Page:Physical Geography of the Sea and its Meteorology.djvu/255

Rh sea, that is many times deeper and larger than the lakes, and the water of which contracts all the way down to its freezing-point of 27°.2'!

450. The heaviest water.—The heaviest water in the sea, uncorrected for the temperature, as shown by the observations before us, is 1.028. This water was found (Figs. 1 and 2) off Cape Horn. Let us examine a little more closely into the circumstances connected with the heaviest water on our side of the equator. It was a specimen of water from the Sea of Okotsk, which is a sea in a riverless region, and one where evaporation is probably in excess of precipitation—thus fulfilling the physical conditions for heavy-water. The Red Sea is in a riverless and rainless region. Its waters ought to be heavier than those of any other mere arm of the ocean, and the dynamical force arising from the increase of specific gravity acquired by its waters after they enter it at Babel-mandeb is sufficient to keep up a powerful inner and outer current through those straits. At the ordinary meeting of the Bombay Geographical Society for November, 1857, the learned secretary stated that recent observations then in his possession, and which were made by Mr. Ritchie and Dr. Giraud (§ 381), go to show that the saltest water in the Red Sea is where theory (§377) makes it, viz., in the Gulf of Suez; and that its waters become less and less salt thence to its mouth, and even beyond, till you approach the meridian of Socotra; after which the saltness again increases as you approach Bombay.

451. Chapman's experiments.—Its waters, from the mouth of the straits for 300 or 400 miles up, have been found as high in temperature as 95° Fahrenheit—a sea at blood heat! The experiments of Professor Chapman, of Canada, which indicated as law—the Salter the water the slower the evaporation, seem to suggest an explanation of this, at least in part. Evaporation ought to assist in keeping the surface of intertropical seas cool in the same way that it helps to cool other wet surfaces. And if the waters of the Red Sea become so salt that they cannot make vapour enough to carry off the excessive heat of the solar ray, we may be sure that nature has provided means for carrying it off. But for the escape which these highly heated waters are, by means of their saltness, enabled to make from that sea, its climate, as well as the heat of its waters, would be more burning and blasting than the sands of Sahara. Even as it is, the waters of this sea are hotter than the air of the desert.