254 
MESSRS. R. T. GLAZEBROOK AND E. B. SARGANT ON THE 
Table HI.—Series C. 
Battery. 
Position. 
Mean double 
throw. 
Mean double 
deflection. 
T. 
Temperature 
R. 
*• 
x\ 
r 
I. 
227'4. 
289-8 
23'379 
12-4 
560 
420 
5 Thomson’s . < 
IT. 
229-6 
292-4 
23-382 
12-5 
655 
575 
III. 
228-0 
290-7 
23-384 
12-8 
705 
620 
l 
IV. 
228-2 
290-5 
23-381 
130 
690 
605 
r 
I. 
252-9 
321-9 
23-389 
13-6 
555 
485 
6 Thomson’s . < 
II. 
253 1 
323-4 
23-391 
13-3 
545 
475 
III. 
254-7 
323-9 
23-393 
13-2 
445 
340 
L 
IV. 
250-2 
318-9 
23-395 
12-9 
425 
335 
r 
I. 
243-25 
310-95 
23-381 
13-4 
950 
860 
G Thomson’s . < 
II. 
III. 
242-8 
240-75 
309-8 
307-1 
23-374 
23-392 
12-7 
14-0 
680 
915 
590 
830 
l 
IV. 
240-65 
306-85 
23-384 
13-8 
280 
190 
These direct experimental results require to be substituted in our formula in order 
that we may obtain the values of It 0 . The coils were placed in the four positions 
I. to IV. in order to eliminate any small unknown error in the position of the mean 
plane. 
Now our first series of experiments have been sufficient to show that this error 
must be exceedingly small, and the result obtained by taking the mean of the four 
will certainly eliminate it. 
Instead, therefore, of giving the value of It,, for each position, we shall only calculate 
the mean value for each set of experiments, using, of course, as our value of M, the 
mean of the values M 1? M 3 , M 3 , M 4 . 
The correction for damping is the same throughout the whole series of observations, 
the value of 1 of course, differs for the different currents used; it therefore 
o'lcr ' 
is included in the table. 
The value of M for each of the three series A, B, C, is also given in the table. 
The value of X found from a large series of closely concordant measurements was 
\=-01368 
In these experiments the temperature was somewhat lower, generally, than in 
Part I., so that the mean value of the temperature of It was about 12° and £ 0 =12°. 
The distance between the mirror and the scale was different, and we found 
o = 218 centims. 
also 
a— '0003 
p— -000072 B.A. unit 
