Interior Condition of the Earth. — Le Conte. 41 
tion of fusing point with pressure and found a mean rate of 
1° for 30 atmospheres. It is possible that the rate of elevation 
for rocks may be less than this : but in any case there must 
be a notable elevation of fusing point by the enormous pres- 
sure of 30-40 miles of rock. Therefore we must go still deeper 
to find fused matter. In the meantime the pressure would 
still increase and the fusing point be still more elevated. 
Whether, in this chase of the increasing temperature after the 
flying fusing point, the former would overtake the latter at 
all; and if so, where, are questions we cannot answer posi- 
tively. It would depend^on the relation of the rate of increas- 
ing temperature with depth to the rate of elevation of fusing 
point with pressure, i e, the relation of the line c e to the line 
/•^(fig.l). 
There are three possible 
cases in this regard. 1. The 
line of fusing point may 
take the direction fg (fig 2.) 
putting the line of actual 
temperature at y and ever 
after lying within. In this 
case the earth would be uni- 
versally liquid below y. This 
would not satisfy the physi- 
cists. 2. It may take the 
direction f g ' and lie wholly 
outside of the line of actual 
temperature. In this case ^ig—. a e=line of actual temperature /p 
the earth would be ^o\\dii,%iX:iZTuit"' '' ''''''''■ '"^'^^ 
throughout. This would not satisfy the geologists. 3. The 
line of fusing point may take the direction /V"touchin<^ or 
cutting and again leaving the line of actual temperature. ° In 
this case at the depth of tangency there would be a layer of 
fused or semifused matter separating a solid nucleus from 
the solid crust. For reasons already given this seems to be 
the most probable case, for this would explain all the phe- 
nomena and satisfy both the physicist and the geologist. 
Now there are some reasons for thinking that this sub-crust 
layer would not be so deep as would seem from the foregoing 
reasoning and figures. We have thus far supposed the line of 
fusing point a straight hne. This would probably be the case if 
