The operations of the siege were in a great measure suspended while the men were obtaining a new supply of stones, and the whole disposable force of the army was employed in going back and forth to bring them. At length an immense quantity were collected; but then the Mongul general changed his plan. Instead of throwing the stones from his engines toward the fortress on the island, which it had been proved was beyond his reach, he determined to build out a jetty into the river toward it, so as to get a stand-point for his engines nearer the walls, where they could have some chance of doing execution. So he set his men at work to prepare fascines, and bundles, and rafts of timber, which were to be loaded with the stones and sunk in the river to form the foundation for the proposed bank. The men would bring the stones down to the bank in their hands, and then horsemen, who were ready on the brink, would take them, and, resting them on the saddle, would drive their horses in until they came near the place where the stones were to go, when they would throw them down and then return for others. In this way they could work upon the jetty in many parts at once, some being employed in building at the end where it abutted on the shore, while the horsemen were laying the foundations at the same time out in the middle of the stream. The work of the horsemen was very difficult and dangerous, on account of holes in the sandy bottom of the river, into which they were continually sinking. Besides this, the garrison on the walls were doing their utmost all the time to impede the work by shooting arrows, javelins, stones, and fiery darts among the workmen, by which means vast numbers, both of men and horses, were killed. The Monguls, however, persevered, and, notwithstanding all the opposition which the garrison made, they succeeded in advancing the mole which they were building so far that Timur was convinced that they would soon gain so advantageous a position that it would be impossible for him to hold out against them. So he determined to attempt to make his escape. His plan was to embark on board his boats, with all his men, and go down the river in the night. In order to prepare for this undertaking, he employed his men secretly in building more boats, until he had in all more than seventy. These boats were kept out of sight, in hidden places in the river, until all were ready. Each of them was covered with a sort of heavy awning or roof, made of wet felt, which was plastered over with a coating of clay and vinegar. This covering was intended both to defend the men from missiles and the boats themselves from being set on fire.