Abstract: This invention relates to pressure indicators, and more particularly to an improved pressure indicator whose use is especially advantageous in sensitive pressure altimeters in which high resolution and low friction are important.

Abstract: A thermostat having a cover plate rotatable about a central horizontal support in which a bimetal or other thermally responsive member supported on the cover plate actuates a mercury switch also on the cover plate. This cover plate also has upon it indicia such as degree marks or simply arrows indicating "colder -- warmer" operable against an imaginary vertical lubber line to indicate a setting. The need for time consuming and expensive levelling of the thermostat during installation is thus obviated because the thermostat is automatically levelled by the user as a result of setting the indicia in relation to the imaginary vertical line.

Abstract: An aircraft instrumentation having inherent self-checking features. Radar and barometric altitude information are displayed on the dial face of a single instrument. A cooperating dial and first pointer displays barometric altitude. A manually settable indicator "bug" cooperates with the dial to provide a presentation of the height of the airstrip relative to sea level. A second indicator "bug" of a different shape from the landing field bug is servo-driven from both radar and barometric altitude signal inputs to provide a presentation of aircraft altitude relative to the terrain beneath the aircraft. The angle between the barometric altitude pointer and servoed radar altitude "bug," measured counterclockwise, constitutes the distance of the aircraft above the airstrip or other terrain which the aircraft is passing over. Upon touchdown both "bugs" should be in exact coincidence, thereby serving as a self-check upon accuracy of the instrumentation.