“Say,” exclaimed George, “where do you suppose they came from?”

“Somebody dropped them here, I suppose,” said Grant dryly.

“Of course,” said George, ignoring his friend’s sarcasm, “but who was it? It must have been a long time ago though. See how that pistol is all rusted and eaten away. I don’t believe they’ve used that kind of a pistol in two hundred years, either.”

“Well, John said this island looked like a good one for pirates,” remarked Fred. “Maybe pirates left these things here.”

“Do you suppose so?” exclaimed George eagerly. “If there were pirates here do you think they could have buried any treasure on the island?”

“I don’t know, I’m sure,” laughed Grant. “Even if they did, I don’t see just how it would do us any good.”

“Can’t we look for it?” demanded George.

“Where shall we look?”

“Maybe they left directions as to where it was buried.”

“Say,” exclaimed John, “speaking of directions, what happened to that code we were looking at on board the Josephine? I suppose it burned up with the ship.”

“Oh, no it didn’t,” said Grant. “It went right into my hip pocket and that’s where it has been ever since and where it is right now.”

“Why don’t you decipher it, Grant?” said Fred.

“Oh, yes,” said Grant grimly, “why don’t I? It’s so easy you know.”

“Well, it can be done,” insisted Fred firmly.

“Of course it can,” laughed George. “The only trouble is we don’t know how.”

“We don’t even know it is a code,” said Grant.

“Petersen said it was,” Fred objected.

“I know it,” said Grant, “but he wasn’t sure of it. That was only his opinion.”

“Didn’t the water and everything hurt it?” asked George.

“Not a bit. Here it is; you can see for yourself,” and Grant produced the piece of parchment from his pocket. He unfolded it while his three companions crowded eagerly around him to inspect the strange document once again. No light was thrown on its secret, if it had one, however, and the same baffling maze of numbers confronted the boys.

“Put it away,” cried John impatiently. “I think it’s a combination to a safe.”

“No, it isn’t either,” said Fred. “It’s a code I tell you and I think that some one of us ought to be able to read it.”

“What good would it do if you did?” demanded John. “Certainly it can’t apply to this island, and I say we forget it and inspect this cave now. That is much more to the point.”

“Put it away, Grant,” said Fred. “To-morrow though, I’m going to get to work on it and see if I can’t make something out of it.”

“I’ll help you,” said Grant.

“That’s the way,” cried Fred enthusiastically. “Grant and I will find the money and Pop and String won’t get a cent.”

“Is that so?” exclaimed George. “Well, if you can find any money and not give me my share you’re a much better man than I think you are.”

“Let’s not fight about the money just now,” advised Grant. “We haven’t found it yet, you know.”

“I know it,” exclaimed John. “I never heard such a lot of crazy talk before either. Who’s coming into the cave?”

The entrance was about ten feet wide and was high enough so that even John could walk in without stooping. Far down towards the back of the cave a patch of light shone on the floor showing that somewhere else besides the spot where the boys stood, there was an opening.

“I can’t see very well,” said Fred as they stepped into the cave.

“Neither can I,” George agreed. “I’m not very anxious to go walking around in strange dark caves either.”

“What can hurt you?” demanded John. “There isn’t another soul on the island besides ourselves and Sam.”

“That may be,” admitted George. “Still there may be holes in the floor or some kind of animals living here.”

“Well, I’m going down to where that spot of light is,” said John. “Is any one coming with me?”

“Oh, I’ll go all right,” exclaimed George quickly. “All I said was that I didn’t like it much.”

“Go slow,” cautioned Grant. “We don’t want to run any risks.”

“I can see better now than I could,” said John who was in the lead. “My eyes are becoming more used to the dim light.”

“So are mine,” said Fred. “The floor looks perfectly flat to me too, and I think I see a box or something up ahead there.”

“I guess you do,” John agreed. “I see something myself.”

They proceeded cautiously on their way until they came to the box in question.

“It’s a chest,” exclaimed John, bending over. “It’s iron, too,” and he gave it a kick. The clang of the metal echoed and reËchoed through the cave producing a weird sound and sending the shivers coursing up and down the spines of the boys.

“It sounds hollow,” said Grant in a low voice.

“I guess it is,” John agreed.

“Lift it and see,” directed George. “Aren’t there any handles on it?”

John felt around the sides of the chest and finally discovered that there was a handle on one end. He pulled and lifted with all his might, but not one inch could he budge it.

“Whew, there must be something in it,” he panted. “It’s certainly heavy enough.”

“It’s probably full of gold,” exclaimed George excitedly. “Gold is awfully heavy.”

“Calm yourself, Pop,” said Grant, but he too, was excited. In fact, the strange cave and the chest suggested all sorts of things to the four youths. What if they should find that the chest was full of money? Stranger things than that have happened.

“It certainly sounded hollow in spite of all you say,” remarked Fred. “See if all four of us can’t get hold and move it.” He kicked it once more and again the weird sound rang through the cave.

“Don’t do that, Fred,” begged George. “It gives me the shivers.”

“Get hold here then,” exclaimed Fred.

The combined efforts of the four boys did not even slightly move the great chest. It was an awkward thing to handle, however, as well as very heavy.

“Perhaps it is empty after all,” remarked Grant, as they all paused to regain their breath. “A chest as big as that would weigh a lot all alone.”

“Maybe,” admitted Fred. “At any rate I say we get it out on the ledge in front there where we can have a good look at it.”

“That’s the idea,” exclaimed George. “We can get it there if we all help. Everybody get to work here now!”

Pushing and hauling, grunting and groaning the young castaways bent to their task. Little by little the great iron chest was moved closer and closer to the entrance of the cave. The sweat poured from the boys in streams and their arms and their backs ached. They would not give up, however. The lure of treasure had them in its grasp and they were determined to find out just what the contents of this chest were if such a thing were possible.

“Just a little more,” urged Grant, and with one final effort the chest was pushed out onto the ledge of rock in front of the cave.

For a few moments the boys were too exhausted to do more than stand around puffing and gasping for breath. Such a task, combined with the heat of the tropics, would tax the strength and endurance of the hardiest.

“Now let’s open it up,” exclaimed Fred. “Where’s the top?”

“It’s over on its side,” said Grant. “Here’s the top and it’s padlocked.”

“So it is,” said Fred disappointedly. “What can we do?”

“Get a rock,” directed Grant. “It’s pretty well rusted and by hammering it we may be able to break it.”

A suitable rock was quickly found and an attack begun on the padlock. Grant pounded away for dear life, while the others stood around and watched him. After a few moments he stopped to inspect the result of his efforts.

“Think you can do it?” inquired John.

“I don’t know,” said Grant. “I think I made a little impression on it, but it’ll take some time.”

“Well, I’m going back into the cave,” announced John. “I’m going to inspect that patch of light back there. When you get the box open, yell at me.”

He disappeared in the dusk of the cave while his three companions took turns at hammering the lock. It was stubborn, but was beginning to show some signs of yielding and the boys stuck manfully to their task. They seemed to be on the verge of succeeding when a great commotion inside the cave suddenly arrested their attention.

A moment later John burst forth. His face was ashen and his eyes bulged wide with fear. His hands shook as if he had the ague and his breath was almost gone.

“What is it, John?” demanded Grant in alarm, while Fred and George also crowded around the frightened boy. He had evidently received a terrible shock of some kind and his three companions were greatly affected by his appearance.

“What’s the matter?” exclaimed Grant anxiously, but all that John could do was to mumble incoherently and point towards the interior of the cave.