"Nelson must stay here, not only to flash us forth to-night, but above all to have the receiving chamber operating to receive us at the destined moment twenty-four hours later. The force required to operate it is too great to use for more than a few minutes at a time, so it is necessary above all that that force be turned on and the receiving chamber ready for us at the moment we flash back. And since Nelson must stay, and Lanier and I wanted another, we wired you, Randall, in the hope that you would want to go with us on this venture. And do you?" * * * * * As Milton's question hung, Randall drew a long breath. His eyes were on the two great cubical chambers, and his brain seemed whirling at what he had heard. Then he was on his feet with the others. "Go? Could you keep me from going? Why, man, it's the greatest adventure in history!" Milton grasped his hand, as did Lanier, and then the physicist shot a glance at the square clock on the wall. "Well, there's little enough time left us," he said, "for we've hardly an hour before midnight, and at midnight we must be in that transmitting chamber for Nelson to send us flashing out!" Randall could never recall but dimly afterward how that tense hour passed. It was an hour in which Milton and Nelson went with anxious faces and low-voiced comments from one to another of the pieces of apparatus in the room, inspecting each carefully, from the great dynamos to the transmitting and receiving chambers, while Lanier quickly got out and made ready the rough khaki suits and equipment they were to take. It lacked but a quarter-hour of midnight when they had finally donned those suits, each making sure that he was in possession of the small personal kit Milton had designated. This included for each a heavy automatic, a small supply of concentrated foods, and a small case of drugs chosen to counteract the rarer atmosphere and lesser gravity which Milton had been warned to expect on the red planet. Each had also a strong wrist-watch, the three synchronized exactly with the big laboratory clock. * * * * * When they had finished checking up on this equipment the clock's longer hand pointed almost to the figure twelve, and the physicist gestured expressively toward the transmitting chamber. Lanier, though, strode for a moment to one of the laboratory's doors and flung it open. As Randall gazed out with him they could see far out over the tossing sea, dimly lit by the great canopy of the summer stars overhead. Right at the zenith among those stars shone brightest a crimson spark. "Mars," said Lanier, his voice a half-whisper. "And they're waiting out there for us now--out there where we'll be in minutes!" "And if they shouldn't be waiting--their receiving chamber not ready--" But Milton's calm voice came across the room to them: "Zero hour," he said, stepping up into the big transmitting chamber.