470 



Mr. W. E. Preece 



[June 4, 



sent. Strong alternating 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 inter- 

 vening space, and if the secondary circuit is so situated as to be 

 washed by these ethereal waves, their energy is transformed into 

 secondary currents in the second circuit which can be made to affect 

 a telephone and thus to reproduce the signals. Of course their 

 intensity is much reduced, but still their presence 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 



CURRENT BREAKER 



Fig. 1 — Diagram of connections of Mr. Preece's system. 



last few years that I have been able to utilise them practically 

 through considerable distances. This has been rendered possible 

 through the introduction of the telephone. 



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

 munication 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 was in- 

 vented 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 



