This is about basis of bearing, it's history, and practical uses, for both in house use, and for publication, with some sort of tolerances, and specifications of accuracy, and certainty factors.
1st, I'm NOT very smart, so what I lack in smarts, I have to make up for in persistence.
I used to go to survey convention, and listen to conversations, that were strange, and odd.
In particular, there was one James Scott, (as I remember) who used to use some sort of elevation to the sun device to determine angle. He was adamant that certain tolerances were impossible, via any means. He had a rather dry sense of humor. Even spoke as an educator/ speaker at a conference. It was always fun. I never have figured out what they were talking about.
My understanding is that there are many ways to determine north (ascending accuracy)
Time, rough guess, it's about 8 am, and the sun comes up in the east, so that's north. (Pointing)
Magnetic Compass. Pull out that lensatic ww2 leftover, from your duffel bag, and look at it, and declare NORTH.
Then, get some sort of better (surveyors) compass, and estimate declination, and there is north.
But, the early surveyors used to use a "Rittenhouse constructed" compass.
They would sleep in the woods. They would find polaris, at night, and carry an ember, from the campfire, and set 2 stakes, that were "on true north". This was the most common method, used by the GLO surveyors, to check, and set declination.
We used to set up transit, and let sun shine backward through it, onto a piece of paper. With an ephemeris, this could generate pretty good bearings. We later got a total station. We were told "you have to buy a solar filter or you will cook your edm". So, we did. Year was 1986, or so.
Then, we got static, single freq GPS. This was where we discovered repeatable brgs in the tolerance of 1" of arc! Wow!
Here we found that most of our sun shots generated bearings were often within 8", 12" and such.
We now use dual freq. GPS, and can use either true, (geodetic) or grid brgs, that are repeatable, to a few seconds, or less, all day long.
I've never gone out and shot polaris. I really should. There has to be some sort of balance between efficiency, and accuracy.
Anyway, can anybody fill me in on what James Scott was doing, shooting an elevation angle, to the sun?
The more we invest into surveying, then the more we can get out of it.
Nate
