Sot and Thermal Springs,, S79 



man found wells and springs of 33°. 3 to 34o.4 in the months of 

 July and August, in such latitudes. At JaTrntzli, therefore, in 

 62° North Lat., the mean temperature of the soil must already 

 be considerably below 32°. Thus, if we suppose it to be only 

 9,T, and that the temperature increases towards the centre of 

 the earth at the same rate as it has been found to do in our cli- 

 mates, the mean temperature of the earth would not reach the 

 melting point of snow until a depth of 230 to 256 feet. 



Chap. XI — The decrease of Temperature in the Waters of the Sea 

 and of Lakes, is not contradictory to the hypothesis of an increase 

 of Temperature towards the Centre of the Earth. On the con- 

 trary, we can only explain the Temperature of Sea and of Lakes 

 by admitting an increase of Temperature towards the Centre of 

 the Earth. 



De Saussure * determined the temperature of the Swiss Lakes 

 at various depths, as in the following table: — 



According to De la Beche's observations on the Lake ofGe- 

 neva,f the temperature of the water, at depths of forty to seventy 

 fathoms, seems everywhere to be 43°.9, except only at Ouclw ; 

 and from eighty fathoms downwards to the greatest depths, he 



• Voyages aux Alpes, § 1351 and 1391. 

 t Gilbert's Annalen, vol. Ixvi. p. 14C. 



