How do you use an engineer's directional compass?
Answer:
There are several types, and the usage is similar. I assume you mean a Lensatic compass.
The Lensatic Engineer's compass has a front sight wire and a rear sight notch. The compass must always be held so the compass card is level and can spin freely.
To set up the compass, open up the cover/front sight so the wire is standing up straight (vertical). The open the rear sight notch and magnifier to an angle that allows you to see through the notch to the wire and beyond, while also having the magnifier focus on the compass index line. The index line is a tick or line over the compass card that lines up with with the bottom of the front sight wire.)
To take a sight along a bearing, turn your entire body while holding the compass until the desired bearing lines up with the index mark - then, while holding the compass at that position, look up through the notchand wire sights to an object or feature along that bearing.
To determine the bearing to an object, reverse the procedure. sight the object through both the front and rear sight. Then look down and take the reading off the compass at the index line. That is the bearing to the object.
Silva and Brunton make compasses that are easier to use that use a mirror and a more typical bezel, which has the advantage of allowing the user to set the bearing ahead of time and just line up the needle in the "box". I prefer these to the lensatic.
How to use the Engineer Compass
Finding real position on Map by compass
Take two azimuth bearing on separate characteristic points visible on the terrain and indicated on map. Then on your oriented map, take the angle degree reading according to (a) and then draw two rays from each of the above points according to the angle reading, where the two rays intersect is your aresent location.
Map Orientation by Compass
Lay map down on flat level surface, then align north indicating line on map with magnetic north on compass. The map is now oriented.
A Magnetic Azimuth
A magnetic azimuth of any object is the compass reading of a direct line across the center of the compass to the object.
(a) when taking the azimuth reading, set sight on object through Slot and Wire, then read degree scale through lens.
Walking in darkness and dense fog and through rough terrain
The line on the glass bezel is for quick walking through rough terrain: (On the surface of the glass are found two lines, long and short. They form on angle of 45° with each other.) First, turn your compass to face True North, then rotate the luminous line on your glass bezel to whatever number of degrees you wish to walk; example: move bezel until line is on 60° when compass is aligned with North, now you may take a quick reading at any time. While you are walking, just turn your compass towards the magnetic North and walk in the direction of the line on the bezel.
Bezel rotates 360 degrees and is marked off in 3 degree notches for easy computation. (A glass plate may be turned around.)
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