Had Bill been there, it isn't likely that he would have approved of their act, but with him away the boys could find plenty of reasons for doing what they wanted to do.
Slim, the cook, had taken no interest in the affair.

He was wrapped up in attending to his misery, and the boys left him in a bunk, soaked with liniment--which by rights was intended for a horse--and trying to sleep and forget his troubles.
As the horses galloped over the rolling plains into the darkness of the south, the boys were thrilled by a glow of excitement.

Each had his rifle hanging in a gun-boat from his saddle.

The mystery of the night; the fresh, keen stirring of the September air; the spirit of adventure; the easy, swinging motion of the horses--all these made the night's hours worth living for.
For a while, by the moon's light, Injun had easily been able to follow the tracks of the horses of the three men, and as they continued toward the south, Whitey felt sure that he had guessed correctly, so the horses were urged to a swifter pace.

Little urging was necessary, however, as Whitey's "Monty" pony and Injun's pinto were fresh and seemed as eager for the chase as their masters.
Whitey's plan for thwarting the bandits was simple.