[72] It is a well-established fact that in polar regions the temperature of the sea decreases from the surface downwards; and the German Polar Expedition found that the water in very high latitudes is actually less dense at the surface than at considerable depths, thus proving that the surface-water could not sink in consequence of its greater density.
[73] Proceedings of the Royal Society, vol. xix., p. 215.
[74] Nature for July 6, 1871.
[75] Since the above objection to the Gravitation Theory of the Gibraltar Current was advanced three years ago, Dr. Carpenter appears to have abandoned the theory to a great extent. He now admits (Proceedings of Royal Geographical Society, vol. xviii., pp. 319−334, 1874) that the current is almost wholly due not to difference of specific gravity, but to an excess of evaporation in the Mediterranean over the return by rain and rivers.
[76] Proceedings of Royal Society, No. 138, § 26.
[77] Proceedings of Royal Geographical Society, January 9, 1871.
[78] Ibid.
[79] See §§ 20, 34; also Brit. Assoc. Report for 1872, p. 49, and other places.
[80] See also to the same effect Brit. Assoc. Report, 1872, p. 50.
[81] Phil. Mag. for Oct. 1871.