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Dan McCosh
02-21-2011, 02:41 PM
I have an antique bearing compass (non nautical) that also takes vertical sight bearings, using a kind of pendulum. The dial has a conventional compass rose (n, nw, ene, etc), but the degrees are marked off in reverse--east 90, west 270, etc. Other degree markings on the dial as well, but the whole thing is kind of mysterious. Any speculation as to why the reverse markings?

Uncle Duke
02-21-2011, 02:45 PM
I have an antique bearing compass (non nautical) that also takes vertical sight bearings, using a kind of pendulum. The dial has a conventional compass rose (n, nw, ene, etc), but the degrees are marked off in reverse--east 90, west 270, etc. Other degree markings on the dial as well, but the whole thing is kind of mysterious. Any speculation as to why the reverse markings?
I'm confused - do you mean that "East" is 90 degrees ( 1/4 circle) counter-clockwise from North?

Dan McCosh
02-21-2011, 02:50 PM
I'm confused - do you mean that "East" is 90 degrees ( 1/4 circle) counter-clockwise from North? No, East is marked as 270 degrees. The degree markings are counter-clockwise on the dial. (I'd post a picture, but don't know how to take in, as the dial is not too large.)

Cuyahoga Chuck
02-21-2011, 02:52 PM
Maybe it was installed to be viewed in a mirror.

For that to be true all the various legends would have to be mirror imaged, too.

ron ll
02-21-2011, 03:38 PM
There are sighting compasses used with a mirror that have the rose reversed, and there are tell-tale compasses designed to be mounted over the captain's bunk that have the rose reversed. But I can't imagine any that would have East marked as 270.

Dan McCosh
02-21-2011, 03:45 PM
I just figured it out. When you take a sight (there is a kind of gunsight affair on top of the compass, marking due north on the card) the north needle points to the bearing in degrees. There is a lock on the needle, so you sight, lock the needle, and the needle is on the bearing in degrees. .

paladin
02-21-2011, 03:53 PM
possibly for use on a submarine/periscope?

ron ll
02-21-2011, 04:00 PM
Here is one I've had for years, don't know a lot about it. Think it is designed to stand on a stick or to hang from a wire. The degrees advance clockwise, with 90 to the right if 0 is on top.

http://www.ronlloyd.com/oddstuff/compass2.jpg

ron ll
02-21-2011, 04:02 PM
Also, remember marine compasses come in both clockwise and counter clockwise roses depending on where the lubber line is.

Dan McCosh
02-21-2011, 04:31 PM
Here is one I've had for years, don't know a lot about it. Think it is designed to stand on a stick or to hang from a wire. The degrees advance clockwise, with 90 to the right if 0 is on top.

http://www.ronlloyd.com/oddstuff/compass2.jpgThat looks a lot like this one--with sight on top instead of the hooks. As I noted, the north heading of the needle indicates the bearing of the sight.

ron ll
02-21-2011, 04:37 PM
It's hard to see in this picture, but the vertical standards are sights. The close one has a narrow slit, and the far one has a vertical wire in the center. And yes, North is aligned with the sight. There are two bubble levels and a lock.

Dan McCosh
02-21-2011, 04:46 PM
It's hard to see in this picture, but the vertical standards are sights. The close one has a narrow slit, and the far one has a vertical wire in the center. And yes, North is aligned with the sight. There are two bubble levels and a lock. It is hard to see--but that is exactly what is on the compass I have here. The thing that looks like a pendant swings, so that if you hold it sideways, you can read vertical elevation in degrees. It appears to be for hiking and rudimentary mapping, since the compass needle is undamped, and wouldn't work on a boat.

Uncle Duke
02-21-2011, 06:52 PM
Thanks, much, for the explanation - now I can sleep...
Gracias!

Bob Adams
02-22-2011, 09:34 AM
Surveyor's copmpass???