Determining longitude with conventional instruments and accurate time is a difficult task. The expected accuracy is at best a couple of hundred feet, I think.
The easiest way to do it is to observe meridian passage of the Sun. That is tough at this time of year because the sun is so high. However this method is probably not as accurate as more rigorous methods.
I played around with celestial navigation a little. I could get within a half nautical mile without too much trouble but getting closer than that is more difficult.
I would think an old boundary like that is already established unless it is out in the desert or large opens spaces and it truly hasn't been established.
We need to set several points on a given longitude to establish its location on the ground. We have several NGS stations in the vicinity. How would you do this?
I am struggling to understand this question. We would put our RTK in latitude display and stake to it. Am I missing something?
That's what I've done also.
I think what you're missing and the rest of are missing is what line of longitude we are talking about. County lines that I know about are placed along some kind of recoverable description. If it's a line of longitude is it a guide meridian? Or some other defined line. Or did they just say the 110degree line of longitude in 1870. That would be hard to figure out.
If you want to just stake the 110degree longitude line my rover will display the location in degrees while you walk around with it. You could set it and check it with static. Simple!
It should be quite simple, actually
"Staking a line of longitude"
First you get ahold of a globe. Measure the circumference as neatly as you can with a ruler. Then measure the width of one of the black lines showing longitude. On my globe its about 15 miles wide. If you can't get your line within 7.5 miles either side of the middle of that "line of longitude" you need to go back to selling french fries for a living.
MD WVA history might be relevant
or at least an interesting read:
"Virginia did not approve of the Michler line, but in 1887 West Virginia passed an act confirming the line as run by Lieutenant Michler in 1859 as the true boundary line between West Virginia and Maryland, but the act was not to take effect until and unless Maryland should pass an act or acts confirming and rendering valid all the entries, grants, patents and titles from the Commonwealth of Virginia to any person, or persons, to lands situate and lying between the new Maryland line and the old Maryland line heretofore claimed by 38*38 Virginia and West Virginia, to the same extent and with like legal effect as though the said old Maryland line was confirmed and established.
The divergence between Michler's line and the line shown on Deakins' map probably arises from the fact that Lieutenant Michler ran a true astronomical line, and that his line is a true north and south line, whereas the Deakins line was probably run with a surveyor's compass, and with less accuracy than the Michler line.
"
MD WVA history might be relevant
Don Teter & I jointly do a workshop about this and other state boundaries. Look for us sometime or get your state to invite us to do our dog and pony show.
JB - thanks for you comments. As usual, there's too much to this to describe in a paragraph, but here are a few replies.
Let me clarify... I am trying to place a line of longitude on the ground. It is specified as a County boundary line in a State statute adopted in the late 1870's.
The county lines established in the 1870's aren't as much a matter of mathematics and techniques as much as they are primarily a matter of historical research. I'd start by researching period maps to determine their placement of the longitudinal line. It certainly predates NAD27.
The period maps are cartoons - they contain no information whatsoever to assist in this task.
It has no fixed ground location at either end, which complicates things enormously.
It's hard for me to imagine that in nearly 150 years, no effort has been made by anyone to determine the location of the county line or at least some portion of it. The determination should have been made nearly a century ago. In light of the territorial statutes, any determination of the county line must be made by a delegation from both counties, paid for by both. I'd suggest a study of the territorial laws before making any attempt to locate the boundary. According to the statutes, the board of supervisors should have undertaken the task and filed a copy of the maps with the clerk. That's the place to start your research.
The only portion of this line that anyone is aware that has ever been surveyed is a ±300' section crossing a State Highway. I know who set them, and over the past 40 years have learned that his work ranged from good to abominable. I can't grasp how he could have set these accurately, but can't arbitrarily rule them out. They lie 2.25 arc-seconds off the current location of the called-for longitudinal line. Our County Surveyor is of the opinion that State Statutes prohibit Counties from determining the location of their boundaries. The adjoining County has no surveyor. There are no known maps showing this line.
Therefore, it would seem to me that it is a "floating" boundary with respect to the ground.
I'd beg to differ. There is no way that the boundary is "floating" about. It has a definite and fixed location. That location is as surveyed and determined by joint action between the counties. If that hasn't been done, then it's the surveyor's duty to place the line on the ground as it was intended in 1870 by the territorial legislature. Again, that will require research to determine the latitudinal position as represented on the early maps of the period. The maps, when the line has not been previously run on the ground, will be the best available evidence of the intended location. Once that line is run on the ground AND is mutually accepted by the adjoining counties, then it will establish the boundary. I wouldn't presume that no prior attempt has been made by anyone in history and that you happen to be the first. It may be. If so, then depend upon the evidence, not the math. Use the math as a tool.
Neither terminus point of this line is defined by a physical location. One end is the intersection of the longitude line and a State boundary line which is described as "approximately" a parallel of latitude. The other end is the the intersection of the longitude line and a physical escarpment. The County Surveyor believes that the line is "floating", and thinks that's why it has apparently never been surveyed.
I can't figure out how to calculate a ground location that falls exactly on that specific line of longitude. What am I missing?
The research that will tell you where the line is.
I need to stake its current location.
I would disagree. The legislative intent in the 1870's will control. The trick is discovering the best available evidence of that intent. That's what you need to stake.
Intent is of course paramount, but what they wrote was "south along such meridian." I don't believe that it is really possible to accurately determine where this meridian was locate in 1879 without extrinsic evidence.
I can't figure out how to calculate a ground location that falls exactly on that specific line of longitude. What am I missing?
The research that will tell you where the line is.
That's what I was hoping! This is part of my research.
I know that I can't just read the longitude off the receiver and move to the line. I need to have a ground coordinate on the longitude line. Corpscon will calculate a SPC on the line, but I can't figure out how to get a ground coordinate on the line.
