An attitude indicator having a circular, annular transparent tube containing a liquid, preferably colored, and a gas bubble, the tube being constructed for encircling and for being fastened non-rotatably upon the forearm, in a position perpendicular to the length of the forearm of a diver. The readily visible position of the bubble in the tube enables the diver to compare and determine instantly, at any moment, the angular attitude, with reference to gravitational lines of force, of the tube itself, the attitude of his forearm and body, and the angular attitudes of nearby structures and surfaces. As this indicator is intended especially for use where light is absent, or minimal, or obstructed by dark colored sediment suspended in the surrounding water, strong illumination is provided. A battery powered lamp filament sends its light rays in a circular path through a strip of light-conducting plastic material, such as "Plexiglas," for example. The strip is positioned radially inwardly but adjacent to the tube, carrying adequate illumination to the tube contents throughout the entire tube length or circumference.
A three-axis gravity switch having a curved chamber to retain a gravity responsive member such as a ball of liquid mercury, the chamber having a three-dimensional pathway defined on at least one of its walls, where the gravity responsive member and pathway are conductive, either electrically or optically, such that a circuit is completed when the gravity responsive member contacts the pathway, where the switch can be rotated, inverted and translated in three dimensions such that the pathway defines an acceptable three dimensional course of rotation for the switch.
A level constructed of clear acrylic plastic including a piece of colored acrylic plastic which serves as a light collector and a continuous passageway in the clear acrylic which reflects the light collected by the piece of colored plastic. By partially filling the passageway with liquid, a line of reflected light appears on the wall of the passageway above the interface between the liquid surface in the passageway and the unfilled portion of the passageway, whereby the level is easier to read than ordinary bubble type levels.
A levelling instrument wherein a non-level condition is indicated by the projection of a light beam within the instrument on an indicator. The light beam is projected in a constant vertical direction by a reflecting surface that is rotatable about a light source. The light is focused on a left or right direction indicator to indicate when the instrument is not level. When the indicators are activated, the instrument is not in a level position. The reflecting surface can comprise a pendulum mirror or a continuous circular conduit partially filled with mercury.
A spirit-level vial comprising a transparent vessel containing a globule of a first liquid suspended in a medium comprising a second liquid, wherein said transparent vessel is essentially completely filled by said medium, and wherein said globule is capable of moving freely through said medium in response to changes in the spatial orientation of said transparent vessel.
A self-illuminating attitude indicator for use by persons who have been buried in snow or the earth. The attitude indicator has a container partially filled with liquid and a manually operated light to illuminate the container. The liquid may be removed from the container and distributed on the snow to make the location more visible to rescuers.
