In a few minutes all were ready to go on again. Harry had asked Maria if she would like to go down the ladder and wait till they returned.  
"No, se?or, I should not like it at all. I don't care how full of bats the rooms are, now that I know what they are. As for Dias, I have no doubt that the first time he heard them he was just as frightened."
 
"No, I was not; but I dare say I should have been if the man I was with—I was then only about José's age—had not told me that the cavern was full of bats. There was a great storm coming on, and he proposed that we should take shelter there. We brought the mules into the mouth of the cave, and he said, 'Now, we will light a torch and go in a bit farther, and then you will be astonished. It is a bat cavern, and I have no doubt there are thousands of them here. They won't hurt us, though they may knock out our torch, and the noise they make is enough to scare one out of one's senses, if one does not know what it is.' Though I did know, I own I was frightened a bit; but since then I have been into several such caves, so I knew in a moment what it was. I ought to have warned the se?ors, for an old house like this, where there is very little light, is just the place for them."
 
"But there were birds too, Dias."
 
"Yes, I expect they were nearer. Perhaps some of them were in the other rooms, where they would be close to the openings. But they were probably scared too by the noise of the bats, and as the windows behind were too small for them all to fly out together, they made for the light instead."
 
"Well, now, let us start," Harry said, getting up. They again lit their torches, and this time found everything perfectly quiet in the passage. Two or three yards beyond the spot at which they had before arrived they saw a staircase to the left. It was faintly lighted from above, and, mounting it, they found themselves in a room extending over the whole width and depth of the house. The roof at the eastern end was not supported by pillars, but by walls three feet wide and seven or eight feet apart. The first line of these was evidently over the wall of the room they had left. There were four lines of similar supports erected, they had no doubt, over the walls of rooms below. The light from the four windows in front, and from an irregular opening at the other end some three feet high and six inches wide, afforded sufficient light for them to move about without difficulty. There were many signs of human habitation here. Along the sides were the remains of mats, which had apparently divided spaces six feet wide into small apartments. Turning these over they found many trifles—arrow-heads, bead-necklaces, fragments of pots, and even a child's doll.
 
"I expect this is the room where the married troops lived and slept," Harry said; "there is not much to see here."
 
The two stories above were exactly similar, except that there were no remains of dividing mats nor of female ornaments. They walked to the narrow end. Here the opening for light was of a different shape from those in the rooms below. It had apparently been originally of the same shape, but had been altered. In the middle it was, like the others, three feet high and six inches wide, but a foot from the bottom there was a wide cut, a foot high and three feet wide. As they approached it Dias gave an exclamation of surprise. Two skeletons lay below it. "They must have been on watch here, se?or, when they died," he said as they came up to them.
 
"It is a rum place to watch," Bertie said, "for you cannot see out."
 
"You are right, Bertie, it is a curious hole."
 
The wall was over two feet thick; all the other openings had been driven straight through it, and, as they had noticed, were doubtless made in the stones before they were placed there, for inside they were cleanly cut, and it was only within three inches of the outer face that the edges had been left rough. This opening was of quite a different character. It sloped at a sharp angle, and no view of the open sea could be obtained, but only one of the line of rocks at the foot of the cliffs. It was roughly made, and by the marks of tools, probably of hardened copper, it had evidently been cut from the inside.
 
Harry stood looking for some time. "I cannot understand their cutting the hole like this. It could not be noticed from the sea that there was an opening at all; that is plain enough. But why make the hole at all when you can see nothing from it? And yet a watch has been placed here, while there was none at the other places where they could make out any passing ship."
 
"Perhaps," Bertie said, "it was done in order that if from the other places boats were seen approaching, they could chuck big stones down from here and sink any boat that might row inside the rocks into the entrance to the passage, which, as this is in the middle of the room, must be just under us."
 
"In that case they would have kept a supply of big stones here. I have no doubt whatever that it was made some time after the castle was built, and I should say, judging by its unfinished state, the work was done in haste. But what for, goodness only knows. Well now, having made no discoveries whatever on the upper floor, we will go down. It is certain that there can be no great treasure hidden under any of these floors, there is not depth enough for hiding-places. I counted the steps as we came upstairs, and there cannot be much more than two feet between the floor of one room and the ceiling in the next. I fancy that this is of single stones, each the flooring length of the space between the half-walls. You see that there is a long beam of stone running on the top of the dividing wall, and the ends of these stones appear to rest on it. It is below that we must look for hiding-places."
 
They descended to the first floor. They found that the space behind the great room was divided into a number of chambers. All of these, with the exception of the small one on the sea-face, were necessarily in absolute darkness, and in all were brackets for torches, similar to those in the principal chamber. Bertie counted them, and found that, including those first met with, they numbered one hundred and twenty-three.
 
