the particles of magnetic bodies^ &c. 107 
close. Omitting in the values of d, in- the 7th column of 
Table VI. all those in which a enters, we shall have the 
Vll 
mean value of d = *6559; and the mean value of M deduced 
from the separate observations will be 49 093. The values 
of a, at the different distances, computed from these values of 
M and are compared with the observed values of a, in the 
following table. 
Table VIII. 
Values of c 
in the different 
obser\alions. 
Observed 
values of 
a. 
V^ilues of a 
computed from 
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. 
indies. 
2756 
2‘256 
1756 
i‘^o6 
i’z^6 
I -006 
35-5 
73 0 
171-25 
282-45 
481-3 
871-2 
35‘398 
73-013 
172-36 
281-90 
483-18 
866-36 
- 0-102 
+ 0013 
+ I-I I 
— 0-55 
4 1-88 
— 4-84 
— -00288 
4 -00018 
4 -00644 
— -00195 
4 'OO389 
— -00559 
49-163 
49-089 
48- 935 
49- 140 
48- 998 
49- 230 
Mean value of M from the separate observations 
49-093 
The quotients in the 5th column are so extremely small, 
that there can be no doubt of the formula 
accurately representing the observations in all cases within 
the above limits of the value of c. 
Having clearly ascertained the law of the force by which 
the magnets urged the copper ring during their rotation 
under it, I next proposed reversing the experiment by making 
the copper ring revolve under the same magnets. For this 
purpose the magnets were placed in the wooden scale, sus¬ 
pended by the wire which in the preceding experiments had 
