Go for it reload!! :hatsoff:
Robby
Robby
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Compass
- Thread starter Chris Hayes
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one of the otherthings is where you are at in relation to the time zone. Each of the time zones are centered on noon in that time zone, if your near the sides of the time zone you will be a 1/2 hour off.
reload said:
Varies with your longitude. We're 12° to 13° hereabouts and in the Great Lakes around NY.
Locally its -12°34'W. Easy to remember and good to know.
http://magnetic-declination.com/
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Chris Hayes
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OK Stumpkiller, I am 2 degrees 58 minutes east. Thanks for the post!
One more thing...,
If you get a copy of Old Farmer's Almanac the calendar tables include "sun time" and how to correct for it in your geographic area, so you don't need to find a topo map.
Thanks also for the time-zone tip. :thumbsup:
LD
If you get a copy of Old Farmer's Almanac the calendar tables include "sun time" and how to correct for it in your geographic area, so you don't need to find a topo map.
Thanks also for the time-zone tip. :thumbsup:
LD
I have the brass TOTW compass. I like it. The sundial is ok but I can't seem to get it to work. Every morning I check it to see how much longer until legal shooting light, but it just does'nt work.
Sorry bad joke. The compass sundial work fine for me. I cover a lot of ground sometimes hunting and the compass is great. The sundial is just something I mess with when I'm taking a break and I'm bored.
Sorry bad joke. The compass sundial work fine for me. I cover a lot of ground sometimes hunting and the compass is great. The sundial is just something I mess with when I'm taking a break and I'm bored.
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I did the same thing, then I thought 
it's to dark out to see what it says. Took it in side and set it on the kitchen table where there was some light. It works ok but needs winding, I've had it sitting there on the table for three days. Each time I turn on the light & check it, it shows the same. :shocked2:
it's to dark out to see what it says. Took it in side and set it on the kitchen table where there was some light. It works ok but needs winding, I've had it sitting there on the table for three days. Each time I turn on the light & check it, it shows the same. :shocked2:The best sundials are accurate to within a second visually. Frankly, even when clocks were available they were not as accurate or trusted, and were adjusted to sundials themselves.
You will want to know the delination of your area from true north and either adjust your alignment of your compass when getting a reading or adjust the surface of the dial within the compass on an annual basis. You can determine true north a number of other ways without the compass if need be.
Take a reading. Then adjust by your longitude correction and the equation of time. You should be within 5 minutes of clock time easily.
For instance, in Winnipeg or near to the same longitude I add 28.5 minutes. There are many resources on the web that will help you calculate it. I would suggest the Shadows software. Then add in your equation of time varriable. The equation of time is a variable dependent on the earths wobbly axis and the eliptical orbit around the sun. On Solctices there is generally no adjustment for the equation. The equation will varry + or - up to 15 min depending on the time of year. Charts are readily available and not that hard to take a quick look at before heading out to know the adjustment for a given day or the next week if travelling. For instance, at the time of this post the adjustment would be aproximatly +14.5 minutes on Febuary 12.
So I would simply find true north, take a reading, and add 43 minutes to find the exact time (+28.5 for longitude and +14.5 for the equation of time)
Once you have adjusted the the ring for longitude you only need to find true north and factor in the equation of time.
I bet anyone could read one of these TOTW compasses to within a few minutes of watch time consistently with a little work on the front end although it would really help to have 1//2 hour or 15 min markings etched or engraved.
You will want to know the delination of your area from true north and either adjust your alignment of your compass when getting a reading or adjust the surface of the dial within the compass on an annual basis. You can determine true north a number of other ways without the compass if need be.
Take a reading. Then adjust by your longitude correction and the equation of time. You should be within 5 minutes of clock time easily.
For instance, in Winnipeg or near to the same longitude I add 28.5 minutes. There are many resources on the web that will help you calculate it. I would suggest the Shadows software. Then add in your equation of time varriable. The equation of time is a variable dependent on the earths wobbly axis and the eliptical orbit around the sun. On Solctices there is generally no adjustment for the equation. The equation will varry + or - up to 15 min depending on the time of year. Charts are readily available and not that hard to take a quick look at before heading out to know the adjustment for a given day or the next week if travelling. For instance, at the time of this post the adjustment would be aproximatly +14.5 minutes on Febuary 12.
So I would simply find true north, take a reading, and add 43 minutes to find the exact time (+28.5 for longitude and +14.5 for the equation of time)
Once you have adjusted the the ring for longitude you only need to find true north and factor in the equation of time.
I bet anyone could read one of these TOTW compasses to within a few minutes of watch time consistently with a little work on the front end although it would really help to have 1//2 hour or 15 min markings etched or engraved.
robert reed
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Not that I am overly concerned, I question the hc/pc of a brass cased pocket compass. The US Army went strait from leather and wood cased compass to Bakelite around WWI. Aluminum after WWII. Ship's compasses would have been wood and brass mounted. Early dry compasses were carried in parts and assembled to take a reading. Cards were paper with a compass rose painted on it...very fragile and parts easily lost. These were probably carried in a small box to protect from the elements.
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Stophel
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I have the little brass one. I cannot even see the shadow on the sundial!!! Maybe the brass is too shiny.
Here is an original one from the 18th century. German (probably Nuernberg, which seems to have been the compass capital!)
Along with a compass with a sundial in a turned wood case, which I'm thinkin' is 19th century.
