right. There is no chance of our separating."

"How far are we going? It seems to me that we have walked at least a
quarter of a mile."

"More than that, I think. There is really no limit to the tombs--at
least, I have never been able to find any. This is a very difficult
place, so I think that I will use our ball of string." He fastened one
end of it to a projecting stone and he carried the coil in the breast of
his coat, paying it out as he advanced. Kennedy saw that it was no
unnecessary precaution, for the passages had become more complexed and
tortuous than ever, with a perfect network of intersecting corridors.
But these all ended in one large circular hall with a square pedestal of
tufa topped with a slab of marble at one end of it. "By Jove!" cried
Kennedy in an ecstasy, as Burger swung his lantern over the marble. "It
is a Christian altar--probably the first one in existence. Here is the
little consecration cross cut upon the corner of it. No doubt this
circular space was used as a church."

"Precisely," said Burger. "If I had more time I should like to show you
all the bodies which are buried in these niches upon the walls, for they
are the early popes and bishops of the Church, with their mitres, their
croziers, and full canonicals. Go over to that one and look at it!"
Kennedy went across, and stared at the ghastly head which lay loosely on
the shredded and mouldering mitre.

"This is most interesting," said he, and his voice seemed to boom
against the concave vault. "As far as my experience goes, it is unique.
Bring the lantern over, Burger, for I want to see them all." But the
German had strolled away, and was standing in the middle of a yellow
circle of light at the other side of the hall.

"Do you know how many wrong turnings there are between this and the
stairs?" he asked. "There are over two thousand. No doubt it was one
of the means of protection which the Christians adopted. The odds are
two thousand to one against a man getting out, even if he had a light;
but if he were in the dark it would, of course, be far more difficult."

"So I should think."

"And the darkness is something dreadful. I tried it once for an
experiment. Let us try it again!" He stooped to the lantern, and in an
instant it was as if an invisible hand was squeezed tightly over each of
Kennedy's eyes. Never had he known what such darkness was. It seemed
to press upon him and to smother him. It was a so