"Of course it is not; the two rooms above occupied the whole width of the house, these only occupy the width between the passage and the rock-wall on each side. You see, the tunnel is twelve feet wide, and we may take it that these walls are at least three feet thick—it is not as if they had been built of brick, or even of stones cut to shape. They knew nothing of the arch, and, as you saw outside, this came up nearly to a point. The stones were longer and longer with each course, each projecting over the one below it, until, when they were within two feet of joining, a very long slab was laid across them. The stones may be three feet wide at the bottom and ten feet at the top, and you see the wall extends over here in the same way—as of course it must have done, otherwise the whole thing would have overbalanced and fallen in before that slab at the top was added. So, you see, there is the width of the tunnel, twelve feet, and the two walls, say six feet more, to be taken off the fifty feet. So the cellars by the side of the passage can only be about sixteen feet and a half at this end, which is what they seem to be, and will go away to nothing at the other end, as we shall see presently."

The first thing they saw was a sunken tank in the floor. This was full of water. It was about four feet square, and on sounding it with one of the ramrods, they found it was about the same in depth, the water coming to within a foot of the top. It was against the wall facing the ravine.

"This must have some connection with the stream. Otherwise it would have been dry long ago."

"We did not see any hole when we went down the passage," Bertie said.

"No. Most likely a hole something like this was cut in the rock outside, and a pipe driven to the bottom of this cistern. They would only have to fill the one in the tunnel with cut blocks to within a foot of the surface, and with smaller stones to the same level as the bed of the stream; then the water in the cistern would always be level with that outside. They put it in this end so as to be well out of reach of the salt water farther in. They were no fools who built this place. However closely they were besieged, and even if the enemy occupied the space in front of the house, their water-supply was secure."

"But in time of floods, Harry, if the water rose a foot in the passage—and we saw it did more than that—it would flood the whole of this basement."

"That is so, Bertie; but you may be sure that there was some provision against that. They would have some valve that they could shut, or possibly there was a block of wood covered with leather that they could push into the pipe at the bottom of this cistern."

Beyond a considerable store of firewood, in large and small blocks, nothing could be seen in the chamber.

"I expect these two places were used as prisons," Harry said, "though in case a very large force were assembled some may have slept here. At ordinary times the upper rooms would be quite sufficient. But you see they had to build the whole height of the rocky arch, and they wanted the entrance to the place to be so far above the ground-level that it would be extremely difficult for an enemy to climb into it. A hostile force could only have come in at that entrance, and a small body of determined men might have held it against a host. These lower chambers were simply cellars; the store-rooms were above them, and the habitable part of the castle. Now let us look at the chamber on the other side; no doubt we shall find it just like this."

This proved to be the case. There were another cistern and more piles of firewood, otherwise it was empty. After a short survey they returned to the main chamber, bringing up with them two of the empty leather bags. In these they placed the bones of the dead, the remains all crumbling when touched, as the first skeleton had done. The bags were lowered to the ground, and the four searchers descended and carried them to the mouth of the ravine. In a spare bag which they brought with them they placed the bones of the two skeletons on the steps, and then carried them all out to the open valley.