tand 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 mass 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.

Dick 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