112 Analysis., ^c. of Cordier'^s Essay upon the 



'•One of the el'^ments of this i)roblem, that which seems to- 

 needs further investigation most, is th- permanent incroasf of 

 temperature in descending f'om the surface loivards the centre 

 of the earth. It may be asked, are the experiments, already 

 made, sufficiently exact? Have they been sulicieiitly examined 

 und criticised as to the manner of conducting them? Are the con- 

 sequences deduced from them, legitimate and conclusive of the 

 question? Let us therefore, in the first place, >?xamine the ex- 

 periments which have already been made with this view ; se- 

 condly, let us give an account <^f the experiments iivhich we have 

 instituted ourselves for the same purpose ; thirdly, let us desig- 

 nate the results and conclus ons they aiford. 



" On the experiments hitherto made as to subterraneous tempera- 

 ture. — These relate, to the temperature of natural springs. 



" The temperature of natural and artificial excavations : these 

 have been pushed as far as four or five hundred metres, (one 

 thousand six hundred and forty English feet.) 



"In France, we possess observations on the temperature of 

 the cave under the Observatory of Paris, during one hundred 

 and fifty years; lately brought to perfection by M. Arago. 

 Those made by M. Gensanne, in the mines of Girmagny, about 

 the middle of the last century ; the experiments of M. D'Aubuis- 

 son, in the mines of Brittany, in 1806. 



" In Switzerland, we have the experiments made by De Saus- 

 sure, about forty years ago, in the salt mines of Bex. 



" In Saxony, we have those of M. M. Friesleben and Hum- 

 boldt, collected in 1791; those of M. D'Aubuisson, in 1802, and 

 especially those of M. Trebra, in 1805, 6, 7 and 15. 



"In Great Britain, we have a great number, from 1815 to the 

 present time ; by Messrs. M'Lean, Reed, and W. Fox, in Corn- 

 wall and Devonshire; and by Messrs. Bald, Dunn, and Fenwick, 

 in the coal mines of the north of England. 



" Nor ought we to omit those made by Humboldt, in the mines 

 of Peru and Mexico, at a former period."* 



* These experiments may all require to be further considered, before the 

 conclusion is permanently established : therefore the authorities cited by Cor- 

 dier, are inserted here. — Reviewer. 



Experiments made in France. See Dissertation sur la Glace par Mairan. 

 Paris, 1749, in 12mo, p. 60, et suiv. Journal des Mines, tom. 21, p. 119. 



In Switzerland. De Saussurc, Voyages dans les Alps, 1088. 



In Saxony. Ann. de Chim. et de Phys. tom. 25, p. 210. Description des 

 mines de Freyberg, tom. 3, pp. 151, 1S6, 200. .Tournal des Mines, tom. 11, p. 

 517 ; tom. 13, p. 113. Annales des Mines, tom. 1, p. 377 ; tom. 3, p. 59. 



In Great Britain. Ann. de Chim. et de Phys. tom. 13, p. 200 ; tom. 16, p. 

 78; tom. 19, p. 438; tom. 21, p. 308. Geographical distribution of plants, bj 

 K. J. Winch, p. 51. 



