A-A-52024
above the revolving ring on top of the compass box to a distance equal to the diameter of the revolving ring. The center of the sights shall be positioned in the north-south axis of the compass dial and also to the centerline of the base parallel to two of the beveled edges of the base. The rear (south) folding sight shall have a narrow vertical peep slot centered in the sight. The length of the slot shall be 75 percent of the total length of the sight. The rear sight shall be located on the south end of the compass box and in line with the north-south axis. The front (north) sight shall have a wider slot, 50 percent of the width of the sight, equipped with a vertical sighting line from 0.010 to 0.015 inch wide running the length of the slot. The line and slot shall be centered on the north-south axis of the compass dial at the north end of the compass box.
Compass base. A 4.50 by 4.50 – inch aluminum, nickel, silver, or other non-magnetic material base shall be secured to the compass box by not less than four countersunk screws with the compass box positioned in the center of the base. The relative position of the base and compass box, in azimuth, shall be that the flat-sides of the base shall be parallel to the north-south and east-west axes of the compass dial. The base shall be smooth and flat on the bottom to permit close and accurate positioning on a flat surface. The base shall have cut away or recessed space for screw adjustment devices and fittings. An internal fitting threaded 0.50-20 UNF-2B, shall be provided in the base to accommodate the male end of the ball and socket join to the ball and socket head. The fitting shall not permit dust or moisture to enter the compass box. The base shall have four beveled and graduated edges. Two adjacent edges shall be graduated in 0.50 degree increments, ±30 seconds, through 90 degrees and numbered every 10 degrees up to 80 degrees in both directions. The 45-degree mark shall be at the intersecting corner of the two adjacent edges. Another edge shall be graduated in 0.125-inch increments, ±0.0156-inch and numbered every 1 inch. The other edge shall be graduated in 0.10-inch increments, ±0.01-inch, and numbered every 1 inch.
Specific salient characteristics
Type II, magnetic compass (pocket transit) using ball and socket head.
Compass dial. The compass dial shall be graduated in 1-degree increments and numbered every graduated 10 degrees.
Declination of adjustment. A mechanism shall be provided to adjust the position of the azimuth of the compass dial not less than 50 degrees in either direction.
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