Abstract: A sphere is supported in a floating condition by a pneumatic bearing so as to be rotated by compressed air sprayed from a nozzle. The sphere has a single point magnetized on its surface, and is placed on its rotating axis. If the sphere has a dynamic imbalance, the single point is subjected to pressesion around its inertia axis, the locus and displacement velocity of which are measured by the Hall elements arranged in an arc line around the pneumatic bearing, thereby obtaining the dynamic imbalance of the share.

Abstract: Marine propulsion apparatus comprising an engine mounted within a buoyant enclosure, which is adapted to be connected to a marine vessel, which requires propulsion. The engine drives a propeller through a simple drive system. The apparatus is adapted to be fitted into position on pivotal mountings for steering purposes, and may itself be fitted with steering apparatus such that it may be maneuvered independently of the marine vessel for positioning relative to it. The enclosure is sized to permit access around the engine for in-situ maintenance and repair.