rule under which this maximum heating occurs. As regards the size of the vessel, I have lately found
that at ordinary or only slightly differing atmospheric pressures, when air is a good insulator, and hence practically
the same amount of energy by a certain potential and frequency is given off from the body, whether the bulb be
small or large, the body is brought to a higher temperature if inclosed in a small bulb, because of the better
confinement of heat in this case.
At lower pressures, when air becomes more or less conducting, or if the air be sufficiently warmed as to become
conducting, the body is rendered more intensely incandescent in a large bulb, obviously because, under otherwise
equal conditions of test, more energy may be given off from the body when the bulb is large.
At very high degrees of exhaustion, when the matter in the bulb becomes "radiant", a large bulb has still an
advantage, but a comparatively slight one, over the small bulb. Finally, at excessively high degrees of exhaustion,
which cannot be reached except by the employment of special means, there seems to be, beyond a certain and
rather small size of vessel, no perceptible difference in the heating.
These observations were the result of a number of experiments, of which one, showing the effect of the size of the
bulb at a high degree of exhaustion may be described and shown here, as it presents a feature of interest. Three
spherical bulbs of 2 inches, 3 inches and 4 inches diameter were taken, and in the centre of each was mounted an
equal length of an ordinary incandescent lamp filament of uniform thickness. In each bulb the piece of filament
was fastened to the leading-in wire of platinum, contained in a glass stem sealed in the bulb; care being taken, of
course, to make everything as nearly alike as possible. On each glass stem in the inside of the bulb was slipped a
highly polished tube made of aluminiun sheet, which fitted the stem and was held on it by spring pressure. The
function of this aluminium tube will be explained subsequently. In each bulb an equal length of filament protruded
above the metal tube. It is sufficient to say now that under these conditions equal lengths of filament of the same
thickness -- in other words, bodies of equal bulk --- were brought to incandescence. The three bulbs were sealed
to a glass tube, which was connected to a Sprengel pump. When a high vacuum had been reached, the glass tube
carrying the bulbs was sealed off. A current was then turned on successively on each bulb, and it was found that
the filaments came to about the same brightness, and, if anything, the smallest bulb, which was placed midway
between the two larger ones, may have been slightly brighter. This result was expected, for when either of the
bulbs was connected to the coil the luminosity spread through the other two, hence the three bulbs constituted
really one vessel. When all the three bulbs were connected in multiple arc to the coil, in the largest of them the
filament glowed brightest, in the next smaller it was a little less bright, and in the smallest it only came to redness.
The bulbs were then sealed off and separately tried. The brightness of the filaments was now such as mould have
been expected on the supposition that the energy given off was proportionate to the surface of the bulb, this
surface in each case representing one of the coatings of a condenser. Accordingly, there was less difference
between the largest and the middle sited than between the latter and the smallest bulb.
An interesting observation was made in this experiment. The three bulbs were suspended from a straight bare wire
connected to a terminal of the coil, the largest bulb being placed at the end of the wire, at some distance from it
the smallest bulb, and an equal distance from the latter the middle-sized one. The carbons glowed then to both the
larger bulbs about as expected, but the smallest did not get its share by far. This observation led me to exchange
thc position of the bulbs, and I then observed that whichever of the bulbs was in the middle it was by far less bright
than it was in any other position. This mystifying result was, of course, found to be due to the electrostatic action
between the bulbs. When they were placed at a considerable distance, or when they were attached to the corners
of an equilateral triangle of copper wire, they glowed about in the order determined by their surfaces.
As to the shape of the vessel, it is also of some importance, especially at high degrees of exhaustion. Of all the
possible constructions, it seems that a spherical globe with the refractory body mounted in its centre is the best to
employ. In experience it has been demonstrated that in such a globe a refractory body of a given bulk is more
easily brought to incandescence than when otherwise shaped bulbs are used. There is also an advantage in
giving to the incandescent body the shape of a sphere, for self-evident reasons. In any case the body should be
mounted in the centre, where the atoms rebounding from the glass collide. This object is best attained in the
spherical bulb; but it is also attained in a cylindrical vessel with one or two straight filaments coinciding with its
axis, and possibly also in parabolical or spherical bulbs with the refractory body or bodies placed in the focus or
foci of the same; though the latter is not probable, as the electrified atoms should in all cases rebound normally
from the surface they strike, unless the speed were excessive, in which case they would probably follow the
general law of reflection. No matter what shape the vessel may have, if the exhaustion be low, a filament mounted
in the globe is brought to the same degree of incandescence in all parts; but if the exhaustion be high and the bulb
be spherical or pear-shaped, as usual, focal points form and the filament is heated to a higher degree at or near
To illustrate the effect, I have here two small bulbs which are alike, only one is exhausted to a low and the other to
a very high degree. When connected to the coil, the filament in the former glows uniformly throughout all its
length; whereas in the latter, that portion of the filament which is in the centre of the bulb glows far more intensely
than the rest. A curious point is that the phenomenon occurs even if two filament: are mounted in a bulb, each
being connected to one terminal of the coil, and, what is still more curious, if they be very near together, provided
the vacuum be very high. I noted in experiments with such bulbs that the filaments would give way usually at a
certain point, and in the first trials I attributed it to a defect in the carbon. But when that phenomenon occurred
many times in succession I recognized its real cause.
In order to bring a refractory body inclosed in a bulb to incandescence, it is desirable, on account of economy, that
all the energy supplied to the bulb from the source should reach without lass the body to be heated; from there,
and from nowhere else, it should be radiated. It is, of course, out of the question to reach this theoretical result,
but it is possible by a proper construction of the illuminating device to approximate it more or less.
For many reasons, the refractory body is placed in the centre of the bulb and it is usually supported on a glass
stem containing the leading-in wire. As the potential of this wire is alternated, the rarefied gas surrounding the
stem is acted upon inductively, and the glass stem is violently bombarded and heated. In this manner by far the
greater portion of the energy supplied to the bulb -- especially when exceedingly high frequencies are used -- may
be lost for the purpose contemplated. To obviate this loss, or at least to reduce it to a minimum, I usually screen
the rarefied gas surrounding the stem from the inductive action of the leading-in wire by providing; the stem with a
tube or coating of conducting material. It seems beyond doubt that the best among metals to employ for this
purpose is aluminium, on account of its many remarkable properties. Its only fault is that it is easily fusible and,
therefore, its distance from the incandescing: body should be properly estimated. Usually, a thin tube, of a
diameter somewhat smaller than that of the glass stem, is made of the finest aluminium sheet, and slipped on the
stem. The tube is conveniently prepared by wrapping around a rod fastened in a lathe a piece of aluminium sheet
of the proper size, grasping the sheet firmly with clean chamois leather or blotting paper, and spinning the rod very
fast. The sheet is wound tightly around the rod, and a highly polished tube of one or three layers of the sheet is
obtained. When slipped on the stem, the pressure is generally sufficient to prevent it from slipping off, but, for
safety, the lower edge of the sheet may be turned inside. The upper inside corner of the sheet -- that is, the one
which is nearest to the refractory incandescent body -- should be cut out diagonally, as it often happens that, in
consequence of the intense heat, this corner turns toward the inside and comes very near to, or in contact with,
the wire, or filament, supporting the refractory body. The greater part of the energy supplied to the bulb is then
used up in heating the metal tube, and the bulb is rendered useless for the purpose. The aluminium sheet should
project above the glass stem more or less -- one inch or so -- or else, if the glass be too close to the incandescing
body, it may be strongly heated and become more or less conducting, whereupon it may be ruptured, or may, by
its conductivity, establish a good electrical connection between the metal tube and the leadinq-in wire, in which
case, again, most of the energy will be lost in heating the former. Perhaps the best way is to make the top of the
glass tube for about an inch, of a much smaller diameter. To still further reduce the danger arising from the
heating of the glass stem, and also with the view of preventing an electrical connection between the metal tube
and the electrode, I preferably wrap; the stem with several layers of thin mica which extends at least as far as the
metal tube. In some bulbs I have also used an outside insulating cover.
The preceding remarks are only made to aid the experimenter in the first trials, for the difficulties which he
encounters he may soon find means to overcome in his own way.
To illustrate the effect of the screen, and the advantage of using it, I have here two bulbs of the same size, with
their stems, leading-in wires and incandescent lamp filaments tied to the latter, as nearly alike as possible. The
stem of one bulb is provided with an aluminium tube, the stem of the other has none. Originally the two bulbs were
joined by a tube which was connected to a Sprengel pump. When a high vacuum had been reached, first the
connecting tube, and then the bulbs, were sealed off; they are therefore of the same degree of exhaustion. When
they are separately connected to the coil giving a certain potential, the carbon filament in the bulb provided with
the aluminium screen in rendered highly incandescent, while the filament in the other bulb may, with the same
potential, not even come to redness, although in reality the latter bulb takes generally more energy than the
former. When they are both connected together to the terminal, the difference is even more apparent, showing the
importance of the screening. The metal tube placed in the stem containing the leading-in wire performs really two
distinct functions: First, it acts more or less as an electrostatic screen, thus economizing the energy supplied to the
bulb; and, second, to whatever extent it may fail to act electrostatically, it acts mechanically, preventing the
bombardment, and consequently intense heating and possible deterioration of the slender support of the refractory
incandescent body, or of the glass stem containing the leading-in wire. I say slender support, for it is evident that
in order to confine the heat more completely to the incandescing body its support should be very thin, so as to
carry away the smallest possible amount of heat by conduction. Of all the supports used I have found an ordinary
incandescent lamp filament to be the best, principally because among conductors it can withstand the highest
degrees of heat.
The effectiveness of the metal tube as an electrostatic screen depends largely on the degree of exhaustion.
At excessively high degrees of exhaustion -- which are reached by using great care and special means in
connection with the Sprengel pump -- when the matter in the globe is in the ultra-radiant state, it acts most
perfectly. The shadow of the upper edge of the tube is then sharply defined upon the bulb.
At a somewhat lower degree of exhaustion, which is about the ordinary "nonstriking" vacuum, and generally as long as the matter moves predominantly in straight lines, the screen still does
well. In elucidation of the preceding remark it is necessary to state that what is a "non-striking" vacuum for a coil
operated, as ordinarily, by impulses, or currents, of low frequency, is not, by far, so when the coil is operated by
currents of very high frequency. In such case the discharge may pass with great freedom through the rarefied gas
through which a low-frequency discharge may not pass, even though the potential be much higher. At ordinary
atmospheric pressures just the reverse rule holds good: the higher the frequency, the less the spark discharge is
able to jump between the terminals, especially if they are knobs or spheres of some site. Finally, at very low
degrees of exhaustion, when the gas is well conducting, the metal tube not only does not act as an electrostatic
screen, but even is a drawback, aiding to a considerable extent the dissipation of the energy laterally from the
leading-in wire. This, of course, is to be expected. In this case, namely, the metal tube is in good electrical
connection with -the leading-in wire, and most of the bombardment is directed upon the tube. As long as the
electrical connection is not good, the conducting tube is always of some advantage for although it may not greatly
economize energy, still it protects the support of the refractory button, and is a means for concentrating more
energy upon the same.
To whatever extent the aluminium tube performs the function of a screen, its usefulness is therefore limited to very
high degrees of exhaustion when it is insulated from the electrode - that is, when the gas as a whole is nonconducting, and the molecules, or atoms, act as independent carriers of electric charges.
In addition to acting as a more or less effective screen, in the true meaning of the word, the conducting tube or
coating may also act, by reason of its conductivity, as a sort of equalizer or dampener of the bombardment against
the stem. To be explicit, I assume the action as follows: Suppose a rhythmical bombardment to occur against the
conducting tube by reason of its imperfect action as a screen, it certainly must happen that some molecules, or
atoms, strike the tube sooner than others. Those which come first in contact with it give up their superfluous
charge, and the tube is electrified, the electrification instantly spreading over its surface. But this must diminish,
the energy lost in the bombardment for two reasons: first, the charge given up by the atoms spreads over a great
area, and hence the electric density at any point is small, and the atoms are rebelled with less energy than they
would be if they would strike against a good insulator; secondly, as the tube is electrified by the atoms which first
come in contact with it, the progress of the following atoms against the tube is more or less checked by, the
repulsion which the electrified tube must exert upon the similarly electrified atoms. This repulsion may perhaps be
sufficient to prevent a large portion of the atoms from striking the tube, but at any rate it must diminish the energy
of their impact. It is clear that when the exhaustion is very low, and the rarefied gas well conducting, neither of the
above effects can occur, and, on the other hand, the fewer the atoms, with the greater freedom they move; in other
words, the higher the degree of exhaustion, up to a limit, the more telling will be both the effects:
What I have just said may afford an explanation of the phenomenon observed by Prof. Crookes, namely, that a
discharge through a bulb is established with much greater facility when an insulator than when a conductor is
present in the same. In my opinion, the conductor acts as a dampener of the motion of the atoms in the two ways
pointed out; hence, to cause a visible discharge to pass through the bulb, a much higher potential is needed if a
conductor, especially of many surfaces, be present.
For the sake of clearness of some of the remarks before made, I must now refer to Figs. 18, 19, and 20, which
illustrate various arrangements with a type of bulb most generally used.
Fig. l8 is a section though a spherical bulb L, with the glass stem s, containing the leading-in wire w, which has a
lamp filament 1 fastened to it, serving to support the refractory button m in the centre. M is a sheet of thin mica
wound in several layers around the stem s, and a is the aluminium tube.
Fig. l9 illustrates such a bulb in a somewhat more advanced stage of perfection. A metallic tube S is fastened by
means of some cement to the neck of the tube. In the tube is screwed a plug P, of insulating material, in the centre
of which is fastened a metallic terminal t, for the connection to the lead-in wire w. This terminal must be well
insulated from the metal tube S, therefore, if the cement used is conducting and most generally it is sufficiently so
-- the space between the plug P and the neck of the bulb should be filled with some good insulating material, as
Fig. 20 shows a bulb made for experimental purposes. In this bulb the aluminium tube is provided with an external
connection, which serves to investigate the effect of the tube under various conditions. It is referred to chiefly to
suggest a line of experiment followed.
Since the bombardment against the stem containing the leading-in wire is due to the inductive action of the latter
upon the rarefied gas, it is of advantage to reduce this action as far as practicable by employing a very thin wire,
surrounded by a very thick insulation of glass or other material, and by making the wire passing through the
rarefied gas as short as practicable. To combine these features I employ a large tube T (Fig. 21), which protrudes
into the bulb to some distance, and carries on the top a very short glass stem s, into which is sealed the leading-in
wire w, and I protect the top of the glass stem against the heat by a small, aluminium tube a and a layer of mica
underneath the same, as usual. The wire w, passing through the large tube to the outside of the bulb, should be
well insulated -- with a glass tube, for instance -- and the space between ought to be filled out with some excellent
insulator. Among many insulating powders I have tried, I have found that mica powder is the best to employ. If this
precaution is not taken, the tube T, protruding into the bulb, will surely be cracked in consequence o~ the heating
by the brushes which are apt to form in the upper part of the tube, near the exhausted globe, especially if the
vacuum be excellent, and therefore the potential necessary to operate the lamp very high.
Fig. 22 illustrates a similar arrangement, with a large tube T protruding into the part of the bulb containing the
refractory button m. In this case the wire leading from the outside into the bulb is omitted, the energy required
being supplied through condenser coatings C C. The insulating packing P should in this construction be tightly
fitting to the glass, and rather wide, or otherwise the discharge might avoid passing through the wire w, which
connects the inside condenser coating to the incandescent button m.
