14 
. Christie on the effects of temperature on 
Table of the Magnetic Intensities corresponding to different Tern- 
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 values of 
F 
m' 
Diff. of succes- 
sive values of 
F 
M ' 
Variation of 
-j^for loFah. 
M 
A F 
M 
0 
62.05 
59.05 
77.65 
74.00 
70.65 
67.15 
63.80 
62.05 
— 3.00 
-f 18.60 
— 3*65 
— 3*35 
— 3-50 
“ 3*35 
-ws| 
S • 
82 37 
85 25 
74 48 
75 58 
77 27 
79 04 
80 46 
82 03 
212.5620 
212.9423 
210.6228 
210.9892 
21 I .4178 
211.8353 
212.2167 
212.4640 
+ 0.3803 
- 2 . 3 > 9 S 
+ 0.3664 
-1-0.4286 
+0-4175 
+0.3814 
+0.2473 
0.1268 
0. 1247 
0 . I 004 
0.1279 
0.1193 
0. 1 138 
0. 1413 
The differences in the deduced values of the variation of 
for a change of temperature in the magnets of i° in the 
last column, are not greater than we may suppose to have 
arisen from small inaccuracies in the observations, or slight 
changes in the terrestrial intensity during the time in which 
they were made ; the latter indeed appear to have taken 
place, since, at the same temperature, the value of was 
82° 37' at the beginning of the observations, and 82° 03' at 
their conclusion. The value 0.1247 deduced from the ob- 
servations at the temperatures 59.05 and 77.65 I should con- 
sider as nearest the truth, since whatever may have been the 
errors, the divisor is here larger than in any other case ; and, 
in taking a mean, this value should be taken with the mean 
of all the others : the contrary may be said of the value 
0.1413, which should have only half the weight of any of 
the others. I therefore first take in this manner the mean 
of all the values excluding 0.1247, and then the mean of this 
