ON THE STRUCTURE AND MOTION OF GLACIERS 9 
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 accom- 
modate itself, while preserving its general continuity, 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 pressure 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 demonstrated 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 phenomena, 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 Vetned Structure of Glacial Ice. 
This structure has been indifferently called the “veined structure,” 
the “banded structure,” the “ribboned structure,” and the “laminar 
structure,” of glacial ice. Inacommunication to the Geological Society 
of France assembled at Porrentruy in September, 1838, M. Guyot 
gave the following interesting description of the phenomenon :— 
“Since the word layer has escaped me, I cannot help recording as 
a subject of investigation for future observers a fact, regarding which 
I dare not hazard an explanation; especially as I have not en- 
countered it more than once. It was at the summit of the Gries, at a 
height of about 7500 feet, a little below the line of the first or high 
nevé, where the ice passes into a state of granular snow...... In 
ascending to the origin of this latter (the glacier of Bettelmatten), for 
the purpose of examining the formation and direction of the great 
transverse fissures, I saw under my feet the surface of the glacier 
entirely covered with regular furrows, from 1 to 2 inches in width, 
hollowed in a half snowy mass, and separated by protruding plates of 
an ice more hard and transparent. It was evident that the mass 
of the glacier was here composed of two sorts of ice, one that of 
the furrows, still snowy and more easily melted, the other that of the 
plates, more perfect, crystalline, glassy and resistent; and that it 
was to the unequal resistance which they presented to the action 
of the atmosphere that was due the hollowing of the furrows and the 
