the Hintereis Glacier, 169 



Every part o£ a glacier was once at the surface in the neve 

 regions. As layer upon layer of snow collects, the weight of 

 the snow above results in the lowering of the freezing-point, 

 and, if the temperature of the ice be at the freezing-point, 

 results in the formation of some interstitial water. When 

 the region of ablation is reached, the thickness of the glacier 

 diminishes, and some of the water again returns to ice. 



The variations of temperature with depth have been deter- 

 mined in some parts of the tongue of the Hintereis Glacier 

 with considerable accuracy by Bliimcke and Hess. They 

 used thermometers which showed temperature variations 

 amounting to thousandths of a degree centigrade. The ther- 

 mometers were immersed in holes bored into the glacier. 

 Their bulbs were embedded in paraffin and did not undergo 

 any change of temperature whilst being drawn up from the 

 positions in which they had been allowed to rest for a long 

 time. 



The following table gives the results obtained : — 



tres depth. 



Temp. C. 



Temp, fall per kg. 



30 



-0-0215 



-0-000234 



40 



-0-0400 



-0-000326 



42 



-0-0380 



-0-000295 



54 



-0046 



-0-000278 



m 



-0-055 



-0-000272 



78 



-0-062 



-0-000259 



82 



-0-062 



— 0-000247 



148 



-0-137 



-0-000302 

 8|-002213 



•000276 Average. 



As the boreholes in which the temperatures were taken by 

 Bliimcke and Hess were full of water, the temperatures 

 found should be those due to the pressure of the head of water, 

 and if the temperature of the glacier were that due to the 

 pressure of the column of ice above, then in the borehole 

 some melting would take place and the temperature would 

 fall to that required by the column of water. On the other 

 hand, if the temperature of the glacier were below the 

 temperature due to the head of water in the borehole, then 

 the water in the borehole would slowly freeze. Bliimcke and 

 Hess state that no such freezing was noticed. But the temper- 

 atures obtained show a gradient per kg. of water-pressure 

 even larger than the theoretical, as will be seen below : — 



Experimental by Kelvin .... 0°*000249 C.per kg. 



Theoretical by James Thomson . . 0°-000231 C. „ 



Experimental borehole by Blumckel ao-ooO^i* O 

 and Hess J 



