I tried to post a reply but apparently have not yet been successful. What gives?
Kevin Samuel, post: 327671, member: 96 wrote: I was just visualizing a spherical triangle and I am cognizant of the difference between a spherical triangle and planar triangle.
Yes, the question was for you. I read your earlier posts and saw the 360-degree proposition. Most folks are concerned with the difference between the two azimuths. It is a good insight into the nature of this problem.
For what it's worth, not reducing the line to the ellipsoid introduces an error of 160 ppm using the elevation factor that I calculated. In more conventional terms, that's an accuracy of 1:6250. I think that the ellipsoid height is probably closer to 900 meters. If that's true, the error introduced by not reducing the ground distance to the ellipsoid is 140 ppm, or an accuracy of about 1:7140.
EFBURKHOLDER, post: 327688, member: 1856 wrote: I tried to post a reply but apparently have not yet been successful. What gives?
Earl, I can see your previous post offering help.
Andy Nold, post: 327243, member: 7 wrote: The only thing I don't understand is why my Latitude is slipping. I thought that if you start out on a given latitude and head due east, your latitude should stay the same?
My initial point is 32å¡00'00.5755"N 103å¡49'53.9675"W
Then E - 2710.185m to 32å¡00'00.5638"N 103å¡48'10.7147"W
Then E - 9652.019m to 32å¡00'00.4158"N 103å¡42'02.9915"W
My latitude seems to be heading south. If I am supposedly headed due east on a circle of latitude, why is the latitude changing when I calc the destination points? I'm missing something here.
Your First point is Clark 26, (mile post 45 is close) then there is an Old Stn Mnd at a Fnc Cor at your second point, just east of it at the called distance from 26 is a Lucchinni cap and your third point is near an OSM, those are along lines unaccepted by the GLO, Davey Edwards has recently completed the "resurvey" of those Blocks Look at Nick Thees rolled sketch for that area, show a ton of stuff along the State Line. There are Brass Cap monuments every mile along the state line.
Is it Clark 27 or 29 they're arguing over, I can send you coordinates of the split top 2" IP that either Twichell or Sanders set in the supposed charred remains of the Clark monument, but it has been discounted by the GLO.
I've found and shot Clark 22-26 and a couple old Stones marked T / NM that are å±100' into NM.
Greg Shoults RPLS, post: 327733, member: 531 wrote: Your First point is Clark 26, (mile post 45 is close) then there is an Old Stn Mnd at a Fnc Cor at your second point, just east of it at the called distance from 26 is a Lucchinni cap and your third point is near an OSM, those are along lines unaccepted by the GLO, Davey Edwards has recently completed the "resurvey" of those Blocks Look at Nick Thees rolled sketch for that area, show a ton of stuff along the State Line. There are Brass Cap monuments every mile along the state line.
Is it Clark 27 or 29 they're arguing over, I can send you coordinates of the split top 2" IP that either Twichell or Sanders set in the supposed charred remains of the Clark monument, but it has been discounted by the GLO.
I've found and shot Clark 22-26 and a couple old Stones marked T / NM that are å±100' into NM.
36 miles from SEc NM falls very, very near the 2"IP near 27/29
Greg Shoults RPLS, post: 327740, member: 531 wrote: 36 miles from SEc NM falls very, very near the 2"IP near 27/29
Sounds like this boundary resolution is going to involve gnashing of teeth, alcohol, conflicting evidence, heartburn, hair loss, lack of sleep, and many peer review meetings!
Think I'm just gonna keep my mouth shut fer a change. Enjoy the silence.
Andy Nold, post: 306111, member: 7 wrote: I find that the survey I am retracing is based on a east-west line which has been broken for curvature every six miles. What is the easiest way to calculate the angle difference at each six mile interval for a given latitude?
Where's Keith Williams when I need him?
Sorry to be so late for the party, but if a PLSS or State line is defined as a latitudinal line it was probably surveyed by the tangent or secant method and the line as monumented is curved between the six mile monuments. The "broken for curvature" correction involved jumping to the last offset monument and hopefully a new observation of true north every six miles to correct up and reset the offsets to zero. The actual "constant bearing" instrument stations were used to place monumentation on the offsets and have no weight except for retracement purposes.
I find it hard to believe a latitudinal line boundary was only corrected for curvature every six miles if run on the ground with monuments set along the way. Agreed the offsets are only a few feet if using the secant method, 25 feet if using the tangent method at average latitudes. Your description implies the survey was conducted by establishing true east thence running six miles on a straight line as defined by the theodolite and deflecting at the six mile marker. That is not a survey of a latitudinal line and will generate 25 foot errors every six miles.
I bring this up because when working for the BLM (early seventies) we used solar transits where every 5 chain pulls or so (1500') we'd ignore our backsight bearing and reorient to true north using the solar attachment. Do you see how we were automagically traversing a line of latitude within a few tenths? And, no corrections for the next six mile leg, orient using solar and off we'd go. The downside was some time each evening calculating the instrument man's peg book numbers for the following day, having to have somewhat accurate time in the field and the instrument man had to be devilishly smart at operating a cranky instrument in tough open sun conditions. The upside was no observations allowed near local noon so there was always a "siesta" midday, and of course, cloudy days were a washout.
MightyMoe, post: 327668, member: 700 wrote: Honestly, I've never heard of such a thing, what kinda lands are to the north, and why aren't they controlling?
Sounds like a court case. I did have one similar, a line of longitude to stake. It was blank also, much easier...........
Ran 4 miles of fence along it, took an afternoon.
The example I had in mind... being the first surveyor running the township exterior. You are establishing the control. Not very common these days.
Kevin Samuel, post: 329352, member: 96 wrote: The example I had in mind... being the first surveyor running the township exterior. You are establishing the control. Not very common these days.
The problem I had was an administrative boundary that turned into a property boundary along a line of longitude. Nothing had been staked along it, although an unmonumented plat had been produced.
There was no directive just what longitude was to be staked NAD27, NAD83/86, 83/93,,,,,,,,
Of course a line of longitude is a moving target constantly changing with the next update of OPUS/CORS NAD83(xxxx).