This had flashed through his mind in a moment. He started work instantly. Beginning at the outer right edge of the aperture, he applied the chisel to the stonework, and was delighted to find that by the mere pressure of his arm it came away in flakes, which fell to the ground eighty feet below. Working quickly, he had soon scratched away an inch of rotted stone for a distance of two feet along each edge of the opening. But as he went on, he found that the stone was becoming harder; it was necessary to exert more force. It would take long to chip the stone away as he had seen masons do. How could he shorten the labour? Cautiously working with the chisel, he slowly bored a hole two inches deep in the wall, at about the same distance from the outer edge. Then inserting the crowbar, he pressed upon it in an outward direction with all the strength he could exert in his cramped position. To his joy the stonework gave way, and pieces fell with a sharp clatter upon the ground. He waited anxiously, wondering whether any of his guards would have heard the sound. All was silent. Feeling with his hand, he found that the stone had broken irregularly, leaving a jagged surface, and this he proceeded to trim with the chisel. He went through the same double process on each side of the opening. At last, after hours of work, when muscles of hand and arm ached unendurably, and his whole body felt bruised from lying so long on the hard stone, he thought that the opening must be large enough. Tying one end of the rope to the crowbar, he paid the other out. A slight tug below told him that it had been received: his unknown helper was still in waiting. Then he tied his rug to the twine, and let it gently down. This, too, being caught, he placed the crowbar horizontally across the window on the inner wall, turned on his side, and began to wriggle out of the opening feet foremost, always holding firmly to the rope. Had his work been successful? The question forced itself upon him as he moved painfully towards the outer air. Alas! half-way through he stuck; his jacket and vest were riding up into a ridge; it would increase the more he struggled; he must return to the room.