lesome bit is in getting over
the bulge, and that doesn't amount to anything. It's safe enough for you
to come down."

"Very well, then, I'll come; so go on down again."

Taking a candle we had brought with us, I set it on a projection where
it would cast a light into the fissure, and seizing the rope, down I
went. The descent was perfectly easy, and in a few seconds I found
myself standing beside Joe at the bottom.

The crevice down here was much wider than above--ten or twelve feet--the
floor, composed of sandstone, having a decided downward tilt towards the
south. In this direction Joe, lantern in hand, led the way.

Piled up in the passage was a large heap of lava-blocks which had
fallen, presumably, through the opening above, and climbing over these,
we saw before us a very curious sight.

[Illustration: "WE SAW BEFORE US A VERY CURIOUS SIGHT"]

On the right hand side of the crevice--that is to say, on the western or
Second Mesa side--between the sandstone floor and the lowest ledge of
lava, there issued a thin sheet of water, coming out with such force
that it swept right across, and striking the opposite wall, turned and
ran off southward--away from us, that is. Only for a short distance,
however, it ran in that direction, for we could see that the stream
presently took another turn, this time to the eastward, presumably
finding its way through a crack in the lava of the First Mesa.

"I'm going to see where it goes to," cried Joe; and pulling off his
boots and rolling up his trousers, he waded in. He expected to find the
water as cold as the iced water of any other mountain stream, but to his
surprise it was quite pleasantly warm.

"I'll tell you what it is, Phil," said he, stepping back again for a
moment. "This water must run under ground for a long distance to be as
warm as it is. And what's more, there must be a good-sized reservoir
somewhere between the lava and the sandstone to furnish pressure enough
to make the water squirt out so viciously as it does."

Entering the stream again, which, though hardly an inch deep, came out
of the rock with such "vim" that when it struck his feet it flew up
nearly to his knees, Joe waded through, and then turning, shouted to me:

"It goes down this way, Phil, through a big crack in the lava. It just
goes flying. Don't trouble to come"--observing that I was about to pull
off my own boots--"you can't see any distance down the crack."

But whatever there was to b