in Alloys of Bismuth and Tin. 



181 



The ends in the hot bath were joined by a copper rod, so that 

 a current could be sent through the two rods in series. 



To the other ends of the rods leads were soldered and the 

 circuit completed through a battery of accumulators B, adjustable 

 resistance R, ammeter A and reversing key Kj (fig. 1). 



K, L 



Fig. 1. 



To measure the changes of temperature thermo-couples of iron 

 and nickel were used, one junction being fastened at a point on 

 one bar, the other at a point on the other bar which assumes as 

 nearly as possible the same temperature as the former. 



The junctions were separated from the bars by thin strips of 

 mica and both rods and baths closely packed with cotton- wool. 



The free ends of the couples were joined up in series with one 

 set of coils of a sensitive differential Thomson galvanometer G of 

 low resistance. 



