Experiment

“The first time machine, gentlemen,” Professor Johnson proudly informed his two colleagues. “True, it is a small-scale experimental model. It will operate only on objects weighing less than three pounds, five ounces and for distances into the past and future of twelve minutes or less. But it works.”

The small-scale model looked like a small scale--a postage scale--except for two dials in the part under the platform.

Professor Johnson held up a small metal cube. “Our experimental object,” he said, “is a brass cube weighing one pound, two point three ounces. First, I shall send it five minutes into the future.”

He leaned forward and set one of the dials on the time machine. “Look at your watches,” he said.

They looked at their watches. Professor Johnson placed the cube gently on the machine’s platform. It vanished.

Five minutes later, to the second, it reappeared.

Professor Johnson picked it up. “Now five minutes into the past.” He set the other dial. Holding the cube in his hand he looked at his watch. “It is six minutes before three o’clock. I shall now activate the mechanism--by placing the cube on the platform--at exactly three o’clock. Therefore, the cube should, at five minutes before three, vanish from my hand and appear on the platform, five minutes before I place it there.”