708 
SIR WILLIAM THOMSON ON THE 
189. Series XXX. and XXXI. were irregular. After putting on and off weights 
several times, and finding as before diminutions and augmentations of residual magnetism, 
a weight of 28 lbs. was left on the wire, and the magnetizing circuit was made with 
current in the same direction as before ; then an additional 28 lbs. on and off : the 
current once more made and broken, still in same direction ; then circuit made in reverse 
direction, and broken ; lastly, 28 lbs. additional put on and taken off. The results were 
as follows, M( — ) being now used to denote institution of current in one final direction, 
and M(+) in the opposite direction. 
Latter part of Series XXX. December 22, 1875. — 28 lbs. permanently hung on wire- 
“ On ” and “ off” means another weight of 28 lbs. put on and taken off. 
On 
+ 5 - 5 
B 
—25 
On 
6 
On 
+ 4-5 
Off 
— 4-5 
On 
-10 
Off 
+ 
6‘5 
Off 
- 7 
M( — 
) — 42 
Off 
+ 5’5 
On 
— 
6 
On 
+ 5 
On 
+ 5*5 
On 
- 6 
Off 
+ 
6 
Off 
- 5 
Off 
- 6 
Off 
+ 6 
M(— ) 
— 
180 
On 
+ 4-5 
B 
+ 24-5 
On 
— 7 
On 
+ 
5 
Off 
- 5 
M(- 
) - 28 
Off 
+ 6-5 
Off 
— 
6-5 
B 
+ 26 
B 
+ 26 
On 
- 6 
On 
+ 
5 
M( + ) +181 
Off 
+ 5 
Off 
— 
4-5 
Series XXXI. December 22, 1875. — Weight of 28 lbs. hung permanently on the wire. 
“ On ” and “ off” means a weight of 56 lbs. hung on in addition and taken off. 
On 
+ 20 
Off 
— 12 
On 
+ 13i 
Off 
— 12 
M(-) 
-40 
On 
+ n 
Off 
— 10 
B 
+ 25J 
M( — ) 
-29 
Then 
immedi 
without waiting 
for image coming 
to rest, 
B 
On +19 
Off — 12 
On +12 
M( — ) -40 
B +36 
M( — ) -35i 
Off - 10 
On + llj 
Off - 9| 
B + 231 
M( + ) +180 
B - 24 
M(— ) -181 
On +9 
B +35 
M( + ) +150 
B - 35 
M( — ) -150 
Off - 11 
B +25 
M( + ) +182 
On and M( — ) and B 
many times quickly. 
M(— )' -34 
B immediately after. 
M( + ) +155 
Off, and B and M( + ) 
and B many times 
quickly. 
M( — ) -185 
M( — ) and B many 
times quickly. 
M( + ) +184 
On. Then M( + ) and 
Bmanytiinesquickly. 
M( — ) 155 
M( + ) reading lost. 
M(— ) -180 
M( + ) +179i 
Then immediately, 
without waiting for 
image coming to rest, 
Off 
M( — ) -199 * 
M( + ) +198 
Then immediately 
On 
M(— ) -181 
M(+) +176 
Then immediately 
Off 
M( — ) -199 
M( + ) +200 
M( — ) —200 
M( + ) +200 
Then immediately 
On 
M( — ) -180 
M( + ) +179 
M(-) -179 
Steel wire removed 
from core, to test 
the direct induction 
from coil to coil. 
M( + ) +20 
B — 191 
190. Interpretation of Series XXX. with help from Series XXXI. — From each 
M( + ) and following B subtract and add respectively + 19f, or, say =f=20, for 
induction of coil on coil measured in last two experiments of Series XXXI. Therefore 
