311 



crease of the temperature of the crust of our earth, from the 

 surface towards the centre. But two-thirds of the surface of 

 our globe are covered with water, and we cannot assume a 

 priori that this large area loses heat at the same rate as the 

 solid parts ; on the contrary, various circumstances indicate 

 that the cooling of our globe proceeds more quickly through 

 the waters of the ocean resting on it than from the solid parts 

 merely in contact with the atmosphere. 



In the first place, we have to remark that the bottom of 

 the ocean is, generally speaking, nearer to the store of heat 

 in the interior of the earth than the dry land is, and hence 

 that the temperature increases most probably in a greater 

 ratio from the bottom of the sea towards the interior of the 

 globe, than it does in our observations on the land. Sec 

 ondly, we have to consider that the whole bottom of the sea 

 is covered by a layer of ice-cold water, which moves con 

 stantly from the poles to the equator, and which, in its pas 

 sage over sand-banks, causes, as Humboldt aptly remarks, 

 the low temperatures which are generally observed in shallow 

 places. That the water near the bottom of the sea, on ac 

 count of its great specific heat and its low temperature, is 

 better fitted than the atmosphere to withdraw the heat from 

 the earth, is a point which requires no further discussion. 



We have plenty of observations which prove that the 

 earth suffers a great loss of heat through the waters of the 

 ocean. Many investigations have demonstrated the existence 

 of a large expanse of sea, much visited by whalers, situated 

 between Iceland, Greenland, Norway, and Spitzbergen, and 

 extending from lat. 76 to 80 N., and from long. 15 E. to 

 15 W. of Greenwich, where the temperature was observed 

 to be higher in the deeper water than near the surface an 

 experience which neither accords with the general rule, nor 

 agrees with the laws of hydrostatics. Franklin observed, in 

 lat. 7-7 N. and long. 12 E., that the temperature of the sea 

 near the surface was , and at a depth of 700 fathoms 



