and of the Planetary Spaces. 61 
after numerous oscillations, arrived at a permanent figure, which 
was determined in this state of fluidity, and that the liquid sub- 
sequently preserved this figure while passing to a solid state. 
The solution of this problem of hydrostaticks requires only a 
knowledge of the temperature of the liquid; but now, if we sup- 
pose that this heat was very great, and much superiour to the 
temperature of the regions of space surrounding the planet, we 
see not what exteriour pressure there could have been which pre- 
vented the liquid from dilating itself to a state of vapour, instead 
of passing from a liquid to a solid state: and if it was possible 
that the layers near the surface had commenced, through conden- 
sation, to assume the solid state, before the interiour layers had 
lost their primitive heat, we can no more clearly understand how 
these last, by their tendency to dilation, of which we 
a power, should not burst the solid, exteriour envelope as often 
_ It is farther to be observed that this high temperature © 
oe our planet, in the liquid state, is a gratuitous assumption of 
which it would be difficult to find an explanation. (5) It is true 
that when a body is at first a liquid, more or less compressible, of 
which the layers would augment in density, in going from the 
surface to the centre, and terminate by passing to a solid state, 
by reason of the pressure from without, this condensation and 
this change of condition would develope a great quantity of heat ; 
but it is necessary to observe that in this view of the subject the 
solidification would probably commence at the centre of the mass : 
the nucleus, thus solidified, would become a focus of heat, which 
would raise the temperature of the immediately surrounding layer, 
still in a liquid state ; this layer, thus heated, and its density di- 
minished, would be elevated, and its place supplied by a new 
layer which, in passing to the solid state, would radiate heat in 
like manner, and so in succession, until the entire mass should 
have become a solid. In this manner the solid nucleus, gradually 
augmenting, would communicate, to the parts still liquid, the 
quantities of heat successively disengaged from newly solidified 
(5) Some int Lyell’ s Geology, Amer- 
ican edition, 1837, vol. 1,2. = and onward. The last English edition, of which 
this one is a copy, was published during the present year ; yet it is pidinible the 
author had not seen M. Poisson’s Theory of Heat, as he quotes both Fourier and 
Cordier, and controverts their theory, but without mention of Poisson. 
