Don answered: "O.K., Jim, but you can use the screen now. We aren't going to make you squint through that pipe for the next few hours straight." "That's all right. I'll use the screen as soon as you can prove we're right. Ready?" "Ready," said Channing. Franks closed a tiny switch. Below, in the transmitter room, relays clicked and heavy-duty contacts closed with blue fire. Meters began to climb upward across their scales, and the generators moaned in a descending whine. A shielded monitor began to glow, indicating that full power was vomiting from the mouth of the reflector. And out from the projector there went, like a spear-head, a wave-front of circularly polarized microwaves. Die-true they sped, crossing the void like a line of sight to an invisible spot above Mars and to the left. Out past the Sun, where they bent inward just enough to make Jim's job tough. Out across the open sky they sped at the velocity of light, and taking sixteen minutes to get there. A half-hour passed. "Now," said Channing. "Are we?" Ten minutes went by. The receiver was silent save for a constant crackle of cosmic static. Fifteen minutes passed. "Nuts," said Channing. "Could it be that we aren't quite hitting them?" "Could be," admitted Franks. "Jim, waggle that beam a bit, and slowly. When we hit 'em, we'll know it because we'll hear 'em a half-hour later. Take it easy and slowly. We've used up thirteen of our fifty-odd hours. We can use another thirty or so just in being sure." Jim began to make the beam roam around the invisible spot in the sky. He swept the beam in microscopic scans, up and down, and advancing the beam by one-half of its apparent width at the receiver for each sweep. Two more hours went by. The receiver was still silent of reflected signals. It was a terrific strain, this necessary wait of approximately a half-hour between each minor adjustment and the subsequent knowledge of failure. Jim gave up the 'scope because of eyestrain, and though Don and Walt had confidence that the beam-control man was competent to use the cross-ruled screen to keep Mars on the beam, Jim was none too sure of himself, and so he kept checking the screen against the 'scope. At the end of the next hour of abject failure, Walt Franks began to scribble on a pad of paper. Don came over to peer over Franks' shoulder, and because he couldn't read Walt's mind, he was forced to ask what the engineer was calculating. "I've been thinking," said Franks. "Beginner's luck?" asked Don with a wry smile. "I hope not. Look, Don, we're moving on the orbit of Venus, at Venus' orbital velocity. Oh, all right, say it scientifical: We are circling Sol at twenty-one point seven five miles per second. The reflected wave starts back right through the beam, remember?" "I get it," shouted Channing in glee. "Thirty-two minutes' transmission time at twenty-one point seven five miles per second gives us--ah--"