COHERERS 



137 



local side of the relay R. The coherer AB was 

 fixed in rigid supports,, and to one end was attached 

 a fixed brass collar fitted with a platinum pin P, 

 the magnet armature MN consisted of a piece of 

 iron tape fitted to an aluminium rod ending in a 

 piece of spring brass fixed to the pillar K. The 

 striker was fitted to the end of this light rod and 

 when it struck, the force of the blow was taken off 

 owing to its ability to work back through a hole 

 in the rod, the spring Q keeping it normally 

 in a fixed position. When the platinum pins 

 touched, the force of impact decohered the coherer, 

 and also completed the circuit of the electrolytic 

 receiver. In this way I was able to get a very 

 precise movement, in which one short wave train 

 caused one tap ; hence one mark was made on the 

 telectrograph paper for one dot or " contact " in 

 the transmitter. 



The " stickiness " of coherers, however, renders 

 good synchronising difficult, and a straight line 

 would always appear somewhat wavy in the re- 

 ceived picture. Moreover, if the apparatus were 

 working with certainty, rapidity was impossible, 

 and after making various interesting records, the 

 work was continued on other lines. 



I will now proceed to describe the most recent 

 wireless methods which promise to give more satis- 

 factory results, especially as original experiments 

 make it probable that half-tone photographs will 



