238 On the Mean Temperature of the 



Springs which, before they issue forth or are formed, collect 

 in considerable numbers into a common reservoir, shew also a 

 very constant temperature ; but, since they are always in contact 

 with the air, so their temperature approaches the mean tempera- 

 ture of the air ; so that in high latitudes, where the temperature 

 of the earth is more elevated than the mean temperature of the 

 air, these reservoirs are colder than the proper springs. The 

 same is the case with wells of at least twenty feet deep, where 

 the cooling may be more considerable, from the colder air al- 

 ways sinking downwards. 



In Kasan I have observed the temperature of two springs 

 well adapted for these inquiries. The first rises from a lime- 

 stone rock at the bottom of the hill on which the citadel is 

 placed, and on its north side ; it is pretty copious, and holds in 

 solution a large quantity of lime : the second is at Butiska, 

 in the neighbourhood of Kabon, and not far from the archie- 

 piscopal Palace. Several springs here rise in a curved line, 

 and, by their union, form a rivulet, which is continually enlarg- 

 ing; one of them, near the bridge, rushes forth from the 

 bed of the rivulet, with sufficient force to create considerable 

 agitation in the water flowing over it. The thermometer was 

 placed in the spring itself, as deep as possible, and at a season 

 when the water of the rivulet had almost the same temperature 

 as the spring itself. The water of this spring holds also in so- 

 lution a little lime, but much less than the former. 



Notwithstanding these springs were above a German mile 

 distant from one another, and issue from very different soils, 

 yet the temperature of both, on 29th October 1828 (tempera- 

 ture of the air about 32°), was found about 43°.7. Bronner 

 found the temperature of the first spring, on the 1 6th January 

 1815, 42°.8. I found it, fourteen years afterwards, in the same 

 month, scarcely even so much. These two observations are, pro- 

 perly speaking, not sufficient to fix with precision the tenipera- 

 ture of the earth, and it is desirable that, in future, they should 

 be continued into every month ; but we may, by a comparison 

 of these with other observations, draw conclusions approaching 

 very near to the truth. For this comparison Erma!i''s observa- 

 tions on the changes of temperature in the spring of Julienthaler, 



