Lieut.-Col. Dufour on the Cavern and 
fill the fissures, and assisting by its own evaporation to maintain 
a very low temperature, reaches the cavern, and, falling upon 
masses already congealed, covers them with new layers : thus 
considerable quantities of ice are formed, which are only partly 
melted when a warmer air penetrates to the extremity of the 
grotto, which must be very rare indeed, if we may judge from 
what we ourselves experienced. In fact, notwithstanding the 
great heat we felt without, the thermometer, suspended at a foot 
from the ground, in different parts of the grotto, remained 
steady to 38°. Let us, however, proceed to the description of 
the Shafloch, which would undoubtedly have been considered 
by the antients as one of the principal gates of Tartarus, had it 
been known to them. 
The opening is towards the east, opposite to the magnificent 
summits of the J ungfrau, the Eiger, and some of the other high 
Alps : it is regular, of a semielliptic forrri, the ground repre- 
senting the large diameter, the length of which is fifty feet ; the 
height of the vault at the entrance is only twenty-five feet, but 
it immediately increases to forty or fifty feet. We proceeded 
about fifty paces in the original direction from east to west : we 
afterwards turned to the south, descending amidst innumerable 
masses, which had detached themselves from the vault, and 
which render the way very dangerous, if care is not taken to 
light it well with flambeaux. It does not appear that these 
masses detach themselves from the vault at intervals. I rather 
think that these blocks are part of a stratum which has tumbled 
in a mass a great while ago. Prudence demands, however, that, 
before advancing, the state of the vault should be ascertained 
as nearly as possible, in order to avoid the danger which might 
be incurred by venturing under a rock which threatened to 
fall. 
We met with the first mass of ice where the external light 
only penetrates in very srfiall quantity, and where, of course, it 
is impossible to attribute it to the snow which might be driven 
in by the opening, when the winter wind blows in that direction. 
After proceeding a little farther, we found ice under foot, so 
transparent that we saw the rock through it which it covered. 
We proceeded for eight or ten minutes to the south, till we 
reached an inclined plane of ice, which, according to our guides, 
