t on his stomach on the incline below, hanging on with his fingers
for dear life. As Nestor looked the boy's fingers slipped on the
smooth rock and he started, feet foremost, down the dark passage.

Calling to the boys above to cling tightly to the rope and to pay it
out slowly, Nestor slid swiftly downward until the slack of the line
was gone, and was then brought up with a quick jerk, with the still
slipping boy's head a foot away from his hands. He whirled about and
dropped his feet down the passage.

There was a second of nervous strain, and then he felt Jimmie's hands
clinging to his shoes. He called to the boy to hang on and to the
others at the top to draw the line, and both were soon on the landing
at the bottom of the shaft.

"I wonder where that hole goes?" Jimmie asked, examining his fingers,
the ends of which were torn from slipping on the rock.

"You came near finding out," Nestor replied. "Regular rabbits, these
old-timers were, to dig tunnels!" he added.

Then assisting Jimmie out of the shaft, Nestor asked the boys to get
all the rope they had in their outfits, making a line as long as
possible, and ease him down the steep incline. In five minutes all was
ready and, with a line 400 feet long attached to his waist, Nestor
started down the tunnel.

As he passed along, half sliding, with the rope holding him back, the
flashlight in hand, he saw that the passage had been cut along the line
of a natural fault in the volcanic rock. It was clear that, during
some seismic disturbance, probably hundreds of years before, the
continuity of strata, until then on the same plane, had been broken,
leaving a fissure where the drop had taken place.

There was no means of estimating the extent of the vertical
displacement, but the boy was satisfied that it was the difference
between the height of the range at the place where the cavern opened
and the height to the north, probably three hundred feet or more. The
north end of the range had dropped down. The horizontal displacement
was not more than six feet, and it was through this that the tunnel ran.

The walls of the passage were smooth, and the floor was like polished
glass, a fact which the boy was at first at a loss to account for. On
the north side the wall was dark and there were no traces of gold,
while that on the south showed spots of precious metal.

Nestor proceeded down the incline until there was little more rope
left, as the boys called o