Gyroscope

GYROSCOPE s. (Gr. guros, circle; skopéô, I watch). Phys. A device that is used to demonstrate the existence of the diurnal rotation of the earth: the gyroscope was developed in 1852 by Foucault. The simplest form of gyroscope essentially consists of a disk rotating on pivots in a circle, and bearing on one side, on the line extending its axis, a rod with a conical depression underneath, to hold the tip of a vertical support. When the disk is made to spin fast enough, the device, instead of falling, performs a revolution around the supporting point, in the same direction as shown by the arrows in our figure. — See: Analysis of Rotary motion as applies to the Gyroscope, J.-G. Barnard (New York, 1857).
 
Extract from the Trousset encyclopedia, 1886 – 1891.