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Buggyman
2005-05-20, 02:06
I wonder if somebody could tell me what navagational purpose a mirror serves on a compass? I recently bought a new Suunto M2 compass at REI because it was the cheapest one I could find that had a declination adjusment (16 degrees east where I hike) and my old basic Silva had a bubble in it that was starting to aggravate me. The Suunto doesn't have a mirror, but I noticed some of the more expensive ones did. I can see where a mirror might come in handy for signaling or shaving, but does it serve any navigational purpose?

Incidentally, I have an old German WWII military compass that my dad left to me. He saw a lot of action in the Army in WWII (D-day, Battle of the Bulge) and somehow obtained this one, never did tell me how. It still works fine, but is a little heavy for hiking. It has these markings on it: Busch, 60727, D.R.G.M., whatever that means. It has a polished metal mirror, a flip up ruler, a rotating dial, appears to be made out of black painted brass, east is marked as the letter "o", and the degree markings go from 0 to 64. Haven't quite figured that one out yet. The luminous markings even still light up!

KLeth
2005-05-20, 03:07
Incidentally, I have an old German WWII military compass that my dad left to me. He saw a lot of action in the Army in WWII (D-day, Battle of the Bulge) and somehow obtained this one, never did tell me how. It still works fine, but is a little heavy for hiking. It has these markings on it: Busch, 60727, D.R.G.M., whatever that means. It has a polished metal mirror, a flip up ruler, a rotating dial, appears to be made out of black painted brass, east is marked as the letter "o", and the degree markings go from 0 to 64. Haven't quite figured that one out yet. The luminous markings even still light up!

DRGM is "Deutsches Reich Gebrauchsmusterschutz".
It's a pattern usage protection in Germany before WWII - much like Patent no.
"O" is for "Ost" which means East.

blackdog
2005-05-20, 07:12
http://www.wwiidaggers.com/20054e.jpg
I found a picture of a compass that fits your description at:
http://www.wwiidaggers.com/POT.htm
(search for the word "busch" on that page. it only occurs once.)

The mirror (when angled at roughly 45 degrees) allows you to see the dial when you're "aiming" (sighting?). The target should be visible through the slot in the mirror. The mirror also doubles as a signal device.

SGT Rock
2005-05-20, 10:22
http://www.du.edu/~jcalvert/astro/mirrorc.htm

A very detailed description of the reason for the mirror and how to use it correctly.

Icemanat95
2005-05-20, 14:35
I wonder if somebody could tell me what navagational purpose a mirror serves on a compass? I recently bought a new Suunto M2 compass at REI because it was the cheapest one I could find that had a declination adjusment (16 degrees east where I hike) and my old basic Silva had a bubble in it that was starting to aggravate me. The Suunto doesn't have a mirror, but I noticed some of the more expensive ones did. I can see where a mirror might come in handy for signaling or shaving, but does it serve any navigational purpose?

Incidentally, I have an old German WWII military compass that my dad left to me. He saw a lot of action in the Army in WWII (D-day, Battle of the Bulge) and somehow obtained this one, never did tell me how. It still works fine, but is a little heavy for hiking. It has these markings on it: Busch, 60727, D.R.G.M., whatever that means. It has a polished metal mirror, a flip up ruler, a rotating dial, appears to be made out of black painted brass, east is marked as the letter "o", and the degree markings go from 0 to 64. Haven't quite figured that one out yet. The luminous markings even still light up!

The compasses with mirrors are used for orienteering. They are a lighter alterinative to a GI Lensatic compass ( a really great tool for navigating by magnetic azimuth. ) THe mirror allows you to read and align the compass while sighting across the notch in the top of the cover. It's a clever arrangement...not as accurate as a lensatic, but the lensatic also lacks the map grid rullers and other features that clear-based compasses offer.

toyfj40
2005-06-18, 06:56
http://www.du.edu/~jcalvert/astro/mirrorc.htm
A very detailed description of how to use it.

The article mentions an import-brass compass for $10 (Store sale).
It happens to be on sale again, FYI, if you're near a store. #42433
http://www.HarborFreight.com/
--toyfj40

blackdog
2005-06-19, 05:49
There are other ways of doing what the mirror does. The suunto M-9 wrist compass has a clever side window. When looking across the top of the compass housing, the arrow of the side window should be kept aligned with two small markings on the other side of the housing. The degrees on the edge of the rotating "card" are clearly visible in the side window. No mirrors are needed and nothing obstructs the view.

