Hot and Thermal Springs. 353 



Although it was to be expected a priori that the temperature 

 of the soil under glaciers, however low they might extend, would 

 never be much above 32°.0, yet I was desirous of satisfying my- 

 self on this point by direct observations. 



Very near the lower extremity of the lower glacier of Grin- 

 (lelwai'd, on the 25th August 1835, I bored a hole six inches 

 deep into the ground, and placed a thermometer in it. It marked 

 36°.5. At the upper glacier I found a temperature of39''.8 

 twelve inches deep in the ground, as near to the ice as possible, 

 but separated from it by the glacier stream, called the Black 

 Lutschine. That neither of these temperatures was as low as 

 32°.0 is not to be wondered at ; for, although they were observed 

 as near as possible to the ice, yet these points were exposed to 

 the air, which, at the lower glacier, had a temperature of 39°.8, 

 and at the upper 45°.5. How trifling the distance is to which 

 the coldness of the ice and the water issuing from the glaciers is 

 felt, is proved by the latter of these experiments. The hole 

 was bored so near the bank of the Lutschine, that its waters, of 

 33°.3, almost washed over the thermometer, yet did not quite 

 communicate with the hole; and, notwithstanding this small dis- 

 tance, there was a difl^erence between them of 6''.53. In like 

 manner I found a difference of 8°.90 between the temperature of 

 the earth and that of the stream, immediately on the bank of 

 the (Schzoarze Lutschine) Black Lutschen, near the bridge, be- 

 tween Grindelwald and the lower glacier, and at a distance of 

 only eight paces, the difference was 14°. 40. There can, there- 

 fore, be no doubt, that an observation made directly under the 

 ice, would give a temperature very near 32°.0. I say very near 

 zero, for the temperature of the soil under glaciers is seldom ex- 

 actly 32°, since the streams that issue from glaciers, at the very 

 moment of their exit, invariably shew a temperature a little 

 above 32°. For example, six observations on the streams which 

 issue from the lower glacier, at Grindelwald, all gave me a tem- 



those glaciers. Those natural philosophers who reside in the Alps, and are 

 able to make their estimates more exactly, may easily make the necessary 

 corrections in this calculation. 



* Even if the stony nature of the soil under the glacier had allowed of such 

 an experiment, the result would have been eijually undecisive, as it would 

 hardly have been possible to prevent the infiltration of water into the hole. 



