Thickness of the Crust of the Earth

Abstract

ARCHDFACON PRATT has given just the answer I expected to my remarks on his defence of Mr. Hopkins. As I said at the time, I scarcely thought it possible that he could have fallen into the mistake of supposing that the disturbing forces to which precision and nutation are due act by fits and starts. But note what follows from this. His whole defence of Mr. Hopkins's method falls to the ground. The very life and soul of that defence was, in almost his own words, that the disturbing forces produced the motion due to their action before friction had time to act; or, in other words, that the disturbing forces gave a pull so sharply and quickly that they did their work before friction, which the Archdeacon looks on as rather a sluggard, could rouse itself and counteract them, that they were, in short, able to steal a march on friction each time they gave a pull or a push.