16 
Mr, Christie on the effects of temperature on 
Table of the positions of the Points of Equilibrium corresponding to 
different Temperatures of the Magnets retaining a Magnetic Nee- 
dle in equilibria f 7 th June. 
Time of 
commencing 
observation. 
Temperature 
of 
N. Magnet. 
j- 
Points of Equilibrium. 
Temperature 
of 
S. Magnet. 
Time of 
concluding 
observation. 
Mean tempe- 
rature of the 
Magnets. 
30.12 
att. 60.50 
West. 
East. 
South. 
h. m. 
# 
0 
0 / 
0 / 
0 
t 
0 
h. m. 
0 
6 i 
9 50 
57.0 
83 18 
^ 16 
0 
loW 
57.0 
9 53 
57.00 
0 s 
10 04 
66.3 
78 16 
78 04 
0 
16 
67.7 
10 07 
67,00 
wH 
10 15 
71 .0 
76 22 
76 10 
0 
H 
70.7 
10 18 
70.85 
10 27 
75.0 
74 36 
74 42 
0 
12 
75.0 
10 31 
75.00 
'0 
10 44 
60.0 
81 18 
80 26 
0 
20 
61 .0 
lo 47 
60.50 
u-> 
A 
0 
Previous to making these observations I had slightly 
changed the distances of the magnets from the centre of the 
needle : the distances of their nearest ends were now 15.26 
inches, or that of their centres 21.22 inches from the needle's 
centre. Substituting this value of R in the equation ( C ) it 
becomes 
M — F (.004683954 + .000827265 cos.^(p) = 0; ) 
and from this I calculated the following table. 
Table of the Magnetic Intensities corresponding to different Tern 
peratures of the Magnets, 
Mean tempe- 
ratures of the 
Magnets. 
DifF. of Temp, 
in successive 
observations. 
Mean of the 
observed values 
of 
Magnetic Inten- 
sity or value of 
F 
m’ 
DifF. of succes- 
sive values of 
F 
M * 
Variation of 
F 
vr for Fah. 
M 
or A . JL . 
M 
5 7.00 
67.00 
70.85 
75.00 
60.50 
-4 10.00 
+ 3*^5 
+ 4 **S 
--I4.50 
0 / 
83 *7 
78 10 
76 16 
74 39 
80 52 
212.9803 
2 II .9209 
211.3907 
210.8848 
212.5489 
-1.0594 
— 0.5302 
-0.5059 
1 • 66 i|.i 
0. 1059 
0.1377 
0. 1219 
0. 1 148 
