The Wireless Telegraph 



this amazing performance are simplicity itself 

 (Fig. 74). A jar, a, containing a solution of sul- 

 phuric acid has two elec- 

 trodes immersed in it; one 

 of them is a lead plate 

 of large surface, 6; the 

 other is a small platinum 

 wire which protrudes 

 from a glass tube, d. A 

 current passing through 

 the cell between the two 

 metals at c is interrupted, 

 in ordinary cases five 

 hundred times a second, 

 and in extreme cases 

 four times as often, 



by bubbles of gas given off from the wire instant 

 by instant. 



Fig. 74 

 Wehnelt interrupter 



123 