The molecular bombardment against the glass stem in the bulb is a source of great trouble. As illustration I will cite
a phenomenon only too frequently and unwillingly observed. A bulb, preferably a large one, may be taken, and a
good conducting body, such as a piece of carbon, may be mounted in it upon a platinum wire sealed in thc glass
stem. The bulb may be exhausted to a fairly high degree, nearly to the point when phosphorescence begins to
appear. When the bulb is connected with the coil, the piece of carbon, if small, may become highly incandescent
at first, but its brightness immediately diminishes, and then the discharge may break through the glass somewhere
in the middle of the stem, in the form of bright sparks, in spite of the fact that the platinum wire is in good electrical
connection with the rarefied gas through the piece of carbon or metal at the top. The first sparks are singularly
bright, recalling those drawn from a clear surface of mercury. But, as they heat the glass rapidly, they, of course,
lose their brightness, and cease when the glass at the ruptured place becomes incandescent, or generally
sufficiently hot to conduct. When observed for the first time the phenomenon must appear very curious, and shows
in a striking manner how radically different alternate currents, or impulses, of high frequency behave, as compared
with steady currents, or currents of low frequency. With such currents - namely, the latter -- the phenomenon
would of course not occur. When frequencies such as are obtained by mechanical means are used, I think that the
rupture of the glass is more or less the consequence of the bombardment, which warms it up and impairs its
insulating power; but with frequencies obtainable with condensers I have no doubt that the glass may give way
without previous heating. Although this appears most singular at first, it is in reality what we might expect to occur.
The energy supplied to the wire leading into the bulb is given off partly by direct action through the carbon button,
and party by inductive action through the glass surrounding the wire. The case is thus analogous to that in which a
condenser shunted by a conductor of low resistance is connected to a source of alternating currents. As long as
the frequencies are low, the conductor gets the most, and the condenser is perfectly safe; but when the frequency
becomes excessive, the role of the conductor may become quite insignificant. In the latter case the difference of
potential at the terminals of the condenser may become so great as to rupture the dielectric, notwithstanding the
fact that the terminals are joined by a conductor of low resistance.
It is, of course, not necessary, when it is desired to produce the incandescence of a body inclosed in a bulb by
means of these currents, that the body should be a conductor, for even a perfect non-conductor may be quite as
readily heated. For this purpose it is sufficient to surround a conducting electrode with a non-conducting material,
as, for instance, in the bulb described before in Fig. 21, in which a thin incandescent lamp filament is coated with a
non-conductor, and supports a button of the same material on the top. At the start the bombardment goes on by
inductive action through the non-conductor, until the same is sufficiently heated to become conducting, then the
bombardment continues in the ordinary way.
A different arrangement used in some of the bulbs constructed is illustrated in Fig. 23. In this instance a nonconductor m is mounted in a piece of common arc light carbon so as to project some small distance above the
latter. The carbon piece is connected to the leading-in wire passing through a glass stem, which is wrapped with
several layers of mica. An aluminium tube a is employed as usual for screening. It is so arranged that it reaches
very nearly as high as the carbon and only the non-conductor m projects a little above it. The bombardment goes
at first against the upper surface of carbon, the lower parts being protected by the aluminium tube. As soon,
however, as the non-conductor m is heated it is rendered good conducting, and then it becomes the centre of the
bombardment, being most exposed to the same.
I have also constructed during these experiments many such single-wire bulbs with or without internal electrode, in
which the radiant matter was projected against, or focused upon, the body to be rendered incandescent. Fig. 24
illustrates one of the bulbs used. It consists of a spherical globe L, provided with a long neck n, on the top, for
increasing the action in some cases by the application of an external conducting coating. The globe L is blown out
on the bottom into a very small bulb b, which serves to hold it firmly in a socket S of insulating material into which
it is cemented. A fine lamp filament f, supported on a wire w, passes through the centre of filament is rendered
incandescent In the middle portion, where the bombardment proceeding from the lower inside surface of the globe
is most intense. The lower portion of the globe, as far as the socket S reaches, is rendered conducting, either by g
tinfoil coating or otherwise, and the external electrode is connected to a terminal of the coil.
The arrangement diagrammatically indicated in Fig. 24 was found to be an inferior one when it was desired to
render incandescent a filament or button supported in the centre of the globe, but it was convenient when the
object was to excite phosphorescence.
In many experiments in which bodies of a different kind were mounted in the bulb as, for instance, indicated in Fig.
23, some observations of interest were made.
It was found, among other things, that in such cases, no matter where the bombardment began, just as soon as a
high temperature was reached there was generally one of the bodies which seemed to take most of the
bombardment upon itself, the other, or others, being thereby relieved. This quality appeared to depend principally
on the point of fusion, and on the facility with which the body was evaporated, or, generally speaking,
disintegrated-- meaning by the latter term not only the throwing off of atoms, but likewise of larger lumps. The
observation made was in accordance with generally accepted notions. In a highly exhausted bulb electricity is
carried off from the electrode by independent carriers, which are partly the atoms, or molecules, of the residual
atmosphere, and partly the atoms, molecules, or lumps thrown off from the electrode. If the electrode is composed
of bodies of different character, and if one of these is more easily disintegrated than the others, most of the
electricity supplied is carried off from that body, which is then brought to a higher temperature than the others, and
this the more, as upon an increase of the temperature the body is still more easily disintegrated.
It seems to me quite probable that a similar process takes place in the bulb even with a homogenous electrode,
and I think it to be the principal cause of the disintegration. There is bound to be some irregularity, even if the
surface is highly polished, which, of course, is impossible with most of the refractory bodies employed as
electrodes. Assume that a point of the electrode gets hotter, instantly most of the discharge passes through that
point, and a minute patch is probably fused and evaporated. It is now possible that in consequence of the violent
disintegration the spot attacked sinks in temperature, or that a counter force is created, as in an arc; at any rate,
the local tearing off meets with the limitations incident to the experiment, where upon the same process occurs on
another place. To the eye the electrode appears uniformly brilliant, but there are upon it points constantly shifting
and wandering around, of a temperature far above the mean, and this materially hastens the process of
deterioration. That some such thing occurs, at least when the electrode is at a lower temperature, sufficient
experimental evidence can be obtained in the following manner: Exhaust a bulb to a very high degree, so that with
a fairly high potential the discharge cannot pass -- that is, not a luminous one, for a weak invisible discharge
occurs always, in all probability. Now raise slowly and carefully the potential, leaving the primary current on no
mote than for an instant. At a certain point, two, three, or half a dozen phosphorescent spots mill appear on the
globe. These places of the glass are evidently mote violently bombarded than others, this being due to the
unevenly distributed electric density, necessitated, of course, by sharp projections, or, generally speaking,
irregularities of the electrode. 13ut the luminous patches are constantly changing in position, which is especially
well observable if one manages to produce very few, and this indicates that the configuration of the electrode is
From experiences of this kind I am led to infer that, in order to be most durable, the refractory button in the bulb
should be in the form of a sphere with a highly polished surface. Such a small sphere could be manufactured from
a diamond or some other crystal, but a better way would be to fuse, by the employment of extreme degrees of
temperature, some oxide - as, for instance, zirconia -- into a small drop, and then keep it in the bulb at a
temperature somewhat below its point of fusion.
Interesting and useful results can no doubt be reached in the direction of extreme degrees of heat. How can such
high temperatures be arrived at! How are the highest degrees of heat reached in nature! By the impact of stars, by
high speeds and collisions. In a collision any rate of heat generation may be attained. In a chemical process we
are limited. When oxygen and hydrogen combine, they fall, metaphorically speaking, from a definite height. We
cannot go very far with a blast, nor by confining heat in a furnace, but in an exhausted bulb we can concentrate
any amount of energy upon a minute button. Leaving practicability out of consideration, this, then, would be the
means which, in my opinion, would enable us to reach the highest temperature. But a great difficulty when
proceeding in this way is encountered, namely, in most cases the body is carried off before it can fuse and form a
drop. This difficulty exists principally with an oxide such as zirconia, because it cannot be compressed in so hard a
cake that it would not be carried off quickly. I endeavored repeatedly to fuse zirconia, placing it in a cup or arc light
carbon as indicated in Fig. 23. It glowed with a most intense light, and the stream of the particles projected out of
the carbon cup was of a vivid white; but whether it was compressed in a cake o~ made into a paste with carbon, it
was carried off before it could be fused. The carbon cup containing the zirconia had to be mounted very low in the
neck of a large bulb, as the heating of the glass by the projected particles of the oxide was so rapid that in the first
trial the bulb was cracked almost in an instant when the current was turned on. The heating of the glass by the
projected particles was found to be always greater when the carbon cup contained a body which was rapidly
carried off -- I presume because in such cases, with the same potential, higher speeds were reached, and also
because, per unit of time, more matter was projected -- that is, more particles would strike the glass.
The before mentioned difficulty did not exist, however, when the body mounted in the carbon cup offered great
resistance to deterioration. For instance, when an oxide was first fused in an oxygen blast and then mounted in the
bulb, it melted very readily into a drop.
Generally during the process of fusion magnificent light effects were noted, of which it would be difficult to give an
adequate idea. Fig. 23 is intended to illustrate the effect observed with a ruby drop. At first one may see a narrow
funnel of white light projected against the top of the globe, where it produces an irregularly outlined
phosphorescent patch. When the point of the ruby fuses the phosphorescence becomes very powerful; but as the
atoms are projected with much greater speed from the surface of the drop, soon the glass gets hot and "tired", and
now only the outer edge of the patch glows. In this manner an intensely phosphorescent, sharply defined line,
corresponding to the outline of the drop, is produced, which spreads slowly: over the globe as the drop gets larger.
When the mass begins to boil, small bubbles and cavities are formed, which cause dark colored spots to sweep
across the globe. The bulb may be turned downward without fear of the drop falling off, as the mass possesses
I may mention here another feature of some interest, which I believe to have noted in the course of these
experiments, though the observations do not amount to a certitude. It appeared that under the molecular impact
caused by the rapidly alternating potential the body was fused and maintained in that state at a lower temperature
in a highly exhausted bulb than was the case at normal pressure and application of heat in the ordinary way -- that
is, at least, judging from the quantity of the light emitted. One of the experiments performed may be mentioned
here by way of illustration. A small piece of pumice stone was stuck on a platinum wire, and first melted to it in a
gas burner. The wire was next placed between two pieces of charcoal and a burner applied so as to produce an
intense heat, sufficient to melt down the pumice stone into a small glass-like button. The platinum wire had to be
taken of sufficient thickness to prevent its melting in the fire. While in the charcoal fire, or when held in a burner to
get a better idea of the degree of heat, the button glowed with great brilliancy. The wire with the button was then
mounted in a bulb, and upon exhausting the same to a high degree, the current was turned on slowly so as to
prevent the cracking of the button. The button was heated to the point of fusion, and when it melted it did not,
apparently, glow with the same brilliancy as before, and this would indicate a lower temperature. Leaving out of
consideration the observer's possible, and even probable, error, the question is, can a body under these
conditions be brought from a solid to a liquid state with evolution of less light!
When the potential of a body is rapidly alternated it is certain that the structure is jarred. When the potential is
very high, although the vibrations may be few -- say 20,000 per second -- the effect upon the structure may be
considerable. Suppose, for example, that a ruby is melted into a drop by a steady application of energy. When it
forms a drop it will emit visible and invisible waves, which will be in a definite ratio, and to the eye the drop will
appear to be of a certain brilliancy. Next, suppose we diminish to any degree we choose the energy steadily
supplied, and, instead, supply energy which rises and falls according to a certain law. Now, when the drop is
formed, there will be emitted from it three different kinds of vibrations -- the ordinary visible, and two kinds of
invisible waves: that is, the ordinary dark waves of all lengths, and, in addition, waves of a well-defined character.
The latter would not exist by a steady supply of the energy; still they help to jar and loosen the structure. If this
really be the case, then the ruby drop will emit relatively less visible and more invisible waves than before. Thus it
would seem that when a platinum wire, for instance, is fused by currents alternating with extreme rapidity, it emits
at the point of fusion less light and more invisible radiation than it does when melted by a steady current, though
the total energy used up in the process of fusion is the same in both cases, Or, to cite another example, a lamp
filament is not capable of withstanding as long with currents of extreme frequency as it does with steady currents,
assuming that it be worked at the same luminous intensity. This means that for rapidly alternating currents the
filament should be shorter and thicker. The higher the frequency -- that is, the greater the departure from the
steady flow -- the worse it would be for the filament. But if the truth of this remark were demonstrated, it would be
erroneous to conclude that such a refractory button as used in these bulbs would be deteriorated quicker by
currents of extremely high frequency than by steady or low frequency currents. From experience I may say that
just the opposite holds good: the button withstands the bombardment better with currents of very high frequency.
But this is due to the fact that a high frequency discharge passes through a rarefied gas with much greater
freedom than a steady or low frequency discharge, and this will say that with the former we can work with a lower
potential or with a less violent impact. As long, then, as the gas is of no consequence, a steady or low frequency
current is better; but as soon as the action of the gas is desired and important, high frequencies are preferable.
In the course of these experiments a great many trials were made with all kinds of carbon buttons. Electrodes
made of ordinary carbon buttons were decidedly more durable when the buttons were obtained by the application
of enormous pressure. Electrodes prepared by depositing carbon in well known ways did not show up well; they
blackened the globe very quickly. From many experiencies I conclude that lamp filaments obtained in this manner
can be advantageously used only with low potentials and low frequency currents. Some kinds of carbon withstand
so well that, in order to bring them to the point of fusion, it is necessary to employ very small buttons. In this case
the observation is rendered very difficult on account of the intense heat produced. Nevertheless there can be no
doubt that all kinds of carbon are fused under the molecular bombardment, but the liquid state must be one of
great instability. Of all the bodies tried there were two which withstood best -- diamond and carborundum. These
two showed up about equally, but the latter was preferable, for many reasons. As it is more than likely that this
body is not yet generally known, I will venture to call your attention to it.
It has been recently produced by Mr. E. G. Acheson, of Monongahela City, Pa., U. S. A. It is intended to replace
ordinary diamond powder for polishing precious stones, etc., and I have been informed that it accomplishes this
object quite successfully. I do not know why the name "carborundum" has been given to it, unless there is
something in the process of its manufacture which justifies this selection. Through the kindness of the inventor, I
obtained a short while ago some samples which I desired to test in regard to their qualities of phosphorescence
and capability of withstanding high degrees of heat.
Carborundum can be obtained in two forms - in the form of "crystals" and of powder. The former appear to the
naked eye dark colored, but are very brilliant; the latter is of neatly the same color as ordinary diamond powder,
but very much finer. When viewed under a microscope the samples of crystals given to me did not appear to have
any definite form, but rather resembled pieces of broken up egg coal of fine quality. The majority were opaque, but
there were some which were transparent and colored. The crystals are a kind of carbon containing some
impurities; they are extremely hard, and withstand for a long time even an oxygen blast. When the blast is directed
against them they at first form a cake of some compactness, probably in consequence of the fusion of impurities
they contain. The mass withstands for a very long time the blast without further fusion; but a slow carrying off, or
burning, occurs, and, finally, a small quantity of a glass-like residue is left, which, I suppose, is melted alumina.
When compressed strongly they conduct very well, but not as well as ordinary carbon. The powder, which is
obtained from the crystals in some way, is practically non-conducting. It affords a magnificent polishing material for
The time has been too short to make a satisfactory study of the properties of this product, but enough experience
has been gained in a few weeks I have experimented upon it to say that it does possess some remarkable
properties in many respects. It withstands excessively high degrees of heat, it is little deteriorated by molecular
bombardment, and it does not blacken the globe as ordinary carbon does. The only difficulty which I have found in
its use in connection with these experiments was to find some binding material which would resist the heat and the
effect of the bombardment as successfully as carborundum itself does.
I have here a number of bulbs which I have provided with buttons of carborundum. To make such a button of
carborundum crystals I proceed in the following manner: I take an ordinary lamp filament and dip its point in tar, or
some other thick substance or paint which may be readily carbonized. I next pass the point of the filament through
the crystals, and then hold it vertically over a hot plate. The tar softens and forms a drop on the point of the
filament, the crystals adhering to the surface of the drop. By regulating the distance from the plate the tar is slowly
dried out and the button becomes solid. I then once more dip the button in tar and hold it again over a plate until
the tar is evaporated, leaving only a hard mass which firmly binds the crystals. When a larger button is required I
repeat the process several times, and I generally also cover the filament a certain distance below the button with
crystals. The button being mounted in a bulb, when a good vacuum has been reached, first a weak and then a
strong discharge is passed through the bulb to carbonize the tar and expel all gases, and later it is brought to a
very intense incandescence.
When the powder is used I have found it best to proceed as follows: I make a thick paint of carborundum and tar,
and pass a lamp filament through the paint. Taking then most of the paint off by rubbing the filament against a
piece of chamois leather, I hold it over a hot plate until the tar evaporates and the coating becomes firm. I repeat
this process as many times as it is necessary to obtain a certain thickness of coating. On the point of the coated
filament I form a button in the same manner.
