248 
DR. J. HOPKINSON AND MR, E. WILSON ON 
accentuating the effect. If we confined ourselves to these limits we should still find 
these effects, but smaller in amount. 
Pig. 21. 
Table I. 
* J) 
a 
Amperes 
( y/ mean 2 ) per 
armature bobbin. 
Exciting current in 
winding on magnets. 
Amperes. 
Pig. 
Fre¬ 
quency. 
With 
varia¬ 
tions in 
current 
in 
magnet 
winding. 
Without 
varia¬ 
tions in 
current 
in 
magnet 
winding. 
With 
varia¬ 
tions in 
current 
in 
magnet 
winding. 
Without 
varia¬ 
tions in 
current 
in 
magnet 
winding;. 
Amperes 
when 
normal. 
Maximum 
variation 
both sides 
from 
normal 
Remarks. 
5 
923 
•255 
20 
8 
per cent. 
C G 
97-7 
95 
•149 
•13 
047 
15 
13-6 
13-6 
7 
7 
22 . 
External resistance altered 
(e 
95 
•104 
•147 
14-1 
13-6 
7 
22 
so as to give same cur¬ 
rent 
External resistance same 
7 
9-2 
093 
•085 
8-9 
91 
G 
21 
in each experiment 
External resistance same 
8 
117 
*05 
•035 
17-6 
17-6 
16 
20 
in each experiment 
External resistance same 
in each experiment 
fi- f*=0 
= il E dt — E dt — ordinate of curve A when x = 0. 
“Jo Je=o 
= n — | ' Rad 1 = difference of ordinates of curves A and B when x = 0, which should he zero on 
J° the usual theory. 
