Nikola Tesla, “On light and other high frequency phenomena”, in Journal of the Franklin Institute, vol 136 #1, July-December 1893. The Tesla article appearing in six sections” pp 1-19, 81-98, 161-177, 259-279, 351-360, and 401-412. Altogether 93pp with 34 text illustrations. Offered in the full volume of 482pp (plus a number of folding maps and tables at the end for Pennsylvania weather records. Condition: bound in half-calf with considerable scuffing to the spine; also, the rear board is nearly detached. This is an ex-library copy, with stamps on the title page as well as a bookplate. Good, sturdy copy, with some good and attractive life left in the binding. $650
“This was a lecture delivered before the Franklin Institute, Philadelphia, February 24, 1893, and before the National Electric Light Association, St. Louis, March 12, 1893, republished many times after publication in the Journal of the Franklin Institute, July, Aug., Sept., Oct., Nov., Dec. 1893.”
“What Tesla described in this lecture should be taken to be the foundation of radio engineering, since it embodied the following principles and ideas of fundamental importance, namely: the principle of adjusting for resonance to get the maximum sensitivity in a selective reception, inductive link between the driver and the tank circuit, an antenna circuit in which the antenna appears as a capacitive load...”--“Nikola Tesla and his Contributions to Radio Development”, in History of Wireless, by Tapan K. Sarkar, Robert J. Mailloux, Arthur A. Oliner, 2006; chapter 5. Wiley-IEEE Press.
“In February 1893 Tesla delivered a third lecture on high-frequency currents before the Franklin Institute in Philadelphia and repeated it in March at the National Electric Light Association in St. Louis. In the first part of the lecture he described a ‘method of conversion of low fiequency AC or DC current into high-frequency currents, all based on using spark gap discharge’. Just as in the previous two lectures he performed again many experiments with high frequency currents and various resonant circuits, illustrating that the current can pass through an open circuit consisting of a coil connected to a terminal of a generator and an insulated plate. Today specialists can easily build circuits used in these experiments but in 1893 they were fascinating and novel. The most significant part of this lecture refers to a system for “transmitting intelligence or perhaps power, to any distance through the earth or intervening medium”.
Sarkar then quotes Tesla from the lectures:
“On wireless energy transmission, Tesla made the following remark in the demonstration of high frequency driven motors by a single wire:
'It is quite possible, that such ‘hot 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 air are rarefied, To reach a number of miles 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'.”
“Before passing on to consider the final phase of wireless communication, as represented by Marconi, mention must be made of one other pioneer, Tesla, who worked perhaps in a less spectacular manner than those who gained a certain amount of publicity. Tesla ’s early efforts are often overlooked, and it is only fair that his name should be mentioned so that he may share in the credit due to the early investigators. TesIa experimented early in the problem of transmitting energy without wires. In February 1893 he advanced a plan of wireless transmission and expressed his conviction in a lecture at the Franklin Institution that “it certainly is possible to produce some electrical disturbance sufficiently powerful to be perceptible by suitable instruments, at any point of the earth’s surface” --Ellison Hawks, Pioneers of Wireless, London: Methuen & Co. Ltd, 1927, found in Sarkar “Nikola Tesla and his Contributions to Radio Development”, in History of Wireless.