***Completely revised version of the original 1904 edition*** "The hypothesis of a universal force called Gravitation is based upon, and was indeed invented with a view to support another hypothesis, namely, that the earth and sea together make up a vast globe, whirling away through space, and therefore needing some force or forces to guide it in its mad career, and so control it as to make it conform to what is called its annual orbit round the sun The theory first of all makes the earth to be a globe; then not a perfect globe, but an oblate spheroid, flattened at the 'poles'; then more oblate, until it was in danger of becoming so flattened that it would be like a cheese; and, passing over minor variations of form, we are finally told that the earth is pear-shaped, and that the 'elipsoid has been replaced by an apoid ' What shape it may assume next we cannot tell; it will depend upon the whim or fancy of some astute and speculating 'scientist.'"