"Who is he?" Eddie asked shortly. What he had overheard made him more than ever impatient with the older man. So clever and yet so dense, Shelton was. Lina avoided his gaze. "Only Carlos--Carlos Savarino," said Shelton, carelessly, "a Chilean, I think. He worked for me for two months during the summer and I fired him for getting fresh with Lina. Good mechanic, but dumb as an ox. Had to tell him every little detail when he was doing something in the shop. I'd have saved time if I'd done it myself." The girl looked at Eddie squarely now. She was flushing hotly. "And I horsewhipped him," she added. "Yes," Shelton laughed; "it was rich. He sneaked away like a whipped puppy, and this is the first time we've seen him since." Eddie whistled. "And you think he doesn't count in this?" he asked. "Of course not. Too dumb, I tell you. Doesn't know the first principles of science. He thinks the only wave motion is that of the ocean." Shelton chuckled over his own jest. "I wouldn't be too sure," Eddie snapped. "And I want to tell you something, Mr. Shelton. Through no fault of my own, I heard some of your conversation with Li--with your daughter, before I returned here. I was puzzled over your reasons for working so absorbedly on this thing, but now I know them and I think you're wasting your time and keeping your daughter in needless danger." "You dare talk to me like this!" Shelton roared. "I do, sir, and you'll thank me later." Eddie returned the older man's glare with one equally savage. Lina's gurgle of laughter broke the tension. "He's right, Dad, and you know it," she interposed. "Let him finish." Eddie needed no such encouragement, though it warmed his heart. And Shelton listened respectfully when he continued, "I'm into this now, sir, and I intend to see it through to the end. I'll keep your secret, too, though I doubt if it'll ever be of much value to you. Know what I think? I think this Carlos is a damn clever fellow instead of the ass you took him to be. He probably just pretended he was ignorant of science. Why shouldn't he? That way he got a liberal education from you in the very things he wanted to find out. Since you tied the can to him he's had plenty of chances to build a duplicate of your control apparatus--with the aid of some foreign government, no doubt--and now they've stolen two of your machines to complete the job. Your secret already is out and in the very hands you've tried to keep it from." * * * * * Shelton paled visibly as Eddie talked. "But--but how--" he stammered. "How should I know how they did it?" the younger man countered. "Here--let's take a look around. I'll bet they've left their trail right here in this room." He walked from one end of the laboratory to the other, peering into corners and under work benches as he passed. Shelton trailed him like a shadow, squinting through the square lenses of his spectacles.