The base of the column was large, and apparently solid, like a smooth unbroken waterfall suddenly frozen.

It fitted into the angle of the cave, and completely filled up the space between the contiguous walls.

I commenced to chop with my axe, and before long found that this ice was hollow, though very thick; and when a sufficient hole was made for me to get through, I saw that what had looked like a column was in truth only a curtain of ice hung across the angle of the cave.

Within the curtain the ice-floor still went on, streaming down at last into a fissure something like that in the other corner.

The curtain was so low, that I was obliged to sit on the ice inside to explore; and after a foot or two of progress, the slope towards the fissure became sufficiently great to require steps to be cut.