"That is what it is. I should not have noticed the wood if the peculiar lettering had not shown up through the coating."
"What are the letters, and do you know what they stand for?"
"We had better not pa.s.s judgment on that until we have removed all the calcium."
At this moment Harry came in to view the slab. It was the slab he had carelessly picked up in the cave, and therefore it had a great fascination for him. The calcium was carefully chipped off, and it was found to be a piece of oak board, with a smooth cut-off end, parallel sides, nine inches wide, nearly two inches thick, and about eleven inches long, the opposite end having the appearance of being broken. The only letters which could be made out were "HI," and a portion of another letter which could not be determined.
[Ill.u.s.tration: _Fig. 14. THE SLAB FOUND IN THE CAVE_]
"What do you think the letters were intended to indicate?"
"They might be the name of a ship, or some sign. I do not think it was part of a ship. I tried to find something in the cave, on the day I went in while you went after the team, which would afford some clue, but so far nothing confirms me in any view which I may have."
"Isn"t it curious that these letters should show through only after the slab was exposed to the light?"
"Why is that any more curious than photography is?"
"Because in photography something is put on the gla.s.s or the sheet that the negatives are made of, and it turns and makes a mark under certain conditions."
"Well, here is something put on this slab that turns also. Photography is a wonderful thing. Dr. Draper, the first great photographer, and who was also a scientist, says that every wall, or other object, which you stand before, has your photograph imprinted on it. The only question is to find some chemical which will develop the picture."
"What is meant by developing the picture?"
"You remember some time ago we talked about reagents, and the properties of certain chemicals to act on others, and in doing so, to make a change. Sometimes the change is a complete one, and makes a new product; in other cases the result is a complete change of color. Now, in photography, if a certain chemical is placed on a gla.s.s or a film, and the film is exposed, the light and dark portions of the object show on the film. The sunlight, or the actinic rays in the sunlight, affect the chemical material so that when the fixing chemical is applied it prevents a change in the condition of the chemical."
"What do you mean by the actinic ray?"
"All light is vibration; the greatest motions which are perceptible to the eye, being known as violet. Now there are still more rapid vibrations than are put forth to make the violet rays, which are called the actinic rays, and are the ones which affect the chemicals so acutely."
"Is it then possible to photograph with a light that is not perceptible to the eye?"
"You have heard of the x-rays, no doubt; they are the actinic or ultra violet, which are above the visible light. These light vibrations are of such a character that they penetrate many substances. A curious effect of this was shown some time ago when a photograph was taken of the side of a vessel which had several coats of paint over the old name, and the photograph showed not only the new name, but also the old one beneath."
The time had now arrived when they must make preparations for the proposed voyage of discovery around the island. It was a momentous time for them. The boys could not help but look with longing eyes to the cave. Before they went it was felt something more should be learned about its mysteries.
The Professor was not at all backward in encouraging this feeling.
"Wouldn"t it be a good thing to take such things out of the cave as we can make use of here, and during our trip?" said Harry.
"What things do you think we could utilize?"
"Probably the guns; and then they have some cooking utensils."
"And why," suggested George, laughingly, "couldn"t we take some of the money along?"
"That would be a comfortable feeling to have plenty of money in our pockets. Very well, we"ll take this afternoon for the trip."
An early start was made, the lamps carefully trimmed and the guns, together with the bolos, collected. It was a short walk to the opening, and Angel, although not invited, accompanied the party.
Together they descended, and soon reached the scene of the conflict at the large recess to the left of the entrance. The Professor, after reviewing the scene, suggested that the bones should be carefully gathered together and deposited at a place where they could be buried.
[Ill.u.s.tration: _Portugese Coin, 1700. Spanish Pistole Peruvian Dollar._]
[Ill.u.s.tration: _Fig. 15. Old Coins found in Cave._]
"We do not want them here as evidences of the strife."
