778 
Proceedings of the Boyal 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 he inserted in its course. 
Assuming, for a moment, that, as above suggested as at least 
approximately true, in one of the wires we have <r ~ \t up to 
the temperature t v a~ = k. 2 t up to temperature t 2 , &c., we have by 
the two equations of thermo-dynamics— 
Now, if both junctions be under , and if <r = kt for the other wire, 
SE = J (Sn + k x - ktSt) 
0 = Sj + (k ± - k)St , 
and we have as before, t 0 being temperature of cold junction, 
7 = -(*,-*)(T-0 
E = -ft-&)(«-«„)(T-t±*V 
But from t ± to t 2 we have 
j = - (h- *) (T, - o 
Now, at t = t x these formulae must agree, so that 
(k 2 - k) (T x - b) = (k x - k) (T - q) 
0 = 0,- Q {ft - *) T, - ft - fc) T - ft - , 
whence 
rp _ (& 2 — h'i)t l 4- — &)T 
1 " kT^k ’ 
and 
c = ft - Q(*, - *,)(*, 1ft - yft - g*. 