There is no doubt that such a button -- properly prepared under great pressure -- of carborundum, especially of
powder of the best quality, will withstand the effect of the bombardment fully as well as anything we know. The
difficulty is that the binding material gives way, and the carborundum is slowly thrown off after some time. As it
does not seem to blacken the globe in the least, it might be found useful for coating the filaments of ordinary
Incandescent lamps, and I think that it is even possible to produce thin threads or sticks of carborundum which will
replace the ordinary filaments in an incandescent lamp. A carborundum coating seems to be more durable than
other coatings, not only because the carborundum can withstand high degrees of heat, but also because it seems
to unite with the carbon better than any other material I have tried. A coating of zirconia or any other oxide, for
instance, is far more quickly destroyed. I prepared buttons of diamond dust in the same manner as of
carborundum, and these came in durability nearest to those prepared of carborundum, but the binding paste gave
way much more quickly in the diamond buttons: this, however, I attributed to the site and irregularity of the grains
of the diamond.
It was of interest to find whether carborundum possesses the quality of phosphorescence. One is, of course,
prepared to encounter two difficulties: first, as regards the rough product, the "crystals", they are good conducting,
and it is a fact that conductors do not phosphoresce; second, the powder, being exceedingly fine, would not be apt
to exhibit very prominently this quality, since we know that when crystals, even such as diamond or ruby, are finely
powdered, they lose the property of phosphorescence to a considerable degree.
The question presents itself here, can a conductor phosphoresce? What is there in such a body as a metal, for
instance, that would deprive it of the quality of phosphorescence, unless it is that property which characterizes it
as a conductor? For it is a fact that most of the phosphorescent bodies lose that quality when they are sufficiently
heated to become more or less conducting. Then, if a metal be in a large measure, or perhaps entirely deprived of
that property, it should be capable of phosphorescence. Therefore it is quite possible that at some extremely high
frequency, when behaving practically as a non-conductor, a metal of any other conductor might exhibit the quality
of phosphorescence, even though it be entirely incapable of phosphorescing under the impact of a low-frequency
discharge. There is, however, another possible way how a conductor might at least appear to phosphoresce.
Considerable doubt still exists as to what really is phosphorescence, and as to whether the various phenomena
comprised under this head are due to the same causes. Suppose that in an exhausted bulb, under the molecular
impact, the surface of a piece of metal or other conductor is rendered strongly luminous, but at the same time it is
found that it remains comparatively cool, would not this luminosity be called phosphorescence! Now such a result,
theoretically at least, is possible, for it is a mere question of potential of speed. Assume the potential of the
electrode, and consequently the speed of the projected atoms, to be sufficiently high, the surface of the metal
piece against which the atoms are projected would be rendered highly incandescent, since the process of heat
generation would be incompatibly faster than that of radiating or conducting away from the surface of the collision.
In the eye of the observer a single impact of the atoms would cause an instantaneous flash, but if the impact were
repeated with sufficient rapidity they would produce a continuous impression upon his retina. To him then the
surface of the metal would appear continuously incandescent and of constant luminous intensity, while in reality
the light would be either intermittent or at least changing periodically in intensity. The metal piece would rise in
temperature until equilibrium was attained -- that is, until the energy continuously radiated would equal that
intermittently supplied. But the supplied energy might under such conditions not be sufficient to bring the body to
any more than a very moderate mean temperature, especially if the frequency of the atomic impacts be very low -just enough that the fluctuation of the intensity of the light emitted could not be detected by the eye. The body
would now, owing to the manner in which the energy is supplied, emit a strong light, and yet be at a comparatively
very low mean temperature. How could the observer call the luminosity thus produced! Even if the analysis of the
light would teach him something definite, still he would probably rank it under the phenomena of
phosphorescence. It is conceivable that in such a way both conducting and nonconducting bodies may be
maintained at a certain-luminous intensity, but the energy required would very greatly vary with the nature and
properties of the bodies.
These and some foregoing remarks of a speculative nature were made merely to bring out curious features of
alternate currents or electric impulses. By their help we may cause a body to emit more light, while at a certain
mean temperature, than it would emit if brought to that temperature by a steady supply; and, again, we may bring
a body to the point of fusion, and cause it to emit less light than when fused by the application of energy in
ordinary ways. It all depends on how we supply the energy, and what kind of vibrations we set up: in one case the
vibrations are more, in the other less, adapted to affect our sense of vision.
Some effects, which I had not observed before, obtained with carborundum in the first trials, I attributed to
phosphorescence, but in subsequent experiments it appeared that it was devoid of that quality. The crystals
possess a noteworthy feature. In a bulb provided with a single electrode in the shape of a small circular metal disc,
for instance, at a certain degree of exhaustion the electrode is covered with a milky film, which is separated by a
dark space from the glow filling the bulb. When the metal disc is covered with carborundum crystals, the film is far
more intense, and snow-white. This I found later to be merely an effect of the bright surface of the crystals, for
when an aluminium electrode was highly polished it exhibited more or less the same phenomenon. I made a
number of experiments with the samples of crystals obtained, principally because it would have been of special
interest to find that they are capable of phosphorescence, on account of their being conducting. I could not
produce phosphorescence distinctly, but I must remark that a decisive opinion cannot be formed until other
experimenters have gone over the same ground.
The powder behaved in some experiments as though it contained alumina, but it did not exhibit with sufficient
distinctness the red of the latter. Its dead color brightens considerably under the molecular impact, but I am now
convinced it does not phosphoresce. Still, the tests with the powder are not conducive, because powdered
carborundum probably does not behave like a phosphorescent sulphide, for example, which could be finely
powdered without impairing the phosphorescence, but rather like powdered ruby or diamond, and therefore it
would be necessary, in order to make a decisive test, to obtain it in a large lump and polish up the surface.
If the carborundum proves useful in connection with these and similar experiments, its chief value will be found in
the production of coatings, thin conductors, buttons, or other electrodes capable of withstanding extremely high
degrees of heat.
The production of a small electrode capable of withstanding enormous temperatures I regard as of the greatest
importance in the manufacture of light. It would enable us to obtain, by means of currents of very high frequencies,
certainly 20 times, if not more, the quantity of light which is obtained in the present incandescent lamp by the same
expenditure of energy. This estimate may appeal- to many exaggerated, but in reality I think it is far from being so.
As this statement might be misunderstood I think it necessary to expose clearly the problem with which in this line
of work we are confronted, and the manner in which, in my opinion, a solution will be arrived at.
Any one who begins a study of the problem will be apt to think that what is wanted in a lamp with an electrode is a
very high degree of incandescence of the electrode. There he will be mistaken. The high incandescence of the
button is a necessary evil, but what is really wanted is the high incandescence of the gas surrounding thee button.
In other words, the problem in such a lamp is to bring a mass of gas to the highest possible incandescence. The
higher the incandescence, the quicker the mean vibration, the greater is the economy of the light production. But
to maintain a mass of gas at a high degree of incandescence in a glass vessel, it will always be necessary to keep
the incandescent mass away from the glass; that is, to confine it as much as possible to the central portion of the
In one of the experiments this evening a brush was produced at the end of a wire. This brush was a flame, a
source of heat and light. It did not emit much perceptible heat, nor did it glow with an intense light; but is it the less
a flame because it does not scorch my hand! Is it the less a flame because it does not hurt my eye by its brilliancy!
The problem is precisely to produce in the bulb such a flame, much smaller in site, but incomparably more
powerful. Were there means at hand for producing electric impulses of a sufficiently high frequency, and for
transmitting them, the bulb could be done away with, unless it were used to protect the electrode, or to economize
the energy by confining the heat. But as such means are not at disposal, it becomes necessary to place The
terminal in a bulb and rarefy the air in the same. This is done merely to enable the apparatus to perform the work
which it is not capable of performing at ordinary air pressure. In the bulb we are able to intensify the action to any
degree -- so far that the brush emits a powerful light.
The intensity of the light emitted depends principally on the frequency and potential of the impulses, and on the
electric density on the surface of the electrode. It is of the greatest importance to employ the smallest possible
button, in order to push the density very far. Under the violent impact of the molecules of the gas surrounding it,
the small electrode is of course brought to an extremely high temperature, but around it is a mass of highly
incandescent gas, a flame photosphere, many hundred times the volume of the electrode. With a diamond,
carborundum or zircon button the photosphere can be as much as one thousand times the volume of the button.
Without much reflecting one would think that in pushing so far the incandescence of the electrode it would be
instantly volatilized. But after a careful consideration he would find that, theoretically, it should not occur, and in
this fact -- which, however, is experimentally demonstrated -- lies principally the future value of such a lamp.
At first, when the bombardment begins, most of the work is performed on the surface of the button, but when a
highly conducting photosphere is formed the button is comparatively relieved. The higher the incandescence of
the photosphere the more it approaches in conductivity to that of the electrode, and the more, therefore, the solid
and the gas form one conducting body. The consequence is that the further is forced the incandescence the more
work, comparatively, is performed on the gas, and the I•3s on the electrode. The formation of a powerful
photosphere is consequently the very means for protecting the electrode. This protectic4n, of course, is a relative
one, and it should not be thought that by pushing the incandescence higher the electrode is actually less
deteriorated. Still, theoretically, with extreme frequencies, this result must be reached, but probably at a
temperature too high for most of the refractory bodies known. Given, then, an electrode which can withstand to a
very high limit the effect of the bombardment and outward strain, it would be safe no matter how much it is forced
beyond that limit. In an incandescent lamp quite different considerations apply. There the gas is not at all
concerned: the whole of the work is performed on the filament; and the life of the lamp diminishes so rapidly with
the increase of the degree of incandescence the economical reasons compel us to work it at a low incandescence.
But if an incandescent lamp is operated with currents of very high frequency, the action of the gas cannot be
neglected, and the rules for the most economical working must be considerably modified.
In order to bring such a lamp with one or two electrodes to a great perfection, it is necessary to employ impulses of
very high frequency. The high frequency secures, among others, two chief advantages, which have a most
important bearing upon the economy of the light production. First, the deterioration of the electrode is reduced by
reason of the fact that we employ a great many small impacts, instead of a few violent ones, which shatter quickly
the structure; secondly, the formation of a large photosphere is facilitated.
In order to reduce the deterioration of the electrode to the minimum, it is desirable that the vibration be harmonic,
for any suddenness hastens the process of destruction. An electrode lasts much longer when kept at
incandescence by currents, or impulses, obtained from a high-frequency alternator, which rise and fall more or
less harmonically, than by impulses obtained from a disruptive discharge coil. In the latter case there is no doubt
that most of the damage is done by the fundamental sudden discharges.
One of the elements of loss in such a lamp is the bombardment of the globe. As the potential is very high, the
molecules are projected with great speed; they strike the glass, and usually excite a strong phosphorescence. The
effect produced is very pretty but for economical reasons it would be perhaps preferable to prevent, or at least
reduce to the minimum, the bombardment against the globe, as in such case it is, as a result, not the object to
excite phosphorescence, and as some loss of energy results from the bombardment. This loss in the bulb is
principally dependent on the potential of the impulses and on the electric density on the surface of the electrode.
In employing very high frequencies the loss of energy by the bombardment is greatly reduced, for, first, the
potential needed to perform a given amount of work is much smaller; and, secondly, by producing a highly
conducting photosphere around the electrode, the same result is obtained as though the electrode were much
larger, which is equivalent to a smaller electric density. But be it by the diminution of the maximum potential or of
the density, the gain is effected in the same manner, namely, by avoiding violent shocks, which strain the glass
much beyond its limit of elasticity. If the frequency could be brought high enough, the loss due to the imperfect
elasticity of the glass would be entirely ne6ligible. The loss due to bombardment of the globe may, however, be
reduced by using two electrodes instead of one. In such case each of the electrodes may be connected to one of
the terminals; or else, if it is preferable to use only one wire, one electrode may be connected to one terminal and
the other to the ground or to an insulated body of some surface, as, for instance, a shade on the lamp. In the latter
case, unless some judgement is used, one of the electrodes might glow more intensely than the other.
But on the whole I find it preferable when using such high frequencies to employ only one electrode and one
connecting wire. I am convinced that the illuminating device of the near future will not require for its operation
more than one lead, and, at any rate, it will have no leading-in wire, since the energy required can be as well
transmitted through the glass. In experimental bulbs the leading-in wire is most generally used on account of
convenience, as in employing condenser coatings in the manner indicated in Fig. 22, for example, there is some
difficulty in fitting the parts, but these difficulties would not exist if a great many bulbs were manufactured;
otherwise the energy can be conveyed through the glass as well as through a wire, and with these high
frequencies the losses are very small. Such illuminating deices will necessarily involve the use of very high
potentials, and this, in the eyes of practical men, might be an objectionable feature. Yet, in reality, high potentials
are not objectionable -- certainly not in the least as far as the safety of the devices is concerned.
There are two ways of rendering an electric appliance safe. One is to use low potentials, the other is to determine
the dimensions of the apparatus so that it is safe no matter how high a potential is used. Of the two the latter
seems to me the better way, for then the safety is absolute, unaffected by any possible combination of
circumstances which might render even a low-potential appliance dangerous to life and property. But the practical
conditions require not only the judicious determination of the dimensions of the apparatus; they likewise
necessitate the employment of energy of the proper kind. It is easy, for instance, to construct a transformer
capable of giving, when operated from an ordinary alternate current machine of low tension, say 50,000 volts,
which miqht be required to light a highly exhausted phosphorescent tube, so that, in spite of the high potential, it is
perfectly safe, the shock from it producing no inconvenience. Still, such a transformer would be expensive, and in
itself inefficient; and, besides, what energy was obtained from it would not be economically used for the production
of light. The economy demands the employment of energy in the form of extremely rapid vibrations. The problem
of producing light has been likened to that of maintaining a certain high-pitch note by means of a bell. It should be
said a barely audible note; and even these words would not express it, so wonderful is the sensitiveness of the
eye. We may deliver powerful blows at long intervals, waste a good deal of energy, and still not get what we want;
or we may keep up the note by delivering frequent gentle taps, and get nearer to the object sought by the
expenditure of mud•1 less energy. In the production of light, as far as the illuminating device is concerned, there
can be only one rule -- that is, to use as high frequencies as can be obtained; but the means for the production
and conveyance of impulses of such character impose, at present at least, great limitations. Once it is decided to
use very high frequencies, the return wire becomes unnecessary, and all the appliances are simplified. By the use
of obvious means the same result is obtained as though the return wire were used. It is sufficient for this purpose
to bring in contact with the bulb, or merely in the vicinity of the same, an insulated body of some surface. The
surface need, of course, be the smaller, the higher the frequency and potential used, and necessarily, also, the
higher the economy of the lamp or other device.
This plan of working has been resorted to on several occasions this evening. So, for instance, when the
incandescence of a button was produced by grasping the bulb with the hand, the body of the experimenter merely
served to intensify the action. The bulb used was similar to that illustrated in Fig. 13, and the coil was excited to a
small potential, not sufficient to bring the button to incandescence when the bulb was hanging from the wire; and
incidentally, in order to perform the experiment in a more suitable manner, the button was taken so large that a
perceptible time had to elapse before,
upon grasping the bulb, it could be rendered incandescent. The contact with the bulb was, of course, quite
unnecessary. It is easy, by using a rather large bulb with an exceedingly small electrode, to adjust the conditions
so that the latter is brought to bright incandescence by the mere approach of the experimenter within a few feet of
the bulb, and that the incandescence subsides upon his receding.
In another experiment, when phosphorescence was excited, a similar bulb was used. Here again, originally, the
potential was not sufficient to excite phosphorescence until the action was intensified -- in this case, however, to
present a different feature, by touching the socket with a metallic object held in the hand. The electrode in the bulb
was a carbon button so large that it could not be brought to incandescence, and thereby spoil the effect produced
Again, in another of the early experiments, a bulb was used as illustrated in Fig. 12. In this instance, by touching
the bulb with one or two fingers, one or two shadows of the stem inside were projected against the glass, the touch
of the finger producing thc same result as the application of an external negative electrode under ordinary
In all these experiments the action was intensified by augmenting the capacity at the end of the lead connected to
the terminal. As a rule, it is not necessary to resort to such means, and would be quite unnecessary with still
higher frequencies; but when it is desired, the bulb, or tube, can be easily adapted to the purpose.
