Ray Cummings

“ The professor smiled again. “A year is the time it takes the Earth to revolve once around the Sun. Thus you see there are 31,558,149 seconds in a year—which is a little more than 3651⁄4 days.”
“Yes,” said Tubby. “I see.”
“Now to find out how far light travels in a year we simply take its speed per second and multiply it by sixty. That is its speed per minute. Multiply that by sixty gives it speed per hour and so on up to a day or a year. Do you understand?” ”

“ The professor pulled at his side-whiskers thoughtfully. “We must get on,” he said. “Now you understand how far the stars are away. And how fast light travels. That brings us to my Light Machine.”
Tubby sat up with interest. “To the Light Machine. Yes, go on.”
“As you can see,” the professor continued. “I know all about Light—I am its master. No one in the world knows as much about Light as I do. And only one man in the world thinks he does.” The professor’s eyes gleamed vindictively. ”

“ Tubby first heard a low hum and then a whirring, clicking sound.
“This projector magnifies the image—throws it up on a screen.” He pointed to the wall; Tubby saw a small square of canvas hung on the wall.
“Now then,” the professor continued, his voice trembling with emotion, “that star my telescope is pointing at is now exactly nine hundred and twenty-seven and one half Light-years away. That means that eighteen hundred and fifty-five years ago to-night the light we are getting back now from that star left the earth. ”

“ The moving tape carried this endless row of little ciphers swiftly under Tubby's nose. He stared at them fascinated. Faster and faster they flew by as the roll of tape wound up on the spindle the professor was turning. For half an hour he turned briskly. Then the row of ciphers stopped just as the other end of the tape fluttered off the unwinding spindle. ”

“ Tubby could see the beam of light entering at one end and emerging at the other—"these are my image extractors. Each takes from the light some of its images—leaving finally only the earthlight and the images that belong to it. ”

“ He led Tubby to a corner of the room. Tubby saw a perfectly enormous roll of narrow paper tape, like the tape that comes from a stock ticker, or is rolled up around baby ribbon. Only this roll was bigger than he was. It was hung vertically on a spindle, which had a handle to rotate it so that the tape could be unwound and wound again easily. A few feet away there was a similar spindle, but empty.
“I wrote it down for you,” the professor repeated—“the distance in miles of the furthest star from the Earth. ”