113 
Mr. Christie on the mutual action of 
Table X. 
Values of c 
in the diiF rent 
observations. 
Observed 
values of 
a. 
Values of a. 
computed from 
f M ) * 
DifF, between 
the observed 
and computed 
values of a. 
Quotient of this 
ditF. divided by 
the computed 
value of a. 
Values of M 
deduced from 
the separate 
observations. 
inches. 
2 'Z^6 
1756 
1*506 
1-256 
i*oo6 
0-756 
69*8 
161-9 
271*4 
4777 
870*3 
^llTl 
68*39 
164*78 
273*98 
480-79 
892*21 
1731-5 
- 1*41 
+ 2*88 
+ 2*58 
+ 3-°9 
+ 21-91 
— 45*8 
—- *02062 
+ -01748 
+ *00942 
4 - *00643 
+ *02455 
— *02645 
47*108 
46*221 
46*410 
46*480 
46*054 
47*242 
Mean value of M from the separate observations 
46*586 
Whether the close agreement between the results deduced 
from the formulas (i) and (5), and the several observations 
which I have detailed, or the small differences in the con¬ 
stants deduced from the separate observations in each of the 
foregoing cases, be considered as a test of the correctness of 
these formulas, there can, I think, be no doubt that they will 
very accurately represent the effects that are produced, 
whether by the rotation of magnets on a copper ring, or on 
magnets by the rotation of a ring, within certain limits of the 
distance between the magnets and the ring. 
Having succeeded in determining from experiment the law 
according to which the forces acting during rotation varied at 
different distances, for which purpose principally I had under¬ 
taken these experiments, my next object was to ascertain 
whether the formula I had obtained would result from the 
principle, that time is necessary both for the developement 
of magnetism by induction, and for its dissipation, and which 
appeared to be implied in the formula. 
