The windows seemed to be sliding slightly, very slowly, and as they slid, the sunlight was damped out. I grinned, thinking of what my ancient Egyptian would make of that. I knew there were two sheets of polarizing glass, probably with a vacuum between to keep out the cold and the heat, and the lights in the room were beautifully synchronized with the polarized sliding glass. I wasn't doing so badly. The rest of the objects might not be too hard to figure out. The spools in the case alongside the teacher's chair could be wire recordings. I looked for something to play them with, but there was no sign of a playback machine. I tried to lift a spool off a spindle. It wouldn't come off. Hah! The wire led down the spindle to the base of the box, holding the spool in place. That meant the spools could be played right in that position. But what started them playing? * * * * * I hunted over the box minutely. Every part of it was featureless--no dials, switches or any unfamiliar counterparts. I even tried moving my hands over it, figuring it might be like a theramin, and spoke to it in different shades of command, because it could have been built to respond to vocal orders. Nothing happened. Remember the Poe story that shows the best place to hide something is right out in the open, which is the last place anyone would look? Well, these things weren't manufactured to baffle people, any more than our devices generally are. But it's only by trying everything that somebody who didn't know what a switch is would start up a vacuum cleaner, say, or light a big chandelier from a wall clear across the room. I'd pressed every inch of the box, hoping some part of it might act as a switch, and I finally touched one of the spindles. The spool immediately began spinning at a very low speed and the screen on the wall opposite the window glowed into life. "The history of the exploration of the Solar System," said an announcer's deep voice, "is one of the most adventuresome in mankind's long list of achievements. Beginning with the crude rockets developed during World War II...." There were newsreel shots of V-1 and V-2 being blasted from their takeoff ramps and a montage of later experimental models. I wished I could see how it all turned out, but I was afraid to waste the time watching. At any moment, I might hear the footsteps of a guard or janitor or whoever tended buildings then. I pushed the spindle again. It checked the spool, which rewound swiftly and silently, and stopped itself when the rewinding was finished. I tried another. A nightmare underwater scene appeared. "With the aid of energy screens," said another voice, "the oceans of the world were completely charted by the year 2027...."