The Problem of Cell 13

One by one these things sank into the brain of The Thinking Machine. When the last possibility had been considered he began an examination of his cell. From the roof, down the walls on all sides, he examined the stones and the cement between them. He stamped over the floor carefully time after time, but it was cement, perfectly solid. After the examination he sat on the edge of the iron bed and was lost in thought for a long time. For Professor Augustus S. F. X. Van Dusen, The Thinking Machine, had something to think about.

He was disturbed by a rat, which ran across his foot, then scampered away into a dark corner of the cell, frightened at its own daring. After awhile The Thinking Machine, squinting steadily into the darkness of the corner where the rat had gone, was able to make out in the gloom many littl