"They're valuable--sometimes," agreed the veteran cow puncher cautiously. "We hope this one is going to be!" frankly laughed Bud. "We're going to build a watch tower, and take turns staying up in it with a telescope. We can see almost the whole valley if we get high enough, and as there aren't many patches of woodland where the rascals can hide, we hope to spot the rustlers as soon as they begin their tricks." "Well, you may do it," and again the cowboy was very cautious. "I never heard of cattle rustlers bein' caught that way, but when other means fail, try suthin' diffrunt! We'll tackle th' tower!" And as the other cowboys, even Four Eyes, pronounced the scheme worth trying, it was put into operation. Mr. Merkel, to whom Bud communicated his idea over the telephone, rather laughed at it. "How about nights?" asked the ranchman. "No matter how high you are up after dark you can't see any better." "But most of the raids of the rustlers have been in daylight," declared Bud. "It's about fifty-fifty," his father told him. "However, it won't do any harm to try it. Only don't fall off that watch tower of yours. I'll come out and look at it when you get it done." The boy ranchers and their cow punchers started work the next day. Dick and Nort remembered, in a dim way, how, as Boy Scouts, they had helped erect towers, hastily constructed of saplings. Their recalled knowledge, together with the natural adaptability and skill of the cowboys, finally succeeded in there being evolved, and erected, on the aide of the valley rather a pretentious tower. "It must look like an oil well derrick from a distance," observed Nort, when it was al most completed. "What do we care how it looks, if it does the trick?" retorted Bud. "From that perch, and with this telescope dad let me take, I can tell the color of a cow clear to the end of our valley." There was no question but what the watch tower did provide an excellent vantage point. From its top platform, reached by rude ladders, any unusual movement in the entire valley could be seen during the day. It was planned that the boys--and by this I mean the hired cowboys also--should take turns in being on watch in the tower during certain periods each day. A schedule was drawn up by Bud and his cousins, and put into operation as soon as the tower was completed. "And now we'll catch the rustlers at work!" boasted Bud. But alas for their hopes! In spite of all their precautions, and setting at naught the hard work of constructing the tower, there was another raid on the cattle in Happy Valley, about a week after the wooden perch had been set up. It was not a disastrous raid, and only a half score of steers were driven off from one of the more distant herds. But the raid took place, and at night. It was discovered one morning, just as Bud was going up into the tower, where a seat and sheltered place had been built. "They fooled us, Bud," said Old Billee, riding in from a distant part of the valley.