I wish I had a hoss!"

"Couldn't use one," retorted Snake Purdee. "It'll work off some of the
fat, if you walk."

"Hu! Fat!" snorted Old Billee. "I ain't fat!"

"Forward!" suddenly called Bud.

Then with waves of their hands, and with the calling of many "good-bye"
farewells, the expedition disappeared into the black depths of the
tunnel.

What would they find? What would be the outcome? Would they ever
reappear again?

These were questions which more than one asked himself, but no one
spoke them aloud.

"Now," remarked Bud, when they were well within the long stretch of
blackness, and lanterns had been lighted, "we walked, the other time,
on the left-hand side of the water course. What say we try the right
one this time?"

"Good enough!" decided Old Billee. "We'll be right for once!" he joked.

"But it really is a good idea," declared Snake Purdee. "There might
have been something--some hidden passage on the side you didn't travel,
boys. You could easily have missed it in the darkness."

So this was decided on. As a matter of fact in many places it was
possible for the party to divide and some walk along either side of the
old stream bed. But this would not be feasible should the water
suddenly appear again.

And so the expedition moved slowly along. I say slowly, for that speed
marked their course. They carried a number of lanterns and these were
flashed over walls and roof as well as on the bottom, to discover, if
possible, a branch tunnel, or hole, where the water might travel to,
and thus be shunted off from the reservoir end. But, for several hours
nothing occurred, and nothing was discovered. Lunch was eaten in the
blackness, relieved as it was only by the lanterns, and then the
expedition started off again.

"Here's the place where we were when the water came spouting before,"
said Bud, as they came opposite the ledge on which he and his cousins
had taken refuge. "I think we ought to spend some time here and----"

"Hark," suddenly interrupted Nort. "Hear that noise!"

They all heard it--a rushing, roaring sound, like the blowing of a
mighty wind.

"The water--the water!" cried Bud. "Look out!"

They could hear the noise more plainly, now, and as Snake and Billee
raised their lanterns, the glows flashed on a white, frothy mass
approaching through the blackness of the tunnel.

"It's the same as before!" cried Nort. "Get to the ledge! The ledge!"

He made a leap, running