778 
Proceedings of the Royal Society 
iron and platinum wires together was in each case not more than 
one such unit. The palladium-iron circuit was so much more 
powerful than the others that a resistance coil of about 146 B. A. 
units had to be inserted in its course. 
Assuming, for a moment, that, as above suggested as at least 
approximately true, in one of the wires we have cr — k x t up to 
the temperature t v cr = k. 2 t up to temperature t. 2 , &c., we have by 
the two equations of thermo-dynamics — 
e = j(sn + sry^+vv*) 
»- +s i C"?*- 
Now, if both junctions be under t x , and if cr = kt for the other wire, 
8E = J (8n -{- k x - ktSf) 
0 = 8 — + (k x - k)8t , 
and we have as before, t 0 being temperature of cold junction, 
?■-(*!-*)( T-0 
E = - ^1°). 
But from t x to t 2 we have 
5 = 
Now, at t - t x these formulas must agree, so that 
C = ft - <„) {ft, - *) T, - (4, - 4) T - (4, - 4j) , 
whence 
rp _ (& 2 — 4- (&J — &)T 
1 h 2 -k 
0 = 0,- Oft, - 4,)( t, - ^ ) = 1(4,* 40ft - 0*. 
and 
