1872.] 



' Shearwater 9 Scientific Researches. 



543 



Equatorial area, — the low conducting-power of water altogether forbidding 

 the idea that such a permanent depression can be sustained by lateral con- 

 duction from the Polar area against the warming influence of the bottom 

 beneath and of the air above. And if this be admitted as probably true 

 with respect to the Temperate area to which my own inquiries have been 

 limited, with how much more force does the same argument apply to the 

 Intertropical region, where, with a surface-temperature rarely, if ever, 

 falling below 75°, we find a temperature of 47° at so small a depth as 400 

 fathoms, and a 60^0^-temperature but little above the freezing-point of 

 fresh water — the " protected " Thermometers used by Commander Chimmo 

 in the Indian Ocean having registered 35°'2 at 1806 fathoms, 33 0, 6 at 

 2306 fathoms, and 32° at 2656 fathoms, in Lat. 3° 18f S., and Long. 

 95° 39' E. (See p. 590.) 



1 1 . If any confirmation of this view be thought requisite, it is supplied 

 by a similar comparison of the Temperatures of two other Inland Seas 

 with those of the Oceanic Basins with which they communicate. The 

 Red Sea, like the Mediterranean, is entirely cut off from communication 

 with the deeper and colder stratum of the Arabian Gulf, with which its 

 surface-layer communicates through the shallow Strait of Babelmandeb. 

 Whilst the lowest(February) temperature observed in that surface-layer, even 

 in the northernmost extension of the Red Sea known as the Gulf of Suez, 

 is 71° (as I learn from Capt. Nares, who has been recently engaged in its 

 survey), that temperature is there carried uniformly down to the bottom at 

 450 fathoms ; and it may hence be pretty certainly affirmed that no lower 

 temperature than this will be found in the southern portion of the Red 

 Sea, even on a bottom exceeding 1000 fathoms in depth, since the lowest 

 surface-temperature of that portion is probably never less than 75°. Yet 

 in the Arabian Gulf the temperature at a depth of 2000 fathoms is cer- 

 tainly not above, and is very probably below 36°'5*. 



] 2. The like contrast is shown by the Temperature- soundings of 

 Commander Chimmo (which have been kindly communicated to me by the 

 Hydrographer), between the deep temperature of the Sulu Sea, — a small 

 area between the north-eastern portion of Borneo and Mindanao, — and that 

 of the China Sea. The former, though not ostensibly an inland sea, being 

 but very partially surrounded by land, is so shut in by reefs and shoals, as 

 to have only a very superficial and limited communication either with the 

 China or with the Celebes Sea. Notwithstanding this enclosure, its depth 

 is very great, ranging to 1778 fathoms; and its Temperature-phenomena 

 present exactly the same contrast with those of the China Sea that the 

 temperature-phenomena of the Mediterranean present when compared with 

 those of the Eastern Atlantic, as will be seen in the Table in the next 

 page. 



* Sec " Report" for 1869, § 120. 



