VALUE OF THE BRITISH ASSOCIATION UNIT OE RESISTANCE. 
255 
a being the coefficient of increase of resistance of R per B.A. unit per degree, p the 
resistance of 1 million of the bridge. 
The values of the resistances S and V were different from those in Part I., for the 
piece of copper wire which was included in the value of V in Part I. had been 
removed while the variable resistance T was no longer in circuit with S. 
The values employed in the calculations are 
v V = 1 '00096 units. 
8=3059-89 
so that 
V+S_ 3060-891 
V — 1-00096 
The temperature of Y and the 3000 ohms, which was in the same water bath with 
it, being 12°, that of the galvanometer 13°'5 ; this latter temperature being the mean 
of the temperatures of the galvanometer during the observations. 
As before, we shall describe later the methods used to determine these values. 
Table IV. gives the results of the calculations. 
The mean value of R 0 deduced from it is 
158 . 386 <*ttli quadra nt 
second 
As we shall see afterwards, the value of R 0 in B.A. units is 160-520. 
Thus 
1 B.A, unit = 
158-386 
160-520 
ohms 
= "986706 ohm. 
Table IY. 
Series. 
Battery. 
M. 
lljp 2 — 8g 3 
32a 2 
B 0 in ohms. 
Error in R„ 
from mean 
of series. 
Mean value 
of R n for 
series. 
Error 
from 
mean. 
Percentage 
error. 
4 D. 
4 D. 
5 Th. 
2 D. 
jl-55587 xl0 8 | 
•00167 
•00167 
•00263 
•00045 
158-233 
158-472 
158-296 
158-564 
-•158 
•081 
-•095 
•173 
1158-391 
•005 
•003 
B { 
5 Th. 
5 Th. 
j 1-25758 x 10 8 | 
•00136 
•00136 
158T71 
158-368 
-•099 
+ •098 
| 158-270 
-416 
-•072 
1 
5 Th. 
6 Th. 
6 Th. 
| -762092 x10 s | 
-•00019 
-•00015 
-•00015 
158-397 
158-301 
158-676 
-•061 
-•157 
•218 
1158-458 
•072 
•045 
Mean of whole series 158"386 ohms. 
Mean error for each series "064. 
Mean percentage error *040. 
