"Well, there aren't no other way," said Josh, whose long sleep had been the cause of the mishap, for had he been awake he would have known that they were staying longer than was safe.

"But," cried Mr Temple, who felt alarmed now on account of his boys and their companions, "what are we to do? We must leave the boat and wade out."

"Wade!" growled Josh. "Why, there's three fathom o' water under where we sit."

"Then we must swim through," cried Mr Temple excitedly. "There is no time to spare. Man, man, why did you not warn us of the danger?"

"Why--why?" growled Josh. "I didn't know. I never see the tide come up that gashly way afore."

"It was while you were asleep, Josh," said d.i.c.k in a whisper; and Josh turned upon him as if he had been stung.

"Now," cried Mr Temple, as he pointed to the low opening through which was the sunshiny sea and safety, while on their side was apparently darkness and death; "now, d.i.c.k, you can swim through there; but first try whether by lying down we can force the boat under."

"Oh, I'll try!" said Josh; "but it's of no use, not a bit of use. Be it, Will?"

"No," said the latter decidedly, as he and Josh urged the boat right up to the entrance, and Mr Temple saw at once that it would be an impossibility.

"Then we must swim," said Mr Temple. "You can swim that, d.i.c.k?"

"Yes, father," said d.i.c.k. "Clothes and all."

"Yes, of course, the distance is so short."

"And you, Arthur, you can swim through there?"

The boy could not speak, for he was battling down the horrible feeling of dread that came over him.

"I say, you can swim that, Arthur?" said Mr Temple sternly.

"Yes, father. I'll try," said the boy quickly.

"That's well. Of course you two can swim?"

"Tidy, sir, tidy," said Josh; "and Will here, he could 'most beat a seal. But there ain't no call to get wetting of ourselves. I'll shove the boat back to where it's highest and where the water never reaches.

We can wait there till she goes down again."

"Do you know what you are talking about, man?" cried Mr Temple sternly.

"We should be suffocated."

"Josh means put the boat, sir, under the opening in the rock that he spoke about," said Will. "There'll be plenty of air. You can stand up on the rocks, sir, and hear it rush out with a regular roar when the water drives in, and when it goes out again the air sucks in so fast that it will take a piece of paper with it, and sometimes blows it out again."

"There is no time to be lost then if you are sure of this," said Mr Temple anxiously; "but are you sure?"

"Yes, sir, quite sure," cried Will.

"Oh! you may trust Will, sir, that's right enough all as he says. Tide never comes up anything like so high as we shall be."

Mr Temple hesitated, and as he paused, wondering which would be the wisest plan to pursue, there was a wave ready to rise up and completely blot out the faint daylight which streamed through the narrow opening.

This was only for a few moments, and then the daylight streamed in again, but only to be eclipsed by what seemed to be a soft green ma.s.s of crystal, that gradually darkened more and more.

Then came sunshine and blue sky again, but a smaller arch than ever, and had the little party not been filled with alarm, nothing could have been more beautiful than the succession of effects.

But in a state of intense excitement Mr Temple was urging Josh and Will to force the boat back to where they would be in safety, if safety it could be called.

d.i.c.k was quite as excited as his father, and eagerly seized an oar to help force the boat back, while Arthur, perhaps the most alarmed of the three, sat perfectly still, for, poor boy, he had been fighting for weeks now to master his cowardice, and, as he called it, to make himself more like his brother.

As the boat floated back more and more along the irregular channel they could see the archway entrance open and close--open and close. Now it seemed as if it would not close again, for the water went suddenly lower, and Mr Temple exclaimed:

"Look! the tide is at its height."

"Not it," said Josh. "She's got another two hours to run, I know. But don't you mind, sir, we shall be all right."

Perhaps Josh felt quite confident, but no one else did, as the water rose and fell, giving lovely little views of sea and sky, and then turned into veils of crystal, green and blue, sparkling sometimes like emerald, then changing to amethystine or sapphire hue.

It was surprising what an amount of light seemed to come in when the water sank, and then by contrast the darkness was horrible, and the lanthorn seemed to emit a dismal yellow glow.

They might have stayed for another quarter of an hour watching the light come and go, but there was the danger of their being inclosed in some portion of the cavern where the roof was low, and the boat would be made a prisoner within a prison. So Josh urged the boat forward towards where Mr Temple had been so busy with his researches, and after a little examination he bade Will cover the lanthorn with his jacket.

"It's a long time since I were in here," he said; "but I think as the air-hole ought to be somewhere about here. One moment, Will, lad; hold the light up and lets see the roof."

The rocky summit was in the highest part, some twelve feet above their heads, and satisfied as to this, Josh had the light darkened, and then began to look upward.

"No," he said. "Must be the next. Show the light."

He thrust the boat along once more, grinding and b.u.mping over fragments of rock, till they had pa.s.sed under another low part of the roof, when this rose once more, and the lanthorn being hidden Josh pointed upward to a narrow crack, through which came a faint light.

"There y'are," he said. "Don't matter how high the water gets, we can get plenty of fresh air. Tide won't get up there."

The position seemed more hopeful now, for the tide would have to rise fourteen or fifteen feet to carry them to the roof; and though in certain places from low water to high water might be perhaps forty feet, they were now so near the height of the tide that it was not likely to rise much farther.

"Don't be frightened, Taff, old chap," said d.i.c.k in a whisper; "father's with us, and he'll mind that we don't get hurt."

"I'm not going to be frightened," said Arthur coolly; and then Mr Temple began to talk cheerily as he stood up in the boat and held the lanthorn here and there; but first of all Will noticed that he took his geological hammer and chipped the rock on a level with the water, and soon after he made a clear bright sparkling chip about a foot higher, the granite rock glittering in the feeble rays of the lanthorn.

"I should not be a bit surprised if a good lode of metal were discovered here," said Mr Temple; and he went on chatting lightly about mines and minerals and Cornwall generally, but somehow he could not draw the attention of his companions from that bright mark on the rock, towards which the water was constantly creeping, and then seemed to glide away, as if exhausted with the effort.

And certainly it was a horrible position to sit there with no light but that shed by the yellow lanthorn, the boat heaving up and sinking beneath them, and the sounds of the water dripping and splashing, and now and then making curious sucking and gasping noises, as it ran in and out of cracks and crevices in the rocks.

All at once there was a loud, ringing, echoing blow upon the rock, as the boat approached close to the side, and Mr Temple struck it sharply with his hammer, for one mark had gone and the water was lipping and lapping fast towards the other.

The sc.r.a.ps of granite flew pattering into the water, as blow succeeded blow, Mr Temple making a deep mark on the rock to relieve his pent-up feelings, and to take the attention of his boys, who kept looking at him nervously, as if asking for help in this time of peril.

This done, he made Josh move the boat from side to side of their narrow prison, inviting d.i.c.k and Will to help as he chipped here and chipped there, and talked about the different kinds of granite and quartz that he cleared from the dark mossy growth and the film of ages.

But there was the water lapping and lapping and rising, and it was plain now that there would hardly be room to turn beneath the arch-like opening that separated them from the portion where Josh had expected to see the daylight.

It seemed to have grown intensely hot too, for the faint current of cool air that they had felt since entering the place had stopped for some time past, and still the water kept rising, and at last seemed to come through the narrowing opening with so horrible a gurgling rush that it affected even stolid Josh, who took his cap off and said that it was "a gashly ugly noise."