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M1918 Lensatic Compass


ccyooper
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Last week while trying to help a poster determine what type of instrument went into his unidentified case Artu and I broadened the discussion to early compasses. Based upon that discussion I would like to post the following information and possibly end the misidentification of a somewhat common compass. In many publications and online resources the M1918 Lensatic Compass is commonly referred to as the M-1938 prismatic compass and sometimes lensatic compass. I'm not sure where this nomenclature originated as the compass shown online and in the many books is clearly not a prismatic compass (no prism). Over the years I have collected many of these compasses. I am aware of 3 different colors; green, black, and grey. The lowest serial numbers I currently have are made by Ainsworth and the cards are so marked. As the serial numbers get higher the cards may only indicate "made in USA" or are left blank. As with most older compasses the dampening liquid (75% distilled water, 25% glycerin) is normally gone. Like the WWI marching compasses (MkVII D/E, 33% pure ethyl alcohol, 67% distilled water) they can be refilled. They can either be found in the lined button pouch with M1910 hanger or the flapped pouch normally dated 1918. The Online Compass Museum indicates the compass is modeled after the Dolland Compass which was patented in 1917. I believe we copied this compass for use during WWI since most of the flap type cases are marked 1918 with an inspectors cartouche. I suspect it was used by artillery men because of all the additional graduations, etc. I have not seen anything in WWI pubs related to the compass but have not really looked. The only reference I have is TR 1320-B Fire control and sighting equipment (small arms and special infantry equipment) dated 2 Apr 1927. It describes the compass in detail and how to use it. The actual M1938 compass was made by Gurley and Superior Magneto and its development is described in AD-785 549 Nov 73. I am interested in any additional information related to this topic.

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