252 SIGNALING THROUGH SPACE WITHOUT WIRES. 



(b) An ordinary battery of about 100 Leclanche cells, of the so-called 

 dry and portable form. 



(c) A Morse telegraph key. 



(d) A telephone to act as receiver. 



(e) A switch to start and stop the rheotome. 



Good signals depend more on the rapid rise and fall of the primary 

 current than on the amount of energy thrown into vibration. 

 Leclanche cells give as good signals at 3.3 miles distant as 2£ horse- 

 power transformed into alternating currents by an alternator, owing to 

 the smooth sinusoidal curves of the latter. Two hundred and sixty 

 vibrations per second give a pleasant note to the ear, easily read when 

 broken up by the key into dots and dashes. 



In my electromagnetic system two parallel circuits are established, 

 one on each side of a channel or bank of a river, each circuit becoming 

 successively the primary and secondary of an induction system, accord- 

 ing to the direction in which the signals are being sent. Strong alter- 

 nating or vibrating currents of electricity are transmitted in the first 

 circuit so as to form signals, letters, and words in Morse character. 

 The effects of the rise and fall of these currents are transmitted as 

 electromagnetic waves through the intervening space, and if the sec- 

 ondary circuit is so situated as to be washed by these ethereal waves, 

 their energy is transformed into secondary currents in the second cir- 

 cuit, which can be made to affect a telephone and thus to reproduce the 

 signals. Of course their intensity is much reduced, but still their pres- 

 ence has been detected, though five miles of clear space have separated 

 the two circuits. 



Such effects have been known scientifically in the laboratory since 

 the days of Faraday and of Henry, but it is only within the last few 

 years that I have been able to utilize them practically through consid- 

 erable distances. This has been rendered possible through the intro- 

 duction of the telephone. 



Last year (August, 1896) an effort was made to establish communi- 

 cation with the North Sandhead (Goodwin) Lightship. The apparatus 

 used was designed and manufactured by Messrs. Evershed and 

 Vignoles, and a most ingenious relay to establish a call invented by Mr. 

 Evershed. One extremity of the cable was coiled in a ring on the 

 bottom of the sea, embracing the whole area over which the lightship 

 swept while swinging to the tide, and the other end was connected 

 with the shore. The ship was surrounded above the water line with 

 another coil. The two coils were separated by a mean distance of about 

 200 fathoms, but communication was found to be impracticable. The 

 screening effect of the sea water and the effect of the iron hull of the 

 ship absorbed practically all the energy of the currents in the coiled 

 cable, and the effects on board, though perceptible, were very trifling — 

 too minute for signaling. Previous experiments had failed to show 

 the extremely rapid rate at which energy is absorbed with the depth 



