Abstract: A rotary positioning device useful for positioning optical devices such as polarizing prisms, or any similar optical device through which light is transmitted and which requires precise rotation thereof. The device is particularly designed to rotate through a limited arc at an extremely fine degree of resolution. The device utilizes cylindrical bearings formed from materials having a spring constant effective to insure lateral stability without experiencing irreversible deformation. In a preferred embodiment, a Beryllium-Copper alloy is utilized for forming the cylindrical bearings.

Abstract: An aquatic exercise device which is to be used within a body of water such as a pool has an element which can be engaged by the foot or hand of an individual, which element is linked to a piston-cylinder combination so that as the user engagement element is moved by the user the piston rides in the cylinder. At the head end of the cylinder there is an opening which provides communication between the cylinder chamber and the water environment. As the piston moves back and forth water is either pushed out of the chamber through that opening or drawn into the chamber through that opening. The size of the opening, which may be selected by the user, determines the degree of resistance to the user's movement against the user engagement element.