Abstract: An enclosure includes a chamber holding a driver with an end at a first opening in a housing and a rear end nearby a first terminal end of a passageway having a second terminal end at a second opening in the housing. The driver projects sound waves into a listening area directly through the first opening and simultaneously projects sound waves along the passageway and out the second opening into the listening area. The passageway comprises expansion and compression zones of different cross-sectional areas.

Abstract: An enclosure includes a chamber holding a driver with an end at a first opening in a housing and a rear end nearby a first terminal end of a passageway having a second terminal end at a second opening in the housing. The driver projects sound waves into a listening area directly through the first opening and simultaneously projects sound waves along the passageway and out the second opening into the listening area. The passageway comprises expansion and compression zones of different cross-sectional areas.

Abstract: There is disclosed an elbow cover formed of a flexible thin sheet having a bistable configuration with: (1) an open stacking shape having an interior concavity and exterior convexity formed with a substantially ellipsoidal central portion and opposite, laterally projecting, substantially parabolic hyperboloidal ears; and (2) a closed, stable configuration forming a tubular elbow shape with the ears folded inwardly, completing the tubular ends of the elbow shape. The elbow cover is characterized by an unstable configuration assumed by compression of the closed tubular shape between its opposite outside tubular edges whereby the elbow shape flexes and spreads open, laterally separating the ears in a position permitting a one-handed application of the cover to an insulated elbow joint of tubular conduits.

Abstract: An improved tray attachment for a chair wherein a mounting mechanism for the tray is attached to the underside thereof, and is provided with a pin extending in parallel with one side of the tray, such pins having a free end for being slidably received in a mounting block, whereby the tray may be moved in forward and rearward directions by such slidable movement and may be pivoted to a vertical storage position about the axis of such pin. The mounting block is also pivotally mounted on a transverse horizontal extension of a vertical rod, wherein the tray may be raised and lowered by raising and lowering the vertical rod, and by fixing such rod to an arm of the chair at its desired height. The pivotal connection between the transverse rod and the mounting block permits the tray to be tilted, and a second vertical rod, attached to the opposite arm of the chair, may be raised and lowered to support the tray in a horizontal or tilted disposition.

Abstract: A cover for covering elbows or angles in tubular conduits formed in the shape of a convoluted sheet of material such as polyethelene, and shaped to form a first stable configuration state fitting part way around the object to be covered. Opposite ends of the cover are caused to encircle the selected portion of the object in a second stable configuration state. In other embodiments, the cover has an integral part thereof, coupling ribs, adhesive, a tongue-in-sleeve or belt-in-loop arrangement or other coupling means or combinations of coupling means by which two opposite ends of the cover are coupled together around an object.