FORCE OF THE WESTON NORMAL CELL IN SEMI-ABSOLUTE VOLTS. 
169 
Table VIII.. 
Thickness. 
Mean temperature of 
observation. 
Value at 20° C. 
cm. 
° C. 
cm. 
4-9786 
22-0 
4-9784 
4-9789 
24-0 
4-9785 
4-9790 
25-3 
4-9785 
Mean .... 
4-9785 
We have therefore at 20° C. 
607158 + 4-9785 
= 32-8472 cm. 
(e) The Determination of “ (5,” the Mean Distance between the Planes of 
the Small Coils. 
The distance between the planes of the small coils was determined by measuring the 
distance between the external edges at ten evenly distributed positions round the 
coils, and subtracting the mean thickness of the channel frames at these points from 
the mean of these measurements. 
The measurement was taken with calibrated vernier calipers. 
Mean of first set of measurements. . . . 7‘4261 cm. at 20° C. 
„ second „ „ .... 7*4261 ,, „ 
The mean thickness of the channel frames at the points used was measured with 
micrometer calipers. Twenty settings were made and the value for the mean thickness 
of a coil was found to be 1'4426 cm. Therefore, at 20° C., 
S = 
7-4261 —U4426 
2 
= 2-9917 cm. 
if) The Calculation of the Mean Radius of the Small Coils. 
We have from the above 
x = 32*8472 at 20° C. 
$ = 2-9917 
and 
IA - 2-75443 „ 
for the mean complete balance. g 2 was 0*75 cm. and >; 2 was 1*00 cm. 
2G : = -137268, see §V. 
VOL. GCXIV.-A. 
z 