Note that the above info is for the mechanical M-9 model, and not the electronic M9 "wrist top computer".

Seeker
2005-06-20, 12:39
I wonder if somebody could tell me what navagational purpose a mirror serves on a compass? I recently bought a new Suunto M2 compass at REI because it was the cheapest one I could find that had a declination adjusment (16 degrees east where I hike) and my old basic Silva had a bubble in it that was starting to aggravate me. The Suunto doesn't have a mirror, but I noticed some of the more expensive ones did. I can see where a mirror might come in handy for signaling or shaving, but does it serve any navigational purpose?

Incidentally, I have an old German WWII military compass that my dad left to me. He saw a lot of action in the Army in WWII (D-day, Battle of the Bulge) and somehow obtained this one, never did tell me how. It still works fine, but is a little heavy for hiking. It has these markings on it: Busch, 60727, D.R.G.M., whatever that means. It has a polished metal mirror, a flip up ruler, a rotating dial, appears to be made out of black painted brass, east is marked as the letter "o", and the degree markings go from 0 to 64. Haven't quite figured that one out yet. The luminous markings even still light up!


the "degree" marks are probably artillerymen's 'mils', not degrees. 0-6400. the US army uses both degrees and mils. maybe the germans only used mils, or you have an artillaryman's compass. i don't know, but there are such things (i had both a mil compass and a lensatic compass as a mortar platoon leader) one mil is the angle formed by a 1 meter change in declination (left or right) at either 100 or 1000m, i forget which. i think it's the latter. so if you drew a polygon 2000m across, with 1 meter sides, it would have 6400 such sides. make sense? the letter "O" marking East means "Ost"... a mil is roughly equal to 1/20th of a degree.

Seeker
2005-06-20, 17:07
Buggyman,

had some time to do a little more research on Mils... amazing what isn't standard in this world... at least we all agree on 24 hours in a day... anyway, i got this off google...

Artillery battalions in many countries use the mil as a unit of angular measure, though there are three different specifications for this unit.
In NATO countries, including Canada, a mil is defined as 1/6,400 of a full circle. This angular measure gets its name from its being approximately a milliradian, a unit which is convenient because 1 mil at 1 km is about 1 metre (and so 100 mils at 2 km is about 200 metres). Or one could say that an object a metre wide one kilometre away from the viewer subtends, to a high degree of accuracy, an angle of one mil. No conversion to Imperial units is worthwhile here, for all armies use metric maps, even the U.S. Army. There are 1600 mils in 90 degrees, 17.8 mils in one degree. This mil is usually used in artillery discussion. It is also used in long-range precision rifle shooting, where the crosshairs on riflescopes are often calibrated in mils. This type of riflescope is usually referred to as a mil-dot scope.
The army of the Soviet Union used a mil that was 1/6000 of a full circle, which means that there were 1,500 of its mils in a right angle, which would be less accurate though easier to remember.
The military of Sweden during the Cold War desired to demonstrate its independence from both NATO and the Warsaw Pact, so they chose a size of greater accuracy. Because a right angle is more nearly 1.5708 radians than 1.600, their mil was 1/6,300 of a circle, so that there were 1,575 of these mils in a right angle.

Jim Henderson
2005-06-20, 21:22
Yeah,

the mirror is so you can see the compass dial which is down, while you are looking thru the sighting notch. Works really well for me.

The USGI version of this compass has a large ring attached on the base. It is for sticking your index finger thru and then using the compass like the end of your finger while your real finger is curled underneath. You sight thru the notch, and the mirror, which BTW should be tilted so the sight near your eye touches the lid of the compass, then you look at the target, line up the target "crosshair" and look into the mirror which displays the compass dial with the sight line clearly showing the degreees. Works really well once you figure it out. From the other article on lensatic compasses, this is what the USGI one is similar to.

I lead cub scouts and they always love this model once I show them how it works. Kind of like sighting a gun crosshair on the traget and reading the compass direction all in one move. It is an "Ah Ha!" type experience, doesn't work at first but then... Ah Ha!

Those brass compasses like at Harbor Freight(mine are from some other outfit and Chinese made) are imho essentially pretty desktop paper weights, if they are the Chinese knock offs of the old British compass. I have two of them, one large and one small, they look like the HF version in the article. They are pretty but the small one is junk and the adjustment screw is stripped and apparently not really designed to turn the entire inner bearing dial. The big one works better but you need a screwdriver to turn the inner dial. It also is not damped so it takes FOREVER for the needle to settle and the sights don't appear to really allow you to use it properlky, at least I haven't figured it out yet even from the instructions supplied. My big one weighs right about 1 pound, not a pocket compass in my mind. It is really pretty though when polished and it does work, like a cheap compass without sighting gear.

