GO SIXTH REPORT 1836. 



According to Von Buch* all springs containing carbonic acid 

 are more or less thermal, and Gustavus Bischof goes so far as 

 to assert, that this remark extends universally to springs of con- 

 stant temperaturef. 



The smallest difference, he says, between the warmth of the 

 springs of a countiy and that of the soil, is never less than 2^ 

 degrees of Fahrenheit. 



But I have already observed, that Bischof generalized on 

 too narrow a basis, when he inferred from the observations 

 quoted in his memoir the universality of such a law. 



It is one indeed directly at variance with the tenour of obser- 

 vations made within the tropics, which seem to show, that in 

 warm climates the mean temperature of the atmosphere is even 

 higher than that of the perennial springs X- 



And if the remark be limited to colder regions, many ano- 

 malies require to be reconciled, and a much more extensive se- 

 ries of observations gone through, before it can be decided, 

 whether this augmentation of temperature be the result of a ge- 

 neral law, or of local circumstances. Thus, for example, if, as 

 Humboldt and others have supposed, the excess of temperature 

 in springs over the atmosphere increases with the latitude, then 

 indeed the temperature assigned by Bischof as the minimum in 

 the case of those near Andernach, in lat. 50^°, squares very well 

 with the rate of progression indicated by observations, on the 

 springs of Paris in lat. 49°, and those of Berlin in lat. 52^° §. 



For at Paris the mean temperature of the climate was found 

 at 51°-6, and that of the springs 52°-7, the excess being 1°-1 ; 

 whilst at Berlin the atmospheric temperature was 46°"4, terres- 

 trial 50°*2, excess 3°"8, indicating a rate of pi'ogression equal to 

 about 1°*8 of temperature to 1° of latitude. 



But, on the other hand, the accurate observations of Playfair 

 have shown, that at Edinburgh, in a still higher latitude, viz. 

 55°-58, the temperature of springs is identical with tliat of the 

 atmosphere, so that the supposed progression would seem to be 

 confined to a still higher latitude than this. 



Neither are the observations of Wahlenberg in the Scandina- 



* Poggendorff's Annalev, vol. xii. p. 415. 



t Edinburgh New Phil. Journal for April 1836. 



X See Von Buch, on the Temperature of Springs, Edinburgh Neio Phil. 

 Journal, October, 1828, or his work on the Canary Islands, p. 84, French 

 translation ; where he accounts for the fact, from the circumstance of the 

 springs being derived from rain, which had fallen exclusively during the 

 colder months, and which does not readily acquire, within the slowly con- 

 ducting substance of the strata containing them, the temperature of the hotter 

 portions of the year. See also Bischof's often quoted memoir, in which he dis- 

 putes the general law, and supposes the tropical springs alluded to, to have been 

 derived from high mountains, and therefore to possess a lower temperature. 



§ Humboldt on Isothermal Lines, Edinburgh New Phil. Journal. 



