Scientific hitelligencc — Geology. SC3 



following is the series of substances traversed, together with 

 their thickness : 



862 10 

 M. Walferdin made an observation on the temperature at a 

 depth of 830 feet in this pit on the 18th of June last. Two 

 of his thermometres a deversement were sent down, each enclosed 

 in a glass tube, sealed by the lamp at its two extremities ; and 

 after a period of ten hours, the one was found to indicate 

 64;°.32 F., and the other 64°.27 F. The mean temperature of 

 the plateau of St Andre being unknown, M. Walferdin has 

 taken as his point of departure the temperature of the only pit 

 existing in the commune^ which he has found to be 53°.96 F. 

 at a depth of 246 feet. By calculating, according to these 

 data, the increase of temperature with the depth, we find it to 

 be I°.8 F. for every 101 feet G,55 inches. M. Walferdin com- 

 pares this result with those obtained previously from observa- 

 tions made in the pit sunk at Grenelle, and in that of the Mi- 

 litary School, adopting as a point of departure the constant 

 temperature (53°.24) of the cellars of the observatory, at a 

 depth of 91 feet 10 inches. Two experiments, made at dif- 

 ferent times in the pit of Grenelle, at a depth of 1312 feet 

 4.31 inches, give for 1°.8 F. 103 feet 3.17 inches, and 101 feet 

 3.39 inches. In the pit at the Military School (also sunk in 

 chalk), and distant about 1968 feet from the pit of Grenelle, 

 at a depth of 567 feet 7 inches, the temperature was found to 

 be 61°.52 F., thus giving for 1°.8 F. 101 feet 2.6 inches. It 

 tlius results from observations made at various depths of from 

 567 feet to 1312 feet, that the rate according to which the tem- 

 perature increases with the depth in the chalk formation, aj>- 

 pears to be regular in the Paris basin. It would be important 

 to ascertain, by experiments made with care, if, in the middle 

 and lower parts of the secondary formations, the temperature 

 increases with the depth at the same rate ; and M. Walferdin 

 now proposes to direct his attention to this point. — (Compter 

 Rendus, \Qth ^i'n71838.) 



