THE SPECIFIC GRAVITY OF THE SEA, ETC. 229 



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, un- 

 corrected 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 con- 

 nected 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 Eed 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. Eitchie 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 bej^ond, till j^ou 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 ex- 

 periments 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 carrj'ing 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. 



