GYROSCOPES
Noun
gyroscopes
plural of gyroscope
Source: Wiktionary
GYROSCOPE
Gy"ro*scope, n. Etym: [Gr. -scope.]
1. A rotating wheel, mounted in a ring or rings, for illustrating the
dynamics of rotating bodies, the composition of rotations, etc. It
was devised by Professor W. R. Johnson, in 1832, by whom it was
called the rotascope.
2. A form of the above apparatus, invented by M. Foucault, mounted so
delicately as to render visible the rotation of the earth, through
the tendency of the rotating wheel to preserve a constant plane of
rotation, independently of the earth's motion.
Source: Webster’s Unabridged Dictionary 1913 Edition