Grant Harvey, age 7, of Salt Lake City, Utah, for his question:

Who invented the microscope?

When glass is shaped with curved hollows or humps, it forms a lens. It lets through the light, as an ordinary flat pane of glass does. But it bends the rays so that what we see is a different size. A bulging lens magnifies objects. So does clear water in a glass globe. People learned this useful trick ages ago, perhaps by noticing how sunbeams make things look bigger when they pass through a round glass bottle.     They say that glass globes of water were used as magnifying glasses 3,000 years ago. The Romans used magnifying lenses made from clear rock crystal. A microscope is really a glorified magnifying, glass. We are not sure, but most people think it was invented by a spectacle maker who lived in Holland about 400 years ago. His name was Zacharias Janssen. It is said that he fixed two of his lenses in a tube to make the first microscope, perhaps in the year 1590 A.D.