A fleet of sixty ships commanded by Marcellus bore down upon the city. The ships were full of men armed with bows and slings and javelins with which to dislodge the men who fought on the battlements. Eight ships had been fastened together in pairs. These double vessels were rowed by the outer oars of each of the pair. On each pair of ships was a ladder four feet wide and of a height to reach to the top of the wall. Each side of the ladder was protected by a railing, and a small roof-like covering, called a penthouse, was fastened to the upper end of the ladder. This covering served to protect the soldiers until they could reach the top of the wall. They thought to bring these double ships close to shore, raise the ladders by ropes and pulleys until they rested against the wall, then scale the wall and capture the city. But Archimedes had crossbows ready, and, when the ships were still at some distance, he shot stones and darts at the enemy, wounding and greatly annoying them. When these began to carry over their heads, he used smaller crossbows of shorter range, so that stones and darts fell constantly in their midst. By this means he checked their advance, and finally Marcellus, in despair, was obliged to bring up his ships under cover of night. But when they had come close to land, and so too near to be hit by the crossbows, they found that Archimedes had another contrivance ready. He had pierced the wall as high as a man's head with many loopholes which on the outside were about as big as the palm of the hand. Inside the wall he had stationed archers and men with crossbows to shoot down the marines. By these means he not only baffled the enemy, but killed the greater number of them. When they tried to use their ladders, they discovered that he had cranes ready all along the walls, not visible at other times but which suddenly reared themselves above the wall from the inside and stretched their beams far over the battlements, some of them carrying stones weighing about five hundred pounds, and others great masses of lead. So, whenever the ships came near, these beams swung round on their pivots and by means of a rope running through a pulley dropped the stones upon the ships. The result was that they not only smashed the ships to pieces, but killed many of the soldiers on board. Another machine made by Archimedes was an "iron hand" or grappling-hook swung on a chain and carried by a crane. The hook was dropped on the prow of a ship, and when it had taken hold the ship was lifted until it stood on its stern, then quickly dropped, causing it either to sink or ship a great quantity of water. With such machines, unknown before, Archimedes drove back the enemy. On the landward side similar machines were used. The Romans were reduced to such a state of terror that "if they saw but a rope or a stick put over the walls they cried out that Archimedes was levelling some machine at them and turned their backs and fled."