on began to feel himself
struggling against a feeling of reluctant admiration.

All his hate could not blind him to the extraordinary mental and
physical efficiency displayed by the engineer. Never once did the
steely muscles permit a slip or false step, never once did the cool
brain miscalculate the next most advantageous movement.

They were now so deep that Blake had to shout his infrequent
directions, to be heard above the booming reverberations of the canyon.
Half way down they came to a forty-foot cliff. Blake made his
preparations, and swung over the edge. Here was an opportunity. Ashton
instantly bent over the knot of the rope.

Close before his eyes he saw the clearly outlined shadow of his head.
He hesitated and straightened on his knees to stare up at the top of
the gorge. He could no longer discern the three down-peering faces,
but he knew that they were still there. And the sunrays still pierced
down to him between the walls of the gorge. The shadows were farther
down, in the lower depths. He must follow and wait.

When he slid to the foot of the cliff, Blake silently cut off the
rope. There was still nearly a hundred and fifty feet left for them
to use below. But they went down more than a thousand feet before they
again had need of it. As Blake had foretold, the lower half of the
descent was far less precipitous than the upper. In places the
vertical measurements were carried down by rod readings, the level
being set without its tripod on the points of rock where the previous
readings had been taken. At other places Blake marked out horizontal
points ahead on the gorge wall, and climbed to them with the chain.

All the time the reverberations of the canyon were becoming louder.
Dark shadows began to gather along one wall of the gorge. The sun was
no longer directly in line with the ravine, and they were now far down
in the lower depths. Ashton's knees were beginning to tremble with
weakness. They had brought no water, for they were descending to the
river. The torment of thirst was added to the torment of his hate. He
began to look with fierce eagerness for the opportunity to do his
work--to accomplish the deed for which he had descended into this
inferno. Then he could go up again, out of the roaring, reverberating
hell about him, away from the burning hell within him.

The shadows were creeping out at him from the side of the gorge. The
sunshine was going--it was flickering away up the opposite pr