IXXX PEOCEEDINGS OF THE GEOLOGICAL SOCEETT. 



(Saone-et-Loire) being throTvn down by a dislocation on the east, 

 which brought the strata of the Trias against the coal-measures, 

 M. Schneider, the director of that great establishment, called in the 

 aid of the eminent bore-master Herr Kind ; and at the time of the 

 experiments (in 1856) one bore-hole, that of Torcy, had reached the 

 depth of 595 metres (1951 feet), and had been suspended; whilst 

 another, that of Mouillelonge, was already down 816 metres 

 (2676 feet), and was destined to be much deeper. 



Mouillelonge is not quite two miles from Creuzot, and 321 metres 

 (1052 feet) above the level of the sea. The bore-hole was 0™-30 

 in diameter at the top, and 0'^'26 at the bottom. At 371 metres 

 (1216 feet) it passed from the New Eed Sandstone into the Coal- 

 measures, which consist there of alternations of blackish shales and 

 pink sandstones. 



The work was temporarily stopped on the 10th May 1856, at 

 11 A.M. ; and in order to guard against error from the heat gene- 

 rated by the percussion of the boring-implements, a considerable 

 time was allowed to elapse, and the slime in the lower part of the 

 bore-hole was, by means of lowering and raising the " sludger," well 

 stirred up into the water over it ; a first experiment was made after 

 80 hours, and the thermometers were lowered for 16 hours. A second 

 experiment, commenced 102 hours after the cessation of the work, 

 and in which the thermometer remained at the bottom for 16| hours, 

 gave a very slightly different result, viz. 38°-31 (100°-9 F.). 



The other bore-hole, at Torcy, is 310 metres (1016 feet) above 

 the sea. It had been so long abandoned that no error from the 

 friction of working was to be apprehended ; and as the lower part had 

 fallen in, the experiment was made at 554 metres (1817 feet). 

 The result was here 27°*23 (81° F.), and on a second occasion, ten 

 days afterwards, 27° '22 C. 



The boring, then, at Mouillelonge, compared with that of Torcy, 

 gives for a difference of depth of 262 metres an increase of tempera- 

 ture of ll°-09 (19°'9 F.), or one degree Centigrade for 13*6 metres 

 (one degree F. for 43-1 feet.) 



The rate of increase from the surface downwards, the mean tem- 

 perature of Torcy being estimated at 9°-2 (48°-5 F.),is 18°-02 for 554 

 metres, or one degree for 30-7 metres (one degree F. for 56 feet). 



These results would appear to give a more rapid ratio of increase 

 between 550 and 800 metres than between the surface and 550 ; 

 and it remained a question whether the effects of percussion in the 

 deeper bore-hole had been entirely eliminated. 



I regret not to have been able to find that M. "Walferdin con- 

 tinued his observations after the depth of the bore-hole had been 

 increased. That undertaking was, in fact, fruitlessly continued 

 until it had obtained a total depth of 920 metres, or 3017 feet 

 English ; and the impression among the local Engineers, when I 

 visited Creuzot in 1866, was, that the increment had remained much 

 the same, i. e. one degree Centigrade to 30 metres. 



By way of comparison, we may be reminded of the elaborate 

 series of observations conducted ia our deepest English coal-shaft. 



