Hot and Thermal Springs. 337 



able the more copious they are, and the more quickly they 

 flow. We wiU suppose, for the sake of example, the mean 

 depth from which a certain number of springs, belonging to a 

 certain district, rise to be thirty feet. Farther, let the specific 

 gravity of the soil be taken at 1.5, and its capacity for heat 

 0.22, the specific gravity and the capacity for heat of water 

 being taken as unity.* Supposing the height of water provid- 

 ing a certain surface for the supply of its springs to be one foot 

 (about as much as we found in the district of the Brohlbach 

 above mentioned), we shall have the proportion between the 

 masses of the water and earth, which come in contact Avith each 

 other, as 1 : 45. Lastly, let the meteoric waters during a whole 

 year be llo.25 colder than the soil, and let the mean temperature 

 of the latter be 63o.50. Under these circumstances, if the whole 

 quantity of water were to fall, in one moment upon the earth, 

 the temperature which the earth would assume would be 

 _ 1 X 1 X 38.75 -f- (45 X 0.22 x 50) 



Txl + (45x0.22) = ^^-96 + 



This would consequently also be the temperature which springs, 

 commg from a depth of thirty feet, would have. 



Thus, even in case the temperature of the meteoric waters 

 throughout the year, were 11°.25 colder than that of the soil, 

 and that they should only sink to a depth of thirty feet, the tem- 

 perature of the soil, and consequently also of the springs rising 

 out of it, would still only be lowered 1.035. But these condi^ 

 tions AviU with difficulty be satisfied either between the tropics, 

 or at any other point on the surface of the globe. And sup- 

 posing they were satisfied, the difference thereby produced be- 

 tween the mean temperature of the air and that of the soil, 

 would fall far short of 1.035, because the cooling of the aii- by the 

 meteoric waters would foUow but shortly after that of the earth's 

 crust. 



• These I found to be the specific gravitj and capacity for heat of the sand 

 used in the above experiments. 



t Let M and m represent the two masses, S and * their capacities for heat ; 

 T and t their temperatures : the temperature T of the two bodies after their 

 intermixture will hp 



T = 



MST + OTj/. 

 M S + fn * 



