and grey in the afternoon sunlight.

Throwing himself flat on the brown hilltop, Ballard trained his glass
first on the inner valley reaches of a bridle-path leading over the
southern hogback. There was no living thing in sight in that field,
though sufficient time had elapsed to enable the Mexican to ride across
the bridge and over the hills, if he had left the camp mounted.

The engineer frowned and slipped easily into the out-of-door man's habit
of thinking aloud.

"It was a bare chance, of course. If he had news to carry to his master,
he would save time by walking one mile as against riding four. Hello!"

The exclamation emphasised a small discovery. From the hilltop the
entrance to the colonel's mysterious mine was in plain view, and for the
first time in Ballard's observings of it the massive, iron-bound door
was open. Bringing the glass to bear on the tunnel-mouth square of
shadow, Ballard made out the figures of two men standing just within the
entrance and far enough withdrawn to be hidden from prying eyes on the
camp plateau. With the help of the glass, the young engineer could
distinguish the shape of a huge white sombrero, and under the sombrero
the red spark of a cigarette. Wherefore he rolled quickly to a less
exposed position and awaited developments.

The suspense was short. In a few minutes the Mexican foreman emerged
from the gloom of the mine-mouth, and with a single swift backward
glance for the industries at the canyon portal, walked rapidly up the
path toward the inner valley. Ballard sat up and trained the field-glass
again. Why had Manuel gone out of his way to stop at the mine? The
answer, or at least one possible answer, was under the foreman's arm,
taking the shape of a short-barrelled rifle of the type carried by
express messengers on Western railways.

Ballard screwed the glass into its smallest compass, dropped it into his
pocket, and made his way down to the camp mesa. The gun meant nothing
more than that the Mexican had not deemed it advisable to appear in the
construction camp armed. But, on the other hand, Ballard was fully
convinced that he was on his way to Colonel Craigmiles as the bearer of
news.

It was an hour later when Otto, the colonel's chauffeur, kicked out the
clutch of the buzzing runabout before the door of the office bungalow
and announced that he had come to take the convalescent back to Castle
'Cadia. Bromley was still asleep; hence there had been no opportuni