"How much do you think they weigh apiece?" he asked Harry when the tour was finished.
 
"I have not the slightest idea, Bertie. I should think about fifteen pounds, but it may be five pounds less than that. They would certainly give a very nasty knock on the head."
 
"Oh, I was not thinking of knocks on the head. If there are a hundred bars at fifteen pounds apiece, it is a big amount of silver; if they are only ten pounds each—and really I think that is nearer the mark—they weigh a thousand pounds. What is silver worth a pound?"
 
"It varies. You can put it at five shillings an ounce; that would be three pounds sterling for one of silver—three thousand pounds in a rough calculation for the lot."
 
"Well, that is not a bad beginning, Harry; it would pay all the expenses and leave a couple of thousand over."
 
Harry shrugged his shoulders. "A drop in the ocean as far as I am concerned, Bertie. Still, it is a beginning; and you may be sure that they did not take all this trouble to guard this castle for the sake of three thousand pounds' worth of silver."
 
They now went down to the next floor. Here there were two staircases, and the space was divided into two parts by a wall along the centre. There were no openings whatever for light. One half had evidently been devoted to arms. Here still lay hundreds of spear-shafts, tens of thousands of arrows, piles of hide shields, and caps of the same material.
 
"This store must have been larger than was required for the garrison of the place," Harry said, "it must have been a reserve for re-arming a whole tribe."
 
Besides the arms there were great bales of rough cloth and piles of skins, all in a marvellous state of preservation owing to the dryness of the air. After thoroughly examining the room they went up the stairs leading into it and descended those into the adjoining chamber. This was divided into compartments by transverse walls four feet shorter than the width, thereby leaving a passage through from end to end. Here in confusion—for the most part turned inside out—were sacks of matting and bags of leather. One of the compartments was filled with great jars arranged in tiers. Some of the compartments were quite empty.
 
"I think, se?or, that these were stores of loose grain, probably maize. I do not see a single grain left."
 
They looked carefully round with the torches. "This carries out our idea, Dias, that the people upstairs died of hunger. I have no doubt, as you say, that the sacks did contain grain. If these had been cleared in the ordinary way there would certainly remain a good deal loosely scattered about. They might have been full or half-full at the time the place was left as we found it. Possibly, instead of ten men, the garrison may have been ten times as strong at first, but in the fifty or hundred years before the last survivors died they may have dwindled to a tenth of that number. However, it is plain that, as you say, the store of food was not carried away, but was consumed to the last grain. In the same way you can see, by the way the sacks and bags are tumbled about and turned inside out, how careful was the search for any remnant that might have been overlooked when they were first emptied. It all points to starvation."
 
Three of the largest divisions bore evident traces that at some time or other, animals, probably llamas or vicu?as, had been closely penned there. Another had been occupied by a store of hay, some of which still remained. When they had thoroughly examined this room, Harry looked at his watch and said, "It is late in the afternoon—our torches are nearly finished; however, there is time for a casual look round at the cellars below. To-morrow we will begin a regular search there."
 
They descended by the staircase to the basement.
 
"How narrow this place is!" Bertie exclaimed. "It is not much more than half the width of the room above."
 
"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.
 
"We will bury them when we move the camp down here to-morrow morning," Harry said. "We forgot the two up at that window. That is no matter, we can throw them out to-morrow; they will lie as well at the bottom of the sea as in the earth here."
 
Not much was said as they returned to the castle. They had been a very silent party all day. The gloom and darkness, the way in which their voices echoed in the empty hall, had exercised a depressing effect on them; and Donna Maria, generally the most talkative of the party, had not quite recovered from the shock which the exit of the bats had given her. It was not until she had cooked a meal, and they all sat down to it, that they quite recovered their spirits. They had found José awaiting their return. He had a blazing fire, having brought down as much firewood as he could carry, and Dias had briefly told him the result of their explorations.
 
"Well, Harry, what do you think altogether?" Bertie asked after the meal was over.
 
"I think we ought to be very well satisfied," he replied. "Everything has borne out the ideas we had. The castle may have been built as a fortress by some great chief, certainly before the time of the Incas, or it may have been used for a prison. The ornaments and things we found showed that it was known to the Incas. They would have had no occasion to use it when they were undisputed masters of the country, but when the troubles came with the Spaniards a garrison was placed here, and possibly some of their chiefs took refuge in the place. Then came the time when all opposition to the invaders ceased, and only a small body of men were left here to guard the secret, and the treasure if there were any. Generations may have passed before the last of the garrison died of hunger, and probably all others who were in the secret fell in some insurrection or died in the mines. All this seems plain enough, except that possibly there was no treasure. That left by the Chimoos may have been discovered by the Incas. I should think it extremely likely that the ship Dias mentioned as setting out with ............