"Remember that the space traveled by a falling body in a vacuum is equal to one half the acceleration multiplied by the square of the elapsed time. The moon, to which I intend to make my first trip, is only 280,000 miles, or 1,478,400,000 feet, from us. With an acceleration of thirty-two feet per second, I would pass the moon two hours and forty minutes after leaving the earth. If I later take another trip, say to Mars, I will have to find a means of increasing my acceleration, possibly by the use of the rocket principle. Then will be time enough to worry about what my body will stand." A short calculation verified the figures the Doctor had given me, and I stood convinced. "Are you really going?" I asked. "Most decidedly. To repeat, I would have started yesterday, had you arrived. As it is, I am ready to start at once. We will go back to the house for a few minutes while I show you the location of an excellent telescope through which you may watch my progress, and instruct you in the use of an ultra-short-wave receiver which I am confident will pierce the Heaviside layer. With this I will keep in communication with you, although I have made no arrangements for you to send messages to me on this trip. I intend to go to the moon and land. I will take atmosphere samples through an air port and, if there is an atmosphere which will support life, I will step out on the surface. If there is not, I will return to the earth." * * * * * A few minutes was enough for me to grasp the simple manipulations which I would have to perform, and I followed him again to the space flier. "How are you going to get it out?" I asked. "Watch," he said. He worked some levers and the roof of the barn folded back, leaving the way clear for the departure of the huge projectile. I followed him inside and he climbed the ladder. "When I shut the door, go back to the house and test the radio," he directed. The door clanged shut and I hastened into the house. His voice came plainly enough. I went back to the flier and waved him a final farewell, which he acknowledged through a window; then I returned to the receiver. A loud hum filled the air, and suddenly the projectile rose and flew out through the open roof, gaining speed rapidly until it was a mere speck in the sky. It vanished. I had no trouble in picking him up with the telescope. In fact, I could see the Doctor through one of the windows. "I have passed beyond the range of the atmosphere, Tom," came his voice over the receiver, "and I find that everything is going exactly as it should. I feel no discomfort, and my only regret is that I did not install a transmitter in the house so that you could talk to me; but there is no real necessity for it. I am going to make some observations now, but I will call you again with a report of progress in half-an-hour." * * * * *