"Have you any extra cartridges?" she asked.

"Not a single one, but the revolver itself is fully loaded. That's just six we have to count on."

She was silent for a moment.

"There isn't any likelihood we'll have to use these for defending ourselves," she said at length. "There doesn't seem to be any living thing in this cave of which we need to be afraid. But, nevertheless, suppose we keep two for emergencies. That would give us four to experiment with, wouldn't it?"

"Experiment? How?" he inquired.

"I was thinking that perhaps father"--here her voice faltered a little--"and Tyke might be somewhere in the neighborhood hunting for us. If we should discharge the revolver they might possibly hear one or more of the shots and get some idea of where we were. I know it's only a forlorn hope, but we've got to try everything just now."

"It's a good idea!" exclaimed Drew, though he knew in his heart how slender a chance it offered. "And in the meantime, I'll keep on digging, so that if the shots aren't heard we won't be any worse off anyway. You fire the four shots at intervals of a minute or two and we'll see what happens."

He went savagely to work again and Ruth at short intervals discharged the revolver. The noise and the echoes in that compressed s.p.a.ce were deafening and it certainly seemed as though the sound ought to penetrate to the world outside.

But though they fairly held their breath as they listened for a response, no answering sound penetrated from the outside into the cavern, and their hearts sank as they realized that one more of their few hopes had failed them.

"It's of no use," observed Ruth sadly, as she handed the weapon back to Allen. "Either they didn't hear the shots, or, if they did, they thought it was some sound made by the volcano. We'll have to try something else."

Both were silent for a few moments, immersed in bitter thoughts that were as black as the darkness that surrounded them.

"Can you ever forgive me, Ruth, for having gotten you into such a trap as this?" he burst out suddenly.

"You didn't get me in it," protested Ruth. "I came in of my own accord."

"I don't mean that," explained Drew. "But you tried to persuade me not to enter the cave in the first place, and if I'd only had sense enough to listen to you; we'd both of us be out in the sunlight at this minute. Headstrong fool that I was!" he ended in an agony of self condemnation.

"Now don't blame yourself a bit for that, Allen," said Ruth earnestly.

"You only did what you thought you ought to do, and ninety-nine times out of a hundred no harm would have come of it."

"And it was our luck to strike the hundredth time," replied Drew bitterly.

"Besides," said Ruth with a trifle of hesitation, "I think I'd have been a little disappointed at the time if you had done as I asked. I'd have felt that perhaps in your secret heart you did it apparently to please me, but really because you were glad enough not to have to take any chances of what you might meet in here."

Drew was somewhat puzzled at this bit of feminine psychology, but he gathered some comfort from it, and this was perhaps after all the result that Ruth was seeking.

"Do you notice, Allen, how fresh the air seems to be in here?" she asked.

"I've been wondering at that," he answered. "To tell the truth my worst fear has been that it would get too close and foul for us to breathe. But it seems to be just as sweet now as it was at the beginning."

"What do you suppose is the reason?"

"It must be that the cave is a little larger than it seems to be. It seemed to be getting bigger and bigger as I went further into it. If that is so, it accounts for the fact that the air supply has not yet begun to be vitiated."

"But mayn't there be any other reason?" she asked.

"I can't think of any other," he answered. Then as a thought suddenly struck him, he jumped as though he had been shot.

"Why didn't I think of that before?" he fairly shouted. "There may be another entrance!"

CHAPTER XXIV

THE ALARM

Unaware of the possible tragedy that was being developed within a few hundred yards of them, Tyke and Captain Hamilton had kept on digging in the excavation. For Tyke had refused to be kept out of the work of recovering the treasure, and when Drew had strolled off with the intention of discovering what had frightened Ruth and had been followed shortly after by the latter, the old man had seized Drew's abandoned shovel and had gone l.u.s.tily to work.

"Too much of a strain on that game leg of yours to be heaving up those shovelfuls," the captain protested.

"Nary a bit of it," answered Tyke. "I ain't ready to be put on the shelf yet, not by a blamed sight, and I guess if it came to a showdown, Rufe, my muscles are as good as yours."

"You're a tough old knot all right," admitted Captain Hamilton, his eyes twinkling. "But there's no sense in your doing Allen's work.

Where in thunder has the boy gone anyway?"

"Oh, he'll turn up in a minute or two," returned Tyke. "Wherever he is you can bet your boots he's doing something connected with this here work of treasure seeking. It simply ain't in that boy to lay down on any job."

"Drew makes a hit with you all right," laughed the captain.

"And why shouldn't he?" asked Tyke belligerently. "He's been with me for some years now, and I've had plenty of chances of sizin' him up.

If there was a yellow streak in him, I'd have found it out long ago.

If I'd had a son of my own, I wouldn't have asked for him to be any better fellow than Allen is, and n.o.body could say any more'n that.

He's got grit an' brains an' gumption, an' more'n that he's as straight as a string."

"Go ahead," laughed the captain, as Tyke paused for want of breath.

"Don't let me stop you."

"I don't mind tellin' you, Rufe, what I've never told yet to any human soul," continued Tyke, waxing confidential, "an' that is that when I lay up in my last harbor, Allen is goin' to come into everything I've got. He don't know it himself yet, but I've got it down shipshape in black and white an' the paper's in my office safe."

"He's a lucky fellow," commented the captain briefly.

"An' let me tell you another thing, Rufe," said Tyke, "an' that is that Allen would make not only a good son, but a mighty good son-in-law."

He nudged the captain in the ribs as he spoke, with the familiarity of old comradeship.

"Lay off on that, Tyke," said the captain, flushing a little beneath his bronze.

"You don't mean to say that you haven't seen the way the wind was blowin'?" rejoined Tyke incredulously. "Why, any one with a pair of good eyes in his head can't help but see that those two are just made for each other."

"I'm not blind, of course," returned the captain, who now that the ice was broken seemed not averse to talking the matter over with his old comrade. "I know of course that I can't keep Ruth forever and that some time some fellow will lay me aboard and carry her off right from under my guns. And I'm not denying that up to a few days ago, I'd rather it would have been young Drew than any one else. But now--"

here he paused.

"Well, but now," repeated Tyke.

"You know just as well as I do what I'm meaning," blurted out Captain Hamilton. "This matter of Parmalee's death has got to be cleared up before I'd even consider him in connection with Ruth. You can't blame me for that, Tyke."

The old man's face clouded.