And between the tower and the cliff there must be a substantial hollow.
The discovery brought me to my feet, and set me running towards the end of the shaft of sunlight.

I left the heather, scrambled up some yards of screes, and had a difficult time on some very smooth slabs, where only the friction of tweed and rough rock gave me a hold.

Slowly I worked my way towards the speck of sunlight, till I found a handhold, and swung myself into the crack.

On one side was the main wall of the hill, on the other a tower some ninety feet high, and between them a long crevice varying in width from three to six feet.

Beyond it there showed a small bright patch of sea.
There was more, for at the point where I entered it there was an overhang which made a fine cavern, low at the entrance but a dozen feet high inside, and as dry as tinder.