That whole paragraph is so far from getting you to the right location, it's not worthy of comment. None of that stuff existed in the 1870's and is totally irrelevant in determining the location of the line. It might be quite handy for reporting the location of the line once you've determined it.
Maybe - time will tell. If the line truly does "float" it is certainly pertinent.
JBS
They lie 2.25 arc-seconds off the current location of the called-for longitudinal line.
That is almost dead on for the difference between NAD83 and NAD27 that I'm used to dealing with.
These were set circa 1965, and the DOT Right-of-Way drawings dated 1968 indicate that they delineate the County line...
"That is almost dead on for the difference between NAD83 and NAD27 that I'm used to dealing with".
Neither NAD83 or NAD27 has nothing to do with locating the Meridian, as when the documentation appeared (1870's ?) these did not exist. GPS also has no place or bearing to determine the Longitudinal line called for. You have to use what was the tools of the trade and methods at the time this line was called for to determine where to place it on the ground, on the surface and not at sea level or on some State Plane derivitive.
Maybe talk to this guy............
Staking a line of longitude-Intent
As always, it boils down to intent; what was the intent of the description, as written in 1870? Was it just some jurisdictional line drawn to say these people living on this side are subject to this counties laws and those on that side conform to that county? Who pays taxes to what county?
Who are the current owners adjacent to the line and how will this affect them? The line drawn by the less than good surveyor, is now relied upon by those adjoining it; you are right, they can not be ignored.
Your best bet is to treat it like a boundary line resolution, where the line is unknown and all the parties involved need to come to an agreement..I never said it woud be easy.;-)
The news people in Charleston will tell you the four corners monument is wrong and that Surveyors say they used satellite maps and gps units to track down the right location.
That does not mean that they are right, or even that they know what they are talking about. It does mean that the general public needs to be educated as to the facts and the means to a resolution.
Doug
MD WVA history might be relevant
> Don Teter & I jointly do a workshop about this and other state boundaries. Look for us sometime or get your state to invite us to do our dog and pony show.
definitely, look forward to that.
by the way, my father in law lived near winchester. hogue creek, near back mountain rd. know it?
MD WVA history might be relevant
Yes, I am somewhat familiar with the area. I've done a fair amount of work near there.
I fully agree the answer to the location of county lines is in the record somewhere. I thought the question was how do a stake out a line of longitude? Answer: with RTK. The issue of where has the been for the last hundred years is not where the current line of longitude is. It is where the evidence of acceptance is on the ground based on whatever records are found.
MD WVA history might be relevant
Since the definition is in terms of astronomic longitude, you need Dave's T4 and a time source.
If the short portion already marked falls within 1870's tolerance of your measurements, then extend that piece using its GPS longitude (any datum) corrected by whatever changes would be caused by deflection of the vertical along the line.
Hey, I got an idea
from your handle you're in Arizona. From what I looked up your principal meridian is(are):
Gila and Salt River Meridian
Adopted 1865. Governing surveys - Arizona. Initial Point - Latitude 33-22-38, Longitude 112-18-19.
Navaho
Adopted 1869. Governing surveys - Arizona. Initial Point - Latitude 35-44-56, Longitude 108-31-59.
(okay, not good to only the nearest second....but maybe a historical reference.)
I don't knwo when they said those were the governing latitudes and longitudes, but is it possible your answer lies in a longitudinal difference from one of these meridians?
Not to mention the parallel range lines.
I don't know where you are, and am not suggesting you survey it in from those points, but maybe therein lies the standard of longitudes and the geoid model used at the time
And when were the state boundaries established? I see calls for longitudes in AZ state statutes:
1. Designation of boundaries (of AZ)
Section 1. The boundaries of the State of Arizona shall be as follows, namely: Beginning at a point on the Colorado River twenty English miles below the junction of the Gila and Colorado Rivers, as fixed by the Gadsden Treaty between the United States and Mexico, being in latitude thirty-two degrees, twenty-nine minutes, forty-four and forty-five one- hundredths seconds north and longitude one hundred fourteen degrees, forty-eight minutes, forty-four and fifty-three one -hundredths seconds west of Greenwich; thence along and with the international boundary line between the United States and Mexico in a southeastern direction to Monument Number 127 on said boundary line in latitude thirty-one degrees, twenty minutes north; thence east along and with said parallel of latitude, continuing on said boundary line to an intersection with the meridian of longitude one hundred nine degrees, two minutes, fifty-nine and twenty-five one-hundredths seconds west, being identical with the southwestern corner of New Mexico; thence north along and with said meridian of longitude and the west boundary of New Mexico to an intersection with the parallel of latitude thirty-seven degrees north, being the common corner of Colorado, Utah, Arizona, and New Mexico; thence west along and with said parallel of latitude and the south boundary of Utah to an intersection with the meridian of longitude one hundred fourteen degrees, two minutes, fifty-nine and twenty-five one-hundredths seconds west, being on the east boundary line of the State of Nevada; thence south along and with said meridian of longitude and the east boundary of said State of Nevada, to the center of the Colorado River; thence down the mid-channel of said Colorado River in a southern direction along and with the east boundaries of Nevada, California, and the Mexican Territory of Lower California, successively, to the place of beginning.
linebender:
"We would put our RTK in latitude display and stake to it. Am I missing something?"
I don't know. You didn't tell me what you did to your base station... Or are you one of those guys that just runs a rover without a base station?
I would google "United States Geographical Surveys West of the One Hundredth Meridian".
Perhaps Capt. Wheeler determined the longitude of a still existing geographic feature in your area. It would be circa 1869-1879.
Bill93 has the correct answer for staking.
