On the Temperature of Thermal Springs. 3^ 



tain either tlie exact proportions of their constituent parts, or 

 the precise nature of the animal matter ; probably it was al- 

 bumen. 



The resemblance of these calculi to pearls (the calculi of the 

 oyster) is very striking ; and their composition being so very 

 similar, gives them an additional interest ; they might indeed 

 without impropriety be called pearls. 



Fort Pitt, Chatham, Ut March 1836. 



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

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

 neral question regarding the Internal Temperature of the 

 Earth. By Professor Gustav Bischof of Bonn. Commu- 

 nicated by the Author. * 



Part First. — What Thermometrical Circumstances on the Surface 

 of the Earth lead us to assume that an Increase of Temperature 

 towards the Centre of the Earth must take place f 



We are indebted to Alexander Von Humboldt •{• for an in- 

 genious inquiry into the principal causes of differences of tempe- 

 rature in the earth. In one of the following chapters we shall 

 endeavour to ascertain to what depth the influence of the exter- 

 nal temperature which occasions those differences continues to be 

 felt. Beyond that boundary other circumstances of tempera- 

 ture present themselves, which are no longer connected with the 

 geographical and physical climates ; and at certain depths, which, 

 however, are not the same in all parts of the earth, we find the 

 same degree of temperature beneath the perpetual ice and snow 

 of the polar regions, as under the torrid zone. That thermo- 



• The " Societe Hollandaise des Sciences" at Haarlem, offered a prize for 

 an Essay on the Temperature of the Interior of the Earth and of Springs, 

 which was gained by Professor Bischof. The memoir now given to the public 

 through this Journal, presents, in an altered and improved form, an account 

 of the experiments, observations, and reasonings, which obtained from the 

 Haarlem Society the high honour just mentioned. 



I have, says Professor Bischof, to express my grateful sense of the assist- 

 ance rendered by my talented young friend Mr Alexander Momay, in the 

 translation and revision of this essay. 



■f Poggendorffs Annalen, vol. xi. p. 1. and fol. 



