tJie intensity of magnetic forces ^ ^c. 
21 
Table of the Magnetic Intensities corresponding to different Tem- 
peratures of the Magnets, 
Mean Tempe- 
rature of the 
Magnets. 
DifF. of Temp, 
in successive 
observations. 
Mean of the 
observed values 
of 9 * 
Magnetic Inten- 
sity, or value of 
F 
m' 
DifF. of succes- 
sive values of 
F 
M ■ 
Variation of 
F 
-^for 1* Fah 
M 
F 
or A 
M 
0 
49*30 
60.25 
68.25 
74.60 
61.75 
73.80 
55 * 5 ^ 
66.00 
73.60 
56.90 
+ 10.95 
-f 8.00 
+ 6.35 
— 12.85 
+ 12.05 
-f 1 0 . 42 
+ 7 * 6 o 
— 16.70 
0 / 
80 22 
75 35 
72 21 
69 52 
74 *8 
70 15 
75 03 
71 13 
68 32 
74 39 
224.0981 
222.8171 
221.7046 
220,7198 
222. 3967 
220.8778 
222.6462 
221 .2655 
220.1532 
222.5145 
— 1.2810 
— 1.1125 
—0.9848 
-f-1 .6769 
— 1.5189 
— 1.3807 
— 1.1123 
— 2.3613 
0.1179 
0.1391 
0.1551 
0.1305 
0. 1260 
0.1315 
0,1461 
0.1314 
After making these obsevations, the distances of the mag- 
nets from the needle were slightly diminished, for the reasons 
I have already mentioned: their nearest ends were now 
15.56 inches from the centre of the needle, or the value of 
R was 21.52 inches. By substituting this value in the equa- 
tion C, it becomes 
M — F . ( .004480433 + .0007664093 cos.^(p ) = 0. ( a^) 
The observations which I made with the magnets at this 
distance from the needle, and the results which I obtain from 
them, are contained in the two following tables. 
