244 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1913. 



Edison. One or both points were adjusted so as to make incipient 

 contact, and the tiny spark observed between the points was an indi- 

 cation of a shock, commotion or wave, electrical in its character, 

 in the ether surrounding the tin vessel mounted on the glass jar. 

 The tests for detecting the impulses were carried on not only in 

 rooms on the same floor, but on the floor above and on the floor above 

 that, and finally at the top of the building, some 90 feet away, in the 

 astronomical observatory. Metallic pieces, even unconnected to the 

 ground, would yield tiny sparks, not only in the basement of the 

 building, but in the highest part, with several floors and walls inter- 

 vening. I mention this old experiment particularly because it has 

 in it the elements, of course in a very crude form, of wireless trans- 

 mission, the wire and tin vessel attached to one terminal of the coil 

 being a crude antenna with its spark-gap connection to ground, as 



afterwards used in 

 wireless work b}' Mar- 

 coni, and it also 

 shoW'S a rudimentary 

 receiver or detector, 

 a metallic body ar- 

 ranged in connection 

 with a tiny spark 

 gap, so that electrical 

 oscillations in such 

 body would declare 

 themselves by a faint 

 spark at the gap. It 

 was understood by us 

 at the time that after 

 each discharge of the 

 coil there was, as it were, a shock, or wave in the ether consisting of 

 a quick reversed electrical condition, and it was even imagined that 

 there might be in this process the germ of a system of signaling 

 through space. This old work was almost forgotten when it was 

 recalled by the later work of Hertz, about 1887, who demonstrated 

 by suitable electrical apparatus that waves of the general nature of 

 light or heat could be generated, which waves are transmitted with 

 the velocity of light, 186^000 miles per second, and that by suit- 

 able resonators or detectors these waves could be made to declare 

 themselves by tiny sparks. The Hertzian oscillator was, as it were, 

 an electrical tuning fork, having an actual rate of vibration peculiar 

 to itself and dependent on its form and dimensions. It was fed with 

 energ}^ from an induction coil and across its spark gap an oscillating 

 discharge took place, which, at each impulse, died out like the dis- 

 (;harge of a condenser, but during this discharge it electrically 



