“Now here, on the most solid side of the mount, is the place for the keep. We use the biggest stones for that. The bottom storey of father's keep is partly cut right out of the rock, and the walls are twenty-five or thirty feet thick. Nobody can knock down that wall with a battering-ram! Here we'll make a great arched door, so that the knights can ride right in without dismounting when they're hard pressed by the enemy. Here's the drawbridge--” Roger hastily whittled off a piece of bark--“and this line I've scratched inside the outer wall is for the wall round the inner bailey. We'll have a watch-tower here--and here--and here. Father says that a good builder places his towers so that each one protects one or two others, and in the end every one is protected. “In the storey above will be the great hall. These walls don't need to be so thick--not more than eighteen feet. Here on this side we'll cut a little room out of the thickness of the wall, for the private chamber of my lord and lady--” “The tapestry chamber!” cried Eleanor. “Yes,” Roger went on, “and here on the other side we have the well-chamber. There's a stone bason with a shaft that goes away down to the well in the lowest part of the castle, and the defenders can always get water by lowering a bucket when they're besieged. Up above is another storey for a guard-room, and a flat roof with battlements around it, where the sentinels can see for miles and miles across the country.” The two children gazed at their castle mount and almost believed the walls, eighteen, twenty, thirty feet thick--rising before their eyes. “But that isn't all of the castle,” said Eleanor at last. “No; we'll build more towers after awhile, and have a banquet hall to entertain the King. And the soldiers and people will live in tents and wattled huts until the stonework is done. But the keep is the first thing to build, because, you see, you have to defend yourself from enemies no matter when they come.” Lady Philippa's garden was cleared of stones in a much shorter time than she had expected. But to build a stone wall simply by laying one stone upon another is less easy than it seems. Roger had done something of the sort before, but he had had fragments of stone from the masons' work instead of water-washed pebbles. And when the keep was actually built as high as the first floor above the foundation, a heavy rain came, streams tore out one side of the mount, and the stone-work tumbled into a hopeless ruin. In the crystal brilliance of the morning after the storm Roger surveyed it ruefully. “Father says,” he recalled, “that everything depends on the foundations. We'll do it over again and make the mount more solid.” “And when it is done,” said Eleanor, never losing faith, “I'll beg some linen of mother and make tapestry for the walls of the little room and the great hall.”