Thursday, July 2, 2015

The Abrams Universal Sun Compass

I have had an Abrams Universal Sun Compass in my 
collection for quite a few years now.

Shortly after I got my Abrams, about 10 years ago, I 
searched for the company and found that they were still 
in business in Lansing MI.  In the directions that come with 
the device it explains how to adjust the sundial to get a 
correct reading for each day of the year.  I have a pretty 
good understanding of sundials and know why that is the 
case.  There is a plate on the device that has the dates for 
adjusting for the specific days for that specified year.  I was 
wondering if they continued to make additional plates for 
other years.  --- and how many years did they continue 
to produce them.  I called the company and I spoke to 
someone there about the item.  After describing the item 
and what I was looking for she broke out into laughter.  
Nobody had asked her for one of those since the end of WWII.  
I was amazed that she had been there that long and that she 
remembered the item.  Anyway, I got a good laugh out of it 
too.

The following information is contained in a post at 
Collecting Military Compassesand was provided by Ted Brink 
for inclusion here thanks to his permission:

The U.S. Army Sun Compass was produced during WW2 in 
the early 1940s by Abrams Instrument Co. of Lansing, MI, 
designated Model SC-1. In operation, it could determine 
direction accurately by noting the angle of the sun at a known 
time of day. It was designed for daylight use, but could  
navigate at night by orientation to the Polar star, mounted on a 
vehicle in environments where a magnetic compass might not 
work properly, such as inside an aircraft or truck due to the 
metal content or electrical circuits nearby.The exterior of the 
box is painted olive drab and the lid is lettered:

                        C. of E.
                                     U.S.A.
                             SUN COMPASS

The  C. of E. stands for the U.S. Army Corps of Engineers, 
responsible for military compasses and other instruments 
during World War II. 

In World War II the SC-1 was used in the North African 
desert by the Long Range Desert Patrol (the famed Desert 
Rats) and other American, British or Australian units. Other 
uses were in B-24 Liberator bombers and by Army ground 
troops in the PhilippinesIt is reported to have been used 
through the 1970s for polar region expeditions where 
magnetic readings are unreliable or in the Sahara desert.

company is still in operation today but it has not made this instrument for a long time. Abrams Instrument
specialised in instruments for the aviation industry and made the Sun Compass under contract for the American
government during the Second World War. (The manual in our possession is dated 1943)
Liberator bombers were equipped with this instrument so that, in case of a crash, the survivors could orientate
themselves in the desert.
45° north and south of it, in 3° divisions. Several different length styluses were provided, the tallest of which 
would have been used within the tropics and the shortest in conjunction with the others for night navigation by 
orientation to Polaris, the north polar star. The tips of the styluses contained a tiny glass capsule apparently filled 
with a luminous substance and was presumably used at night but its exact function and method have yet to be 
discovered. The date plate was calibrated for both northern and southern latitudes. Thus the instrument was 
which American patent 2441636 later applied.11 It was calibrated for both hemispheres and from the Equator to 
45° north and south of it, in 3° divisions. Several different length styluses were provided, the tallest of which 
would have been used within the tropics and the shortest in conjunction with the others for night navigation by 
orientation to Polaris, the north polar star. The tips of the styluses contained a tiny glass capsule apparently filled 
with a luminous substance and was presumably used at night but its exact function and method have yet to be 
discovered. The date plate was calibrated for both northern and southern latitudes. Thus the instrument was  3
most others. 
 
immediately usable in either hemisphere and so was consistently universal within its calibrated latitudes, unlike 
The Sun Compass was manufactured by the Abrams Instrument company in Lansing, Michigan, USA. The
company is still in operation today but it has not made this instrument for a long time. Abrams Instrument
specialised in instruments for the aviation industry and made the Sun Compass under contract for the American
government during the Second World War. (The manual in our possession is dated 1943)
The Sun Compass seems to have been used mainly in the North African desert by the American Army. B24
Liberator bombers were equipped with this instrument so that, in case of a crash, the survivors could orientate
themselves in the desert.

3 comments:

  1. Hello, I have two of these compasses. One is completely complete (sorry!) -- everything noted in the accompany manual (TM5-9422). The other is missing some pieces and has three carefully drilled holes in the bottom of the wooden case over a marked X. I have seen two other pictures of these cases with the bottoms opened -- one with two drilled openings over a similarly marked X and the other with a large circular saw drilled opening of about 2 inches. My assumption is that the holes were made for the units used in aviation (B-24s) to prevent high altitude air pressure from hindering an airman from opening the compass. Plausible?

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  2. I, too, have two of these compasses -- one with two drilled holes in the bottom over the marked X. I agree that this version is the one designed for aircraft use, to reduce pressurization when opening.

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  3. The dates for adjustments are the same every year with very minor changes, insignificant for the accuracy of this compass. They pertain to the sun's declination and the equation of time. You can use the compass with confidence even now, more than 70 years later.

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