e was
about to become the leader in a very difficult enterprise in which the
other was to be a follower.

The mine boss, with a quick penetration of human character, gained by
years of study and experience, suspected something of this weakness on
Derrick's part, but did not consider that either the proper time or
opportunity had yet come for warning him against it.

So Derrick's plan was discussed in all its details, and before they
separated that night it was adopted.

In order that the mistake made by Derrick in his slight alteration of
the plan of the old workings, as shown in his tracing, may be
understood, a few words of explanation are necessary.

The old drift-mouth, that he had discovered almost hidden beneath a
tangle of vines and bushes, was on a mountain side above a deep valley.
Farther down was the mouth of a second drift, which he had not
discovered, and knew nothing of. On the opposite side of the mountain
was another valley, the bottom of which was on about the same level as
the higher of these drifts. The old workings ran from them through the
mountain, and under this valley in which the present colliery was
located.

When the gangway from the upper of the two drifts had been opened as far
as the valley, the vein that it followed took a sudden dip. The gangway
was in consequence changed into a slope, which finally led into the
workings beneath. Some time after they had been abandoned a great
"break" or cave-in of the ground above there had occurred at the edge of
the valley, and by it an opening was made into the lower set of
workings. It was on the opposite side of the valley from this break that
the new workings were now being pushed; and somewhere between it and
them was the old air-shaft and the chamber that the Mollies had selected
as their place of secret meeting.

Now Derrick had got hold of a plan of the lower set of these old
workings which he knew nothing of, and thought it was a plan of the
upper set, which in reality only extended to the edge of the valley. He
knew that the upper drift-mouth was on about the same level as the top
of the old air-shaft, and thought he had a plan showing that the two
were connected. He reasoned that by entering the old gangway at the
break, and following it under the valley, they would not only save
distance, but would be conducted directly to the top of the air-shaft
which they wished to reach. By the joining of those two lines at the
blurred place on