52 Dr Daubeny on Thermal Springs, 



which may be traced from the Geysers of Iceland, to the nearly 

 boiling waters connected with that dormant volcanic action, 

 which we observe in some spots in the neighbourhood of Na- 

 ples, and from thence, again, to those of somewhat more mode- 

 rate temperature, which issue from the trachytic and other ig- 

 nigenous rocks of Mont Dor in Auvergne, or of Glasshutte near 

 Schemnitz. In such cases as these, the combined weight of evi- 

 dence derived from their temperature, their geological position, 

 and the nature of their gaseous products, appears almost irre- 

 sistibly to establish a volcanic origin. 



I proceed, then, to the second class of hot springs, those con- 

 nected with ridges or chains of mountains, which are generally 

 regarded as produced, in consequence of the strata composing 

 them having been lifted up into their present highly incUned 

 position, from one more nearly approaching to an horizontal one, 

 by some cause acting from beneath. 



Perhaps there is no chain which affords a fairer illustration 

 of this class of springs, than the Pyrenees, these mountains 

 being, along the whole extent of their northern declivity, ac- 

 companied by a succession of thermal waters, which from their 

 supposed medicinal virtues have long attracted attention. 



Now, if we assume the elevation-theory as applicable to this 

 system of mountains, we might expect to trace a continuance of 

 that volcanic action, which originally produced these effects, any 

 where within the limits of the chain, where the valleys had been 

 excavated to a depth sufficiently great to bring us nearly into 

 contact with the central granite, or, more correctly speaking, the 

 radius over which the force in question had been exerted in its 

 greatest intensity. Hence we might reasonably look for hot 

 springs even at a distance from the axis of the chain, in gorges 

 cut to a great depth through the strata ; whilst, near the axis, 

 we should be prepared to meet with them bursting out occa- 

 sionally even at a considerable elevation. Thus the distance of 

 Bagneres di Bigorre from the axis of the chain does not prevent 

 the occurrence of thermal waters in this locality, the valley from 

 which they issue being at a low level ; neither does the elevation of 

 Barege occasion its springs to come out cold, because, from its 

 situation near the centre of the chain, the source of the heat may 

 be presumed to lie almost immediately underneath it. 