After all had been gathered and carried to the spot selected, the first task was to gather the treasure found in the chests. And here a sight met their eyes which staggered them. One of the chests which Harry first found contained not only an immense quant.i.ty of gold coin, of Spanish and other mintages, but curious other pieces, all ancient, as shown by the inscriptions, and long yellow bars, the last of which attracted George"s attention.
"What are these bars?"
"They are gold bullion, made by melting up various articles, and probably the coin itself, so as to make it convenient for transportation."
"My! how heavy they are! and look at the number!"
When all had been a.s.sorted the Professor suggested that as they had plenty of copper utensils, the latter might be used as receptacles for the gold. The other chest contained but little coin, but here the interest was not less p.r.o.nounced than in the other chest, because the vessels found were not only of beautiful, but many of curious, design.
Some were of silver, as well, and the boys knew that those would be serviceable for their table, and at their suggestion all such were laid aside to be removed to the Cataract.
The kitchen utensils afforded a more varied collection than had been antic.i.p.ated. Six of the larger copper vessels were required to hold the money, jewelry and other articles taken from the two decayed chests, and there were still remaining at least a dozen more smaller jars and pots, some with handles, which would be exceedingly useful in their kitchen.
All these were carefully put aside, and the smaller silver articles deposited in them. And now the guns! Seven skeletons were found, two of which had been removed to the Cataract by the Professor. After all the guns had been collected, twelve were counted.
"I suppose each fellow had two of them," was Harry"s conclusion.
"If you will go over into the chamber to the east you will find a sufficient number to a.s.sure you that they were not lacking firearms."
The boys now understood. He had told them on the second day"s exploration that he did not find anything new, but only something more.
Why not go and see it now. But they were restrained. A dozen guns were certainly enough. These were also set aside, and it was then agreed to place the vessels containing the treasure in a secluded nook, in the extreme corner of the large recess. Samples of the clothing, some of the knives or daggers, as well as the little trinkets, found near each of the bodies, were deposited in the receptacles that had been selected for removal.
All this acc.u.mulation of material was more than they had bargained for when they left the Cataract, so that the failure to bring the team was keenly felt. However, it was the work of an hour, only, to get the team, and it was a pretty fair load which went from the pirates" haunts to the home on the river.
George"s curiosity could not keep him from taking some of the coins which he exhibited when they returned, and which they would have ample leisure to examine.
Harry"s thoughts were turned to the firearms. They were certainly of an antiquated pattern. The first thing was their length. Two of them were unusually long, fully six and a half feet.
"I wonder why it was they made their guns so long?" he inquired.
"The reason was, probably, that the quality of powder was so bad that the bullet would get out before all the powder was consumed. All the ancient pistols were very inefficient, because of the short barrel. Even down to the time of the American Revolution the guns on board of war vessels were not capable of throwing shot very far, and the most effective ones were those with long barrels."
"In what respect is the powder of to-day more powerful than in olden times?"
"Particularly in the fact that formulas have been devised which make a higher expansion, or give a greater volume of gas. The other feature of value is, that chemical means have been discovered whereby the moment a sufficient amount of heat has developed in the powder it instantly burns--not a slow fusing, like the old powders--but the combustion is instantaneous. These two factors working together have greatly improved even the black powders."
After their return the interest in the articles was so great, and the inventory took so much time, that the disappearance of Angel had been entirely forgotten. All remembered him going along, and no one had seen him enter the cave. None of them believed he could be induced to go in, hence no particular notice was taken of his movements.
An hour after the return, Harry saw Angel coming over the field at the east of the Cataract, dragging something after him laboriously. All stood and watched him as he neared home. He had a stick, apparently, but it seemed to be unusually heavy.
George ran out to a.s.sist him, and when he came up he gravely handed to article to George. It was the barrel of a gun, with part of the flintlock still attached, but it was rusted almost beyond recognition, the bore completely filled with dirt, acc.u.mulation and rust.