HE SHUT his eyes and set about concentrating his mind upon some subject other than the fact that he was a prisoner, of his own free will to be sure, but a prisoner nevertheless.
He always had prided himself upon the fact that he had the ability to drive from his thoughts at will all topics but the one which he desired. Now, he chose, at random, to begin preparing an outline of a lecture which he was scheduled to deliver within two weeks before a convention of medical men.
Back home in his study, Blalock was accustomed to stretching out at length in an easy chair, his feet upon a stool, a pillow beneath his head. Here his legs were stretched out upon the floor at night angles to his body, held bolt upright by the steel wall at his back. He sought to relieve the strain by keeping his knees in the air, but the floor offered no firm foothold and his heels slipped.
Irritated, Blalock slid away from the corner and tried lying upon his back, his eyes staring up into the darkness above him. Immediately that position, too, grew irksome and he turned over upon first one side, then the other, and finally he got upon his feet and leaned against the wall. Thus another fifteen or twenty minutes passed, he judged. He found that it was impossible to concentrate his thoughts, so he resolved to let them wander.
Leaning against the wall speedily proved uncomfortable, and Blalock began to pace around and around the narrow confines of the cell. Four paces one way, two at right angles, then four, then two. It reminded him of a big bear he once had watched in a zoo, striding back and forth behind the bars, but never very far from the door which shut him off from the outside world and freedom.
Suddenly Blalock discovered that he had made the circuit so many times in the darkness that he was turned around, that he did not know at which end lay the door to the cell. He began to hunt for it, feeling with his sensitive surgeon’s fingers for the place where the door fitted into the wall of the cell.
It annoyed him, after making two trips around, that he had failed to locate the door. He could tell by counting the corners as he came to them. The door fitted into its casing so well that he could not distinguish it from the grooves where the plates of the cell were joined together.
Immediately it became to him the most important thing in the world to know where lay that door. He thought of sounding the walls to see if at some point they would not give back a different sound and thus tell him what he felt he must know.
It was becoming a mania with him now. So, gently, he began rapping with his knuckles against the steel, here, there, in one place, then in another. Then he tried it all over with his ear, trained to detect, even without the aid of a stethoscope, the variations in the beating of a human heart, pressed close against the walls.
But again he was foiled. Every spot gave forth the same hollow sound.