In Fig. 24, for example, an experimental bulb L is shown, which is provided with a neck n on the top for the
application of an external tinfoil coating, which may be connected to a body of larger surface. Sum a lamp as
illustrated in Fig. 25 may also be lighted by connecting the tinfoil coating on the neck n to the terminal, and the
leading-in wire w to an insulated plate. If the bu15 stands in a socket upright, as shown in the cut, a shade of
conducting material may be slipped in the neck n, and the action thus magnified.
A more perfected arrangement used in some of these bulbs is illustrated in Fig. 26. In this case the construction of
the bulb is as shown and described before, where reference was made to Fig. 13. A zinc sheet Z, with a tubular
extension T, is slipped over the metallic socket S. The bulb hang3 downward from the terminal t, the zinc sheet Z,
performing the double office of intensifier and reflector. The reflector is separated from the terminal t by an
extension of the insulating plug P.
A similar disposition with a phosphorescent tube is illustrated in Fig. 27. The tube T is prepared from two short
tubes of a different diameter, which are sealed on the ends. On the lower end is placed an outside conducting
coating C, which connects to the wire w. The wire has a hook on the upper end for suspension, and passes
through the centre of the inside tube, which is filled with some good and tightly packed insulator. On the outside of
the upper end of the tube T is another conducting coating C1, upon which is slipped a metallic reflector Z, which
should be separated by a thick insulation from the end of wire w.
The economical use of such a reflector or intensifier would require that all energy supplied to an air condenser
should be recoverable, or, in other words, that there should not be any losses, neither in the gaseous medium nor
through its action elsewhere. This is far from being so, but, fortunately, the losses may be reduced to anything
desired. A few remarks are necessary on this subject, in order to make the experiences gathered in the course of
these investigations perfectly clear.
Suppose a small helix with many well insulated turns, as in experiment Fig. 17, had one of its ends connected to
one of the terminals of the induction coil, and the other to a metal plate, or, for the sake of simplicity, a sphere,
insulated in space. When the coil is set to work, the potential of the sphere is alternated, and the small helix now
behaves as though its free end were connected to the other terminal of the induction coil. If an iron can be held
within the small helix it is quickly brought to a high temperature, indicating the passage of a strong current through
the helix how does the insulated sphere act in this case! It can be a condenser, storing and returning the energy
supplied to it, or it can be a mere sink of energy, and the conditions of the experiment determine whether it is more
one or the other. The sphere being charged to a high potential, it acts inductively upon the surrounding air, or
whatever gaseous medium there might be. The molecules, or atoms, which are near the sphere are of course
more attracted, and move through a greater distance than the farther ones. When the nearest molecules strike the
sphere they are repelled, and collisions occur at all distances within the inductive action of the sphere. It is now
clear that, if the potential be steady, but little loss of energy can be caused in this way, for the molecules which are
nearest to the sphere, having had an additional charge imparted to them by contact, are not Attracted until they
have parted, if not with all, at least with most of the additional charge, which can be accomplished only after a
great many collisions. From the fact that with a steady potential there is but little loss in dry air, one must come to
such a conclusion. When the potential of the sphere, instead of being steady, is alternating, the conditions are
entirely different. In this case a rhythmical bombardment occurs, no matter whether the molecules after coming in
contact with the sphere lose the imparted charge or not; what is more, if the charge is not lost, the impacts are only
the more violent. Still if the frequency of the impulses be very small, the loss caused hg the impacts and collisions
would not be serious unless the potential were excessive. But when extremely high frequencies and more or less
high potentials are used, the loss may be very great. The total energy lost per unit of time is proportionate to the
product of the number of impacts per second, or the frequency and the energy lost-in each impact. But the energy
of an impact must be proportionate to the square of the electric density of the sphere, since the charge imparted to
the molecule is proportionate to that density. I conclude from this that the total energy lost must be proportionate
to the product of the frequency and the square of the electric density; but this law needs experimental
confirmation. Assuming the preceding considerations to be true, then, by rapidly alternating the potential of a body
immersed in an insulating gaseous medium, any amount of energy may be dissipated into space. Most of that
energy then, I believe, is not dissipated in the form of long ether waves, propagated to considerable distance, as is
thought most generally, but is consumed -- in the case of an insulated sphere, for example -- in impact and
collisional losses -- that is, heat vibrations -- on the surface and in the vicinity of the sphere. To reduce the
dissipation it is necessary to work with a small electric density the smaller the higher the frequency.
But since, on the assumption before made, the loss is diminished with the square of the density, and since
currents of very high frequencies involve considerable waste when transmitted through conductors, it follows that,
on the whole, it is better to employ one wire than two. Therefore, if motors, lamps, or devices of any kind are
perfected, capable of being advantageously operated by currents of extremely high frequency, economical
reasons will make it advisable to use only one wire, especially if the distances are great.
When energy is absorbed in a condenser the same behaves as though its capacity were increased. Absorption
always exists more or less, but generally it is small and of no consequence as long as the frequencies are not very
great. In using extremely high frequencies, and, necessarily in such case, also high potentials, the absorption -or, what is here meant more particularly by this term, the loss of energy due to the presence of a gaseous medium
-- is an important factor to be considered, as the energy absorbed it the air condenser may be any fraction of the
supplied energy. This would seem to make it very difficult to tell from the measured or computed capacity of an air
condenser its actual capacity or vibration period, especially if the condenser is of very small surface and is
charged to a very high potential. As many important results are dependent upon the correctness of the estimation
of the vibration period, this subject demands the most careful scrutiny of other investigators. To reduce the
probable error as much as possible in experiments of the kind alluded to, it is advisable to use spheres or plates of
large surface, so as to make the density exceedingly small. Otherwise, when it is practicable, an oil condenser
should be used in preference. In oil or other liquid dielectrics there are seemingly no such losses as in gaseous
media. It being impossible to exclude entirely the gas in condensers with solid dielectrics, such condensers should
be immersed in oil, for economical reasons if nothing else; they can then be strained to the utmost and will remain
cool. In Leyden jars the loss due to air is comparatively small, as the tinfoil coatings are large, close together, and
the charged surfaces not directly exposed; but when the potentials are very high, the loss may be more or less
considerable at, or near, the upper edge of the foil, where the air is principally acted upon. If the jar be immersed
in boiled-out oil, it will be capable of performing four times the amount of work which it can for any length of time
when used in the ordinary way, and the loss will be inappreciable.
It should not be thought that the loss in heat in an air condenser is necessarily associated with the formation of
visible streams or brushes. If a small electrode, inclosed in an unexhausted bulb, is connected to one of the
terminals of the coil, streams can he seen to issue from the electrode and the air in the bulb is heated; if, instead
of a small electrode, a large sphere is inclosed in the bulb, no streams are observed, still the air is heated.
Nor should it be thought that the temperature of an air condenser would give even an approximate idea of the loss
in heat incurred, as in such case heat must be given off much more quickly, since there is, in addition to the
ordinary radiation, a very active carrying away of heat by independent carriers going on, and since not only the
apparatus, but the air at some distance from it is heated in consequence of the collisions which must occur.
Owing to this, in experiments with such a coil, a rise of temperature can be distinctly observed only when the body
connected to the coil is very small. But with appartus on a larger scale, even a body of considerable bulk would be
heated, as, for instance, the body of a person; and I think that skilled physicians might make observations of utility
in such experiments, which, if the apparatus were judiciously designed, would not present the slightest danger.
A question of some interest, principally to meteorologists, presents itself here. How does the earth behave! The
earth is an air condenser, but is it a perfect: or a very imperfect one -- a mere sink of energy! There can be little
doubt that to such small disturbance as might be caused in an experiment the earth behaves as an almost perfect
condenser. But it might be different when its charge is set in vibration by some sudden disturbance occurring in
the heavens. In such case, as before stated, probably only little of the energy of the vibrations set up would be lost
into space in the form of long ether radiations, but most of the energy, I think, would spend itself in molecular
impacts and collisions, and pass off into space in the form of short heat, and possibly light, waves. As both the
frequency of the vibrations of the charge and the potential are in all probability excessive, the energy converted
into heat may be considerable. Since the density must be unevenly distributed, either in consequence of the
irregularity of the earth's surface, or on account of the condition of the atmosphere in various places, the effect
produced would accordingly vary from place to place. Considerable variations in the temperature and pressure of
the atmosphere may in this manner be caused at any point of the surface of the earth. The variations may be
gradual or very sudden, according to the nature of the general disturbance, and may produce rain and storms, or
locally modify the weather in any way.
From the remarks before made one may see what an important factor of loss the air in the neighborhood of a
charged surface becomes when the electric density is great and the frequency of the impulses excessive. But the
action as explained implies that the air is insulating -- that is, that it is composed of independent carriers immersed
in an insulating medium. This is the case only when the air is at something like ordinary or greater, or at extremely
small, pressure. When the air is slightly rarefied and conducting, then true conduction losses occur also. In such
case, of course, considerable energy may be dissipated into space even with a steady potential, or with impulses
of low frequency, if the density is very great.
When the gas is at very low pressure, an electrode is heated more because higher speeds can be reached. If the
gas around the electrode is strongly compressed, the displacements, and consequently the speeds, are very
small, and the heating is insignificant. But if in such case the frequency could be sufficiently increased, the
electrode would be brought to a high temperature as well as if the gas were at very low pressure; in fact,
exhausting the bulb is only necessary because we cannot produce (and possibly not convey) currents of the
Returning to the subject of electrode lamps, it is obviously of advantage in such a lamp to confine as much as
possible the heat to the electrode by preventing the circulation of the gas in the bulb. If a very small bulb be taken,
it would confine the heat better than a large one, but it might not be of sufficient capacity to be operated from the
coil, or, if so, the glass might get too hot. A simple way to improve in this direction is to employ a globe of the
required site, but to place a small bulb, the diameter of which is properly estimated, over the refractory button
contained in the globe. This arrangement is illustrated in Fig. 28.
The globe L has in this case a large neck n, allowing the small bulb b to slip through. Otherwise the construction is
the same as shown in Fig. 18, for example. The small bulb is conveniently supported upon the stem s, carrying the
refractory button m. In tube a by several layers of mica M, in order to prevent the cracking of the neck by the rapid
heating of the aluminium tube upon a sudden turning on of the current. The inside bulb should be as small as
possible when it is desired to obtain light only by incandescence of the electrode. If it is desired to produce
phosphorescence, the bulb should be larger, else it would be apt to get too hot, and the phosphorescence would
cease. In this arrangement usually only the small bulb shows phosphorescence, as there is practically no
bombardment against the outer globe. In some of these bulbs constructed as illustrated in Fig. 28 the small tube
was coated with phosphorescent paint, and beautiful effects were obtained. Instead of making the inside bulb
large, in order to avoid undue heating, it answers the purpose to make the electrode m larger. In this case the
bombardment is weakened by reason of the smaller electric density.
Many bulbs were constructed on the plan illustrated in Fig. 29. Here a small bulb 6, containing the refractory
button m, upon being exhausted to a very high degree was sealed in a large globe L, which was then moderately
exhausted and sealed off. The principal advantage of this construction was that it allowed of reaching extremely
high vacua, and, at the same time use a large bulb. It was found, in the course of experiences with bulbs such as
illustrated in Fig. 29, that it was well to make the stem J near the seal at e very thick, and the leading-in wire w
thin, as it occurred sometimes that the stem at e was heated and the bulb was cracked. Often the outer globe L
was exhausted only just enough to allow the discharge to pass through, and the space between the bulbs
appeared crimson, producing a curious effect. In some cases, when the exhaustion in globe L was very low, and
the air good conducting, it was found necessary, in order to bring the button m to high incandescence, to place,
preferably on the upper part of the neck of the globe, a tinfoil coating which was connected to an insulated body,
to the ground, or to the other terminal of the coil, as the highly conducting air weakened the effect somewhat,
probably by being acted upon inductively from the wire w, where it entered the bulb at e. Another difficulty -which, however, is always present when the refractory button is mounted in a Fig. 29 very small bulb -- existed in
the construction illustrated in Fig. 29, namely, the vacuum in the bulb b would be impaired in a comparatively short
The chief idea in the two last described constructions was to confine the heat to the central portion of the globe by
preventing the exchange of air, An advantage is secured, but owing to the heating of the inside bulb and slow
evaporation of the glass the vacuum is hard to maintain, even if the construction illustrated in Fig. 28 be chosen, in
which both bulbs communicate.
But by far the better way -- the ideal way -- would be to reach sufficiently high frequencies. The higher the
frequency the slower would be the exchange of the air, and I think that a frequency may be reached at which there
would be no exchange whatever of the air molecules around the terminal. We would then produce a flame in which
there would be no carrying away of material, and a queer flame it would be, for it would be rigid! With sud•1 high
frequencies the inertia of the particles, would come into play. As the brush, or flame, would gain rigidity in virtue of
the inertia of the particles, the exchange of the latter would be prevented. This would necessarily occur, for, the
number ~f the impulses being augmented, the potential energy of each would diminish, so that finally only atomic
vibrations could be set up, and the motion of translation through measurable space would cease. Thus an ordinary
gas burner connected to a source of rapidly alternating potential might have its efficiency augmented to a certain
limit, and this for two reasons -- because of the additional vibration imparted, and because of a slowing down of
the process of carrying off. But the renewal being rendered difficult, and renewal being necessary to maintain the
burner, a continued increase of the frequency of the impulses, assuming they could be transmitted to and
impressed upon the flame, would result in the "extinction" of the latter, meaning by this term only the cessation of
the chemical process.
I think, however, that in the case of an electrode immersed in a fluid insulating medium, and surrounded by
independent carriers of electric charges, which can be acted upon inductively, a sufficiently high frequency of the
impulses would probably result in a gravitation of the gas all around toward the electrode. For this it would be only
necessary to assume that the independent bodies are irregularly shaped; they would then turn toward the
electrode their side of the greatest electric density, and this would be a position in which the fluid resistance to
approach would be smaller than that offered to the receding.
The general opinion, I do not doubt, is that it is out of the question to reach any such frequencies as might -assuming some of the views before expressed to be true produce any of the results which I have pointed out as
mere possibilities. This may be so, but in the course of these investigations, from the observation of many
phenomena I have gained the conviction that these frequencies would be much lower than one is apt to estimate
at first. In a flame we set up light vibrations by causing molecules, of atoms, to collide. But what is the ratio of the
frequency of the collisions and that of the vibrations set up! Certainly it must be incomparably smaller than that of
the knocks of the bell and the sound vibrations, or that of the discharges and the oscillations of the condenser. We
may cause the molecules of the gas to collide by the use of alternate electric impulses of high frequency, and so
we may imitate the process in a flame; and from experiments with frequencies which we are now able to obtain, I
think that the result is producible with impulses which are transmissible through a conductor.
In connection with thoughts of a similar nature, it appeared to me of great interest to demonstrate the rigidity of a
vibrating gaseous column. Although with such low frequencies as, say 10,000 per second, which I was able to
obtain without difficulty from a specially constructed alternator, the task looked discouraging at first, I made a
series of experiments. The trials with air at ordinary pressure led to no result, but with air moderately rarefied I
obtain what I think to be an unmistakable experimental evidence of the property sought for. As a result of this kind
might lead able investigators to conclusions of importance I will describe one of the experiments performed.
It is well known that when a tube is slightly exhausted the discharge may be passed through it in the form of a thin
luminous thread. When produced with currents of low frequency, obtained from a coil operated as usual, this
thread is inert. If a magnet be approached to it, the part near the same is attracted or repelled, according to the
direction of the lines of force of the magnet. It occurred to me that if such a thread would be produced with
currents of very high frequency, it should be more or less rigid, and as it was visible it could be easily studied.
