180 -Nature's AMractes. 



between the signals, strikes the glass tube with 

 a succession of light blows. 



Briefly stated, the wireless system of Mar- 

 coni, in its essentials, consists of a powerful 

 induction-coil with one end of the secondary 

 wire connected with the earth, while the other 

 extends into the air a greater or less distance 

 according to the distance it is desired to send 

 signals. The greater the distance the higher 

 the wire should extend into the air. At the 

 receiving-end a wire of corresponding height 

 is erected, also connected with the earth. In 

 this wire as a part of its circuit is placed 

 the coherer. In a local circuit that is con- 

 nected to the upright wire in parallel with the 

 coherer is placed a battery*, a sounder, or a 

 bell, that is rung when the filings cohere. 



When an ether- wave is set up by a discharge 

 of electricity into the air it strikes the per- 

 pendicular wire of the receiver, and that por- 

 tion of the wave that strikes is converted into 

 electricity, which is called an induced current. 

 It is this current, as it discharges through the 

 coherer to the earth, that causes the filings to 

 unite so as to close the local circuit and oper- 

 ate the sounder. To send a message it is only 

 necessary to make the discharges into the air, 

 at the sending-end, correspond to the Morse 

 alphabet. 



While Marconi has done more than any 

 other man to improve and popularize wireless 



