140 On the Artesian Well of Grenelle. 



Count Kej^serling", who. has traced the shales with Ammonites near 

 Ust-Sisolsk (N. Lat. 61°, E. Long. 51°*), has indeed contributed most 

 powerfully to these results, both by his patient observation, sound know- 

 ledge of natural history, and by his barometrical admeasurement of 

 heights, — a point of great geological importance in those, central parts of 

 tlie country where the strata are not deranged. By one of his observa- 

 tions, it appears, that the younger pleioccne deposits on the Dwina, which 

 he detected in company with M. de Verneuil and Mr Murchison, are 

 about 150 feet above the White Sea. Count Keyserling, now at St 

 Petersburgh, will accompany the authors in their journey to the Ural 

 Mountains this summer.t 



I. On the Artesian Well of Gretielle. By M. Walferdin. 



We have all.lieard. with the greatest interest, of the com- 

 plete success which M. Mulct has obtained at Grenelle. After 

 seven years of continued exertion, and after having surmounted 

 difficulties of whose amount it would not have been prudent to 

 speak during the course of the operation, M. Mulct at length, 

 on the 26th February 1841, at half-past two o'clock, had the 

 satisfaction of seeing burst forth from a depth of 548 metres, 

 the water which he was in search of, in the green sand under 

 the Gault. 



The jet of water springs up with an abundance which sur- 

 passes every hope that had been formed ; for it yields no less than 

 4,000,000 of litres in the twenty-four hours.. The temperature 

 was not determined byM. Arago and myself till the following 

 day, the 27th ; and the state of the basin into which the water 

 flowed, not admitting of an accurate direct determination of 

 the temperature of the jet, a bucket was placed in the basin 

 which was immediately filled with the green sand brought up 

 in abundance by the water. After allowing the thermometer 

 to remain 30 mhiutes in this basin, it indicated 27° 6' Cent. 

 (81°. 68Fahr.) 



I propose to continue daily the observations on the tempe- 

 rature, in order to study the differences which may occur ; 

 these observations shall be made with all desirable precision, 

 when it becomes possible to place thermometrical instruments 

 in the jet itself, and thus to read oif the results directly. 



* Similar Jurassic beds had been previously observed by Colonel Ilel- 

 mcrsen in the' N. Ural,, I^at. 64° north. 



t Ahctracted/ron the ilfp<jrl vf the Briiich Acsodalijn fuv ihc Ailvanccmait 

 cf S<knc^/or 1840^ and from a Momir nadbf/or€ tU Qeoiogictd Society qf Lon» 





