io(> Mr. Christie on the mutual action of 
Assuming M = 48-518, and e 2 = -6020, the values of a 
corresponding to the different values of c may be computed 
from the formula (5). The comparison between the values 
of a., thus computed, and those observed, is made in the 
following table. 
Table VII. 
Values of c 
in 1 lie dif- 
ferent obser- 
vations. 
Observed 
values of 
a 
Values of * 
computed from 
. s _jl_ r 
Diff. between 
the observed 
and computed 
values of u . 
Quotient of this 
did', divided by 
the computed 
value of a. 
Values ofM 
deduced from 
the separate 
observations. 
inches 
2756 
35-5 
35-°3 
— 0-47 
— •01342 
48-842 
2'2,6 
73-0 
72-67 
— 0-33 
— -00454 
48-628 
I 75(1 
171-25 
173-3! 
+ 2-06 
+ -oi 1 89 
48 229 
1-506 
282-45 
285-79 
+ 3 34 
4 -01471 
48-234 
I256 
4** 1 '3 
495 '5 6 
I d r ' 26 
4 -02878 
47-814 
i -006 
871-2 
90305 
+ 3 2 '45 
4 -03591 
47 639 
0-756 
1811-7 
I 7 ° 9"4 
—102-3 
— ■05985 
49-949 
Mean value of M frem the separate observations - - 
48-476 
The agreement of the computed with the observed values 
of a, which I estimate by the quotients in the 5th column, is, 
upon the whole, as near as we could expect with this adjust- 
ment of the magnets. In the last observation, where the 
distance between the surfaces of the ring and magnets was 
only '456 inch, the forces of some points in the magnets 
were exerted in directions so much more oblique than in the 
other observations, that this observation scarcely admits of 
comparison with the others, without taking into account the 
effect which this obliquity in the direction of the forces will 
have on the situation of the pole of the magnets. If in the 
comparison we reject this observation, the agreement between 
the computed and observed values of a. becomes extremely 
