; but the bottom seems very level, and the depth keeps about the
same. Nice and cool here. Keep close up. What's that, Cross?"

"Only a stone standing right up, sir; water washes round it. It's best
to keep right in the middle, I think."

"You must judge about that," said my uncle. "Go on."

"How far do you think we've come, sir, now?"

"About a quarter of a mile, I should say."

"That's what I thought, sir," said the carpenter, and he waded steadily
on, with us following.

After a time it grew very monotonous, but we persevered, finding the
underground river sometimes a little deeper, then shallower, so that the
water rippled just above our ankles, while we knew at times that the
cavern was wide and high, at others that it closed in on either side,
and twice over the roof was so close that I could touch it with my
stick.

The times when it opened out were plain enough, for our splashings or
voices echoed and went whispering far away. But otherwise the journey
was very tame, and as the feeling of awe died away, the journey seemed
uncommonly free from danger, for I felt it was absurd to imagine the
waters to be peopled with strange creatures.

We had been wading on for quite a couple of hours, when the water began
to grow more sluggish, and to flow very quietly, rising, too, higher and
higher, till it was above our waists, and the light reflected from the
surface showed that it was very smooth.

"Keep on, sir?" said Cross.

"Yes," said my uncle. "Keep on till it nearly touches your chin. Then
we'll turn back."

Pete uttered a low groan, but followed in a despairing way, while we
went on for another quarter of an hour, with the water deeper and
deeper, and at last, to our great delight, my uncle said:

"There, the water is rippling up in my beard, so it is time to go back."

"Hah!" ejaculated Pete, and then he groaned, for Cross said:

"Not so deep now as it was ten minutes ago, sir."

"Are you sure?"

"Yes, sir. I know by my stick. I keep my hand so that it touches the
water, and I've had to move it twice in the last five minutes. It's not
so deep now by three inches."

"Go on, then," said my uncle, and we followed, to find the water getting
shallower rapidly now. Ten minutes later it was below my waist, and in
another ten minutes not above mid-thigh; but it had evidently widened
out, for our voices seemed to go off far away into the distance, and my
uncle suddenly said:

"Why, Nat, the