Abstract: In a positioning device, expandable bodies which expand and contract by air pressure are disposed at opposite sides of a movable member in its moving direction, the movable member being able to reciprocate, and a valve device for holding the expandable bodies in their extended states by valve-closing action is provided in an air path device which supplies air from an air supplying device to the expandable bodies. In a massager including this positioning device, the movable member is movably guided in up and down directions by a guide member provided in a back rest of a chair body, and the movable member is provided with a massage element which is projected from a surface of the back rest and is abutted against a body of a person sitting on the chair body.

Abstract: The invention provides an efficient and accurate method for reducing the diameter of a rod or tube of glass, e.g. fused quartz glass rod as a base material of optical fibers, by drawing when the rod or tube is heated and in a softened and plastically deformable state. Different from conventional methods in which the glass rod or tube is held in a horizontal disposition and drawn in the horizontal axial direction or the rod or tube is held vertically and drawing is effected by the downward movement of the lower grip, the rod or tube in the inventive method is held vertically and drawing thereof is effected by the upward movement of the upper grip along with the gradual downward shift of the heating zone relative to the lower grip so that the problems in the prior art methods such as warp and an uneven diameter profile of the drawn rod or tube can be minimized.