find they were upon a rugged shelf, about four feet wide,
sloping downward right by the side of the gulf; and passing along this,
they soon reached the other side of the great chasm, to stand nearly
opposite to the end of the passage where they had entered, but about
twenty feet lower; and here they again looked down into the awesome
depths. But nothing was to be seen. The water fell from somewhere
beneath where they had entered; and as they judged, plunged deep down
into a wide chasm, and from thence ran out and under the great crack,
which the boy found out as the way they had to go.

"Stream runs right under that, Master Mark. I went along some way, and
every now an' then I could hear it, deep down. I say, did you bring
anything to eat?"

"Some bread that I couldn't manage at breakfast."

"So did I," said the boy. "P'r'aps we may want it by-and-by."

"We want better lights, Dummy," said Mark, after they had progressed
some distance.

The boy turned round with a merry look, and was about to suggest torches
once more, but at a glance from Mark's eyes, he altered his mind and
said:

"Yes, those don't give much."

But pitiful as the light was, it was sufficient for them to see walls
covered with fossils, stalactites hanging from the roofs of chambers,
others joined to the stalagmites on the floor, and forming columns,
curtains, and veils of petrifaction, draping the walls as they went
through passage, hall, and vast caverns whose roofs were invisible. And
all the time, sometimes plainly, sometimes as the faintest gurgling
whisper, they heard the sound of flowing water beneath their feet.

"Well, this is grand!" said Mark; "but it's of no use."

"Aren't no lead," said the boy quietly; "but it's fine to have such a
place, and be able to say it's ours. May be some use."

"But I say, how are you going to find your way back?"

"Oh, I dunno," said the boy carelessly. "I've often been lost in the
other parts, and I always found my way out."

"Yes, but how?"

"Oh, I dunno, quite, Master Mark," said the boy earnestly, "but it's
somehow like this. I turn about a bit till I feel which is the right
way, and then I go straight on, and it always is."

"Mean that, Dummy?"

"Oh yes, Master Mark; that's right enough. But come along."

There was a certain excitement in penetrating the dark region, with its
hills and descents, passages and chambers, deep cracks and chasms, down
in which water was running, and