Abstract: A rotary thumbwheel switch assembly has a switch module including a translucent light ring for indicating positions of the rotary thumbwheel. The ring is illuminated from within by a light emitting diode which can be snap-mounted in place in the center of the translucent ring. The switch module comprises a thumbwheel to which contact brush sets can be easily secured by a spring biased tab. The switch module can be combined with a separable bezel. The switch module can be mounted from either side of a front panel, and can be connected to circuit assemblies housed by the panel prior to the insertion of the bezel. The bezel secures the switch modules to each other and to the panel. A kit comprising the separable elements of the illuminating diode, the bezel and the switch modules is described. A method for installing the separable elements includes the steps of inserting the modules from the front of the housing panel for testing each module's connection with circuit assemblies prior to installing the bezel.

Abstract: A radiation reflective surface for use with non-reflective type marine vessels has dimple-type retroflective surfaces having right angle corners. The reflecting surface of the target comprises a generally smooth, substantially spherical structure having no sharp cutting edges, while providing retro-reflecting surfaces to impinging radiation at the frequencies expected in the "radar" range.

Abstract: A construction element, such as a slat holding clamp is described having tabs and lungs for engaging the slat. The clamp engages the slat on four sides, and includes a tab through which a cable can be run. Certain tabs may optionally include lugs engaging the slat interiorly. The clamp connects the construction element to means for arranging a series of the construction elements in a row to provide a variable shade curtain for an outdoor work area, or to provide slidable curtains.

Abstract: A threaded fastener of the self-tapping type is described having the conventional head, shank, and pilot end. The shank includes a helically wound thread member impregnated with a carbide or other, harder substance than the metal from which the fastener is made. A thread-cutting fastener, having its pilot tip end impregnated is also described. A thread-rolling machine with a unique impregnating electrode is disclosed. The electrode is shown to engage the fastener selectively during the thread-rolling operation itself.

Abstract: A ground working implement control system having a stationary operating station and a moving ground working station is described having a control clutch arrangement operable at the stationary operating station, for controlling through connection cables the directional movement of the ground working station.

Abstract: A mechanical drive arrangement for a cinematograph projector. A double-sided tooth drive belt passes, in succession, over a motor driven, film take-up sprocket, idler sprocket, intermittent drive sprocket, film feed sprocket and shutter drive sprocket. The intermittent drive sprocket and intermittent motion film sprocket are mounted on a rotatable disc. The axis of rotation of the disc coincides with the circumference of the intermittent drive sprocket at the point where the plane through the axes of both mounted sprockets cuts the region of engagement of the drive belt around that circumference. In consequence, rotation of the disc moves the film anchor point, on the intermittent motion film sprocket, with only slight rotation of the shutter drive. Thereby, ghosting is avoided when racking.

Abstract: Film tensioning and controlling transport mechanism for a cinematograph film projector. The film take-up mechanism has a torque motor drive separate from the projector mechanism drive motor. The torque motor is energised first to tension film before the projector drive motor is energised. The torque motor is first energised with a series temperature-sensitive resistor so that torque, and film-tension, increases before the projector mechanism starts up. Film between the projector mechanism and the take-up spool is formed into a loop over a movable roller, which is spring-tensioned in the loop-lenghtening direction but is restrained by a dashpot in the loop-shortening direction. Film-tension reduces the loop length, but the projector drive motor is energised before the whole loop is taken up.

Abstract: A composite projector gate, aperture and light dowser assembly for a cinematograph film projector. The film guide surface through the gate area is curved convex towards the light source, film being held to curved marginal guides by flexible bands anchored before the gate, in the direction of film motion. A quick-release anchor is provided to retain the tension springs. The projection aperture comprises a removable plate in front of which, towards the light source, are spaced-apart heat screens with a horizontally-moving light-dowser blade therebetween in a space in which is provided forced air ventilation.