Abstract: In one aspect of the invention, a piston is sized to slide along a first axis within a hollow cylinder, and the piston and cylinder assembly is rotatable about a second axis with respect to a support structure. In another aspect of the invention, a container is sized to receive a bag having a mouth larger than a characteristic cross-section of an article to be deposited therein. A member supported by the container has a hole sized in accordance with the characteristic cross-section of the article, and the mouth of the bag is releasably secured to the hole so that the bag is gathered to provide an opening into the bag sized in accordance with the characteristic cross-section of the article.

Abstract: A linkage assembly includes a first link connected at a first point to a translation mechanism attached to a support structure. The translation mechanism is arranged to allow the first point of the first link to translate along a substantially straight axis. A second link is pivotally connected at a first point to the support structure, and at a second point to the first link. A second point of the first link travels on or near an arc of substantially constant finite radius when the first link pivots with respect to the second link.

Abstract: A ball and socket joint for connecting one end of a rail member to a base member includes a ball mounted on the end of the rail member. A socket and a radial slot in the base member permit pivoting of the rail section relative to the base between a first position and a second position. The socket also permits rotation of the ball in the socket to permit rotation of the rail member about its longitudinal axis relative to the base member between a locked orientation and a unlocked orientation. When the rail section is in the locked orientation it cannot pivot relative to the base member and when the rail section is in the unlocked position it is free to pivot relative to the base member.

Abstract: Apparatus for moving within a region includes a base, a tray and a plurality of legs intercoupling the base and the tray. The tray carries a seat and is constructed and arranged so that a person sitting in the seat may use foot power to translate in any direction within a predetermined region and rotate.

Abstract: A collapsible playpen having a pair of spaced apart articulated end frames, wherein the end frames are separated by articulated upper and lower rails. The end frames and rails are constructed so that the playpen is collapsed by folding the lower rails to draw lower portions of the end frames together and simultaneously rotating the upper portion of the opposing end frames away from each other such that the distance between the upper portion of the end frames is greater than the distance between the lower portion of the end frames.

Abstract: A counterbalancing mechanism allows a weight or constant force to be counterbalanced for any practical linear range of travel, including means for effortlessly adjusting the mechanism for a constant force or load of any practical magnitude. A load support slides along an axis substantially passing through a fixed lower pivot point. The load support member is pivotally connected to the top end of an upper lever arm. The upper lever arm is pivotally connected by a horizontal link to the upper end of a lower lever arm that is pivotally connected to the fixed point. A pully that may swivel about its swivel axis embraces the axis and guides a cable connected to the horizontal link at one end to a spring assembly at the other end. The spring assembly may be adjusted.

Abstract: A support structure that may be used as a seat, table or step stool has a top panel substantially 10".times.18" secured between two angled panels substantially 10" above the floor. A pair of normally vertical support members extend between the end panels in contact with the bottom of the top panel and are each formed with a groove that accommodates a tension rod fastened between the end panels. A handle opening is formed near the top of each end panel. The end panels are formed with legs that project beyond the projection of the top panel as seen from the top, both longitudinally and transversely.

Abstract: A balance for teaching arithmetic principles has a balance arm pivotal about a central horizontal pivot axis coincident with the axis of a support rod supported in openings at the top of opposed vertical upstanding members of a support. The balance arm has a central rectangular housing and end rectangular housings at each end extending upward carrying vertical calibrations at intervals corresponding to the height of annular washers that balance the arm. A number of upstanding vertical pins similarly vertically calibrated are spaced at one-inch intervals on either side of the pivot axis at horizontal locations on the arm along respective horizontal calibration indicia of diameter corresponding substantially to the diameter of the central openings in the washers. The front face of the balance arm is transparent along its length for exposing scales on a central mandrel carrying a number of scales that may be rotated to expose a selected scale.