In his recent Tolume on “Vesuvius,” Professor Phillips has added the weight of his great authority to the popular opinion as to the complete internal fluidity of the globe. It may not, therefore, be out of place to examine very shortly the chief argument which appears to have led him to adopt this view, and to discredit that advocated in my paper in your December number, namely, that “pressure, by raising the temperature of fusion” in the matter immediatelybeneath the exterior crust, probably prevents its liquefaction; inother words, maintains it in a solid state, except where some upheavalof the surface rocks, or the production of some deeply penetrating fissure, has by a sudden reduction of pressure admitted of its local liquefaction.