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Definition: gyroscope from The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide

Mechanical instrument, used as a stabilizing device and consisting, in its simplest form, of a heavy wheel mounted on an axis. The direction of the axis is stable; if it is displaced, the gyroscope tends to resist the change. Applications of the gyroscope principle include the gyrocompass, the autopilot for automatic control of an aircraft, and gyro-directed torpedoes.


Summary Article: gyroscope
from The Columbia Encyclopedia

(jì'rəskōp´´), symmetrical mass, usually a wheel, mounted so that it can spin about an axis in any direction. When spinning, the gyroscope has special properties. Many spinning objects exhibit some of these properties; the rotation of the earth about its axis gives it the properties of a huge gyroscope. Once a gyroscope starts to spin, it will resist changes in the orientation of its spin axis. For example, a spinning top resists toppling over, thus keeping its spin axis vertical. If a torque, or twisting force, is applied to the spin axis, the axis will not turn in the direction of the torque, but will instead move in a direction perpendicular to it. This motion is called precession. The wobbling motion of a spinning top is a simple example of precession. The torque that causes the wobbling is the weight of the top acting about its tapering point. The modern gyroscope was developed in the first half of the 19th cent. by the French physicist Jean B. L. Foucault, and its first notable use was in a visual demonstration of the earth's rotation. In the second half of the 19th cent., with the invention of the electrically driven rotor, its uses multiplied. It became possible to rotate the gyroscope's wheel at desired speeds without interfering with the precession. Large gyroscopes are used in ship stabilizers to counteract rolling. The gyroscope is the nucleus of most automatic steering systems, such as those used in airplanes, missiles, and torpedoes. It is also used in the gyrocompass, a directional instrument used on ships. Unaffected by magnetic variations, its spinning axis, when brought in line with the north-south axis of the earth, provides an accurate line of reference for navigation.

  • See Scarborough, J. B., The Gyroscope: Theory and Applications (1958);.
  • Wrigley, W., et al. Gyroscopic Theory, Designs and Instrumentation (1969).
The Columbia Encyclopedia, © Columbia University Press 2017

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