It was while I was acting as a prison doctor in the Midlands that I had this experience.

I was going my round one morning when, passing along a passage, I became aware of a strange, muffled roar from the other side of the wall.
"'What is that noise ?' I asked the warder who was with me.
"'Prisoners seeing their friends,' he answered.

'Like to have a look at them, sir ?' "He unlocked a small door and, as he threw it open, the distant, muffled sound swelled into a deafening roar.

I passed through the door and found myself in a narrow alley at one end of which a warder was sitting.

The sides of the alley were formed by two immense cages with stout wire bars, one for the prisoners and the other for the visitors; and each cage was lined with faces and hands, all in incessant movement, the faces mouthing and grimacing, and the hands clawing restlessly at the bars.