When the work was raised to the height of one story, they laid a floor over it, the extremities of whose beams were concealed in the thickness of the wall; that they might not by appearing on the outside, be liable to be set on fire. Thence they continued the wall directly upwards, as far as their galleries and mantles would allow. Here they laid two beams crosswise, whose extremities almost reached the angles of the wall, for supporting the floor, which was to serve as a roof to the whole. Over these beams they laid the joists of the roof, and boarded them with planks. The roof was so contrived as to project a little beyond the wall, in order to suspend from it what might be necessary to shelter the workmen, while employed in completing the story. This floor was paved with tiles and clay, to render it proof against fire, and had besides a covering of strong mattresses, to break the force of stones and darts. At the same time they suspended from the beams of the roof, that projected beyond the wall, curtains made of strong cables, woven to the depth of four feet, and which went round the three sides of the tower that were exposed to the engines of the enemy; having experienced on former occasions, that this kind of cover was impenetrable to any dart or engine whatever. When this part of the tower was finished, roofed, and sheltered from the enemy's blows, they removed their mantles to another, and by means of engines elevated the roof entire from the first story, as far as the curtains would allow. There, secure from all insult, they laboured at the wall, elevating the roof a second time, and thereby enabling themselves both to continue the work, and lay the interjacent floors. In this manner they proceeded from story to story, mounting them one upon another, till without danger or wounds, they had completed the number of six, leaving loop-holes in convenient places, for the engines to play through.