"I am Professor Zepplin, a sort of companion, you know, for the young men." "Huh!" grunted Big-foot. "I reckon you'd better forget the hard boiled hat you're wearin' or the boys'll be for shooting it full of holes. Take my advice--drop it, pardner." "Oh, you mean this," laughed the Professor, removing his derby hat. "Thank you. I shall profit by your advice, and leave it here when I start." "All the bunch got hard boiled ones?" "Oh, no. The boys have their sombreros," answered the Professor. Big-foot grunted, but whether in disapproval or approval, Professor Zepplin did not know. The cowpuncher threw himself into his saddle, on which he sat, stolidly awaiting the arrival of the Pony Riders. In a short time they came galloping from the stable at the rear of the hotel, and pulled up, facing the cowman. "This, Mr. Sanders, is Tad Butler," announced the Professor. "Huh!" grunted Big-foot again. "Hello, Pinto!" he said after a sharp glance into the freckled face. "Who's the gopher over there?" "That's Stacy Brown, otherwise known as 'Chunky,'" laughed Tad. "This is Ned Rector, and the young gentleman at your left is Walter Perkins, all members of the Pony Rider Boys' party. We are ready to start whenever you are." For answer, Big-foot touched his pony with a spur, the little animal springing into a gallop without further command. The Pony Riders followed immediately, Tad riding up beside the big, muscular looking cowboy, which position he held for half an hour without having been able to draw a word from him. Leaving the town due east of them, the party galloped off across the country in a straight line until finally the cowman pointed off across the plain to indicate where their destination lay. A slow moving mass of red and brown and white met the inquiring gaze of the boys. At first they were unable to make out what it was. "Cows," growled the guide, observing that they did not understand. "What are they doing, Mr. Sanders?" asked Tad. "Don't 'mister' me. I'm Big-foot. Never had a handle to my name. Never expect to. They're grazing. Be rounding them up for bed pretty soon. Ever been on a trail before?" Tad shook his head. "We have been up in the Rockies on a hunting trip. This is my first experience on the plains." "Huh! Got good and plenty coming to you, then." "And I am ready for it," answered the lad promptly. "The rougher the better." "There's the bunch waiting for us. All of them got back from town. The foreman don't allow the fellows to hang out nights when they're on a drive like this." Now, the rest of the Pony Rider Boys, understanding that they were nearing the camp of the cowboys, urged their ponies into a brisk gallop and drew up well into line with Tad and Big-foot. That is, all did save Stacy Brown, who, as was his habit lagged behind a few rods.