"Thank you, Bertie," Harry said quietly; "we will make up our minds that if it is there, we sha'n't get it at present. The foot of the valley is so flat that it would need a cut at least a mile long to let the water off, and we should therefore require either an army of men or a regular diving apparatus, which there would be no getting this side of England. However, it may not be there. Let us search now behind the fall."

There were some four or five feet clear between the sheet of water and the rock. At times, as Harry pointed out, there would be an even wider s.p.a.ce, for the weather had been dry for the past two months, and the quant.i.ty of water coming down was but small, while in the wet season a mighty flood would shoot far out from the rock. The width of the stream in the wet season was shown by the broad bed of what was now but a rivulet. Looking upwards as they stood, the wall actually overhung them, and they could see the edge where the water poured over unbroken.

"There may be a cave here," Harry went on, "and it may be covered by these rocks piled up for the purpose. On the other hand, they may have fallen. I think that is the most likely explanation, for as the top projects beyond the bottom it is possible that some time or other there was a big fall."

They searched every foot of the rock within reach, but there were no signs of any man's handiwork. The rock was solid, thickly covered with dripping moss and ferns which had flourished in the mist and spray that rose from the foot of the fall. This they had ruthlessly sc.r.a.ped off with their picks. Silently they went out again at the end, and stood hopelessly looking at the fall. It was some time before Harry said, "We must move some of those stones now. Let us go at once and cut down some young trees, for we can do nothing with our hands alone, but must use levers. For that purpose we shall want straight wood, and strong. We had better get half a dozen, in case some of them break; make them about ten feet long, and from four to six inches thick, and sharpened slightly at the lower end."

In an hour the levers were ready.

"We had better breakfast before we begin, Dias. Your wife went off to prepare it when we came out from the waterfall. I dare say it is ready by this time."

In half an hour they were back again. They chose the central spot behind the fall, and then set to work. Some of the rocks were dislodged without much difficulty, but to move others, it was necessary to first get out the smaller ones, on which they rested. So they toiled on, stopping for half an hour in the middle of the day for food, and then renewing their work. By evening they had made an opening four or five feet wide at the top, and six feet deep, close to the wall. It was now getting dark, and all were f.a.gged and weary with their work, the light was fading, and they were glad to return to camp. Maria came out to meet them. She asked no questions, but said cheerfully, "I have a good olla ready, I am sure you must want it."

"I feel almost too tired to eat," Bertie said.

"You will feel better when you have had some coffee. I have fed the mules, Jose, and taken them down to water."

"I think," Bertie said, when they had finished their meal, "that we might splice the main brace."

"I do think we might," Harry laughed. "We have not opened a bottle since we started, and certainly we have worked like n.i.g.g.e.rs since seven o'clock this morning. I will open the case; it is screwed down, and I have a screwdriver in the handle of my knife;" and he rose to his feet.

"What does Don Bertie want?" Dias said. "I will get it, senor. I do not understand what he said."

"It is a sea expression, Dias. After a hard day's work the captain orders that the main brace shall be spliced, which means that the crew shall have a gla.s.s of grog--that is, a gla.s.s of spirits and water--to cheer and warm them after their exertions. Jose, will you bring a blazing brand with you? I shall want it to see the screws."

In a few minutes he returned.

"This is brandy, Dias. I don't suppose you have ever tasted a gla.s.s of good brandy. Is your kettle boiling still, senora? We shall want hot water, sugar, and five of the tin mugs. Have you any of those limes we picked the other day?"

"Yes, senor."

"That is good. Just a slice each will be an improvement." Harry mixed four mugs, and a half one for Maria. "There, Dias!" he said. "You will allow that that is a considerable improvement on pulque."

He and his brother had already lighted their pipes. The other three had made cigarettes. Dias and Jose were loud in their commendations of the new beverage. Donna Maria had at first protested that she never touched pulque, and this must be the same sort of thing. However, after sipping daintily, she finished her portion with evident satisfaction. They did not sit up long, and as soon as they had finished their first smoke all retired to bed, leaving for once the llamas and mules to act as sentries. As soon as it was fairly daylight, they drank a cup of coffee and started again to work. Harry went first into the hole they had made, and, kneeling down, struck a match to enable him to see the rock more thoroughly. He gave a slight exclamation, then said: "Open your knife, Bertie, and come in here and strike another match. I want both my hands."

"I have a torch here, senor,"

"That is best; then light it, Bertie."

There was just room at the bottom for Bertie to stand by the side of his brother, who was lying down.

"Hold the torches as low as you can, Bertie."

Harry picked away with the point of his knife for a minute or two and then sat up.

"That is the top of a cave," he said. "Do you see, this crack along here is a straight one. That, I fancy, was the top of the entrance to the cave. That stone under it has a rough face, but on the top and sides it is straight. It is fitted in with cement, or something of that sort, and is soft for some distance in, and then becomes quite hard. I can just see that there are two stones underneath, also regularly cut."

He made room for Bertie to lie down, and held the torch for him. "I think you are right, Harry. Those three stones would never fit together so closely if they had not been cut by hand, though, looking at the face, no one could tell them from the rock above them."

Dias next examined the stones.

"There is no doubt that that is the entrance to a cave, senor," he said as he joined them; and the three went out beyond the fall, for the noise of the water was too great for them to converse without difficulty behind the veil of water. Jose stayed behind to examine.