Accordingly I prepared a tube about 1 inch in diameter and 1 metre long, with outside coating at each end. The
tube was exhausted to a point at which, by a little working the thread discharge could be obtained. It must be
remarked here that the general aspect of the tube, and the degree of exhaustion, are quite different than when
ordinary low frequency currents are used. As it was found preferable to work with one terminal, the tube prepared
was suspended from the end of a wire connected to the terminal, the tinfoil coating being connected to the wire,
and to the lower coating sometimes a small insulated plate was attached. When the thread was formed it extended
through the upper part of the tube and lost itself in the lower end. If it possessed rigidity it resembled, not exactly
an elastic cord stretched tight between two supports, but a cord suspended from a height with a small weight
attached at the end. When the finger or a magnet was approached to the upper end of the luminous thread, it
could be brought locally out of position by electrostatic or magnetic action; and when the disturbing object was
very quickly removed, an analogous result was produced, as though a suspended cord would be displaced and
quickly released near the point of suspension. In doing this the luminous thread was set in vibration, and two very
sharply marked nodes, and a third indistinct one, were formed. The vibration, once set up, continued for fully eight
minutes, dying gradually out. The speed of the vibration often varied perceptibly, and it could be observed that the
electrostatic attraction of the glass affected the vibrating thread; but it was clear that the electrostatic action was
not the cause of the vibration, for the thread was most generally stationary, and could always be set in vibration by
passing the finger quickly near the upper part of the tube. With a magnet the thread could be split in two and both
parts vibrated. By approaching the hand to the lower coating of the tube, or insulated plate if attached, the
vibration was quickened; also, as far as I could see, by raising the potential of frequency. Thus, either increasing
the frequency or passing a stronger discharge of the same frequency corresponded to a tightening of the cord. I
did not obtain any experimental evidence with condenser discharges. A luminous band excited in a bulb by
repeated discharges of a Leyden jar must possess rigidity, and if deformed and suddenly released should vibrate.
But probably the amount of vibrating matter is so small that in spite of the extreme speed the inertia cannot
prominently assert itself. Besides, the observation in sud•1 a case is rendered extremely difficult on account of the
The demonstration of the fact -- which still needs better experimental confirmation -- that a vibrating gaseous
column possesses rigidity, might greatly modify the views of thinkers. When with low frequencies and insignificant
potentials indications of that property may be noted, how must a gaseous medium behave under the influence of
enormous electrostatic stresses which may be active in the interstellar space, and which may alternate with
inconceivable rapidity! The existence of such an electrostatic, rhythmically throbbing force -- of a vibrating
electrostatic field -- would show B possible way how solids might have formed from the ultra-gaseous uterus, and
how transverse and all kinds of vibrations may be transmitted through a gaseous medium filling all space. Then,
ether might be a true fluid, devoid of rigidity, and at rest, it being merely necessary as a connecting link to enable
interaction. What determines the rigidity of a body! It must be the speed and the amount of moving matter. In a gas
the speed may be considerable, but the density is exceedingly small; in a liquid the speed would be likely to be
small, though the density may be considerable; and in both cases the inertia resistance offered to displacement is
practically nil. But place a gaseous (or liquid) column in an intense, rapidly alternating electrostatic field, set the
particles vibrating with enormous speeds, then the inertia resistance asserts itself. A body might move with more
or less freedom through the vibrating mass, but as a whole it would be rigid.
There is a subject which I must mention in connection with these experiments: it is that of high vacua. This is a
subject the study of which is not only interesting, but useful, for it may lead to results of great practical importance.
In commercial apparatus such as incandescent lamps, operated from ordinary systems of distribution, a much
higher vacuum than obtained at present would not secure a very great advantage. In such a case the work is
performed on the filament and the gas is little concerned; the improvement, therefore, would be but trifling. But
when we begin to use very high frequencies and potentials, the action of the gas becomes all important, and the
degree of exhaustion materially modifies the results. As long as ordinary coils, even very large ones, were used,
the study of the subject was limited, because just at a point when it became most interesting it had to be
interrupted on account of the "non-striking" vacuum being reached. But presently we are able to obtain from a
small disruptive discharge coil potentials much higher than even the largest coil was capable of giving, and, what
is more, we can make the potential alternate with great rapidity. Both of these results enable us now ~o pass a
luminous discharge through almost any vacua obtainable, and the field of our investigations is greatly extended.
Think we as we may, of all the possible directions to develop a practical illuminant, the line of high vacua seems to
be the most promising at present. But to reach extreme vacua the appliances must be much mote improved, and
ultimate perfection will not be attained until we shall have discarded the mechanical and perfected an electrical
vacuum pump. Molecules and atoms can be thrown out of a bulb under the action of an enormous potential: this
will be the principle of the vacuum pump of the future. For the present, we must secure the best results we can
with mechanical appliances. In this respect, it might not be out of the way to say a few words about the method of,
and appatatus for, producing excessively high degrees of exhaustion of which I have availed myself in the course
of these investigations. It is very probable that other experimenters have used similar arrangements; but as it is
possible that there may be an item of interest in their description, a few remarks, which will render this
investigation more complete, might be permitted.
The apparatus is illustrated in a drawing shown in Fig. 30. S represents a Sprengel pump, which has been
specially constructed to better suit the work required. The stopcock which is usually employed has been omitted,
and instead of it a hollow stopper has been fitted in the neck of the reservoir R. This stopper has a small hole h,
through which the mercury descends; the size of the outlet o being properly determined with respect to the section
of the fall tube t, which is sealed to the reservoir instead of being connected to it in the usual manner. This
arrangement overcomes the imperfections and troubles, which often arise from the use of the stopcock on the
reservoir and the connection of the latter with the fall tube.
The pump is connected through a U-shaped tube t to a very large reservoir R1. Especial care was taken in fitting
the grinding surfaces of the stoppers p and P,, and both of these and the mercury caps above them were made
exceptionally long. After the U-shaped tube was fitted and put in place, it was heated, so as to soften and take off
the strain resulting from imperfect fitting. The U-shaped tube was provided with a stopcock C, and two ground
connections g and gl -- one for a small bulb b, usually containing caustic potash, and the other for the receiver r, to
The reservoir R1 was connected by means of a rubber tube to a slightly larger reservoir R2, each of the two
reservoirs being provided with a stopcock C1 and C2 respectively. The reservoir R2 could be raised and lowered
by a wheel and rack, and the range of its motion was so determined that when it was filled with mercury and the
stopcock C, closed, so as to form a Torricellian vacuum in it when raised, it could be lifted so high that the mercury
in reservoir R1 would stand a little above stopcock C1: and when this stopcock was dosed and the reservoir R2
descended, so as to form a Torricellian vacuum in reservoir R1, it could be lowered so far as to completely empty
the latter, the mercury filling the reservoir R2 up to a little above stopcock C2.
The capacity of the pump and of the connections was taken as small as possible relatively to the volume of
reservoir, R1, since, of course, the degree of exhaustion depended upon the ratio of these quantities.
With this apparatus I combined the usual means indicated by former experiments for the production of very high
vacua. In most of the experiments it was convenient to use caustic potash. I may venture to say, in regard to its
use, that much time is saved and a more perfect action of the pump insured by fusing and boiling the potash w
soon as, or even before, the pump settles down. If this course is not followed the sticks, as ordinarily employed,
may give moisture off at a certain very slow rate, and the pump may work for many hours without reaching a very
high vacuum. The potash was heated either by a spirit lamp or by passing a discharge through it, or by passing a
current through a wire contained in it. The advantage in the latter case was that the heating could be more rapidly
Generally the process of exhaustion was the following: -- at the start, the stopcocks C and C1 being open, and all
other connections closed, the reservoir R32 was raised so far that the mercury filled the reservoir R1 and a part: of
the narrow connecting U-shaped tube. When the pump was set to work, the mercury would, of course, quickly rise
in the tube, and reservoir R2 was lowered, the experimenter keeping the mercury at about the same level. The
reservoir R2 was balanced by a long spring which facilitated the operation, and the friction of the parts was
generally sufficient to keep it almost in any position. When the Sprengel pump had done its work, the reservoir R2
was further lowered and the mercury descended in R1 and filled R2, whereupon stopcock C2 was closed. The air
adhering to the walls of R, and that absorbed by the mercury was carried off, and to free the mercury of all air the
reservoir R2 was for a long time worked up and down. During this process some air, which would gather below
stopcock C2, was expelled from R2 by lowering it far enough and opening the stopcock, closing the latter again
before raising the reservoir. When all the air had been expelled from the mercury, and no air would gather in R2
when it was lowered, the caustic potash was resorted to. The reservoir R2 was now again raised until the mercury
in R1 stood above stopcock C1. The caustic potash was fused and boiled, and the moisture partly carried off by
the pump and partly re-absorbed; and this process of heating and cooling was repeated many times, and each
time, upon the moisture being absorbed or carried off, the reservoir R2 was for a long time raised and lowered. In
this manner all thc moisture was carried off from the mercury, and both the reservoirs were in proper condition to
be used. The reservoir R2 was then again raised to the top, and the pump was kept working for a long time. When
the highest vacuum obtainable with the Dump had been reached the potash bulb was usually wrapped with cotton
which was sprinkled with ether so as to keep the potash at a very low temperature, then the reservoir R2 was
lowered, and again reservoir R1 being emptied the receiver r was quickly sealed up.
When a new bulb was put on, the mercury was always raised above stopcock C1, which was closed, so as to
always keep the mercury and both the reservoirs in fine condition, and the mercury was never withdrawn from R1
except when the pump had reached the highest degree of exhaustion. It is necessary to observe this rule if it is
desired to use the appartus to advantage.
By means of this arrangement I was able to proceed very quickly, and when the apparatus was in perfect order it
was possible to reach the phosphorescent stage in a small bulb in less than 1S minutes, which is certainly very
quick work for a small laboratory arrangement requiring all in all about 100 pounds of mercury. With ordinary small
bulbs the ratio of the capacity of the pump, receiver, and connections, and that of reservoir R was about 1--20, and
the degrees of exhaustion reached were necessarily very high, though I am unable to make a precise and reliable
statement how far the exhaustion was carried.
What impresses the investigator most in the course of these experiences is the behavior of gases when subjected
to great rapidly alternating electrostatic stresses. But he must remain in doubt as to whether the effects observed
are due wholly to the molecules, or atoms, of the gas which chemical analysis discloses to us, or whether there
enters into play another medium of a gaseous nature, comprising atoms, or molecules, immersed in a fluid
pervading the space. Such a medium, surely must exist, and I am convinced that, for instance, even if air were
absent, the surface and neighborhood of a body in space would be heated by rapidly alternating the potential of
the body; but no such heating of the surface or neighborhood could occur if all free atoms were removed and only
a homogeneous, incompressible, and elastic fluid -- such as ether is supposed to be -- would remain, for then
there would be no impacts, no collisions. In such a case, as far as the body itself is concerned, only frictional
losses in the inside could occur.
It is a striking fact that the discharge through a gas is established with ever increasing freedom as the frequency of
the impulses is augmented. It behaves in this respect quite contrarily to a metallic conductor. In the latter the
impedance enters prominently into play as the frequency is increased, but the gas acts much as a series of
condensers would: the facility with which the discharge passes through seems to depend on the rate of change of
potential. If it act so, then in a vacuum tube even of great length, and no matter how strong the current, selfinduction could not assert itself: to any appreciable degree. We have, then, as far as we can now see, in the gas a
conductor which is capable of transmitting electric impulses of any frequency which we may be able to produce.
Could the frequency be brought high enough, then a queer system of electric distribution, which would be likely to
interest gas companies, might be realized: metal pipes filled with gas -- the metal being the insulator, the gas the
conductor -- supplying phosphorescent bulbs, or perhaps devices as yet uninvented. It is certainly possible to take
a hollow core of copper, rarefy the gas in the same, and by passing impulses of sufficiently high frequency through
a circuit around it, bring the gas inside to a high degree of incandescence; but as to the nature of the forces there
would be considerable uncertainty, for it would be doubtful whether with such impulses the copper core would act
as a static screen. Such paradoxes and apparent impossibilities we encounter at every step in this line of work,
and therein lies, to a great extent, the charm of the study.
I have here a short and wide tube which is exhausted to a high degree and covered with a substantial coating of
bronze, the coating allowing barely the light to shine through. A metallic clasp, with a hook for suspending the
tube, is fastened around the middle portion of the latter, the clasp being in contact with the bronze coating. I now
want to light the gas inside by suspending the tube on a wire connected to the coil. Any one who would try the
experiment for the first time, not having any previous experience, would probably take care to be quite alone when
making the trial, for fear that he might become the joke of his assistants. Still, the bulb lights in spite of the metal
coating, and the light can be distinctly perceived through the latter. A long tube covered with aluminium bronze
lights when held in one hand -- the other touching the terminal of the coil -- quite powerfully. It might be objected
that the coatings arc not sufficiently conducting; still, even if they were highly resistant, they ought to screen the
gas. They certainly screen it perfectly in a condition of rest, but not by far perfectly when the charge is surging in
the coating. But the loss of energy which occurs within the tube, notwithstanding the screen, is occasioned
principally by the presence of the gas. Were we to take a large hollow metallic sphere and fill it with a perfect
incompressible fluid dielectric, there would be no loss inside of the sphere, and consequently the inside might be
considered as perfectly screened, though the potential be very rapidly alternating. Even were the sphere filled with
oil, the loss would be incomparably smaller than when the fluid is replaced by a gas, for in the latter case the force
produces displacements; that means impact and collisions in the inside.
No matter what the pressure of the gas may be, it becomes an important factor in the bearing of a conductor when
the electric density is great and the frequency very high. That in the heating of conductors by lightning discharges
air is an element of great importance, is almost as certain as an experimental fact. I may illustrate the action of the
air by the following experiment: I take a short tube which is exhausted to a moderate degree and has a platinum
wire running through the middle from one end to the other. I pass a steady or low frequency current through the
wire, and it is heated uniformly in all parts. The heating here is due to conduction, or frictional losses, and the gas
around the wire has - as far as we can see - no function to perform. But now let me pass sudden discharges, or a
high frequency current, through the wire. Again the wire is heated, this time principally on the ends and least in the
middle portion; and if the frequency of the impulses, or the rate of change, is high enough, the wire might as well
be cut in the middle as not, for practically all the heating is due to the rarefied gas: Here the gas might only act as
a conductor of no impedance diverting the current from the wire as the impedance of the latter is enormously
increased, and merely heating the ends of the wire by reason of their resistance to the passage of the discharge.
But it is not at all necessary that the gas in the tube should be conducting; it might be at an extremely low
pressure, still the ends of the wire would be heated -- as, however, is ascertained by experience -only the two
ends would in such case not be electrically connected through the gaseous medium. Now what with these
frequencies and potentials occurs in an exhausted tube occurs in the lightning discharges at ordinary pressure.
We only need to remember one of the facts arrived at in the course of these investigations, namely, that to
impulses of very high frequency the gas at ordinary pressure behaves much in the same manner as though it were
at moderately low pressure. I think that in lightning discharges frequently wires or conducting objects are
volatilized merely because air is present, and that, were the conductor immersed in an insulating liquid, it would be
safe, for then the energy would have to spend itself somewhere else. From the behavior of gases to sudden
impulses of high potential I am led to conclude that there can be no surer way of diverting a lightning discharge
than by affording it a passage through a volume of gas, if such a thing can be done in a practical manner.
There are two more features upon which I think it necessary to dwell in connection with these experiments -- the
"radiant state" and the non-striking vacuum".
Any one who has studied Crookes work must have received the impression that the ''radiant state'' is a property of
the gas inseparably connected with an extremely high degree of exhaustion. But it should be remembered that the
phenomena observed in an exhausted vessel are limited to the character and capacity of the apparatus which is
made use of. I think that in a bulb a molecule, or atom, does not precisely move in a straight line because it meets
no obstacle, but because the velocity imparted to it is sufficient to propel it in a sensibly straight line. The mean
free path is one thing, but the velocity -- the energy associated with the moving body -- is another, and under
ordinary circumstances I believe that it is mere question of potential or speed. A disruptive discharge coil, when
the potential is pushed very far, excites phosphorescence and projects shadows, at comparatively low degrees of
exhaustion. In a lightning discharge, matter moves in straight lines at ordinary pressure when the mean free path
is exceedingly small, and frequently images of wires or other metallic objects have been produced by the particles
thrown off in straight lines.
