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An alidade (archaic forms include alhidade, alhidad, alidad) is an instrument for taking bearings, consisting of two arms revolving around a circular brass plate or dial marked with points and degrees of the compass. It is secures on top of the binnacle hood and set to the ship's course, so that any bearing given by it will represent the magnetic bearing as by the compass beneath. Transparent compass, projection compass is suitable for map work or projection. The compass consists of a case with a needle bearing, a transparent degree scale with the cardinal points, an orienting arrow, a magnetic needle with jewel bearing, and a transparent lid. Azimuth compass a portable, dry card compass provided with sight vanes and used for taking bearings. Azimuth attachment is a small, portable, mechanical device, consisting of two revolving arms or sight vanes for resting on the compass glass and by which bearings are taken (see alidade)

Restrictions Only for Ireland and United Kingdom

Attachment Azimuth Bearings Compass Degrees Dial Jewel Magnetic Mechanical Navigational Needle Points Portable Projection Transparent Vanes

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