The only way would be to escape at the rear.

I have often thought it over, but it was of no use breaking out there, if I could not get any farther.

The wall is built of loose stone, without mortar.

You see, it would have been a big job to bring up either mortar or bricks from down below, so most of the buildings are entirely of stone.

The wall is two feet thick, but there would be no great difficulty in getting out the stones, and making a hole big enough to crawl through.