118 C. FE. Dutton on the Contractional Hypothesis. 
some function of the temperature. But if a function of the 
temperature, it must also be a function of the time and depth, 
and hence would alter the general form of the law, and affect 
all quantitative evaluations derived from it.* The general 
Graphical representation of increase of temperature downward in the earth. (Sir W. 
Thomson.) 
ON=z a=2/ kt. 
Se en -— ¥ = Ne 
NP’=be *=y/’. dz a bh/r 
NP = area ONP’A+a= x 7x y’de, 
0 
a@x05?| 
exii’r 
ax1°5 
ax20 
a@x256 x 
> 
‘7000 F. 
OPQ showing excess of temperature above that of the surface. 
rd. 
A P’R showing rate of augmentation downwa: 
establish an increase of ;',.;° F per foot of descent would also 
* The identical curve here given might still be used with a slight modification in 
the axis of abscissas. If instead of equal divisions of that axis, we were to take 
