I also proved that the wave-transit period of the unshattered material of these rocks was greatest in a direction _transverse_ to the bedding, and least in line parallel with that; but the effect of this in the rocky mass itself may be _more_ than counterbalanced by the discontinuity and imperfect contact of the adjacent beds. These results indicate, therefore, that the superficial rate of translation of the solitary sea-wave of earthquakes may, when over very deep water, equal or even exceed the transit rate (in some cases) of the elastic wave of shock itself. These results have since received general confirmation by the careful determinations of the transit rates of actual earthquake waves, in the rocks of the Rhine Country and in Hungary, by Nöggerath and Schmidt respectively, and by those made since by myself in those of Southern Italy, to which I shall again refer. In an elastic wave propagated from a centre of impulse in an infinitely extended volume of a perfect gas, normal vibrations are alone propagated--as is the case with sound in air. In the case of like movements propagated in elastic and perfectly homogeneous and isotropic solids, the wave possesses both normal and transversal vibrations, and is, in so far, analogous to the case of light. Mr. Hopkins, in his Report above referred to, has based certain speculations upon the assumed necessary co-existence of both orders of vibration in actual earthquake shocks in the materials of which our earthy crust is actually composed. The existence of transversal vibration in those materials has not been yet proved experimentally, though there is sufficient ground to preclude our denying their probable existence.