32 " N" RAYS 



the platinum wire and the accumulators, and 

 consequently the strength of the current, but 

 not sufficiently for the observer to perceive a 

 variation in the glow of the wire. In spite of 

 this, the electrometer was deflected three divi- 

 sions of the micrometer in the eye-piece. The 

 following is another verification : raising the 

 temperature of the wire one degree would 

 alter its resistance in the ratio of about i "004 to 

 one ; the difference of potential between A and 

 B would alter in about the same ratio, since, 

 the resistance external to the wire being very 

 great, the current strength does not change. 

 In my experiments this variation would deflect 

 the electrometer by fifteen divisions. As abso- 

 lutely no deviation occurred, and as, moreover, 

 a quarter of a division could have been easily 

 observed, the rise in temperature is certainly 

 very inferior to A x i = ^ of a degree, and, 

 consequently, quite insufficient to produce the 

 observed increase in glow. It is thus super- 

 abundantly established that the increase in 

 glow produced by the rays is not due to a rise 

 in temperature. 



In the experiments with a plate of platinum, 