So get yourself a real compass. I really like the USGI Lensatic style.

Good Luck,

Jim Henderson

Jim Henderson
2005-06-20, 21:40
As I read the instructions this guy gave, I think I understand a bit better how the Mirror Compass works, but still seems a bit of a PITA. The Lensatic is very easy and automatic once you get it right.

Will Have to play with my mirror Chinese knockoff some more.

Jim Henderson

Buggyman
2005-06-21, 01:19
Belated thanks for all the information guys. And Blackdog, yes that is the German compass I have. I think mine is in better shape though.

bird dog
2005-06-28, 02:24
I was excited to see that I actually could explain a question posed on the site when I saw the "64" degrees. But much to my dismay, Seeker beat me to the punch. I have to say that he did a much better job describing mills than I ever could have done. An artilleryman has a better grasp on such things than an old scout does! Bird Dog

Seeker
2005-06-28, 17:31
I was excited to see that I actually could explain a question posed on the site when I saw the "64" degrees. But much to my dismay, Seeker beat me to the punch. I have to say that he did a much better job describing mills than I ever could have done. An artilleryman has a better grasp on such things than an old scout does! Bird Dog

bird dog,

you take that back! i'm NOT an artilleryman... i am DEEPLY offended... (just kidding... a little parochial humor, for those not of the military sort. artillerymen are notoriously anal, fussy, and detailed. most of them print like it's typewritten, and they're mostly deaf. but thank god they're that way, or we'd all be ducking.). but i was a mortar platoon leader for a few years, among other things, before i saw the light and joined the cavalry. i just mentioned that artillerymen use mils, while the rest of the world uses normal degrees. but thanks for the compliment. and in all honesty, i have to thank both google and my old platoon sergeant, mike rhodes, who taught me how to be an officer. and under his tutelage, i learned to use those damned mils to shoot mortars in a straight line.

bird dog
2005-06-28, 23:42
Seeker - You forgot "One arm bigger than the other"; does that apply to mortarmen as well? No hard feelings, I didnt mean to insult you. I guess that would be like someone calling me a tanker!

Seeker
2005-06-29, 02:34
no offense taken. really.

no, didn't see any limbs bigger or smaller with mortarmen...

saw in an earlier post where you were in c/1/2 acr, but not 'when'. i was in m/3/2 back in the late 80s... never had the honor of being a scout plt ldr though... (did the bradley course and shot it well. gunnery is gunnery... even my wife could hit stuff in the m-1 simulator... but that's not really 'cav scout' stuff...) if you were here at polk in the 2000-2002 timeframe, you might remember a 1sg edd watson. he was my wingman. good nco. taught me a lot about being a leader.

anyway, i digress... this was about compasses, not war stories... sorry, but i miss it some days.

bird dog
2005-06-29, 19:51
Seeker - I was one of the very first scouts at Polk when they moved from Lewis to Polk in 1993. I stayed at Polk until 1999 (I think) when I went to Korea. I was a light Scout my entire 71/2 years. The only time I saw a Bradley was in Basic and then I had to pass the Bradley Gunnery Test in BNCOC. Man I was sweating that. I had already made the points for E-6 and just had to pass that stupid Gunnery Test to get pinned. Thank goodness for a guy named SGT Ayers that helped me with the Bradley part (he had always been a Bradley guy) and I helped him with the light stuff. Worked out to be a win-win situation for the both of us. I miss it everyday. I wound up getting divorced and got custody of the kids. I got out to take care of them. Oh well, such as life. Happy now. Remarried. Good Job. Get to hike where I pick what I pack! Bird Dog

Seeker
2005-06-30, 01:26
army sent me to bradley course after officer basic in 1986. didn't get to use it much, except to run bradley ranges for the regiment in germany when i moved up to staff... i was at drum 91-95. got out in 95, moved to knoxville, opened a business, lost it in 2001, and got back working for DoD in 2002 when i moved here.

i quit camping for fun altogether while i was in except for the occassional odd dayhike. i know what you mean about getting to pick what you pack!

thanks for the info... glad it's all worked out for the best.

bird dog
2005-07-01, 02:03
Did you know a guy named Wayne Citrin while you were at Drum? He was a Scout and should have been there about the same time as you.