178 PROFESSOR FORBES ON THE VISCOUS THEORY OF GLACIER MOTION. 
face of the Schonhorn, somewhat about an hour’s steep climb above the hospice ; 
consequently about 1400 feet higher. The hospice is itself 6580 English feet above 
the level of the sea ; the mean height of the Schonhorn glacier may be taken at 8000 
feet. I had not an opportunity of ascertaining it more accurately. 
Plate X. figs. 1 and 2, shows a sketch of a front view of the Schonhorn taken from 
the opposite heights, and a ground plan of the glacier. The latter is sketched 
merely by the eye, but the scale is furnished by some actual measures. I first visited 
the glacier on the 20th of July 1844. It was then covered over, by far the greater 
part of its extent, with snow, as shown in the plan. This snow is in great part 
manifestly permanent, and the glacier is therefore in the state of ntvd. The general 
slope is from top to bottom of the plan, and its inclination is variable, depending 
upon the direction of the avalanches by which it is fed, of which the principal 
descends the rapid couloir marked C, when the inclination is about 35°. This ava- 
lanche forms a sort of ridge down the glacier, as indicated by the shading of the 
map, leaving a considerable space comparatively flat to the eastward. On the west, 
the snow thins off from the ridge until it exposes the ice near the part marked B, 
where the slope is still considerable, being 20°, and here we have the real mass of 
the glacier exposed, although the ice is not of an exceedingly hard or crystalline 
character. The front or lower termination of the glacier all along presents a steep, 
nearly precipitous surface of ice, sloping from 45° to 60°. This ice rests on a bed of 
debris of rock which appears to be inclined about 25°. Except near the precipitous 
termination of the glacier, there are no apparent crevasses. The surface is uniform 
and uninterrupted. Some water issues from beneath the steepest part of the ice ; 
but even in the middle of the day, near the end of July, there was exceedingly little. 
The length, if it may be so termed, of the glacier, from back to front is about 1000 
feet, and its greatest breadth 1300 feet. Its surface may be roughly estimated at 
twenty-six acres. 
The rock of which the Schonhorn is composed, is an alternation of the slaty rocks 
resembling gneiss with talc slate, which are so common in this part of the Alps. To 
my great surprise, on one of my visits, I heard the sound of hammers and blasting 
in this elevated and remote spot ; and found two men employed in quarrying Pot- 
stone ( Lapis ollaris ) for building ovens, from a retired nook beyond the glacier; the 
quarry is marked on the plan at E. 
On the 20th of July 1844, I ascended to the glacier, accompanied by M. Alt, one 
of the clerical members of the Simplon establishment, and an assistant ; and I fixed 
upon a position, marked St. on the rock on the east side of the glacier, for planting 
the instrument, which was then directed, as nearly as I could judge, in a line 
transverse to the prevailing slope of the glacier, and the telescope was made to de- 
scribe a vertical plane. It was then sighted upon a well-marked quartz vein on the 
rock on the distant side of the glacier, marked D, by which it could at any time be 
brought into precisely the same position ; the position of the instrument itself being 
