220 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



to the temperature of 40°. Its specific gi'avity at that terapera- 

 ture would have been 1.030, or specifically 30 per cent, heavier 

 than the sea water of our own coasts.' Could two such currents 

 of water meet anywhere at sea, except as upper and under cur- 

 rents ? If water that freezes at 32°, that grows light and remains 

 on the sorface as you cool it below 39°, is prevented from freezing 

 in our great fresh water lakes by vertical circulation, how much 

 more would both vertical and horizontal circulation prevent conge- 

 lation in the open polar sea, that is many times deeper and larger 

 than the lakes, and the water of which contracts aU the way down 

 to its freezing-point of 27°. 2. 



450. The heaviest water in the sea, micorrected for the tempera- 

 The heaviest water, turc, as showu by the obscrvatious before us, is 1.028. 

 This water was found {Figs. 1 and 2) off Cape Horn. Let us ex- 

 amine a little more closely into the circumstances connected with 



"the heaviest water on om' side of the equator. It was a specimen 

 of water from the Sea of Okotsk, w^hich is a sea in a riverless 

 region, and one where evaporation is probably in excess of precipi- 

 tation — 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 Babelmandeb is suffi- 

 cient 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 Eed 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 meri- 

 dian of Socotra ; after which the saltness again increases as yon 

 approach Bombay. 



451. Its waters, from the mouth of the straits for 300 or 40Q 

 ciiapman's experi- milcs up, havo boeu fouud as high in temperatm^o 

 °''^"*'- 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 sug- 

 gest an explanation of this, at least in part. Evaporation ought 

 to assist in keeping the sm-face of intertropical seas cool in the 

 same way that it helps to cool other wet surfaces. And if the 



