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MR. HENNESSY’S RESEARCHES IN TERRESTRIAL PHYSICS. 
State a considerable quantity of latent heat will be eliminated. A portion of this 
heat will pass upwards through the shell, and another portion will pass into the im- 
perfect fluid immediately below, tending to bring it back to a state of more perfect 
fluidity. If the quantity of latent heat thus eliminated should be great, it may exert 
an influence in changing the arrangement of the parts of the shell which it may be 
hereafter useful to consider. The effect of the elimination of latent heat upon the 
process of circulation would be evidently such as to render that process still more 
complex than what it was before, and its examination would thus be attended with 
still more difficulty and uncertainty. A very accurate examination of this portion 
of the phenomena attending the earth’s refrigeration, appears not to be necessary for 
the present, and it will be found most convenient to defer its consideration, if it 
should be required in any future portion of these researches. 
7 . The motions of the shell and internal fluid matter, and their mutual actions 
depend so much upon the arrangeinent of the molecules of the primitive fluid mass, 
that it would be desirable before attempting their investigation to form if possible a 
few precise ideas respecting the last mentioned subject. The results which may be 
thus obtained with respect to the dimensions and law of density of the primitive 
fluid, will also enable us to find the probable values for <p (a), or Q, which should be 
substituted in this case respectively in either equations (5.) or (6.), in order to 
obtain the ellipticity of the spheroid. 
Let the mass be supposed to have arrived at the state alluded to in the foregoing 
article, when “ it would consist of a series of spheroidal strata, each of uniform 
density throughout its own mass, and having that density expressible as a function 
of its axes.” Each stratum would have to sustain the normal pressures of all the 
strata above it, whether these pressures be produced by the action of gravity or other 
causes. The compressive force exercised by the upper strata upon those farther 
from the surface, would tend to increase the density of the latter. How far this in- 
crease of density from compression may proceed without solidification, we have no 
precise experimental evidence by which to judge. The celebrated experiments of 
8ir James Hall appear, however, to show that from the action of a great com- 
pressive force, matter in a fused state may very nearly retain the volume, and there- 
fore the specific gravity which it had when solid. If from the combined action of 
increased pressure and increased temperature the specific gravity of the matter 
should be augmented, while its fluidity should be retained, it would fulfil the condi- 
tions of the hypothesis made in explanation of the earth’s figure. If it can be assumed 
that the substances composing those portions of the globe inaccessible to observers 
are similar in constitution to those which are found at the surface, this portion of the 
subject appears to be susceptible of experimental examination. Until such an ex- 
amination shall have been made, the mass may be supposed to have an arrangement 
such as that indicated in art. 6. If a solid nucleus of comparatively small mass 
