Hot and Thermal Springs. SS5 



flow, the less considerable will be the loss occasioned by the waters 

 in the temperature of the strata. But, even supposing that by 

 degrees a considerable local depression of temperature should 

 take place in the channels of the springs, or, in other words, 

 that in them the increase of temperature towards the centre of 

 the earth should have become less rapid ; then the heat in their 

 environs would be conveyed to them the more quickly, because 

 the rapidity with which heat is transmitted from one body to 

 another, increases in proportion to tha difference between the 

 temperatures of the two bodies. In no case, then, is it conceiv- 

 able that a local cooling of the earth should be continually in 

 progress, as Anglada is inclined to assume ; so that a gradual 

 diminution of the heat of thermal springs can only be imagined 

 in the case of a general coolinfr of the interior of the earth. But 

 since the existence of thermometers, and since observations have 

 been made on the temperature of springs, this general cooling 

 has certainly not taken place in a perceptible degree. An ac- 

 tual diminution in the temperature of thermal springs, if no 

 longer doubted, can therefore only proceed from the causes 

 above enumerated. 



Chap. IV. — Can Springs convey Heat from the Interior of the 

 Earth to the Surface ? 



The universal occurrence of warm springs is alone sufficient 

 to answer this question. But, independently of that, the possi- 

 bility of springs pursuing a very long subterranean course, where- 

 ever their temperature may have been obtained, without suffer- 

 ing any considerable change, may also be indirectly shewn.. 



The coldest springs of the temperate zones rise in the vicinity 

 of the glaciers, and on the limits of perpetual snow. Professor 

 Ennemoser, at my request, determined the temperature of thir- 

 teen fresh-water springs near the glaciers, and on the limits of 

 the snowy regions of the Tyrolese Alps, in the summer of 1833, 

 and found them to vary from 36°.50 to 43°.2. 



On the 28th August 1835, I found the temperature of four 

 fresh-water springs, at the foot of the Gandecke, or Morene, 

 of the upper glacier near Grindelwald, in Switzerland, 3684 

 feet above the level of ihe sea, to fall between 37°. 40 and 

 38°.075 ; and, on the 3d of September, I found the tempera- 



