190 
MR. H. L. CALLENDAR ON THE PRACTICAL 
By observations on linear expansion we deduce the mean cubical coefficient 
from 0° to t. 
y = -0000204 + 8T X 10 -9 d 
Pressure correction :— 
£C=3'12, 2=0-0; 
X— 0, q= — ’A25 ; 
x=7, 
Two pairs of observations were taken in ice and steam to determine the fixed 
points. 
From observations (2) and (3), taken on February 23, we have 
„ 100 - 30 x 37-435 in , 0 Q ocor ._ 
B "= 13-885 -=270-42. log-=-858 ,d. 
From (4) and (5), taken on February 24, 
_ 100-18x 37-400 , 0„ A 
On — - , -=270"10 .log — = ‘85864. 
Po 
13-872 
On February 25, at the beginning and end of the series, we have at 100 c "20 C., 
observation (6), 
P=51"25 ; and, observation (10), P=51"22 in steam. 
For the platinum spiral the resistance of the connexions at 0° was "0501, and at 
470° was "0635, only a small portion being heated. 
For the platinum spiral.—Resistance at 0°, corrected, 
R 0 = 6-2374, log R 0 =-79500. 
In the values of the resistance calculated for comparison— 
( b ) refers to the formula 
- = 1 + a t —/3 1 3 ; 
K o 
( e ) to the exponential formula 
J> •0034259£ 
—- - pl + -001529 1 
R _ ^ 
which last agrees best with the observations. 
