Learn how to use the lensatic compass used by the US Military. PRECISION COMPASS. * LENSATIC *. PROVEN • RUGGED ACCURATE. CAMMENGA. FAX ( ANILINE AVE. HOLLAND, MICHIGAN I get lots of questions via email from people wanting to know how to use a lensatic compass, and I think I’ve covered that pretty well in a series of two posts.
Use the illustration above to familiarize yourself with the components of a lensatic compass.
Coming across an old FM, Elementary Map and Aerial Photograph Readingfrom reminded me of the lensatic compass, an instrument not as commonly known these days as it once was. Rotate the bezel on the face of the compass until the indicator is directly over the “north” position indicated by an upper case “N”.
Close is good enough in horsehoes, but I’m hoping exact is the standard for artillery fire. This one will deal with night and low light navigation, a topic that could emgineer several lengthy articles on its own. The regular diurnal variation, with a period of 24 hours, is associated with the daytime increase in ionization producing the ionospheric D layer, and with solar tides in the atmosphere.
The other runs more directly through North and South America. These come from sunspots in the normal sun, but in increased amounts from disturbances called solar flares. Place your thumb in the loop on the side of the compass. Since the ultimate goal is to transfer the angle between the map and compass, why not do it directly? Hold the compass level by your thumb and index cokpass. When you sight a distant object, the magnetic bearing can be read from the dial to an accuracy of a degree or two, with care.
Martin Cortez discovered declination variation inand a certain Norman magnetic dip in A bearing is the angular position of a line in a horizontal plane. A forward bearing is specified from the point you occupy to the distant point, while a back bearing is in the other direction.
The normal method to transfer angles from your lensatic compass to your map and back is with a protractor and a pencil. The reference direction and sense of measurement must be stated, by using compass directions or quoting it as an azimuth.
Robin Reichert is a certified nutrition consultant, certified personal trainer and professional writer. Whenever the luminous magnetic arrow lines up with the luminous short line, you’re following your intended azimuth. You want to find your position using the technique of partial resection, so you need to know that tower’s bearing with a high degree of accuracy.
The compass is often filled with an alcohol and water solution for damping. How to Find a Map Direction. Turn your entire body as a unit until your predetermined azimuth falls under the fixed black index line. Deviation cannot be predicted, and must always be considered when using a compass. Their exact nature and cause are unknown. You can’t take bearings with a GPS receiver, either.
Most mid-latitude inhabited areas have smaller and more regularly varying declinations. According to United States Army Corps of Engineers, the engineer compass is also called a lensatic compass. The Pacific is a region of easterly declination, the Atlantic of westerly. Those lines will intersect at some point if you’re done your resection properly.
Lensatic Compass Guide
With a hand-held compass, we cannot set the compass on line, and then look down and note engiheer position of cmpass needle, as with a surveying compass, but must read the bearing simultaneously with the sighting. Still another is making a closed compass traverse of a field, pacing the distances. What I haven’t covered in much detail is some of the nuances of lensatic compasses, such as the tips and tricks to getting the most out of them in the field.
I can’t see how this compass could be used for taking bearings, and its map uses aside from orientation also escape me. When doing this, the lid is opened flat with the compass case. At the 24 year mark it will be another half of that, and so on.
I cannot find the origin of the word “compass” as applied to the magnetic compass. In the last article we talked about declination, and how magnetic north and true north will vary depending on location and surrounding features. This works in the northern temperate zone. Now we go to intersection and measure the bearing to the west peak from there, as well as a back bearing to intersection An engimeer of how to use a lensatic lensatlc may be mabual. Get your own customized topographical maps, built according to your specifications.
Using your protractor or other straight edge, you draw a line from your current position in the direction of where lenzatic want to go. Hosmer, The Principles and Practice of Surveying: Small maps of the inclination, declination and total intensity for the U.
Most people are aware that lensatic compasses are fitted with small amounts of tritium around the dial.