I have prepared a bulb to illustrate by an experiment the correctness of these assertions. In a globe L (Fig. 31), I
have mounted upon a lamp filaments of a piece of lime l. The lamp filament is connected with a wire which leads
into the bulb, and the general construction of the latter is as indicated in Fig. 19, before described. The bulb being
suspended from a wire connected to the terminal of the coil, and the latter being set to work, the lime piece l and
the projecting parts of the filament f are bombarded. The degree of exhaustion is just such that with the potential
the coil is capable of giving phosphorescence of the glass is produced, but disappears as soon as the vacuum is
impaired. The lime containing moisture, and moisture being given off as soon as heating occurs, the
phosphorescence lasts only for a few moments. When the lime has been sufficiently heated, enough moisture has
been given off to impair materially the vacuum of the bulb. As the bombardment goes on, one point of the lime
piece is more heated than other points, and the results is that finally practically all the discharge passes through
that point which is intensely heated, and a white stream of lime particles (Fig. 31) then breaks forth from that point.
This stream is composed of "radiant" matter, yet the degree of exhaustion is low. But the particles move in straight
lines because the velocity imparted to them is great, and this is due to three causes -- to the great electric density,
the high temperature of the small point, and the fact that the particles of the lime are easily torn and thrown off -far more easily than those of carbon. With frequencies such as we are able to obtain, the particles are bodily
thrown off and projected to a considerable distance, but with sufficiently high frequencies no such thing would
occur: in such case only a stress would spread or a vibration would be propagated through the bulb. It would be
out of the question to reach any such frequency on the assumption that the atoms move with the speed of light; but
I believe that such a thing is impossible; for this an enormous potential would be required. With potentials which
we are able to obtain, even with a disruptive discharge coil, the speed must be quite insignificant.
As to the "non-striking vacuum", the point to be noted is that it can occur only with low frequency impulses, and it
is necessitated by the impossibility of carrying off enough energy with such impulses in high vacuum since the few
atoms which are around the terminal upon coming in contact with the same are repelled and kept at a distance for
a comparatively long period of time, and not enough work can be performed to render the effect perceptible to the
eye. If the difference of potential between thc terminals is raised, the dielectric breaks down. But with very high
frequency impulses there is no necessity for such breaking down, since any amount of work can be performed by
continually agitating the atoms in the exhausted vessel, provided the frequency is high enough. It is easy to reach
-- even with frequencies obtained from an alternator as here used -- a stage at which the discharge does not pass
between two electrodes in a narrow tube, each of these being connected to one of the terminals of the coil, but it is
difficult to reach a point at which a luminous discharge would not occur around each electrode.
A thought which naturally presents itself in connection with high frequency currents, is to make use of their
powerful electro-dynamic inductive action to product: light effects in a sealed glass globe. The leading-in wire is
one of the defects of the present incandescent lamp, and if no other improvement were made, that imperfection at
least should be done away with. Following this thought, I have carried on experiments in various directions, of
which some were indicated in my former paper. I may here mention one or two more lines of experiment which
have been followed up.
Many bulbs were constructed as shown in Fig. 32 and Fig. 33. In Fig. 32 a wide tube r was sealed to a smaller Wshaped tube U, of phosphorescent glass. In the tube T was placed a coil C of aluminium wire, the ends of which
were provided with small spheres t and tl of aluminium, and reached into the U tube. The tube T was slipped into a
socket containing a primary coil through which usually the discharges of Leyden jars were directed, and the
rarefied gas in the small U tube was excited to strong luminosity by the high-tension currents induced in the
coil C. When Leyden jar discharges were used to induce currents in the coil C, it was found necessary to pack the
tube T tightly with insulating powder, as a discharge would occur frequently between the turns of the coil,
especially when the primary was thick and the air gap, through which the jars discharged, large, and no little
trouble was experienced in this way.
In Fig. 33 is illustrated another form of the bulb constructed. In this case a tube T is sealed to a globe L. The tube
contains a coil C, the ends of which pass through two small glass tubes t and tl, which are sealed to the tube T.
Two refractory buttons m and ml are mounted on lamp filaments which are fastened to the ends of the wires
passing through the glass tubes t and tl. Generally in bulbs made on this plan the globe I. communicated with the
tube T. For this purpose the ends of the small tubes t and t1 were just a trifle heated in the burner, merely to hold
the wires, but not to interfere with the communication. The tube T, with the small tubes, wires through the same,
and the refractory buttons m and m1 was first prepared, and then sealed to globe L, whereupon the coil C was
slipped in and the connections made to its ends. The tube was then packed with insulating powder, jamming the
latter as tight as possible up to very nearly the end, then it was closed and only a small hole left through which the
remainder of the powder was introduced, and finally the end of the tube was closed. Usually in bulbs constructed
as shown in Fig. 33 an aluminium tube a was fastened to the upper end s of each of the tubes t and tl, in order to
protect that end against the heat. The buttons m and ml could be brought to any degree of incandescence by
passing the discharges of Leyden jars around the coil C. In such bulbs with two buttons a very curious effect is
produced by the formation of the shadows of each of the two buttons.
Another line of experiment, which has been assiduously followed, was to induce by electro-dynamic induction a
current or luminous discharge in an exhausted tube or bulb. This matter has received such able treatment at the
hands of Prof. J. J. Thomson that I could add but little to what he has made known, even had I made it the special
subject of this lecture. Still, since experiences in this line have gradually led me to the present views and results, a
few words must be devoted here to this subject.
It has occurred, no doubt, to many that as a vacuum tube is made longer the electromotive force per unit length of
the tube, necessary to pass a luminous discharge through the latter, gets continually smaller; therefore, if the
exhausted tube be made long enough, even with low frequencies a luminous discharge could be induced in such a
tube closed upon itself. Such a tube might be placed around a hall or on a ceiling, and at once a simple appliance
capable of giving considerable light would be obtained. But this would be an appliance hard to manufacture and
extremely unmanageable. It would not do to make the tube up of small lengths, because there would be with
ordinary frequencies considerable loss in the coatings, and besides, if coatings were used, it would be better to
supply the current directly to the tube by connecting the coatings to a transformer. But even if all objections of
such nature were removed, still, with low frequencies the light conversion itself would be inefficient, as I have
before stated. In using extremely high frequencies the length of the secondary -- in other words, the site of the
vessel -- can be reduced as far as desired, and the efficiency of the light conversion is increased; provided that
means are invented for efficiently obtaining such high frequencies. Thus one is led, from theoretical and practical
considerations, to the use of high frequencies, and this means high electromotive forces and small currents in the
primary. When he works with condenser charges -- and they are the only means up to the present known for
reaching these extreme frequencies -- he gets tr. electromotive forces of several thousands of volts per turn of the
primary. He cannot multiply the electro-dynamic inductive effect by taking more turns in the primary, for he arrives
at the conclusion that the best way is to work with one single turn -- though he must sometimes depart from this
rule -- -and he must get along with whatever inductive effect he can obtain with one turn. But before he has long
experimented with the extreme frequencies required to set up in a small bulb an electromotive force of several
thousands of volts he realizes the great importance of electrostatic effects, and these effects grow relatively to the
electro-dynamic in significance as the frequency is increased.
Now, if anything is desirable in this case, it is to increase the frequency, and this would make it still worse for the
electro-dynamic effects. On the other hand, it is easy to exalt the electrostatic action as far as one likes by taking
more turns on the secondary, or combining self-induction and capacity to raise the potential. It should also be
remembered that, in reducing the current to the smallest value and increasing the potential, the electric impulses
of high frequency can be more easily transmitted through a conductor.
These and similar thoughts determined me to devote more attention to the electrostatic phenomena, and to
endeavor to produce potentials as high as possible, and alternating as fast as they could be made to alternate. I
then found that I could excite vacuum tubes at considerable distance from a conductor connected to a properly
constructed coil, and that I could, by converting the oscillatory current of a condenser to a higher potential,
establish electrostatic alternating fields which acted through the whole extent of a room, lighting up a tube no
matter where it was held in space. I thought I recognized that I had made a step in advance, and I have perserved
in this line; but I wish to say that I share with all lovers of science and progress the one and only desire -- to reach
a result of utility to men in any direction to which thought or experiment may lead me. I think that this departure is
the right one, for I cannot see, from the observation of the phenomena which manifest themselves as the
frequency is increased, what there would remain to act between two circuits conveying, for instance, impulses of
several hundred millions per second, except electrostatic forces. Even with such stifling frequencies the energy
would be practically all potential, and my conviction has grown strong that, to whatever kind of motion light may be
due, it is produced by tremendous electrostatic stresses vibrating with extreme rapidity.
Of all these phenomena observed with currents, or electric impulses, of high frequency, the most fascinating for an
audience are certainly those which are noted in an electrostatic field acting through considerable distance, and the
best an unskilled lecturer can do is to begin and finish with the exhibition of these singular effects. I take a tube in
the hand and move it about, and it is lighted wherever I may hold it; throughout space the invisible forces act. But I
may take another tube and it might not light, the vacuum being very high. I excite it by means of a disruptive
discharge coil, and now it will light in the electrostatic field. I may put it away for a few weeks or months, still it
retains the faculty of being excited. What change have I produced in the tube in the ad of exciting it! If a motion
imparted to the atoms, it is difficult to perceive how it can persist so long without being arrested by frictional
losses; and if a strain exerted in the dielectric, such as a simple electrification would produce, it is easy to see how
it may persist indefinitely but very difficult to understand why such a condition should aid the excitation when we
have to deal with potentials which are rapidly alternating.
Since I have exhibited these phenomena for the first time, I have obtained some other interesting effects. For
instance, I have produced the incandescence of a button, filament, or wire enclosed in a tube. To get to this result
it was necessary to economize the energy which is obtained from the field and direct most of it on the small body
to be rendered incandescent. At the beginning the task appeared difficult, but the experiences gathered permitted
me to teach the result easily. In Fig. 34 and Fig. 35 two such tubes are illustrated which are prepared for the
occasion. In Fig. 34 a short tube T1, sealed to another long tube T, is provided with a stem s, with a platinum wire
sealed in the latter. A very thin lamp filament I is fastened to this wire, and connection to the outside is made
through a thin copper wire w. The tube is provided with outside and inside coatings, C and C1 respectively, and is
filled as far as the coatings reach with conducting, and the space above with insulating powder. These coatings
are merely used to enable me to perform two experiments with the tube -- namely, to produce the effect desired
either by direct connection of the body of the experimenter or of another body to the wire w, or by acting
inductively through the glass. The stem s is provided with an aluminium tube a for purposes before explained, and
only a small part of the filament reaches out of this tube. By holding the tube T1 anywhere in the electrostatic field
the filament is rendered incandescent.
A more interesting piece of apparatus is illustrated in Fig. 35. The construction is the same as before, only instead
of the lamp filament a small platinum wire P, sealed in a stem s, and bent above it in a circle, is connected to the
copper wire w, which is joined to an inside coating C. A small stem sl is provided with a needle, on the point of
which is arranged to rotate very freely a very light fan of mica v. To prevent the fan from falling out, a thin stem of
glass g is bent properly and fastened to the aluminium tube. When the glass tube is held anywhere in the
electrostatic field the platinum wire becomes incandescent, and the mica vanes are rotated very fast.
Intense phosphorescence may be excited in a bulb by merely connecting it to a plate within the field, and the plate
need not be any larger than an ordinary lamp shade. The phosphorescence excited with these currents is
incomparably more powerful than with ordinary apparatus. A small phosphorescent bulb, when attached to a wire
connected tl, a coil, emits sufficient light to allow reading ordinary print at a distance of five to six paces. It was of
interest to see how some of the phosphorescent bulbs of Professor Crookes would behave with these currents,
and he has had the kindness to lend me z few for the occasion. The effects produced are magnificent, especially
by the sulphide of calcium and sulphide of zinc. From the disruptive discharge coil they glow intensely merely by
holding them in the hand and connecting the body to the terminal of the coil.
To whatever results investigations of this kind may lead, their chief interest lies for the present in the possibilities
they offer for the production of an efficient illuminating device. In no branch of electric industry is an advance more
desired than in the manufacture of light. Every thinker, when considering the barbarous methods employed, the
deplorable losses incurred in our best systems of light production, must have asked himself, What is likely to be
the light of the future! Is it to be an incandescent solid, as in the present lamp, or an incandescent gas, or a
phosphorescent body, or something like a burner, but incomparably more efficient!
There is little chance to perfect a gas burner; not, perhaps, because human ingenuity has been bent upon that
problem for centuries without a radical departure having been made -- though this argument is not devoid of force
-- but because in a burner the higher vibrations can never be reached except by passing through all the low ones.
For how is a flame produced unless by a fall of lifted weights! Such process cannot be maintained without renewal,
and renewal is repeated passing from low to high vibrations. One way only seems to be open to improve a burner,
and that is by trying to reach higher degrees of incandescence. Higher incandescence is equivalent to a quicker
vibration; that means more light from the same material, and that, again, means more economy. In this direction
some improvements have been made, but the progress is hampered by many limitations. Discarding, then, the
burner, there remain the three ways first mentioned, which are essentially electrical.
Suppose the light of the immediate future to be a solid rendered incandescent by electricity. Would it not seem
that it is better to employ a small button than a frail filament! From many considerations it certainly must be
concluded that a button is capable of a higher economy, assuming, of course, the difficulties connected with the
operation of such a lamp to be effectively overcome. But to light such a lamp we require a high potential; and to
get this economically we must use high frequencies.
Such considerations apply even more to the production of light by the incandescence of a gas, or by
phosphorescence. In all cases we require high frequencies and high potentials. These thoughts occurred to me a
long time ago.
Incidentally we gain, by the use of very high frequencies, many advantages, such as a higher economy in the light
production, the possibility of working with one lead, the possibility of doing away with the leading-in wire, etc.
The question is, how far can we go with frequencies! Ordinary conductors rapidly lose the facility of transmitting
electric impulses when the frequency is greatly increased. Assume the means for the production of impulses of
very great frequency brought to the utmost perfection, every one will naturally ask how to transmit them when the
necessity arises. In transmitting such impulses through conductors we must remember that we have to deal with
pressure and flow, in the ordinary interpretation of these terms. Let the pressure increase to an enormous value,
and let the flow correspondingly diminish, then such impulses -- variations merely of pressure, as it were -- can no
doubt be transmitted through a wire even if their frequency be many hundreds of millions per second. It would, of
course, be out of question to transmit such impulses through a wire immersed in a gaseous medium, even if thc
wire were provided with a thick and excellent insulation for most of the energy would be lost in molecular
bombardment and consequent heating. The end of the wire connected to the source would be heated, and the
remote end would receive but a trifling part of the energy supplied. The prime necessity, then, if such electric
impulses are to be used, is to find means to reduce as much as possible the dissipation.
The first thought is, employ the thinnest possible wire surrounded by the thickest practicable insulation. The next
thought is to employ electrostatic screens. The insulation of the wire may be covered with a thin conducting
coating and the latter connected to the ground. But this would not do, as then all the energy would pass through
the conducting coating to the ground and nothing would get to the end of the wire. If a ground connection is made
it can only be made through a conductor offering an enormous impedance, or through a condenser of extremely
small capacity. This, however, does not do away with other difficulties.
If the wave length of the impulses is much smaller than the length of the wire, then corresponding short waves will
be sent up in the conducting coating, and it will be more or less the same as though the coating were directly
connected to earth. It is therefore necessary to cut up the coating in sections much shorter than the wave length.
Such an arrangement does not still afford a perfect screen, but it is ten thousand times better than none. I think it
preferable to cut up the conducting coating in small sections, even if the current waves be much longer than the
If a wire were provided with a perfect electrostatic screen, it would be the same as though all objects were
removed from it at infinite distance. The capacity would then be reduced to the capacity of the wire itself, which
would be very small. It would then be possible to send over the wire current vibrations of very high frequencies at
enormous distance without affecting greatly the character of the vibrations. A perfect screen is of course out of the
question, but I believe that with a screen such as I have just described telephony could be rendered practicable
across the Atlantic. According to my ideas, the gutta-percha covered wire should be provided with a third
conducting coating subdivided in sections. On the top of this should be again placed a layer of gutta-percha and
other insulation, and on the top of the whole the armor. But such cables will not be constructed, for ere long
intelligence -- transmitted without wires will throb through the earth like a pulse through a living organism. The
wonder is that, with the present state of knowledge and the experiences gained, no attempt is being made to
disturb the electrostatic or magnetic condition of the earth, and transmit, if nothing else, intelligence.
