Abstract: A vent cover for vehicles equipped with roof vents is raisable and lowerable from within the vehicle by rotating a crank. The cover includes a dome formed by a top wall, sidewalls that depend from the top wall, and a venturi cone member secured to an underside of the top wall. A vent base mounted to the roof of the vehicle has upstanding sidewalls so that air molecules exiting the vehicle must flow upwardly to pass over the top of the sidewalls and then downwardly to enter the atmosphere external to the vehicle. The air molecules are forced to flow downwardly after they have passed over the top of the vent base sidewalls by the sidewalls that depend from the top wall of the dome. The cooperative shape of the venturi cone member, the walls that depend from the top wall of the dome, and the upstanding sidewalls of the vent base creates a constricted area above the upstanding sidewalls where upwardly flowing air molecules must change their path of travel to flow downwardly.

Abstract: A structure that provides a substantially unrestricted view of the surrounding environment to its occupants. The structure includes a lower portion defined by upstanding transparent walls, and an upper transparent portion having the general appearance of an inverted funnel. The inverted funnel shape of the structure directs rising hot air currents to the inlet of a chimney positioned at the apex of the inverted funnel. The vertical position of a closure member which forms a part of the chimney is adjustable by the occupants of the structure to control air flow within the structure.