A small brass gyroscope for teaching purposes. A string wound around the axle was to rapidly spin the rotor so that the properties of a gyroscope could be observed.
The gimbal mounts allow the balanced rotor to maintain its orientation even though the mount is moved about, and if one end of the axle is loaded with a weight, the phenomenon of precession (that is, instead of being tipped over by the weight, the gyroscope slowly turns about a vertical axis) can be demonstrated.