It has been my chief aim in presenting these results to point out phenomena or features of novelty, and to advance
ideas which I am hopeful will serve as starting points of new departures. It has been my chief desire this evening
to entertain you with some novel experiments. Your applause, so frequently and generously accorded has told me
that I have succeeded.
In conclusion, let me thank you most heartily for your kindness and attention, and assure you that the honor I have
had in addressing such a distinguished audience, the pleasure I have had in presenting these results to a
gathering of so many able men and among them also some of those in whose work for many years past I have
found enlightenment and constant pleasure -- I shall never forget.
Tesla era un’ingegnere elettrico al quale sia la scienza ufficiale, sia quella non
ufficiale, devono molto. Questo è un dispositivo di risonanza, utile per
tramettere onde attraverso la terra. Ma, una volta costruito, va maneggiato
con estrema cautela.
L’Oscillatore di Tesla
A Nikola Tesla si pensa principalmente come ad un genio dell’elettricità, ma fu pure autore di un
mucchio di dispositivi meccanici. Uno dei più famosi di questi fu la sua "Macchina per Terremoti" anche
conosciuta come l’Oscillatore di Tesla. La macchina che Tesla ha provato fu piccola, circa 7 pollici di
lunghezza, e pesante solo uno o due pounds; del tipo "potresti metterlo nella tasca del tuo cappotto". Nel
1898, il laboratorio di Tesla a New York fu vicino cadere a pezzi con questo piccolo dispositivo, azionato
solo da solo cinque pounds di pressione dell’aria che agiscono contro uno speciale pistone pneumatico.
L’intero sistema fu progettato per essere alimentato dalla pressione del vapore.
Tesla stava sperimentando modi per trasmettere forza motrice attraverso la Terra! Versioni più grandi di
questi oscillatori, forse pesanti 200 pounds, e essendo circa alta tre piedi poteva trasmettere forza motrice
utilizzabile ovunque nell’intero pianeta. Se vi sembra fantastico, questo dispositivo poteva anche trovare
navi, sottomarini e palazzi ovunque e su scala globale. Il dispositivo di Tesla era del tutto meccanico, ed
è mostrato qui di seguito:
Il vapore potrebbe essere forzato nell’oscillatore, e uscire attraverso una serie di portelli, il cui effetto era
di portare l'armatura a vibrare ad alta velocità. Il rivestimento era per necessità molto forte, in quanto le
temperature dovute alla pressione di riscaldamento nella camera superiore superavano i 200 gradi, e la
pressione portata a 400psi. Furono create altre versioni di questa macchina, progettate per produrre
energia elettrica sia alternata che continua (senza il bisogno di aggiustamenti).
Con questo in mente, ho iniziato a pensare al modo in cui poter costruire uno di questi oscillatori più
facilente che con un recipiente a pressione in acciaio. Poichè il pistone ad aria fa affidamento sull'aria
compressa per realizzare il movimento d’oscillazione, mi sembra che dovrebbe essere utile un altro modo
di forzare pistone a muoversi. Ho battuto sull'idea di usare un campo magnetico per creare parte del
movimento. Il disporre di una corrente alternata a frequenza variabile potrebbe essere la soluzione
perfetta a questo problema, permettendo una perfetta modulazione delle frequenze d’oscillazione con la
sistemazione di una semplice bobina, senza il bisogno di aria o di vapore. Eventualmente, la soluzione
che meglio sembra essere adatta al lavoro può essere la seguente:
Il sistema lavora come segue. L’aria compressa entrando nel vano d'ingresso forza la testa pistone verso
l'alto. Comunque, l'asta del pistone è impedita a muoversi verso l'alto dall’azione di campi magnetici
opposti tra le due bobine. La corrente nelle bobine può essere variata per creare un campo di una forza
specifica, e quindi l'ammontare di forza richiesta per il pistone da dover aumentare. Il campo preme giù e
l’aria preme su. Quando la spinta dell'aria supera la spinta del campo, il pistone verrà sparato verso l'alto,
ma appena la testa del pistone supera l'apertura dell'aria, la cavità verrà depressurizzata. Quando accade,
il campo sbatterà il pistone verso il basso, e la testa del martello colpirà la lamiera d'acciao alla base. Al
variare della pressione dell’aria e della forza del campo magnetico, si può creare qualsiasi intervallo di
frequenza si desideri.
Buttiamo Giù la Casa!
Ogni cosa in natura vibra ad una certa frequenza. Quando un oggetto è vibrato alla sua risonanza naturale,
inizia a subire un pesante shock, appena prova a scuotere se stesso a distanza. Potrebbe sembrare ridicolo
immaginare che un minuscolo oscillatore possa da solo buttare giù un palazzo, se non per il principio di
risonanza. Come un bambino sull’altalena, solo una piccolissima forza è richiesta per mantenere un
movimento reciproco e abbastanza ampio. Una maggiore vibrazione potrebbe essere stabilita in una casa
facendo coincidere ciascun colpo del pistone col ritorno delle singole vibrazioni attraverso il palazzo
dove si trova l’oscillatore. Ogni volta che il pistone batte,ingrandisce la forza un po’ di più. Alla
frequenza di 1000Hz, la forza accumulata può essere molto apprezzabile! La frequenza di risonanza è
collegata al tempo che prende per le vibrazioni per espandersi attraverso l'edificio, riverberare, ed
“echeggiare” per ritornare ancora all’oscillatore. Trovando la corretta frequenza, può essere distrutta
OGNI struttura. Infatti, più grande è la struttura, più è bassa la frequenza di risonanza, più è facile da
distruggere. Tesla una volta scherzava quando diceva che poteva spaccare la Terra con una di queste
macchine, e nessuno sa veramente se stava scherzando...
Sto attualmente considerando di costruire un oscillatore per prova, basato sul progetto di questa pagina. Il
dispositivo è alquanto pericoloso così avrò bisogno di lavorarci con cautela. Se qualcuno ha un
suggerimento su ulteriori miglioramenti che possono essere fatti, è pregato di
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Tesla's Earthquake Machine
Excerpt from the New York World
Telegram, July 11, 1935 -
Nikola Tesla revealed that an earthquake which drew police and ambulances to the region of
his laboratory at 48 E. Houston St., New York, in 1898, was the result of a little machine he
was experimenting with at the time which "you could put in your overcoat pocket." The
bewildered newspapermen pounced upon this as at least one thing they could understand and
Nikola Tesla, "the father of modern electricity" told what had happened as follows:
Tesla stated, "I was experimenting with vibrations. I had one of my machines going and I
wanted to see if I could get it in tune with the vibration of the building. I put it up notch
after notch. There was a peculiar cracking sound. I asked my assistants where did the
sound come from. They did not know. I put the machine up a few more notches. There
was a louder cracking sound. I knew I was approaching the vibration of the steel building.
I pushed the machine a little higher. "Suddenly all the heavy machinery in the place was
flying around. I grabbed a hammer and broke the machine. The building would have been
about our ears in another few minutes. Outside in the street there was pandemonium.
The police and ambulances arrived. I told my assistants to say nothing. We told the police
it must have been an earthquake. That's all they ever knew about it."
Some shrewd reporter asked Dr. Tesla at this point what he would need to destroy the Empire State
Building and the doctor replied: "Vibration will do anything. It would only be necessary to
step up the vibrations of the machine to fit the natural vibration of the building and the
building would come crashing down. That's why soldiers break step crossing a bridge."
"On the occasion of his annual birthday celebration interview by the press on July 10, 1935 in his
suite at the Hotel New Yorker, Tesla announced a method of transmitting mechanical energy
accurately with minimal loss over any terrestrial distance, including a related new means of
communication and a method, he claimed, which would facilitate the unerring location of
underground mineral deposits. At that time he recalled the earth-trembling "quake" that brought
police and ambulances rushing to the scene of his Houston Street laboratory while an experiment
was in progress with one of his mechanical oscillators..."
Excerpt from: "Tesla: Man Out of Time"
by Margaret Cheney
He attached an oscillator no larger than an alarm clock to a steel link 2' long and 2" thick. "For a
long time nothing happened, but at last the great steel link began to tremble, increased
its trembling until it dilated and contracted like a beating heart, and finally broke.
Sledgehammers could not have done it", he told a reporter, "crowbars could not have
done it, but a fusillade of taps, no one of which would have harmed a baby, did it."
Pleased with this beginning, he put the little oscillator in his coat pocket. Finding a half-built steel
building in the Wall Street district, 10 stories high with nothing up but the steelwork, he clamped
the oscillator to one of the beams. "In a few minutes I could feel the beam trembling.
Gradually the trembling increased in intensity and extended throughout the whole great
mass of steel. Finally the structure began to creak and weave, and the steelworkers came
to the ground panic-stricken, believing that there had been an earthquake. Before
anything serious happened, I took off the oscillator, put it in my pocket, and went away.
But if I had kept on 10 minutes more, I could have laid that building flat in the street. And
with the same oscillator I could drop Brooklyn Bridge in less than an hour."
Sparling, Earl: N. Y. World-Telegram (July 11, 1935), "Nikola Tesla, at 79, Uses Earth to
Transmit Signals; Expects to have $100,000,000 Within Two Years" ~ Here Tesla tells the
story of the earthquake generated by the mechanical oscillator in his NYC laboratory in 1898, which
brought the police there to stop him. They entered the lab just in time to see Tesla swing a sledge
hammer and smash the tiny device, which was mounted on a girder: Nikola Tesla revealed that an
earthquake which drew police and ambulances to the region of his laboratory at 48 E. Houston
St., New York, in 1898, was the result of a little machine he was experimenting with at the time
which "you could put in your overcoat pocket."
The bewildered newspapermen pounced upon this as at least one thing they could understand and
"the father of modern electricity" told what had happened as follows: "I was experimenting with
vibrations. I had one of my machines going and I wanted to see if I could get it in tune
with the vibration of the building. I put it up notch after notch. There was a peculiar
"I asked my assistants where did the sound come from. They did not know. I put the
machine up a few more notches. There was a louder cracking sound. I knew I was
approaching the vibration of the steel building. I pushed the machine a little higher.
"Suddenly all the heavy machinery in the place was flying around. I grabbed a hammer
and broke the machine. The building would have been about our ears in another few
minutes. Outside in the street there was pandemonium. The police and ambulances
arrived. I told my assistants to say nothing. We told the police it must have been an
earthquake. That's all they ever knew about it."
Some shrewd reporter asked Dr. Tesla at this point what he would need to destroy the Empire State
Building and the doctor replied: "Vibration will do anything. It would only be necessary to
step up the vibrations of the machine to fit the natural vibration of the building and the
building would come crashing down. That's why soldiers break step crossing a bridge."
In another interview, he (Tesla) boasted that, "With this principle one could split the earth in
half like an apple"...
Century Magazine, p. 921, Figure 2 (April 1895) ~ In 1893 Tesla constructed a preferred
embodiment of the mechanical oscillator which he described as a "double compound
mechanical and electrical oscillator for generating current of perfect, constant,
dynamo frequency of 10 horsepower."
Allan L. Benson: World Today (Feb. 1912); "Nikola Tesla, Dreamer" ~ An illustration for the
article shows an artist's conception of the planet splitting in two. The caption reads: "Tesla
claims that in a few weeks he could set the earth's crust into such a state of
vibration that it would rise and fall hundreds of feet and practically destroy
civilization. A continuation of this process would, he says, eventually split the earth
New York Sun (July 10, 1935); "New Apparatus Transmits Energy - Tesla Announces
Method of Remote Control"
N. Y. American (July 11, 1935), Section 2; "Tesla's Controlled Earth Quakes Power
Through the Earth, A Startling Discovery".
New York Herald Tribune (July 11, 1935), pp. 1, 8; "Tesla, at 79, Discovers New Message
Wave - At Birthday Luncheon He Announces Machine for 1-Way Communication"
New York Sun (July 11, 1935); "Nikola Tesla Describes New Invention - Art of TeleGeodynamics"
New York Times (July 11, 1935), p. 23, col. 8; "Tesla, 79, "Promises to Transmit Force Transmission of Energy Over World"
Prodigal Genius: The Life and Times of Nicola Tesla
by John O'Neill
Tele-Geo-Dynamics is the transmission of sonic or acoustic vibrations, which can be produced with
comparatively simple apparatus. There is of course much sonic equipment available now for
different applications, but this has little or nothing to do with Nikola Tesla's oscillator-generator.
What Tesla proposed represents a new technology in sonic transmission even today. In Tesla's
oscillator-generator, a Resonance effect can be observed. Since resonance seems to be an ever
increasing effect with this oscillator-generator, it can be deduced that there must be a great source
of energy available through it.
Why can a resonance be created in the oscillator-generator when it cannot in a ordinary
reciprocating engine? With the oscillator-generator, all governing mechanisms are eliminated. On
the other hand, consider the car engine. Starting with the cylinder, a reciprocating motion is
converted into rotary motion by a means of shafts, cranks, gears, drivetrains, transmissions, etc.
These parts all consume work by friction, but the greatest loss occurs in the change from
reciprocating to rotary motion. At each point every varying inclination of the crank and pistons work
at a disadvantage and result in loss of efficiency.
In Tesla's oscillator-generator, the piston is entirely free to move as the medium impels it
without having to encounter and overcome the inertia of a moving system and in this respect the
two types of engines differ radically and essentially. This type of engine, under the influence of an
applied force such as the tension of compressed air, steam, or other gases under pressure, yields
an oscillation of a constant period. The objective of the Tesla oscillator-generator is to provide a
mechanism capable of converting the energy of compressed gas or steam into mechanical power.
Since the oscillator-generator is denuded of all governing devices, friction is almost nonexistent. In other words, the piston floats freely in air and is capable of converting all
pressure into mechanical energy.
Our objective in building the engine is to provide an oscillator which under the influence of an
applied force such as the elastic tension of a gas under pressure will yield an oscillating movement
which within very wide limits, will be of constant period, irrespective of variation of load, frictional
losses, and other factors which in ordinary engines change in the rate of reciprocating. It is a wellknown principle that if a spring possessing a sensible inertia is brought under tension, i.e., being
stretched, and then freed, it will perform vibrations which are isochronous. As far as the period in
general is concerned, it will depend on the rigidity of the spring, and its own inertia or that of the
system of which it may form an immediate part. This is known as Simple Harmonic Motion. This
simple harmonic motion in the form of isochronous sound vibrations can be impressed upon the
earth, causing the propagation of corresponding rhythmical disturbances through the same which
pass through its remotest boundaries without attenuation so that the transmission is affected with
an efficiency of one hundred percent.
The Patent; Tesla's Mechanical Oscillator:
US Patent # 514,169 - Reciprocating Engine - Nikola Tesla
To all whom it may concern:
Be it known that I, Nikola Tesla, a citizen of the United States, residing at New York, in the county
and State of New York, have invented certain new and useful Improvements in Reciprocating
Engines, of which the following is a specification, reference being had to the drawing accompanying
and forming a part of the same. In the invention which forms the subject of my present application,
my object has been, primarily to provide an engine, which under the influence of an
applied force such as the elastic tension of steam or gas under pressure will yield an
oscillatory movement which, within very wide limits, will be of constant period,
irrespective of variations of load, frictional losses and other factors which in all ordinary
engines produce change in the rate of reciprocation.
The further objects of the invention are to provide a mechanism, capable of converting the energy
of steam or gas under pressure into mechanical power more economically than the forms of engine
heretofore used, chiefly by overcoming the losses which result in these by the combination with
rotating parts possessing great inertia of a reciprocating system; which also, is better adapted for
use at higher temperatures and pressures, and which is capable of useful and practical application
to general industrial purposes, particularly in small units.
The invention is based upon certain well known mechanical principles a statement of which will
assist in a better understanding of the nature and purposes of the objects sought and results
obtained. Heretofore, where the pressure of steam or any gas has been utilized and applied for the
production of mechanical motion it has been customary to connect with the reciprocating or moving
parts of the engine a fly-wheel or some rotary system equivalent in its effect and possessing
relatively great mechanical inertia, upon which dependence was mainly placed for the maintenance
of constant speed. This, while securing in a measure this object, renders impossible the attainment
of the result at which I have arrived, and is attended by disadvantages which by my invention are
entirely obviated. On the other hand, in certain cases, where reciprocating engines or tools have
been used without a rotating system of great inertia, no attempt, so far as I know, has been made
to secure conditions which would necessarily yield such results as I have reached.
