Natural FJislo?y of Volcaiios and Earthquakes. 73 



last case, in order to exhibit the possibility of hot springs rising in 

 the Alps^ when water descends from great heights to the interior 

 of the rocks, flows through warmer strata of earth, and then 

 makes its exit in the valleys. It is clear that such springs merely 

 flow from above downwards, when the raised strata make their 



■ 



ap[)earance externally, but that they will, on the other hand, rise 

 again, if the strata are upraised in the form of a trough on the 

 opposite side. 



w 



Phenomena lately observed, may perhaps present cases, where 

 the effect of the internal heat of the earth nearly approaches the 

 surface. Marcel de Serres * for instance, describes a cave near 

 Montpellier, situated in the Jura Hmestone, in which, at depths 

 of 135 and 15U feet, a constant temperature of 72^.5 F. prevails, 

 which exceeds by 10^ the mean temperature of Montpellier 

 (62^.5-) He shows that no accidental circumstance, such as de- 

 compositions, the burning of tapers, or the respiration of those 

 who visit the cave, can be the case of this phenomenon; but 

 believes it is to be sought for in the central heat, which rises 

 through clefts and affects one point more, another adjacent one 

 less. Thus, at the distance of about 120U feet from this cave is 

 found a cleft in the same formation, from which issue watery va- 

 pors, whose temperature, 73^.5 (that of the external air being 

 52'^-54^'.5,) is nearly the same as of an artesian well close in the 

 vicinity of tlic cave (70^.-72^.) These vapors, which probably 

 rise from thermal springs existing beneath, are constantly disen- 

 gaged, and maintain a temperature of 73^.5, though in constant 

 contact with the external air. The cleft from which they issue, 

 commuru'cates with other wider clefts, which expand into caves, 

 into which the inhabitants of the estate of Astter have already 

 penetrated. The laborers on this estate are in the habit of 

 warming themselves pretty frequently in the hole where these 

 vapors are formed. On examinations, this vapor has all the " 

 purity of distilled water. At an earlier period there existed, at 



the distance of 150 to 180 feet N.E. of the grotto of Astier^ an- 

 other opening from which an equally warm vapor was evolved, 

 which could be perceived at some distance off. This opening 

 has, however, been since filled up. This constant vaporization 

 of water, in the middle of the same rock in which the cave 



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* Des Cavernes chaudes dea environs de MontpoHier in Annal. de Chim. et de 

 Phys. t. Ixv, p. 280. 

 Vol. ixxvxi, No. 1.— July, 1839, bis. 10 



