Rudy Harrison, age 9, of Vancouver, Wash., for his question:

HOW DOES A LIGHTNING ROD WORK?

A lightning rod is a device that protects homes and other buildings from damage by lightning. A common type has a pointed metal rod installed on top of a building. A wire or cable leads from this rod to a ground rod buried 10 feet or more in the earth.

The ground rod should be buried at least two feet from the building in moist earth. It should be as straight as possible.

If a building has several metal supports, each should be connected to a lightning rod and there should be several ground connections.

Lightning rods are most often used in farming regions to protect homes, barns and windmills. They are not often seen in cities because there is so much metal used and the buildings stand close together.

Other kinds of lightning protectors are used on power stations and telephone wires.