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, I shall abstain from recapitulating them. ‘These results are 
principally :-— 
Ist. 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. 
* TI 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 indepth. Thesecond is by M. Scoresby, in the 
80th degree of N. lat. and 5° lon. from Greenwich, between Greenland and Spitz- 
bergen. He found that the temperature increases to 7° F. or 3°.9 C., at a depth of 
758 fathoms or about 1516 metres. (I do not exactly know how 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. t See Bib. Univ., 1831, tome 1, (xLv1r.) p. 275. 
