He was on the far side of the herd, toward Devil's Hole, and he was chanting the refrain from a simple cowboy song as he looked at the watch.
The hands of the timepiece pointed to "one." Thus he still had an hour to stand watch before awakening the nest man.

He placed the watch is a pocket, shook the reins over Streak's neck and spoke to him.
"Seems like old times to be ridin' night-watch, eh, Streak ?" he said.
The words had hardly escaped his lips when there arose a commotion from the edge of the herd nearest the corrugated land that lay between the herd and the trail back to the Double A.
On a ridge near the cattle a huge, black, grotesque shape was clearly outlined.

It was waving to and fro, as though it were some giant-winged monster of the night trying to rise from the earth.
Sanderson could hear the flapping noise it made; it carried to him with the sharp resonance of a pistol shot.
"Damnation!" he heard himself say.

"Some damned fool is wavin' a tarp!" He jerked Streak up shortly, intending to ride for the point where the tarpaulin was being waved before it was too late.

But as he wheeled Streak he realized that the havoc had been wrought, for the cattle nearest him were on their feet, snorting with fright--a sensation that had been communicated to them by contact with their fellows in the mass.
At the point where the commotion had occurred was confusion.