Chap. II.]
CORAL BANK
55
1841
August 11.
August 11.
growth might be hereafter ascertained, would have been desirable; but our present object did not admit of our bestowing so much time on the investigation as it would have required. The temperature of the sea at different depths over this bank were as follows: at four hundred fathoms, 45º.3; at three hundred fathoms, 48º.1; at two hundred fathoms, 51º; and at one hundred and fifty fathoms, 53º; which, when compared with those at corresponding depths obtained in the deeper sea yesterday, would seem to bear out the following remark extracted from the instructions prepared for me by the Meteorological Committee of the Royal Society.[1]
"As no sea can be supposed absolutely motionless, the presence of a shoal, by casting up to the surface water which, but for it, would have continued to sweep along at a greatly lower level with the general body of the current, must bring the temperature of the surface water into nearer correspondence with that below. In low latitudes the surface water is hotter than that below; and accordingly it is a general remark, that the temperature sinks as the water shoals, or even in passing over banks whose depth is very considerable. If this theory of the phenomenon be correct, the contrary ought to be observed in situations where the surface water is colder than that below, as it is known to be, under particular circumstances, in the polar seas." The subject is one of considerable interest- ↑ Page 50.
