Once more he dropped into the hole, and with more confidence crawled to the corner of the space where he had located a means of communication with the corresponding cavity on the other side of the dividing wall.
It was a dangerous performance wriggling through the narrow aperture. More than once Hamerton had to stop through sheer exhaustion. The rough stonework grazed his ribs and lacerated his elbows and thighs. It seemed as if he stood a great chance of becoming jammed, for, having succeeded in forcing his shoulders through, his hips obstinately refused to scrape between the sides of the opening. To add to his discomfort, the air was far from pure, and he was seized by an attack of dizziness.
Temporarily panic-stricken, he struggled furiously and contrived to back out of his dangerous predicament.
"It will mean enlarging that hole," he thought. "I've done enough for the time being. To-morrow night I'll have another shot at it."
With this resolution he returned to his cell, washed off the dirt, and turned in, glad to rest the bruised angularities of his aching body.
Presently he began to ponder over the difficulties that had beset him. "Either I'll have to make that hole larger or I'll have to reduce my fat," he said to himself, with a laugh. "Talk about a square peg in a round hole, or a round peg in a square hole. By Jove! I'm an ass. The hole is square right enough, but my midship section isn't round--it's oval. If I had only kept my hips in two opposite corners instead of trying to squeeze through on my stomach I could have done it hands down. I wonder what the time is?"
He sat up and pulled out his watch. There was too much gloom to see the hands.
Even as he looked a brilliant beam of light flashed straight in through the window. It was a quarter to one. For a few seconds only the searchlight rays played upon the building; then all was darkness, rendered the more opaque by reason of the sudden change.
"A searchlight from an airship," exclaimed the Sub. He knew perfectly well that since from his window he could see nothing of the searchlight apparatus placed on the fortifications, it was conversely impossible for one of those searchlights to throw a direct beam through the window of his cell.