Allow me to make a few remarks on the two interesting papers contained in your last number,—one by M. Delaunay, on the Supposed Internal Fluidity of the Earth, the other by Mr. Shaler, on the Formation of Mountain Chains. I wish, in the first place, to protest against the assumption contained in the first paper (pp. 507 and 509) that the internal fluidity of the globe is “generally accepted by geologists,” on the evidence of its high internal temperature. No doubt the arguments employed in that paper go to shew that, whether fluid or rigid within, the precession and nutation of its axis would remain equally unaffected. So far, therefore, the well-known astronomical argument of Mr. Hopkins and Sir W. Thomson, as to its entire or nearly entire solidity, must be considered to be invalidated. But as Mr. Shaler justly remarks in the second paper, p. 512, “the proved increase of temperature from the surface towards the centre, and the extreme elevation of heat which must exist at considerable depths (as shewn in volcanic and other igneous phonomena) cannot be regarded as evidence of general fluidity, until it has been shown that the internal pressure has not a greater influence in preventing liguefaction than internal heat in producing that condition.”