AND STRAIN ON THE ACTION OP PHYSICAL FORCES. 
159 
Condition of 
electromagnet. 
“On 1 ’ signifies 
magnet excited ; 
not excited. 
Off 
On 
Off' 
On 
Off 
Deflection of the 
image of the 
illuminated wire on 
the scale. 
Difference effected 
in the deflection 
by the action of the 
electromagnet. 
+ signifies increase, 
— signifies decrease 
produced by exciting 
the electromagnet. 
Number of trial. 
227 
1 
226 
2 
227 
3 
270 
43 + 
1 
223 
2 
186 
41- 
3 
186 
4 
186 
5 
212 
26- 
1 
202 
16- 
2 
202 
3 
233 
31 + 
1 
187 
15- 
2 
187 
3 
212 
25- 
1 
200 
2 
198 
11- 
3 
198 
4 
The current through the electromagnet was then reversed. 
Condition of 
electromagnet. 
Deflection of the image 
of the wire. 
Difference effected in 
the deflection by the 
action of the 
electromagnet. 
Number of trial. 
r 
198 
i 
On 
192 
2 
l 
192 
3 
r 
250 
58- 
1 
Off 
212 
20- 
2 
l 
212 
20- 
3 
r 
204 
8- 
1 
On < 
202 
10- 
2 
l 
202 
10- 
3 
It will he noticed that for both directions of the M.C. the induced current is less 
with the electromagnet excited than when not. 
Several phenomena connected with the experiments in the paper above alluded to 
can be explained by referring the apparent alteration of resistance to the permanent, 
sub-permanent, or temporary alteration of the magnetic susceptibility of the soft iron 
