The vessel was slowly threading its way down the river among the many vessels, large and small, that lay at their moorings. At times it stopped altogether, and from the deck resounded shouts and oaths at the obstacles that checked its course. By and by some of the sailors came forward for a spell of sleep, and Harry, kept wide awake by his hunger and discomfort, saw them tumble into their bunks and soon heard their snores. It would take several hours to reach the open sea. Was there a chance that, before the vessel left the Thames, he might even yet escape? To make the attempt was mere instinct with a high-spirited boy. The odds seemed all against him. To begin with, he was bound hand and foot to a plank, so that it was impossible even to bend his body. Suppose he rid himself of his bonds, there would be many of the crew on deck while the vessel threaded the crowded water-way, and he would be seen if he sprang overboard; and how could he free himself from the ropes? The idea had not come to him for the first time. When he was being trussed up he had remembered an old trick taught him by Sherebiah, acquired during his mountebank days, when he had mystified rustic spectators by escaping from ropes tied by the most expert hands in the village. He had so stiffened his muscles that he could wriggle out of any ordinary knot. But the situation was rendered more difficult by the plank. He could not lift himself, nor turn on his side. Lying on his back, he tried to ease the pressure of the ropes by the muscular movements he had practised with Sherebiah in sport. But he found, not to his surprise, that sailors were more skilful than anyone who had previously experimented with him. The tension was so great that he had the barest margin to work upon. Force was useless; it would only have the effect of cutting into his flesh and causing his hands and wrists to swell. But his whole mind was now bent upon one desperate venture, and, while the men snored around him, he began to strain on the ropes.