It keeps their hand in; they have a pleasure in spiting those above them whenever they can do it.
The getting out of the cell was easy enough, but there was a lot of danger after you had got out.

A passage to cross, where the warder, with his rifle, walked up and down every half-hour all night; then a big courtyard; then another smaller door in the wall; then the outer yard for those prisoners who are allowed to work at stone-cutting or out-of-door trades.
After all this there was the great outer wall to climb up and drop down from on the other side.
We managed to pick our night well.

A French convict, who liked that sort of thing, gave me the means of undoing the cell door.

It was three o'clock in the morning, when in winter most people are sleepy that haven't much on their minds.

The warder that came down the passage wasn't likely to be asleep, but he might have made it up in his mind that all was right, and not taken as much notice as usual.