Various Tesla book cover images

Nikola Tesla Books

Books written by or about Nikola Tesla

Colorado Springs

June 1, 1899

The following seems to be the best plan for constructing small batteries of very high e.m.f. required for exciting vacuum tube to be used as receiver in telegraphy: As the current for exciting the tube need be only very small the battery can furnish a minute current. From previous experiments about $!{1\over20,000}$! amp. is amply sufficient. Approximate dimensions of box 1/4 cu. foot. The price will not be prohibitory. Tin caps, plugs and carbons will be readily obtainable.

The connection of the receiver is to be as in experiments in New York: If necessary the resistance R1 will be used to strain the tube exactly just to point of breaking down. It is very important as in all sensitive devices so far used that the dielectric is strained exactly to the breaking point. The magnet M is to have a resistance nearly equal to the internal resistance of the battery, so as to get best output. The relay will suit as it is with 1000 ohms resistance. The magnet must be strong to blow out tube when lighted. This device should by very sensitive and should break down by very minute currents propagated through the earth from a similarly connected oscillator.


June 1

Tesla foresees the use of a tube filled with rare gas for the signal detection in the receiver shown. By suitable choice of battery voltage the over-stress is achieved so that even a small voltage increase leads to flashover. That increase is supposed to create the signal which gets to the tube wire system antenna-ground. The adjustment of gas overstress would be performed by the change of resistance R. The magnet M is supposed to extinguish the tube right after the flashover. Without magnet M, the achieved gas flashover would be continued and it would prevent the reception of signals following. A similar magnet application for the purpose of arc extinguishing in the tube of rare gas was mentioned by Tesla in his lecture at the Institute of Electrical Engineers in London in 1892.(5) It is possible that the idea for this type of detector originates from the period when Tesla worked intensively on discoveries related to what occurred in a vacuum when current is passed through it. Tesla informed scientific circles about these studies in his three famous lectures: in 1891 in the American Institute of Electrical Engineers(4) and in 1893 in the Franklin Institute(6).


Lowercase tau - an irrational constant defined as the ratio of the circumference of a circle to its radius, equal to the radian measure of a full turn; approximately 6.283185307 (equal to 2π, or twice the value of π).
A natural rubber material obtained from Palaquium trees, native to South-east Asia. Gutta-percha made possible practical submarine telegraph cables because it was both waterproof and resistant to seawater as well as being thermoplastic. Gutta-percha's use as an electrical insulator was first suggested by Michael Faraday.
The Habirshaw Electric Cable Company, founded in 1886 by William M. Habirshaw in New York City, New York.
The Brown & Sharpe (B & S) Gauge, also known as the American Wire Gauge (AWG), is the American standard for making/ordering metal sheet and wire sizes.
A traditional general-purpose dry cell battery. Invented by the French engineer Georges Leclanché in 1866.
Refers to Manitou Springs, a small town just six miles west of Colorado Springs, and during Tesla's time there, producer of world-renown bottled water from its natural springs.
A French mineral water bottler.
Lowercase delta letter - used to denote: A change in the value of a variable in calculus. A functional derivative in functional calculus. An auxiliary function in calculus, used to rigorously define the limit or continuity of a given function.
America's oldest existing independent manufacturer of wire and cable, founded in 1878.
Lowercase lambda letter which, in physics and engineering, normally represents wavelength.
The lowercase omega letter, which represents angular velocity in physics.