247 
VALUE OF THE BRITISH ASSOCIATION UNIT OF RESISTANCE. 
We proceed now to give in tabular form the results of our first series of experi¬ 
ments made in June, 1881. 
The table will contain the values of the temperature of It, the mean 
values of x and x, and the time of swing. The corrections introduced by the varia¬ 
tion in the temperature of S and the galvanometer we shall show, when we come to 
discuss the results, are so small that they may be neglected. We may, therefore, treat 
the results throughout as if the temperature of S were 13 0, 2, and that of the galvano¬ 
meter 14°. 
The battery used in all cases was four Daniell’s cells. 
The average difference between p 1 and p. 2 , irrespective of sign, was about - 32 millirn., 
in one case only was it as great as - 9 miJlim. ; it is hardly necessary, therefore, to give 
both p 1 and p z in the table. 
The rods used to separate the two coils, primary and secondary, were the same, but, 
as has been explained, the coils were placed in each of four positions, numbered 
respectively I., II., III., and IV. 
Table I. 
i 
The first four observations were made on June 7th, 1881, the last eleven on 
June 8th. 
For the first four observations, therefore, we take the time of swing as 23 //, 264, for 
the last eleven as 23 /,- 275. 
The mean temperature of R during the experiments is about 14°'6 ‘ we take this 
then as the value of t 0 . The temperature coefficient of It—a platinum-silver coil— 
may for the small range considered be taken as ’0003 per ohm per degree. 
Thus the values of the constants in the formula (5) for R 0 are 
—- 
Position. 
Mean throw. 
Mean deflection. 
T. 
Temperature R. 
X. 
X. 
226-10 
142-15 
23-277 
O 
15 1 
670 
590 
226-25 
142-40 
15-2 
583 
500 
223-00 
140-25 
15 1 
420 
350 
L ^ 
222-70 
139-70 
23-250 
15-2 
540 
470 
224-55 
14T40 
23-277 
13-8 
690 
600 
l 
224-90 
140-85 
13-7 
440 
355 
r 
223-65 
140-30 
13-7 
750 
665 
II. i 
222-80 
140-20 
13-9 
505 
420 
222-25 
139-85 
13-9 
265 
175 
218-00 
137-05 
14-2 
770 
670 
III. 
217-60 
136-90 
14-2 
480 
390 
l 
217-50 
136-70 
14-3 
325 
240 
r 
216-05 
135-85 
14-3 
778 
680 
IV. J 
216-10 
135-55 
14-5 
532 
440 
1 
l 
215-85 
135-50 
23-274 
14-5 
400 
310 
