the roof by the water filtering through. The stalagmite was of the
double-edged-sword shape, and the limestone deposit collected chiefly at
one of its edges, the edge nearer to that part of the cave where thaw
prevailed; so that the real edge was a ridge of deposit beyond the edge
of the ice.[8] Patches of limestone paste lay on many parts of the
ice-floor.

In the loftier part of the cave, water dropped from the roof to so
large an extent, that ninety-six drops of water in a minute splashed
on to a small stone immediately under the main fissure. This stone was
in the centre of a considerable area of the floor which was clear of
ice; and it struck me that if the columns were formed by the freezing
of water dropping from the roof, there ought to have been at some time
a large column under this, the most plentiful source of water in the
cave. Accordingly, I found that the edge of the ice round this clear
area was much thicker than the rest of the ice of the floor, and was
evidently the remains of the swelling pedestal of a column which had
been about 12 feet in circumference. This departed column may account
for a fact which I discovered in another glaciere, and found to be of
very common occurrence, viz., that in large stalagmites there is a
considerable internal cavity, extending some feet up from the ground,
and affording room even for a man to walk about inside the column.
When the melted snows of spring send down to the cave, through the
fissures of the rock, an abundance of water at a very low
temperature, and the cave itself is stored with the winter's cold,
these thicker rings of ice catch first the descending water, and so a
circular wall, naturally conical, is formed round the area of stones;
the remaining water either running off through the interstices, or
forming a floor of ice of less thickness, which yields to the next
summer's drops. In the course of time, this conical wall rises,
narrowing always, till a dome-like roof is at length formed, and
thenceforth the column is solid. Of course, the interior cannot be
wholly free from ice; and it will be seen from the account of one of
these cavities, which I explored in the Schafloch, that they are
decked with ice precisely as might be expected.[9] Another possible
explanation of this curious and beautiful phenomenon will be given
hereafter.[10]

The temperature was half a degree lower than when there were three of us
in the cave two days before. I deposited o