Snatching up his bonnet he waved it out of the narrow window, and at that the whistle sounded for the last time far away, and died on the wind. Muckle John was ready. Hastily Rob took out the file and pistol, and laid them upon the floor. There was little chance that anyone would visit him again that night. He had eight hours before him to file through the bars of his cell, and conceal himself, just before the dawn, upon the cart of hay below. His chains he had already filed nearly through, concealing the marks with mud scraped off the damp floor of his cell. But in case of a surprise visit he left his chains on, and set upon the rusty bars of the window, scraping and rasping until his fingers began to peel and bleed, and his arms ached with weariness. At midnight one bar was filed through and laid inside the cell. Weak and dizzy with want of food and exercise, he was forced to rest for half an hour, and then, crawling back, he attacked the cross-bar; and two hours later he had cut it away, and the main part of the work was done. It took him only a few minutes to work himself loose of his chains. Then, uncoiling the rope, he tied one end to the fragment of iron bar left in the window casement, and unwinding it softly he let it run down the rough, grey wall. All was very quiet and dark. No sound reached him from below. Far away, on the outer guard, he caught the dull tramp of the sentry, marching to and fro in the wintry darkness. The time was ripe. Slipping his pistol about his waist, Rob wormed his way, legs first, through the open window, and coiling his feet about the rope, he took a grip of it with his hands and began to slide slowly downwards. Down, down he went; past rooms where all was dark, skinning his knees upon the sharp edges of stone, bumping and swaying, but nearing ground at every yard, and with the breath of sweet night air upon his cheek. And so at last, without misadventure, he reached the inner courtyard, and looked about for the cart of hay. The dawn was not far distant now, and he crept about the place feeling his way, seeing but dimly, and fearful that there was no cart at all. At last, however, some ten yards away, his hand touched a wheel. With a gasp of relief he ran his fingers through soft wisps of hay over his head. Then climbing up, he wormed his way beneath a bundle of horse-cloths, and waited for the morning. The cart had apparently unloaded and was ready to leave the fort. Fortunately for Rob the cloths were heavy, and the horses' nose-bags and other articles made sufficient to entirely conceal his presence. But how Muckle John could hope to avert suspicion falling on such an obvious place of concealment, he could not imagine. Very gradually the grey, flickering lights of another day glimmered above the fort, and still there was no sound of alarm--no sign of Muckle John.