84 
THE GEOLOGIST. 
spot nearer, no matter how slightly nearer, to the sun, although upon 
the same straight line, and so year by year the circumference of the 
orbit would be ever constantly contracting ; and what must be the 
inevitable result ? — a spiral orbit ! 
JSTow, let us consider what would be the physical results of this 
retardation produdng a spiral orbit. If the retardation be ten feet 
annually, — we will take it hypothetically as such for the present, and 
to still further simplify the proposition we want to put, we will also 
take for the present a perfectly circular orbit, because by so doing 
we shall get a total result at once, instead of having to eliminate a 
total result from a period of duration. If the earth be retarded ten 
inches a month, the total retardation would be ten feet for the year, 
so we may assume, for simplicity of explanation, a full total at once. 
Now, then, if the earth were thrown back in her orbit suddenly for 
ten feet, what effect would her momentum exert upon her constituent 
material particles ? AVould not every one of these particles have a 
tendency to fly on, and would not this tendency produce tension and 
iuter-particle motion, and thence, of course, friction, rearrangement, 
crystallization, upheaval, and subsidence of masses, and internal heat? 
Has the internal heat of our globe any other source than results 
from the constant retardation of our earth in a spiral orbit ? And is 
not the primary physical force which evolves all, or principally all, 
structural alterations and constituent rearrangement of rock-masses ? 
And if so, is not this force calculable ? If the earth be retarded ten 
feet per annum, will not this force be equal to the momentum of the 
mass of our globe for the time our globe takes to pass through ten 
feet of space ? Griven this rule, can we not estimate the quantity of 
heat that would be evolved ? It seems to me we can ; and as by such 
a cause the temperature of the whole of the interior of the earth be- 
neath that mere rind, subject to solar and atmospheric variations, 
might be and would be equally warmed to a certain point, whatever 
that may hereafter be determined to be, and thus the internal heat 
would be naturally accounted for by natural phenomena. And even 
if it should be found that this cause should be a sufficient source for 
an intense degree of heat, — and it is possible it may be, — we should 
be relieved of much of the embarrassment which the internal heat 
theory provokes, because we never can get its theorists to assign a 
natural and intelligible cause for its production and maintenance. 
