Jim Sackville West, age 10, of Spokane, Washington, for his question:

How does a gyroscope help a ship?

This gifted gadget can keep its balance when everything around it is tipping and tilting, swaying and swerving. What's more, it can point a dependable finger in the right direction when everything else is in a dizzy whirl. We use it to adjust the balance of moving objects and to keep them on course. Gyroscopes can guide a ship across the vast trackless ocean and gyroscopes can help to stabilize it when stormy waves toss it around like a bobbing cork.

The first gyroscope was made in 1852 by Leon Foucault, the famous French scientist who arranged a dramatic demonstration with a pendulum to prove that the earth rotates. This subject fascinated him. Later he made this new gadget so that one and all could observe the earth's rotation. He named it the gyroscope    which means a rotation viewer. You can check this built in talent if you point a spinning gyroscope at the sun. Its pointing finger gradually moves away from the sun    because even the rotating earth does not make it change its direction.

So long as the rotating wheel keeps spinning, its axis remains true. Even if it is pushed off course, it adjusts itself back to its original position. For some years, the gyroscope was regarded as merely a fascinating novelty. Then various inventors began to see how its built in talents could be useful. In the late 1800s, the gyroscope was attached to an electric drive to keep it spinning. Early in the 1900s, it was used to build the gyrocompass, pointed in a charted direction and set spinning. A ship's metal plates did not upset it, as they upset a magnetic compass, and it ignored the rather unreliable magnetic field of the earth. In daylight, darkness and foggy clouds it faithfully pointed in the charted direction.

The gyrocompass was just the beginning. The gyroscope was hitched to other instruments to stabilize the balance of a ship. A set of gyrostablizers checks weight distribution and triggers power instruments to adjust it when stormy seas shift around the bulky cargo. A two inch gyrocompass, spinning 35,000 revolutions per minute, can guide a plane. In 1933, three giant gyrostablizers were installed to balance a great liner. Each weighed 110 tons and its 13 foot rotor wheel made 800 turns per minute.

Later the gyroscope was used to build the automatic pilot. When a gyrocompass is set on course, it can work with a team of other instruments to steer the ship  ¬without help from the pilot. The old toy gyroscope went to sea and took to the air to guide planes. It now works in numerous mechanical systems on earth, in guided missiles, and into space with the astronaut.

The forces that govern a gyroscope are somewhat like those that keep you upright when you ride a bike. A. spinning wheel tends to stay in the same plane, at right angles to its axle. As long as the gyroscope rotor spins, it axle strives to point in the same direction. If some outside force pushes it aside, it adjusts itself back into line. Ships, planes and a multitude of complex modern instruments depend on its pointing finger.