“That’s my engineer, mister,” he said grimly; “an’ I ain’t lettin’ you make me go to the trouble of sendin’ east for another.  You’re ready now, eh?”

The man behind the boulder had reached a position that satisfied him.  Sanderson saw him snuggle the stock of his rifle against his shoulder.

Sanderson’s rifle cracked viciously.  The man behind the boulder was lying on a slight slope, and when Sanderson’s bullet struck him, he gently rolled over and began to slide downward.  He came—­a grotesque, limp thing—­down the side of the defile, past the engineer, sliding gently until he landed in a queer-looking huddle at the bottom, near the trail.

Sanderson intently examined other rocks and boulders on the opposite side of the defile.  He had paid no attention to Williams’ “Good work, Sanderson!” except to grin and assure himself that Williams hadn’t “lost his nerve.”

Presently at an angle that ran obliquely upward from a flat, projecting ledge, behind which another Double A man lay, partly concealed, Sanderson detected movement.

It was only a hat that he saw this time, and a glint of sunlight on the barrel of a rifle.  But he saw that the rifle, after moving, became quite motionless, and he suspected that it was about to be used.

Again the cheek snuggled the stock of his rifle.

“This is goin’ to be some shot—­if I make it!” he told himself just before he fired.  “There ain’t nothin’ to shoot at but one of his ears, looks like.”

But at the report of the rifle, the weapon that had been so rigid and motionless slipped from behind the rock and clattered downward.  It caught halfway between the rock and the bottom of the defile.  There came no sound from behind the rook, and no movement.

“Got him!” yelled Williams.  “Go to it!  There’s only two more on this side, that I can see.  They’re trying mighty hard to perforate me—­I’m losing weight dodging around here trying to keep them from drawing a bead on me.  If I had a rifle——­”

Williams’ voice broke off with the crash of a rifle behind him, though a little to one side.  Talking to Sanderson, and trying to see him, Williams had stuck his head out a little too far.  The bullet from the rifle of the watching enemy clipped off a small piece of the engineer’s ear.

Williams’ voice rose in impotent rage, filling the defile with profane echoes.  Sanderson did not hear Williams.  He had chanced to be looking toward the spot from whence the smoke spurt came.

A fallen tree, its top branches hanging down the wall of the defile, provided concealment from which the enemy had sent his shot at Williams.  Sanderson snapped a shot at the point where he had seen the smoke streak, and heard a cry of rage.

A man, his face distorted with pain, stood up behind the fallen tree trunk, the upper part of his body in plain view.

His rage had made him reckless, and he had stood erect the better to aim his rifle at the fissure in which Sanderson was concealed.  He fired—­and missed, for Sanderson had ducked at the movement.  Sanderson heard the bullet strike the rock wall above his head, and go ricochetting into the cleft behind him.