Behind the bridge which is now called Ponte San Sisto, on the flat of the Janiculum, Belisarius caused two boats to be fastened with ropes, and laid mills over their flat decks, so that the wheels were driven by the river, which streamed from between the arches of the bridge with increased force. The besiegers, who were informed of these arrangements by deserters from the city, soon attempted to destroy them. They threw beams, rafts, and trees into the river above the bridge, and in a single night all the mills were destroyed. But Belisarius caused them to be reconstructed, and ordered strong chains to be drawn across the river above the bridge, which caught and arrested everything that floated down. These iron river-bolts were not only intended to protect the mills, but also to prevent the Goths from reaching the city on boats or rafts. For now Witichis began to make preparations for storming the city. He caused wooden towers, higher than the ramparts, to be built, which, placed upon four wheels, could be drawn by oxen. Then he caused storming-ladders to be prepared in great numbers, and four tremendous rams or wall-breakers, which were each pushed and served by fifty men. The deep moats were to be filled up with countless bundles of brushwood and reeds. To defeat these plans, Belisarius and Cethegus, the first defending the city in the north and east, the latter in the west and south, planted catapults and other projectile machines on the walls, which were able to cast immense spears to a great distance, with such force that they could pierce the strongest coat of mail. They protected the gates by means of "wolves," that is, cross-beams set with iron spikes, which were let crashing down upon the assaulters as soon as the latter approached the gate. And, lastly, they strewed innumerable caltrops and steel-traps upon the space between the town-moats and the camp of the besiegers. CHAPTER VIII. In spite of all this, it was said by the Romans that the Goths would long since have climbed the walls, had it not been for the Prefect's "Egeria." For, strange to say, each time the barbarians prepared an assault, Cethegus went to Belisarius and warned him of the day and hour. Whenever Teja or Hildebad attempted to carry a gate by storm or sweep away a redoubt--Cethegus foretold their coming, and the assaulters met with double the usual number of defenders at that particular point. Whenever the chains across the Tiber were to be broken in a night surprise--Cethegus seemed to have guessed it, and sent fire-brands and fire-ships against the boats of the enemy. So passed many months. The Goths could not hide from themselves the fact that, in spite of continual assaults, they had made no progress since the commencement of the siege. For a long time they bore with patience the betrayal and frustration of their plans.