Sir William Thompson on the Centre of the Earth.
A REMARKABLE address has been delivered by Sir William Thompson, in the Physical Section of the British Association, on the subject of the fluid or solid nature of the earth’s kernel. While not denying that certain portions of the earth’s interior are in a molten or fluid state, Sir William Thompson maintained, on various more or less recondite grounds, that no large proportion of the earth’s interior can, by any possibility, be in the condition of molten fluid. “I may say, with almost perfect certainty, that whatever may be the relative densities of rock, solid and melted, at or about the temperature of liquefaction, it is, I think, quite certain that cold solid rock is denser than hot melted rock; and no possible degree of rigidity in the crust could prevent it from breaking in pieces and sinking wholly below the liquid lava. Something like this may have gone on, and probably did go on, for thousands of years after solidification commenced—surface portions of the melted material losing heat, freezing and sinking immediately, or growing to the thickness of a few meters when the surface would be cool, and the whole solid dense enough to sink. This process must go on until the sunk portions of the crust build up from the bottom a sufficiently close-ribbed skeleton or frame to allow fresh incrustations to remain, bridging across the now small areas of lava pools or lakes.” That is a striking picture of the growth of the “round earth,” which was once supposed to have been made from the first “so fast that it cannot be moved.” We are rather sorry to be robbed of the belief in the central lava ocean after all.—London Spectator.