if a stone thrown down upon it would sink immediately
into it, out of sight.

The crater seemed to be four or five hundred feet across, and the walls
of it were eighty or a hundred feet high.

After Mr. George and the children had been standing upon the brink of
this abyss some time, watching the explosions, the guide who had come up
with them from the Hermitage beckoned to Mr. George, and saying
something at the same time in Italian, made signs as if he wished the
party to go with him to some other place.

"Come, boys," said Mr. George; "he wants us to go with him."

"Where does he want us to go?" asked Rollo.

"I don't know," said Mr. George. "I cannot understand what he says; but
let us go and see."

So the whole party followed the guide, Mr. George leading Rosie by the
hand. The guide conducted them along a narrow path through the sand,
which led away from the crater behind a hill which formed one of the
sides of it at a place where it was so steep below the path down the
mountain side, that Rosie was almost afraid to go. Mr. George, however,
held her firmly by the hand, and he charged Rollo and Josie to follow
very carefully. After going on in this way for some distance, they came
to another crater very similar to the first, only the sides of it,
instead of being formed, like the first, of perpendicular cliffs,
consisted of steep, sloping banks of volcanic sand and gravel. There
was, however, the same pitchy bed of lava spread out all over the bottom
of it below, and in the centre a black cone thirty feet high, with a
fiery furnace mouth at the top, glowing with heat, and throwing out
continually the same thundering puffs of steam, and projecting the same
masses of melted lava and hot stones into the air.

"Ah, here is another crater!" said Mr. George.

"Yes," said Rollo; "only it is smaller than the first. I like the first
the best."

While they were standing on the narrow ridge which formed the brink of
the crater, looking down, their guide by their side, another guide came
by, conducting two young men; and they, instead of stopping on the
brink, as Mr. George and his party had done, began at once to go down.
There was a sort of track in the sand down the slope, and in this track
the young men, half walking, half sliding, descended.

"Why, uncle George!" exclaimed Rollo, "they are going down into the
crater. Let Josie and me go too."

Mr. George saw by a glance that the descent into the crater must