366 E.. L. Nichols— Electrical Resistance and the 
e the uncorrected scale of the platinum ther- 
The latter scale is expressed by the formula 
(f) ¢=1, (1+ °00000886 ¢). 
These being almost the only data we possess for the calcula- 
tion of the temperature of a hot wire, the question of their 
accuracy is of some importance. The formule may be best 
compared by plotting side by side the curves which represent 
them (fig. 2). 
r we ma 
mometer. 
Temperature. 
aa ane one cee 
Resistance. 
In fig. 2, resistance is substituted for length in curves (e) 
and 0 using for that purpose the measurements given in 
Table The following table affords a further comparison of 
the six ie 
In the columns (a) to (/) are given the temperatures, ¢ calcu- 
lated by the several formule, at which the resistance of the 
wire, compared with its resistance at 0°, is given in the column 
marked “ 
