The ruby rolled across the table and fell to the floor. He smiled as he picked the ruby up from the floor. He estimated that he'd lived more than twenty years in ten-minute intervals, and therefore the trap was not a death-trap. He'd discovered countless ways of fighting boredom and knew he would never succumb to it and resultant insanity. He had entered the other apartments by using the stone ledge and breaking through the windows. In them he had found a total of hundreds of books ... a pair of binoculars that he used to study a multitude of new things from his window ... a typewriter that he used to write books although there was never a completed manuscript ... a chess set ... decks of cards ... hobbies.... There were many more possibilities that he hadn't explored yet and he realized that the Martian had given him a valuable gift: extra years of life. It seemed incredible that a machine could operate continuously for twenty years, but the ancient Martians had been expert in constructing devices without moving parts. He knew little science, but he could vaguely imagine a sort of "gateway" to the space-time continuum that the removal of the ruby had opened. Perhaps during a ten-minute period a predetermined amount of energy passed through the "gateway" and flowed against a radioactive substance in a way and with a force that thrust a few atoms backward in time to the point when the energy didn't exist and that established the cycle. With moving parts, the machine wouldn't have run continuously for twenty years. Something would have broken down. Even without moving parts, the machine wouldn't run forever; the materials themselves would deteriorate sooner or later, or the energy passing through them from the space-time continuum would gradually disintegrate them no matter how strong they were. But for as long as the device operated, he would live without growing old. If it ran a hundred years, he would live a hundred years.... The ruby rolled across the table and fell to the floor. He rubbed his aching head. He had lived approximately thirty years at ten-minute intervals, but the headache had started and grown in intensity during the last year and it was difficult to recall and appreciate all the things he had done. The ruby rolled.... How many years had he lived? Fifty? A hundred? He was unable to calculate it any more, and it was even difficult to think about much