"Well, Dias, we have found the place where the treasure is hidden, but I don't think that we are much nearer. Certainly we have not strength sufficient to clear away those fallen stones, and probably the cave is blocked by a wall several feet thick. We should want tools and blasting-powder to get through it. No doubt it is a natural cave, and it seems to me probable that they altered the course of the stream above, so that it should fall directly over the entrance. I think before we talk further about it we will go up there and take a look at it. If we find that the course has been changed that will settle the matter."

It took them an hour to climb the hill and make their way down to the gorge through which the river ran. They examined it carefully.

"It must always have come along here," Dias said. "There is no other possible channel; but there are marks of tools on the rocks on each side of the fall, and the water goes over so regularly that I think the rock must have been cut away at the bottom."

"It certainly looks like it, Dias. The rocks widen out too, so that however strong the rush of water may be it will always go over in a regular sheet. Let us follow it along a little way."

Fifty yards farther on, the gorge widened out suddenly, and they paused with an exclamation of astonishment. Before them was a wide valley, filled to the spot where they were standing with a placid sheet of water four or five hundred yards wide, and extending to another gorge fully a mile away. Bertie was the first to find his voice.

"Here's a go! Who would have thought of finding a lake up in the hills here?"

"I did not know there was one," Dias said. "I have never heard of it.

But that is not strange, for no one who came up the valley would dream that there was anything beyond that fall."

Harry had sat down and thought for some minutes, looking over the lake without speaking.

"I am afraid, Dias," he said at last, "that your tradition was a true one after all, and that the gold lay in the bed of a stream in the valley we now see filled up."

"But it must always have been a lake, senor," Dias said after thinking for a minute, "and could not have been shallower, for there is no other escape than the waterfall; and however heavy the rains it could not have risen higher, except a few feet, as one can see by the face of the rock."

"It may have had some other way out," Harry said.

Dias looked carefully round the side of the valley. "There is no break in the hills that I can see, senor."

"No; but my firm conviction is that the top of that cave that we found behind the fall is really the top of a natural tunnel through which the stream originally flowed. There are two or three reasons for this. In the first place, it is certainly remarkable that there should be a cave immediately behind that fall. I thought at first that the stream above might have been diverted to hide it, but the ravine is so narrow that that could not be possible. In the next place, your tradition has proved absolutely true in the matter of the star, and in the hour of its appearance in the exact line to the mouth of that cave. How correctly the details have been handed down from generation to generation! If they are right on that point it is hardly likely that they can be inaccurate on other points, and that the tale of an extraordinarily rich treasure could have been converted into one of an exceptional deposit of gold in the bed of a river.

"I think that the pa.s.sage was probably closed by the old people when they were first threatened by the invasion of the Incas. No doubt they would choose a season when the stream was almost dry. They had, as the remains of their vast buildings will show, an unlimited supply of labour. They would first partially block up the tunnel, perhaps for the first fifty yards in, leaving only a small pa.s.sage for the water to run through. They might then close the farther end with sacks of sand, and having the other stones all cut, and any number of hands, build it up behind the sacks, and then go on with the work till it was solid; then no doubt they would heap stones and boulders against the face of the wall. By the time the Incas had conquered the country the valley would be a lake many feet deep. The Incas, having gained an abundant supply of treasure elsewhere, would take no steps towards opening the tunnel, which in any case would have been a terrible business, for the pressure of water would drive everything before it. Having plenty of slave labour at their disposal, they knew that it could be done at any time in case of great necessity, when the loss of the lives of those concerned in it would be nothing to them. When the valley became full the water began to pour out through this gap, which perhaps happened to be immediately over the mouth of the tunnel, or it may have been altered by a few yards to suit, for they were, as we know from some of their buildings, such good workmen that they could fit slabs of the hardest stone so perfectly together that it is hardly possible to see the joints. Therefore they would only have to widen the mouth of the gorge a little, and fit rocks in on either side so that they would seem to have been there for all time; and indeed the natural growth of ferns and mosses would soon hide the joints, even if they had been roughly done."

"And that all means, Harry--?" Bertie asked.

"That all means that we have no more chance of getting at the gold than if it were lying in the deepest soundings in the Pacific."

Bertie sat down with a gasp.

"There is no way of getting that water out," Harry went on quietly, "except by either cutting a channel here as deep as the bottom of the lake, or by blasting the stone in the tunnel. The one would require years of work, with two or three hundred experienced miners, and ten times as many labourers. The other would need twenty or thirty miners, and a hundred or two labourers. There is possibly another way; but as that would require an immense iron siphon going down to the bottom of the lake, along one side of this ravine, and down into the bottom of the pool, with a powerful engine to exhaust the air in the first place and set it going, it is as impracticable, as far as we are concerned, as the other two.

"In the same way I have no doubt that, with a thousand-horse-power engine, the lake could be pumped dry in time; but to transport the plant for such an engine and its boiler across the mountains would be an enormous undertaking; and even were it here, and put up and going, the difficulty of supplying it with fuel would be enormous. Certainly one could not get up a company with capital enough to carry out any one of the schemes merely on the strength of an Indian tradition; and with the uncertainty, even if they believed the tradition, whether the amount of gold recovered would be sufficient to repay the cost incurred.

"Well, we may as well go down to dinner."

He shouldered his pick and led the way back. Scarce a word was spoken on the way. Bertie tried to follow the example of his brother, and take the matter coolly. Dias walked with his head down and the air of a criminal going to execution. The disappointment to him was terrible. He had all along felt so confident that they should be successful, and that he should be enabled to enrich those he considered as the preservers of his life, that he was utterly broken down with the total failure of his hopes.