116 Analysis, cj-r. of Cordier''s Essay upon the 



" The first set of experiments, were made at the coal mines 

 of Carmeaux, September, 1825. The mine was 316 metres 

 (1028 feet) deep, with one air shaft. There was a si'allery 62 

 metres long, made about four months past, perfectly dry. The 

 exte nal air was 24". Hardly any circulation of air took place 

 in the gallery: at 4 decimetres from the ceiling, the air was 23'' 

 6'. A hole was bored in the coal, in a coiner of the gallery, 65 

 centimetres deep, and 4 in diameter, with an inclination of 16°. 

 It took six minutes to make the hole. The thermometer was 

 inserted, and the hole stopped with paper. After an hour, it in- 

 dicated 19"^ 5'. The temperature of a well, 11,5 metres (37 3-4 

 feet) deep, was 13'^^ 15'. The hole in which the thermometer 

 was inserted, was 192 metres (630 feet) from the surface. Hence, 

 192 metres less 11,5 = 180 metres produced an accession of 

 heat of 6° 35' : about one degree for 28,42 metes in depth. In 

 another experiment at Ravin, there was an accession of 3 ' 95' 

 at 170,4 metres deep: or one degree lor 43,14 metres. 



" The rays of the sun do not produce any appreciable effect; 

 for by the experiments of M. de Saussure they take six months 

 to become sensible at ten metres (thirty-two feet; dee[>. Voya- 

 ges dans les Alps § 1423. Annales de Chim. et de Phys. torn. 30, 

 p. 396, by M. Arago. In the cave under the observatory ;'t Pa- 

 ris, twenty eight metres deep, (91,86 English feet,) the ther- 

 mometer never varies, during the whole year, more than one- 

 thirfy-third of a degree. 



" in three other experiments made at the coal mine of Decise, 

 one gave one degree of the Cent. Ihormometer for 15,16 me- 

 tres; another one degree for 15,52 metres; and another one de- 

 gree for 14,81 metres. At Littry the accession of heat appeared 

 to he one degree for 19,28 metres." 



At Carmeaux, Cordier made ten experiments ; at Littry 

 as many ; and at Decise the same number. The average 

 accession of heat, was one degree for thirty six metres at 

 Carmeaux ; one degree for nineteen metres at Littry : one 

 degree for fifteen metres at Decise. Average one degree for 

 twenty-three and one-third metres deep. Paris observatory 

 one degree for twenty-eight metres. 



M. Cordier, after these details, proceeds to draw the gen- 

 eral conclusions which he thinks they suggest. But in this 

 stage of our analysis of this important paper, we think it 

 right to make two or three observations, including a notice 

 of the circumstances which in our opinion he has not suffi- 

 ciently adverted to. 



