"Look! Look!" whispered Andy.

"Yes," answered his brother in a low voice. "The tide is rising. It's running into the cave, and we--we're trapped here, Andy. No wonder that man said it was the last time. We're trapped by the rising tide!"

CHAPTER XXI

DEATH IS NEAR

"Frank, are you there?"

"Yes, Andy. Give me your hand."

The two brothers spoke softly. It was in the darkness of the cave, for they had both released the pressure on the springs of their portable lights to make the little dry batteries last as long as possible. It was several minutes after the first awful discovery of the incoming tide, and they had maintained a silence until the younger lad, unable to longer endure the strain, had called out.

Silently they clasped hands in the blackness.

"Frank, do you--do you think there's any way out?"

"Why, of course there is, Andy. All we've got to do is to wait a while, and someone will surely come to our rescue. Father and mother know we started for this island, and if we don't get home soon they'll start a searching party after us."

"Yes, but the rising tide, Frank. We--we may drown."

"Nonsense. The water can't get very high in here. We'll simply go to the highest part of the pa.s.sage, and wait until the tide goes out.

That won't be so very long. What makes me mad though, is to think how that man fooled us. That was his object all along. He wanted to get us in here so he could drop that rock across the opening and have us caged."

"Can't we try to get out?" asked Andy. his usually joyous spirits had departed. He was very much subdued now, and in the momentary flash of his light, which he permitted himself, Frank saw that his brother was very pale.

"Of course we'll try!" exclaimed the elder lad, with all the a.s.surance he could put into his voice. "Perhaps we can manage it, too. Let's have a try. It's of no use to do it here. We must go back to where he pushed down the rock. Perhaps it isn't in as tight as we thought at first. Come on. But don't use your light. Mine is enough, and we must save them as long as we can."

By the gleam of the single electric torch they made their way back.

Soon they were at the rock which made them prisoners. It loomed grim and black in the semi-darkness.

"The water's higher," said Andy, in a low voice. Frank had noticed that, for it now reached to his ankles as he splashed his way back along the pa.s.sage. But he had said nothing, hoping Andy had not observed it.

"Yes," said the older boy cheerfully, "It's bound to rise until the tide is at flood, and then--why, it will go down again--that's all."

"But suppose it fills this cave?"

"Nonsense! It can't. I'm not going to suppose anything of the sort.

Now come on. Let's see if we can move this rock."

Together they pressed on the stone with all their strength. They might as well have tried to budge the side of a mountain. The rock was firmly wedged in place.

"It's no use," spoke Andy, in a dull, hopeless tone.

"Oh, don't give up so easily," urged his brother. "If we can't do it one way, we may another. See, it has slid down in a sort of groove.

Only a little ridge of rock on either side holds it in place. Now if we can break away those upright ridges, which are like the pieces on a window sash up and down which the window slides, we may be able to push the rock out. Let's try. Use your knife and take a rock for a hammer."

Frank placed his torch on a ledge of rock, tying the spring down by a piece of cord so that the light would focus on the big bowlder. Then, with their pocket-knives as chisels, and stones as mallets, they began their futile attempts to cut away the holding ridges of rock.

That it was a futile attempt was soon made evident, for their knives slipped off the flint-like stone, and several times when the blades unexpectedly shut, the lads received severe cuts on their hands.

Suddenly Andy uttered an exclamation:

"The water! It's getting deeper!" he cried

It was up to their knees now.

"Of course it getting deeper," said Frank, with a cheerfulness that he was far from feeling. "The tide isn't half in yet."

Andy shuddered.

"What will we do when it's high water?" he asked.

Frank did not answer, but kept on chipping away at the rock. He managed to break off several pieces, but it was easy to see that it would take much more work to loosen the retaining ridges so that the bowlder that imprisoned them would fall outward.

"There it goes!" suddenly exclaimed the older brother in despair.

"I've broken my knife blade! You'll have to do all the work, Andy."

"Oh, what's the use?" sighed the younger lad. "The water is coming in faster. See, it's up to our waists now, and the tide is nowhere at full! We're doomed, Frank!"

"Not a bit of it. See that ledge of rock up there? We'll climb up on it and wait until the water goes down. Then maybe someone will come for us, or we can get out. Climb up, Andy. We won't try to break off any more rock."

Frank helped his brother to take a position on the narrow ledge. It was barely wide enough for two, but, somehow, they managed to cling to it. The surface was wet, and there were little puddles of water here and there. Seeing them in the gleam of his light, Frank could not repress a shudder.

"The tide must come up even to here," he thought. "If it comes up to the roof--well, that's the end of us." But he said nothing to Andy.

Slowly the water rose. They boys watched it, sitting on the narrow ledge with their feet and legs dangling off. From time to time Frank would flash his light on the little lapping waves.

"It will soon stop," he said, as cheerfully as he could. But he did not believe himself. He held Andy's hand in a firm grip.

Higher and higher rose the tide. It was at the knees of the boys now, and still mounting.

"Let's stand up," proposed Frank at length. "I'm tired of sitting."

They took an upright position on the ledge of rock. Their heads just touched the rocky roof of the cave. In fact Frank, who was a trifle taller than his brother, had to stoop.

"Now we'll be all right, Andy," he said. "We can stand here until the water goes down."

"If--if it doesn't touch the roof," was the solemn answer.

Frank said nothing.

Standing on the ledge, high above the floor the cave, the water now lapped their ankles once more. Frank could feel it creeping higher--ever higher. In spite of himself, a horrible fear took possession of him. Death was very near, he thought--a terrible death by drowning in the cave where they were caged like rats in a trap.