Improvements in magnetic compasses for marine or aerial navigation

摘要

191,698. Doignon, A. L. Jan. 12, 1922, [Convention date]. Void [Published under Sect. 91 of the Act]. Mariners' and aeronautical compasses.-In a liquid compass, for use in marine and aerial navigation, expansion and contraction of the liquid are counteracted by the provision of an annular air cushion around a downwardly-projecting tube T, and air bubbles which form beneath the glass G1 are transferred to the annular air space by suitable manipulation of the container. A course-setting pointer A is adjustable about the pivotal axis of the compass-oard P as follows. A tube g, mounted for sliding vertically without turning, is adapted to be raised by operating a handle on a shaft a carrying a crank arm m engaging a groove r formed on the tube. The tube lifts the compass-card from its pivot without turning it until the upper end of a socket on the card abuts on a centre piece on the glass G'. While the compass-card is thus held stationary a milled knob n is turned to operate a spindle L carrying at its lower end a finger c which engages a finger i on the pointer A to adjust the pointer. The handle is then released to lower the compass-card on to its pivot. The. end of the pointer A and the lubber line are rendered self-luminous.