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.

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A plot of the traverse can then be made, lendatic the enclosed area calculated. The point where those lines lemsatic is your location, and the accuracy of that location is only as high as the readings and calculations that you’ve made. The whole dial rotates, and the magnetic needle is out of sight below it.

I get lots of questions via email from people wanting to know how to use a lensatic compassand I think I’ve covered that pretty well in a series of two posts. One disadvantage is, unlike the orienteering compass, it’s not easy to make it double as a protractor, meaning you’ll have to carry a protractor with you. This is exactly the way land surveys were made in former days, except that a chain was used for the distance measurement. An agonic line runs through the U. Now draw a line between the two points on the map, and determine the true bearing with a protractor.

Another useful exercise is locating yourself on a map by taking bearings to two or more visible points and then plotting the back bearings comapss a map. The back azimuth is nothing more than the opposite direction of the reading you’re taking.

The compass card may have a sapphire cap and an agate point for its lensaatic. Ionospheric currents also affect the magnetic field on a manaul basis, and during magnetic storms, but the effects on a compass are smaller than the usual errors of measurement.

If the north directions are shown on the map in a diagram, true north is a full arrowhead or a star, magnetic north a half-arrowhead, and grid north by a “y”. Tritium is considered safe for external use because manhal is a weak beta particle emitter – so weak in fact that the radiation it emits cannot penetrate human skin. The results are shown in the diagram.


The bezel clicks as it moves–three degrees for every click. Coronal Mass Ejections CME’sin which large bubbles of plasma are ejected by magnetic action, are also responsible.

Some compasses are like this, but they could not be used in the same way to measure a bearing. If you point compzss hour hand of a watch manua the direction of the sun, then south is halfway between the 12 and the hour leensatic. I, Elementary Surveying11th ed. If you don’t happen to be in Northern Colorado, you can construct a similar example any convenient place near you, and do it as a compass or a map enginer. The use of the compass is responsible for some of the oddities in the early public land surveys.

With a hand-held compass, we cannot set the compass on line, and then look down and note the position of a needle, as with a surveying compass, but must read the bearing simultaneously with the sighting. Iron on or near one’s person is a fertile source of deviation. We know all the angles and a side opposite one of them. You need to write things down, draw lines, perform lensaitc, and make sure you do so with a reasonable degree of accuracy.

The classical engineer’s transit had a compass in its base. At the 24 year mark it will be another half of that, and so on. Except along agonic lines, the needle points east or west of true north, and this is called the declination.

That’s the reason for this page, where I’ll tell what Lensatid know about the lensatic compass from long acquaintance though not much recent use. An iron Flinder’s bar is one example. Turn your entire body as a unit until your predetermined azimuth falls under the fixed black index line. When doing this, the lid is opened flat with the compass case.

I can’t see how this compass could be used for taking bearings, and its map manuaal aside from orientation also escape me. This, in a nutshell, is how to perform a resection lensatif a lensatic compass.

Next we’re going to talk about some of the uses of a lensatic compass, starting with the resection. There may be a good site out there, but some I tried had vanished, and the rest were by people who would like to sell you a compass.


Lensatic Compass

Point of Interest In addition to degrees to measure directions in a circle, the oensatic also uses 6, mils. So with that in mind, I’ll start a series of short articles that each focus on a single tip for getting the most out of your compass. Now, hold the compass level and squarely in front of you. A forward bearing is specified from mabual point you occupy to the distant point, while a back bearing is in the other direction. This procedure can be rendered accurate enough for critical use by considering the actual position of Polaris and using a transit, but just assuming that Polaris is N will be satisfactory for compass work.

You will only see a soldier using a compass with his helmet on in a movie. If you examine the measurements of the field, on some days the records are smooth and only slowly varying.

The total intensity F of the geomagnetic field is now quoted in nT nanoteslawhich were once called gammas. Locate yourself and a prominent distant object on the map, and measure its magnetic bearing with the compass. Using your protractor or other straight edge, you draw a line from your current position in the direction of where you want to go.

Lensatic Compass Guide

Wide areas of China have almost zero declination, for example. In the event that you’re under strict light discipline in a military setting, for example you can simply sup your hands around the compass and the head of the flashlight so that no light escapes. How to Hold a Lensatic Compass.

That’s the heading that you need to move along to reach your desired end or way point. There should be an index mark above the dial aligned with these marks. Deviation cannot be predicted, and must always be considered when using a compass.

They have no significance for compass measurements, but are of intrinsic interest, and this seems the best place to discuss them.