They were built for prison purposes, and a cat could not find entry for its claws between the stones.

I resigned myself to my fate as well as I could.

Wrapping my blanket round me, I lay down and looked up at the sky.

I wished to see it whilst I could.

I was just dropping to sleep--the unutterable silence of the place broken only now and again by some remark by my captors in the rooms below me--when there was a strange appearance just over me--an appearance so strange that I sat up, and gazed with distended eyes.
Across the top of the tower, some height above, drifted, slowly and silently, a great platform.