SIMPLE "HOW TO" ABOUT THE HIKING AND MILITARY COMPASS.
August 24, 2002. Saturday morning before nine. This morning I have a clear picture of how to write this. Allow me to give you mental pictures, to explain. More detail will be added, later.
WHAT IS DRIFT?
Imagine yourself traveling on the tines of a fork. You know, the eating utensil. Your compass has given you your direction of travel, but you keep running into natural obstacles. When you get where you are going, you probably moved from one tine to another.
You can overcome drift by deliberately picking up some natural feature to one side of where you want to be. You might choose a stream that runs into a lake. Suppose you sight yourself a good ways East of the mark, and follow that setting until you hit the stream. Now, by traveling West along the stream itself, you will find the lake. The same would work for the ridge of hill.
ALL COMPASSES WORK THE SAME, OR THEY WOULD NOT BE COMPASSES
The face of the common, flat, hiking compass yields the same result of the face of the opened flat military compass. On the hiking compass, you point your base plate, and its arrow, where you want to go. By turning the outside dial, so that the red N lines up with the North Compass Arrow, where you are standing, you have the compass set. Whenever N and North line up again, during travel, you are again traveling on one of the "tines" of your fork. (Along a line at least parallel to the one you want.)
On the Military Compass, also called an Engineer's or Lensatic Compass, you point your compass, folded out flat, and its fixed black line on the center of the dial, where you want to go. By turning the outside dial, so that the small luminous mark lines up with North on the Compass face, where you are standing, you have the compass set. Whenever the small luminous mark lines up with North on the Compass face again, during travel, you are again traveling on one of the "tines of your fork."
This example works for simple compass use, like "I walked into the woods on this setting, walking out the reverse will get me home." Stand yourself in front of the forward direction on your "set" compass. (When you set it, you were behind it.) Now, just turn it around. Align your red N or luminous mark with North on the compass dial, with your compass in the new, opposite direction, and the compass is reset. (The books call this a Back Azimuth.)
WHY DO THE MILITARY COMPASS "BEND" LIKE THAT?
The cover of the military compass has a slot with a sighting thread. The finger side of the compass has a lens that magnifies the face of the compass. The housing of this lens has a notch that lines up with the thread in the front slot, while you look through the lens at the face of the compass. What you now have is a very accurate way to sight your compass. The magnified image of the compass face and the thread in the slot are viewed together. Instead of a general compass orientation, you have a really exact one. Whatever you have chosen to sight to will be measured exactly. The good news is that most people don't need that.
Once you have determined your degree setting, fold the military compass flat, line up the fixed line with the degree setting, and rotate the outer ring with its little luminous mark until the luminous mark is over North on the compass dial. Things are set up as before.
There is really not that much to this, but most technical writing makes it seem harder. Paul