﻿M. A. Heim on Glaciers. 489 



to measure the surface below this, and to sum up the 425 sur- 

 faces would be a needless labour, because all our other numbers 

 are not correspondingly accurate. 



We have now the equation : — Surface multiplied by ablation 

 equal to original volume times x. If the hypothesis of Hugi 

 and Grad is correct, we must obtain for x above 1000 ; if no real 

 increase of mass takes place in the ice, a value near 1. Inserting 

 our values, 



3740000000 x 3 = 6150000000 x x, /. a?=l-8. 



That is, in order to compensate for the thousandfold increase of 

 volume which would ensue from the growth of the granules, 

 the ablation Iwould have to be nearly 1000 times as great as it 

 is ; otherwise, instead of the volume of the glacier having quite 

 vanished at the end of the 425 years, it would be nearly 1000 

 times as great as at the beginning. 



From this calculation it appears to me certain that, if it were 

 true that the glacier-grains are the developed neve-granules — if 

 it were true that the large glacier-grain of the lower regions ori- 

 ginates from the smaller granule of the upper through growth 

 produced by the freezing upon it of infiltrated water, then the 

 glacier would become larger, it would never come to an end, and 

 at the present time the whole earth must be lying under a deep 

 covering of ice. 



In the above we have rounded off all the numbers in favour of 

 the hypothesis of Hugi and Grad, and hence have found for 

 x a greater value than 1 ; but we could take them still more 

 favourably for that theory, and yet the result would be strikingly 

 adverse to the hypothesis. 



But the old dilatation theory must accept an increase of mass 

 through the water freezing in the capillary fissures. M. Grad 

 insists upon the dilatation theory, without adducing a single ex- 

 periment to confute the numerous objections which, years before, 

 were advanced against it. The measurements made by himself 

 and M. Duprein 1869, on the Aletsch Glacier, contain evidence 

 against the dilatation theory ; for he there finds that the lower 

 part of the glacier moves considerably more slowly than the 

 upper. As Forbes acknowledged, according to the dilatation 

 theory, that should be exactly reversed, since we have to regard 

 the upper end of the glacier as a fixed point of support for the 

 glacier-tongue, and the dilatation must sum up to a continually 

 greater motion for a point the further it is removed from the 

 beginning of the glacier. 



Some other facts can be adduced which are opposed to the 

 derivation of the grain of the glacier from that of the neve. The 

 distention occasioned in the mass by the growth of the granules 



