ME. ROBERT MALLET ON VOLCANIC ENERGY. 
207 
intervals of temperature within which the mean coefficients for contraction in volume 
have been calculated ; the results are probably sufficiently clear on inspection, but may 
be tabulated thus : — 
Table I. — Coefficient of Contraction of Slags experimented upon at Barrow. 
1 . 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9. 
10. 
Higher 
tempe- 
rature 
Fahr. 
Bower 
tempe- 
rature 
Fahr. 
Range 
of tempe- 
rature. 
Volume 
at higher 
tempe- 
rature 
taken as 
Volume 
at lower 
tempe- 
rature 
then 
equals 
Volume at 
3680° Fahr. 
taken as 1000, 
then volume 
at other 
temperatures 
is as 
Total con- 
traction from 
volume at 
3680° to 
volume at each 
following 
temperature. 
Amount of 
contraction 
between 
each two 
temperatures. 
Coefficients 
of 
contraction 
per degree 
Fahr. 
Mean coefficient. 
3810 
3680 
130 
1014 
1000 
1014 
14 
1014 
14 
1014 
0-0001061 
36S0 
3419 
261 
1000 
9877 
987-7 
123 
1000 
12-3 
1000 
0-00004 77 
1 
3419 
3000 
419 
1000 
989 
976-9 
23 1 
1000 
10-8 
1000 
0-0000257 
3000 
2500 
500 
1000 
991 
967-6 
32-4 
1000 
9-3 
1000 
0-0000186 
2500 
2000 
500 
1000 
992 
959-35 
40-65 
1000 
8-35 
looo 
0-0000167 
48 
1000 
7"5 
■ 0000020087 
2000 
1500 
500 
1000 
993 
952-00 
1000 
0-0000147 
1500 
1000 
500 
1000 
993 
944-80 
55-2 
1000 
7-2 
1000 
0-0000144 
1000 
500 
500 
1000 
993 
93800 
62 
1000 
6-8 
1000 
00000136 
500 
53 
447 
1000 
995 
933-00 
67 
1000 
5 
1000 
00000100 
From inspection of the diagram fig. 1 and Table I., the upper and lower portions of 
both of which (between 3680° and 53°) are reliable as being experimentally obtained, 
we may observe that the mean coefficient of contraction in volume for the total range of 
temperature shown in the diagram is =0-00002972 for one degree of Fahr. reduction 
in temperature, or to 0-000020087, or very nearly 0-0000201 for the limits of tempe- 
rature actually embraced by experiment, being those employed by the Rev. O. Fisher. 
We also observe that the rate of dilatation or of contraction in volume for the two 
uppermost segments of the curve, viz. between the temperatures 3419° and 3810°, or a 
range of 391°, is 6-4 times greater than that for the two lowermost segments of the 
curve, viz. from 53° to 1000°, or a range of 947° Fahr. If, therefore, the mean tempe- 
rature of the nucleus of our globe be assumed within the limits of the former, and that 
of the shell within those of the latter, and the capacity for heat of both the same, the 
contraction in volume of the former will be 6-4 times that of the latter for an equal 
decrement of temperature in both. 
It is immaterial as to what follows whether we regard the nucleus of our globe as 
solid or liquid, or in what way or through what intermediate state of viscosity the solid 
2 f 2 
