12 Temperature of the Terrestrial Globe. 



to say, to a depth, two hundred and sixty or three hundred and twelve 

 times greater. Neither shall we undertake to bring forward the dis- 

 sertation contained in the fourth chapter, where he treats the prob- 

 lem under a geological point of view. We shall satisfy ourselves with 

 offering to our readers the second and third chapters, in which the 

 author is occupied with the temperature of seas and lakes, and with 

 the manner in which he reconciles the facts obtained, with those which 

 relate to the places where the earth has been penetrated. 



" It has been proved above," says M. Parrot, " that the observa- 

 tions made upon the temperature of the earth, at different depths, are 

 in no wise capable of founding the hypothesis of a central fire. But 

 these proofs are merely negative. Nature furnishes others of a posi- 

 tive character, in observations made upon the temperature of the sea 

 at different depths. The experiments of Irwine, Forster, Peron, 

 Horner, and Lenz, made at so many points of the ocean, attest that 

 this temperature diminishes with the depth, entirely contrary to what 

 the experiments on the continent furnish.* Those of M. Lenz, have 

 doubtless attained to the greatest depths, and at the same time pro- 

 duce the most exact results. As I have already exhibited them in the 

 Bulletin Universel, and as this labor of M. Lenz, has appeared a short 

 time since in the Memoirs of the Academy of Sciences, of Peters- 

 burg,f I shall abstain from recapitulating them. These results are 

 principally : 



1st. That the temperature diminishes as the depth increases. 



2nd. That it diminishes at first rapidly, then very slowly. From 

 the surface to 413 fathoms depth, this diminution exceeds 23° C. 

 and from that to 915 fathoms, it does not diminish 1° C. 



* I need not dissemble that two contrary experiments, have come to my knowl- 

 edge. One is of M. Irwine, who in lat. 80° 31' N. found in December, the tempe- 

 rature of the surface of the sea + 2°.2 F. =— 16°. 6 C. and at 60 fathoms depth 

 -^-3°.9 F. = — 15°.6 C. which makes an augmentation of temperature of a degree 

 in 60 fathoms, or about 120 metres in depth. The second is by M. Scoresby, in the 

 80th degree of N, lat. and 5° Ion. from Greenwich, between Greenland and Spitz- 

 bergen. He found that the temperature increases to 7° F. or 3° .9 C, at a depth ot 

 758 fathoms or about 1516 metres. (I do not exactly know bow much the fathom 

 of the English seamen is ; but it is, if 1 am not mistaken, nearly equal to two metres.) 

 If we consider that one of these augmentations of heat only amounts to 1° C. for 126 

 metres, and the other for 388 metres, we might infer that these two anomalies may 

 be explained by the severity of the climate and the season, and do not weigh against 

 so many other experiments made in all other climates and in so many different lon- 

 gitudes, i See Bib. Univ., 1831, tome 1, (xlvi.) p. 275. 



