( 132 ) 



On the Cause of the Temperature of Hot and Thermal Springs; 

 and on the bearings of this subject, as connected with the 

 general question regarding the Internal Temperature of the 

 Faith. By Professor GusTAv BiscHOFF of Bonn. Com- 

 municated by the Author. (Continued from Vol. XXIII. 

 p. 330.) 



Part II Are the obscrvatiojis hitherto made in mines sufficient to 



determine the late of the increase of temperature towards the cen- 

 tre of the Earth ? 

 All our former investigations have led us to conclude an in- 

 crease of temperature towards the centre of the earth ; no phe- 

 nomena, no observations, were contradictory to such an hypo- 

 thesis ; indeed, without its previous admission, many were in- 

 capable of explanation. We have now to determine whether 

 this increase of temperature follows any fixed law, and whe- 

 ther that law is the same departing from all points equally dis- 

 tant from the centre of the earth, for example, from the level 

 of the sea. Although it would seem that this inquiry could only 

 be made by means of experiment, by compax-ing observations 

 actually made, it may yet be deemed not inexpedient, first to 

 consider what causes may influence the internal temperature of 

 the earth, or in general, to determine what modifications the 

 external temperature may operate on that of the interior. 



Chap. XII What influence do tJte meteoric waters exert on the in- 

 ternal temperature of the Earth 9 



In Chap. VII. it has been shewn that the temperature of 

 the meteoric waters has no great influence on that of the crust 

 of the earth through whicli they flow. But small as this in- 

 fluence is, it will yet be found to be very various in different 

 parts of the earth, according as the strata be more or less per- 

 vious to water, or as the waters sink to a greater or less depth. 

 But such variations must naturally disturb any supposed fixed 

 law in the increase of temperature towards the centre of the 

 earth. 



The uninterrupted infiltration of the meteoric waters into 

 mines, must cause a general coohng of the surroun ing rock ; 



