with the glaciere.
The NW. side of the larger pit, being the side at the bottom of which is
the arch of entrance, is vertical, and we spent the time necessary for
growing cool in measuring the height of this face of rock from above.
The plummet ran out 115 feet of string, and struck the slope of snow,
down which the descent to the cave must be made, about 6 feet above the
junction of the snow with the floor of the glaciere, which was visible
from the S. side of the edge of the pit; so that the total depth from
the surface of the rock to the ice-floor was 121 feet.

[Illustration: VERTICAL SECTION OF THE GLACIERE OF GRAND ANU, NEAR
ANNECY.]

When we were sufficiently cool, we scrambled down the side of the pit
opposite to that in which the archway lies, finding the rock extremely
steep, and then came to a slope of 72 feet of snow, completely exposed
to the weather, which landed us at the mouth of the glaciere. The arch
is so large, that we could detect the change of light in the cave,
caused by the passage of clouds across the sun, and candles were not
necessary, excepting in the pits shortly to be described. We saw at once
that rapid thaw was going on somewhere or other; and when we stepped off
the snow, we found ourselves in a couple of inches of soft green
vegetable mud, like a _compote_ of dark-coloured duckweed--or, to use a
more familiar simile, like a mass of overboiled and ill-strained
spinach. To the grief of one of us, there was ice under this, of most
persuasive slipperiness. The maire said that he had never seen these
signs of thaw in his visits in previous years; and as we went farther
and farther into the cave, he was more and more surprised at each step
to find such a large quantity of running water, and so much less ice
than he had expected. The shape of the glaciere is a rough circle, 60
feet in diameter; and the floor, which is solid ice, slopes gradually
down to the farther end. The immediate entrance is half-closed by a
steep and very regular cone of snow, lying vertically under the small
shaft we had seen in the rock above. The snow which forms the cone
descends in winter by this shaft; and the formation must have been going
on for a considerable time, since the lower part of the cone has become
solid ice, under the combined influences of pressure and of _degel_ and
_regel_. I climbed up the side of this, by cutting steps in the lower
part, and digging feet and hands deep into the snow higher up; an