It is a well known principle that if a spring possessing a sensible inertia be brought under
tension, as by being stretched, and then freed it will perform vibrations which are
isochronous and, as to period, in the main dependent upon the rigidity of the spring, and
its own inertia or that of the system of which it may form an immediate part. This is known
to be true in all cases where the force which tends to bring the spring or movable system into a
given position is proportionate to the displacement. In carrying out my invention and for securing
the objects in general terms stated above, I employ the energy of steam or gas under pressure,
acting through proper mechanism, to maintain in oscillation a piston, and, taking advantage of the
law above stated, I connect with said piston, or cause to act upon it, a spring, under such
conditions as to automatically regulate the period of the vibration, so that the alternate impulses of
the power impelled piston, and the natural vibrations of the spring shall always correspond in
direction and coincide in time.
While, in the practice of the invention I may employ any kind of spring or elastic body of which the
law or principle of operation above defined holds true, I prefer to use an air spring, or generally
speaking a confined body or cushion of elastic fluid, as the mechanical difficulties in the use of
metallic springs are serious, owing mainly, to the tendency to break. Moreover, instead of
permitting the piston to impinge directly upon such cushions within its own cylinder, I prefer, in
order to avoid the influence of the varying pressure of the steam or gas that acts upon the piston
and which might disturb the relations necessary for the maintenance of isochronous vibration, and
also to better utilize the heat generated by the compression, to employ an independent plunder
connected with the main piston, and a chamber or cylinder therefore, containing air which is
normally, at the same pressure as the external atmosphere, for thus a spring of practically constant
rigidity is obtained, but the air or gas within the cylinder may be maintained at any pressure.
In order to describe the best manner of which I
am aware in which the invention is or may be
carried into effect, I refer now to the
accompanying drawing which represents in
central cross-section an engine embodying
my improvements. A is the main cylinder in
which works a piston B. Inlet ports CC pass
through the sides of the cylinder, opening at the
middle portion thereof and on opposite sides.
Exhaust ports DD extend through the wall of the
cylinder and are formed with branches that open
into the interior of the cylinder on each side of
the inlet ports and on opposite sides of the
The piston B is formed with two circumferential
grooves EF, which communicate through
openings G in the piston with the cylinder on
opposite sides of said piston respectively. I do not
consider as of special importance the particular
construction and arrangement of the cylinder, the
piston and the ports for controlling it, except that
it is desirable that all the ports, and more
especially, the exhaust ports should be made
very much larger than is usually the case, so that
no force due to the action of the steam or
compressed air will tend to retard of affect the
return of the piston in either direction. The piston
B is secured to a piston rod H, which works in suitable stuffing boxes in the heads of the cylinder A.
This rod is prolonged on one side and extends through bearings V in a cylinder I suitably mounted
or supported in line with the first, and within which is a disk or plunger J carried by the rod H.
The cylinder I is without ports of any kind and is air-tight except as a small leakage my occur
through the bearings V, which experience has shown need not be fitted with any very considerable
accuracy. The cylinder I is surrounded by a jacket K which leaves an open space or chamber around
it. The bearings V in the cylinder I, extend through the jacket K which leaves an open space or
chamber around it. The bearings V in the cylinder I, extend through the jacket K to the outside air
and the chamber between the cylinder and jacket is made steam or air tight as by suitable packing.
The main supply line L for steam or compressed air leads into this chamber, and the two pipes that
lead to the cylinder A run from the said chamber, oil cups M being conveniently arranged to deliver
oil into the said pipes for lubricating the piston. In the particular form of engine shown the jacket K
which contains the cylinder I is provided with a flange N by which it is screwed to the end of
cylinder A. A small channel O is thus formed which has air vents P in its sides and drip pipes Q
leading out from it through which the oil which collects in it is carried off.
To explain now the operation of the device above described. In the position of the parts shown, or
when the piston is at the middle point of its stroke, the plunger J is at the center of the cylinder I
and the air on both sides of the same is at the normal pressure of the outside atmosphere. If a
source of steam or compressed air be then connected to the inlet ports CC of the cylinder A and a
movement be imparted to the piston as by a sudden blow, the latter is caused to reciprocate in a
manner well understood. The movement of the piston in either direction ceases when the force
tending to impel it and the momentum which it has acquired are counterbalanced by the increasing
pressure of the steam or compressed air in that end of the cylinder toward which it is moving and
as in its movement the piston has shut off at a given point, the pressure that impelled it and
established the pressure that tends to return it, it is then impelled in the opposite direction, and
this action is continued as long as the requisite pressure is applied. The movements of the piston
compress and rarify the air in the cylinder I at opposite ends of the same alternately. A forward
stroke compresses the air ahead of the plunger J and tends to drive it forward. This action of the
plunger upon the air contained in the opposite ends of the cylinder is exactly the same in principle
as though a piston rod were connected to the middle point of a coiled spring, the ends of which are
connected to fixed supports. Consequently the two chambers may be considered as a single spring.
The compressions of the air in the cylinder I and the consequent loss of energy due mainly to the
imperfect elasticity of the air, give rise to a very considerable amount of heat. This heat I utilize by
conducting the steam or compressed air to the engine cylinder through the chamber formed by the
jacket surrounding the air-spring cylinder. The heat thus taken up and used to raise the
temperature of the steam or air acting upon the piston is availed of to increase the efficiency of the
engine. In any given engine of this kind the normal pressure will produce a stroke of determined
length, and this will be increased or diminished according to the increase of pressure above or the
reduction of pressure below the normal.
In constructing the apparatus I allow for a variation in the length of stroke by giving to the
confining cylinder I of the air spring properly determined dimensions. The greater the pressure
upon the piston, the higher will be the degree of compression of the air-spring, and the consequent
counteracting force upon the plunger. The rate or period of reciprocation of the piston, however, is
no more dependent upon the pressure applied to drive it, than would be the period of oscillation of
a pendulum permanently maintained in vibration, upon the force which periodically impels it, the
effect of variations in such force being merely to produce corresponding variations in the length of
stroke or amplitude of vibration respectively. The period is mainly determined by the rigidity of the
air spring and the inertia of the moving system, and I may therefore secure any period of
oscillation within very wide limits by properly portioning these factors, as by varying the
dimensions of the air chamber which is equivalent to varying the rigidity of the spring, or by
adjusting the weight of the moving parts. These conditions are all readily determinable, and an
engine constructed as herein described my be made to follow the principle of operation
above stated and maintain a perfectly uniform period through very much wider limits of
pressure than in ordinary use it is ever likely to be subjected to, and it may be
successfully used as a prime mover wherever a constant rate of oscillation or speed is
required, provided the limits within which the forces tending to bring the moving system
to a given position are proportionate to the displacements, are not materially exceeded.
The pressure of the air confined in the cylinder when the plunger J is in its central position will
always be practically that of the surrounding atmosphere, for while the cylinder is so constructed as
not to permit such sudden escape of air as to sensibly impair or modify the action of the air spring
there will be a slow leakage of air into or out of it around the piston rod according to the pressure
therein, so that the pressure of the air on opposite sides of the plunger will always tend to remain
at that of the outside atmosphere.
As an instance of the uses to which this engine may be applied I have shown its piston rod
connected with a pawl R the oscillation of which drives a train of wheels. These may constitute the
train of a clock or of any other mechanism. The pawl R is pivoted at R’ and its bifurcated end
engages with the teeth of the ratchet wheel alternately on opposite sides of the same, one end of
the pawl at each half oscillation acting to propel the wheel forward through the space of one tooth
when it is engaged and locked by the other end on the last half of the oscillation which brings the
first end of the oscillation into position to engage with another tooth. Another application of the
invention is to move a conductor in a magnetic field for generating electric currents, and
in these and similar uses it is obvious that the characteristics of the engine render it
especially adapted for use in small sizes or units.
Having now described my invention, what I claim is: (Claims not included here). END.
His early experiments in vibration, he explained, "led to his invention of his "earth vibrating"
machine." (For more detailed information on this device, please check out a fantastic book, by
Dale Pond - "Tesla's Earthquake Machine." Much of the material presented in this book is
related to the construction of a class of machine invented by Tesla and known as the reciprocating
Mechanical Oscillator. Serious students of Tesla's work may recognize this machine as the basis of
his system for producing electrical vibrations of a very constant period.
In 1898 another variation was used to create a small earthquake in the neighborhood surrounding
his Houston Street lab. Tesla called this method of transmitting mechanical energy
"telegeodynamics." Included are mechanical drawings that will guide you through the construction
of a working model of the Tele-Geo-Dynamic Oscillator, plus a comprehensive description of the
machine in Tesla's own words. Pick one up from Amazon.com (below). Also: see the newest article
on this site, written by Dale Pond and used by permission - "Sympathetic Vibratory Physics; It
Truly Is A Musical Universe!"
Tesla's Steam Engine Patent:
US Patent # 517,900 - Steam Engine - Nikola Tesla
To all whom it may concern:
Be it known that I, Nikola Tesla, a citizen of the United States, residing at New York, in the county
and State of New York, have invented certain new and useful Improvements in Steam Engines, of
which the following is a specification, reference being had to the drawing accompanying and
forming a part of the same.
Heretofore, engines, operated by the application of a force such as the elastic tension of steam or a
gas under pressure, have been provided with a flywheel, or some rotary system equivalent in its
effect and possessing relatively great mechanical inertia, which was relied upon for maintaining a
uniform speed. I have produced, however, an engine which without such appurtenances produces,
under very wide variations of pressure, load, and other disturbing causes, an oscillating movement
of constant period, and have shown and described the same in [ US Patent # 514,169 ]. A
description of the principle of the construction and mode of operation of this device is necessary to
an understanding of my present invention. When a spring which possess a sensible inertia is
brought under tension as by being stretched and then freed it will perform vibrations which are
isochronous and, as to period, in the main dependent upon the rigidity of the spring, and its own
inertia or that of the system of which it may form an immediate part. This is known to be true in all
cases where the force which tends to bring the spring or movable system into a given position is
proportionate to the displacement. In utilizing this principle for the purpose of producing
reciprocating movement of a constant period, I employ the energy of steam or gas under pressure,
acting through proper mechanism, to maintain in oscillation a piston, and connect with it or cause
to act upon such piston a spring, preferably an air spring, under such conditions as to automatically
regulate the period of the vibration, so that the alternate impulses of the power impelled piston and
the natural vibrations of the spring shall always correspond in direction and coincide in time. In
such an apparatus it being essential that the inertia of the moving system and the rigidity of the
spring should bear certain definite relations, it is obvious that the practicable amount of work
performed by the engine, when this involves the overcoming of inertia is a limitation to the
applicability of the engine. I therefore propose, in order to secure all the advantages of such
performances as this engine is capable of, to utilize it as the means of controlling the admission
and exhaust of steam or gas under pressure in other engines generally, but more especially those
forms of engine in which the piston is free to reciprocate, or in other words, is not connected with a
flywheel or other like device for regulating or controlling its speed.
The drawings hereto annexed illustrate devices
by means of which the invention may be carried
out, Figure 1 being a central vertical section of
an engine embodying my invention, and Figure 2
a similar view of a modification of the same.
Referring to Figure 1, A designates a cylinder
containing a reciprocating piston B secured to a
rod C extending through on or both cylinder
heads. DD; are steam ducts communicating with
the cylinder at or near its ends and E is the
exhaust chamber or passage located between the
steam ports. The piston B is provided with the
usual passages FF’ which by the movements of
the piston are brought alternately into
communication with the exhaust port. G
designates a slide valve which when reciprocated
admits the steam or the gas by which the engine
is driven, from the pipe G’ through the ducts DD’
to the ends of the cylinder. The parts thus
described may be considered as exemplifying any
cylinder, piston and slide valve with the proper
ports controlled thereby, but the slide valve
instead of being dependent for its movement
upon the piston B is connected in any manner so
as to be reciprocated by the piston rod of a small
engine of constant period, constructed
substantially as follows: a is the cylinder, in
which works the piston b. An inlet pipe c passes
through the side of the cylinder at the middle
portion of the same. The cylinder exhausts
through ports dd into a chamber d’ provided with
an opening d. the piston b is provided with two
circumferential grooves e, f which communicate
through openings g in the same with the cylinder
chambers on opposite sides of the piston. The special construction of this device may be varied
considerably, but it is desirable that all the ports, and more particularly, the exhaust ports be made
larger than is usually done, so that no force due to the action of the steam or compressed air in the
chambers will tend to retard or accelerate the movement of the piston in either direction. The
piston b is secured to a rod h which extends through the cylinder heads, the lower end carrying the
slide valve above described and the upper end having secured to it a plunger j in a cylinder I fixed
to the cylinder a and in line with it. The cylinder I is without ports of any kind and is air-tight
except that leakage may occur around the piston rod which does not require to be very close
fitting, and constitutes an ordinary form of air spring.
If steam or a gas under pressure be admitted through the port c to either side of the piston b, the
latter, as will be understood, may be maintained in reciprocation, and it is free to move, in the
sense that its movement in either direction ceases only when the force tending to impel it and the
momentum which it has acquired are counterbalanced by the increasing pressure of the steam in
that end of the cylinder toward which it is moving, and as in its movement the piston has shut off
at a given point, the pressure that impelled it and established the pressure that tends to return it,
it is then impelled in the opposite direction, and this action is continued as long as the requisite
pressure is applied. The movements of the piston compress and rarify the air in the cylinder I at
opposite ends of the same alternately, and this results in the heating of the cylinder. But since a
variation of the temperature of the air in the chamber would affect the rigidity of the air spring, I
maintain the temperature uniform as by surrounding the cylinder I with a jacket a’ which is open to
the air and filled with water.
In such an engine as that just described the normal pressure will produce a stroke of determined
length, which may be increased or diminished according to the increase of pressure above or the
reduction of pressure below the normal and due allowance is made in constructing the engine for a
variation in the length of stroke or amplitude of vibration respectively. The period is mainly
determined by the rigidity of the air spring and the inertia of the moving system and I may
therefore secure any period of oscillation within very wide limits by properly adjusting these
factors, as by varying the dimensions of the air chamber which may be equivalent to varying the
rigidity of the spring, or by adjusting the weight of the moving parts. This latter is readily
accomplished by making provision for the attachment to the piston rod of one or more weights h’.
Since the only work which the small engine has to perform is the reciprocation of the valve
attached to the piston rod, its load is substantially uniform and its period by reason of its
construction will be constant. Whatever may be the load on the main engine therefore the steam is
admitted to the cylinder at defined intervals, and thus any tendency to a change of the period of
vibration in the main engine is overcome.
The control of the main engine by the engine of
constant period may be effected in other ways of which Figure 2 will serve as an illustration. In
this case the piston of the controlling engine
constitutes the slide valve of the main engine, so
that the latter may be considered as operated by
the exhaust of the former. In the figure I have
shown two cylinders AA’ placed end to end with a
piston B and B’ in each. The cylinder of the
controlling engine is formed by or in the casing
intermediate to the two main cylinders but in all
other essential respects the construction and
mode of operation of the controlling engine
remains as described in connection with Figure 1.
The exhaust ports dd, however, constitute the
inlet ports of the cylinders AA’ and the exhaust of
the latter is effected through the ports m,m
which are controlled by the pistons B and B’
respectively. The inlet port for the admission of
the steam to the controlling engine is similar to that in Figure 1 and is indicated by the dotted circle
at the center of the piston b.
An engine of the kind described possess many and important advantages. A much more
perfect regulation and uniformity of action is secured, while the engine is simple and its weights for
a given capacity is very greatly reduced. The reciprocating movement of the piston may be
converted into rotary motion or it may be utilized and applied in any other manner
desired, either directly or indirectly.
In US Patent # 514,169, I have shown and described two reciprocating engines combined in such
manner that the movement or operation of one is dependent upon and controlled by the other. In
the present case, however, the controlling engine is not designed nor adapted to perform other
work than the regulation of the period of the other, and it is moreover an engine of defined
character which has the capability of an oscillating movement of constant period. Nikola Tesla.
What I claim is: (Claims not included here) END.
I hope this got some of you thinking...Tesla's inventions; they have a way of working.