I would like to have or make myself a compass like this one, of more common type. The lid, glass and needle are missing on this example:
I recently got the "Lewis and Clark" compass, and though it is larger, I like it very much. The cardinal points are even in German! (N, S, O, W. Norden, Süden, Osten, Westen)
I may end up eventually making a new case for it. This one is a little too "rustic". :grin:
Here is an original one from the 18th century. German (probably Nuernberg, which seems to have been the compass capital!)
Along with a compass with a sundial in a turned wood case, which I'm thinkin' is 19th century.
I would like to have or make myself a compass like this one, of more common type. The lid, glass and needle are missing on this example:
I recently got the "Lewis and Clark" compass, and though it is larger, I like it very much. The cardinal points are even in German! (N, S, O, W. Norden, Süden, Osten, Westen)
I may end up eventually making a new case for it. This one is a little too "rustic". :grin:
robert reed
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Wow! Those are beautiful. I need to go antiquing.
I have two of these that I use participating with Jaeger's Bn of Rogers Rangers. They are sold as a copy of the Lewis and Clark compass. Not quite as easy to use as modern pieces with no rotating bezel. The one problem I found with this compass (and I'm wondering if anyone else noticed) The bearings or degree readings on the card are backwards. The numbers read from "0" to "360" counter clockwise instead of clockwise! So I took one of them, disassembled it and made a new card for it with the bearing reading clockwise.
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Anyone ever make their own with a cork and needle?
Years ago I got caught on a mesa by lowering clouds (i.e. dense fog). No way to tell direction. No compass in my kit and darkness wasn't far away. Going off the wrong side of the mesa would have been a bad deal.
I was getting ready to set up a makeshift camp for a long cold night when I remembered the cork and needle demo from cub scouts. Pulled a needle from my sewing kit, ripped a piece of styrofoam from a Cup-o-Noodles (the strictly PC version of course :wink: ) and poured a little water into the bottom of the noodle cup. Viola!
Stopped to confirm direction every 100' or so. Made it back to my truck just as it was getting too dark to see.
Now there's always a little bitty compass in my shooting bag, as well as a cork in my sewing kit.
Years ago I got caught on a mesa by lowering clouds (i.e. dense fog). No way to tell direction. No compass in my kit and darkness wasn't far away. Going off the wrong side of the mesa would have been a bad deal.
I was getting ready to set up a makeshift camp for a long cold night when I remembered the cork and needle demo from cub scouts. Pulled a needle from my sewing kit, ripped a piece of styrofoam from a Cup-o-Noodles (the strictly PC version of course :wink: ) and poured a little water into the bottom of the noodle cup. Viola!
Stopped to confirm direction every 100' or so. Made it back to my truck just as it was getting too dark to see.
Now there's always a little bitty compass in my shooting bag, as well as a cork in my sewing kit.
kopfjaeger
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Robby,
That's one super nice horn. :thumbsup:
That's one super nice horn. :thumbsup:
Not to be too picky but 15 min "accuracy" for a sundial is a bit much. (if comparing to a watch)
The difference in Mean Solar Time (what we use day to day) and Apparent Solar Time (astronomical event) can be up to 15 min different.
i.e. The Sun is only directly South at Noon at your location in reference to Apparent Solar Time. Not your wrist watch.
Also, take into account the fact that direction of the Sun at say Noon depends on your position within the Time Zone at "Noon". That is, your Longitude or how far East/West you are from the center of the Zone.
That's probably even a bigger error than the previous one.
Apparent Solar Time was typically used, and was different in each town, up until 1883 when railroads in particular adopted Standard Time Zones.
So 15 minute accuracy from a sundial is a stretch.
https://en.wikipedia.org/wiki/Equation_of_time
https://en.wikipedia.org/wiki/Time_zone
The difference in Mean Solar Time (what we use day to day) and Apparent Solar Time (astronomical event) can be up to 15 min different.
i.e. The Sun is only directly South at Noon at your location in reference to Apparent Solar Time. Not your wrist watch.
Also, take into account the fact that direction of the Sun at say Noon depends on your position within the Time Zone at "Noon". That is, your Longitude or how far East/West you are from the center of the Zone.
That's probably even a bigger error than the previous one.
Apparent Solar Time was typically used, and was different in each town, up until 1883 when railroads in particular adopted Standard Time Zones.
So 15 minute accuracy from a sundial is a stretch.
https://en.wikipedia.org/wiki/Equation_of_time
https://en.wikipedia.org/wiki/Time_zone
That's fine if you're making a map, sailing, or launching an artificial satellite, but seriously, how exact must we be when doing living history of the 18th and 19th century?
Don't get me wrong, I like gadgets, and having a really good period compass and a really accurate sundial would be very cool, but I don't need the precision to the minute when at an event or in the woods. (IF I can see my front and rear sight, it's past the legal shooting time; if I can't see my front and rear sights in an open field, it's not quite past legal shooting time.)
LD
Don't get me wrong, I like gadgets, and having a really good period compass and a really accurate sundial would be very cool, but I don't need the precision to the minute when at an event or in the woods. (IF I can see my front and rear sight, it's past the legal shooting time; if I can't see my front and rear sights in an open field, it's not quite past legal shooting time.)
LD
That tells me you plan well for your outings and are one woods savvy dude. :thumbsup:
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