372 Professors Tyndall and Huxley on the Structure 



of us has to tliauk the kindness of Professor Clausius, the phse- 

 nomena which they exhibit are thus described* : — "The appear- 

 ance of a large glacier of the first order has been compared, not 

 without reason, with that of a high-swelled and suddenly solidi- 

 fied stream. It winds itself in a similar manner through the 

 curving of the valley, is deflected by obstacles, contracts its width 

 or spreads itself out. .... In short, the form is modified in the 

 most complete manner to suit the character and iregularities of 

 its bed. To this capacity to change its form, the ice of glaciers 

 unites another property, which reminds us of the fluid condition; 

 namely, the capability of joining and blending with other ice. 

 Thus we see separate glacier-branches perfectly uniting them- 

 selves to a single trunk ; regenerated glaciers formed from 

 crushed fragments ; fissures and chasms closed u]), and other 

 similar appearances. These phfenomena evidently point to a 

 slow movement of the particles of which the glacier consists, 

 strange as the application of such an idea to a solid brittle mass 

 such as glacier ice may appear to be. The solution of this 

 enigma constitutes one of the most difficult points in the expla- 

 nation of glaciers. 



When the appearances here enumerated are considered with 

 reference to the experiments on the regelation of ice above 

 described, the enigma referred to by the writer appears to have 

 received a satisfactory solution. The glacial valley is a mould 

 through which the ice is pressed by its own gravity, and to 

 which it will accommodate itself, while preserving its general con- 

 tinuity, as the hand specimens do to the moulds made use of in 

 the experiments. Two glacial branches unite to form a single 

 trunk, by the regelation of their pressed surfaces of junction. 

 Crevasses are cemented for the same reason, and the broken ice 

 of a cascade is reconstituted, as a heap of fragments under pres- 

 sure become consolidated to a single mass. To those who occupy 

 themselves with the external conditions merely of a glacier, it 

 may appear of little consequence whether the flexures exhibited 

 by the ice be the result of viscosity or of the principle demon- 

 strated by the experiments above described. But the natural 

 philosopher, whose vocation it is to inquire into the inner 

 mechanism concerned in the production of the phsenomena, will 

 discern in the yielding of a glacier a case of simulated fluidity 

 hitherto unexplained, and perhaps without a parallel in nature. 



§ 4. On the Veined Structure of Glacier Ice. 



This structure has been indifferently called the " veined struc- 

 ture," the "banded structure," tlie "ribboned structure," and the 

 " laminar structure " of glacier ice. In a communication to the 

 * Dip Gletscher des Jetzfzeit, by Albert Moiisson. Zurich, 1854. 



