THE MECHANICAL EQUIVALENT OP HEAT. 
481 
where the observations are taken at two temperatures and $ 2 , the second suffix of 
the T’s referring to these temperatures. 
Hence, by division, we obtain the value of f, the temperature-coefficient of the 
specific heat of water. 
And. if 9q is our standard temperature, the value of J is found without any know¬ 
ledge of the water-equivalent of the calorimeter. 
Now (Tg.o — T 2 ,o)/(W 2 — Wj) is the time that grins, of water at tempera¬ 
ture 9q would take to rise 1° C. Subtracting this from and dividing by 
(T,,„-T,,,)/(W,-W 1 ) we obtain the number of grins, of water at 6q, to which 
the calorimeter also at 9q is equivalent ..(ifi)* 
Similarly the expression 
(T,.2 - Ti.,)/(W2 - WQ 
(T2.0 - - v\h) . 
gives the number of grammes of water at 0q to which the calorimeter at is equiva¬ 
lent. Thus we obtain both the water-equivalent of the calorimeter and also its 
temperature-coefficient g. 
Finally J is calculated from 
T EhT 
“ M (I + Z 0^^). 
3 Q 
MDCCCXCIII.—A. 
