It had been in progress for days. Twice a year on the big, western ranches, the cattle are driven in from the outlying ranges, to be tallied, inspected, marked and shipped away. The spring and fall round-ups are always busy seasons at any ranch. During the times between round-ups the new calves attained their growth, but they needed to have branded into their hides the marks of their owners. Then, too, some yearlings escaped branding at times, either by remaining out of sight at the round-up, or in the attending confusion. Unbranded calves who had partly attained their growth, were termed "mavericks," and when the herds of different owners mingled, there was, usually, a division of the mavericks, since it could not be accurately told who owned them. The title maverick was derived from a stock man of that name, whose practice was to claim _all_ unbranded calves in a herd. His cowboys would ride about, cutting out the unmarked animals, with the cool statement: "That's a maverick," meaning that it belonged to their "boss." And so the name has commonly become associated with any half-grown, unbranded calf. Mr. Merkel was the owner of several ranches, Square M, Triangle B and Diamond X, not to mention Diamond X Second, or Flume Valley, of which his son Bud, and the latter's cousins, Norton and Richard Shannon, were the nominal proprietors. The cattle from Flume Valley, or "Happy Valley" as Bud called it after the mystery of the underground water was solved, were in the round-up with the others from his father's ranches. For days preceding the lively doings I have just described, the cowboys, called in from distant ranges, had driven the cattle toward the central assembling point--the corrals at Diamond X. Slowly the longhorns, the shorthorns and cattle with no horns at all, had been "hazed" in from their feeding grounds toward Diamond X. The cow punchers had galloped hard all day, and they had ridden herd at night, to keep the animals from straying. At night this was not so hard, for the animals were glad to rest during the darkness. But during the day there was always some steer--often more than one--that wanted to run away from the herd. As this might start a stampede it was necessary to drive the "striker" back, and this was, often enough, a difficult task. Bud, Nort and Dick had borne their share of this difficult round-up task, and now, when the thousand or more of steers, calves and mavericks had been gathered at Diamond X, the work of tallying them, branding those that were without marks and shipping away the best was well under way. In and out of the herd rode the boy ranchers, doing their best alongside of more seasoned "punchers." Calves were cut out, thrown and branded, to be quickly released and again mingle with the herd. "Oh, I'm Captain Jinks, Of the Horse Marines!"