[time-nuts] Discussion of precise time and frequency measurement

jimlux jimlux at earthlink.net
Mon Nov 13 14:00:14 EST 2017

On 11/13/17 9:32 AM, Gregory Beat wrote:
> I grew up east of the Iowa/Missouri border, so this boundary dispute was well-known ... and occurred at same time Joseph Smith (Mormons) was at Nauvoo, IL (1839-1844).
> In 2006, the Iowa-Missouri border was investigated with GPS, as much an archeology project as locating the historic Sullivan & Brown survey markers.
> http://www.theamericansurveyor.com/PDF/TheAmericanSurveyor_MO-IABoundaryLineInvestigation_Mar-Apr2006.pdf
> Iowa-Missouri Border War (1826-1849)
> http://iagenweb.org/history/soi/soi32.htm
> NOAA’s : National Geodetic Survey (NGS) made news in 2009 when media reported that the Four Corners monument was in wrong place (by 2.5 miles).
> Deseret News
> https://www.deseretnews.com/article/705299160/Four-Corners-Monument-is-indeed-off-mark.html
> NOAA statement and clarification
> https://www.ngs.noaa.gov/INFO/fourcorners.shtml
> ==
> I’m in France and I don’t think that any borders in Europe were defined by astronomical observation, but in the US I believe that at least some of the state borders were thus fixed. As a second’s error in time will be about a nautical mile in US latitudes, I wonder if anyone has measured with GPS, how good the original surveys were?

Googling "cadastral survey" would be how you'd find out.

There's also a famous case of the border between New Mexico and Colorado 
being crooked because of poor surveying, but the monuments define the 
border not the words in the laws defining the border.

Same with the border between Utah and Colorado.

The increased use of GPS has made it trivial to go out and find a 
particular position - but remember - it's the monument that controls the 
location and boundary, not the coordinates.  My house sits on a lot 
where the corners are defined relative to some physical monumentation (a 
brass disk nailed to the sidewalk typically,with a dimple in the nail 
head) - so as my house gradually drifts north a few cm/year, I don't 
have to worry about the line shifting.

Sometimes this "tied to the monument" thing breaks down - and that's 
what court cases are made of.

In any case, most of the state boundaries in the western United States 
were done with astronomical measurements.  Probably using a chronometer 
for time, as opposed to using lunar occultation of stars.

The Commissioner of the General Land Office employed Ehud N. Darling, a 
surveyor and astronomer, to make this survey. He made the survey in 
1868, and filed his field notes in the Land Office. In accordance with 
his instructions, he adopted as the northeast corner of New Mexico a 
stone monument that had been established by Capt. J. N. Macomb, an Army 
Engineer, in 1859, to mark the intersection of the 37th parallel with 
the 103d meridian, and, taking this as his beginning point, surveyed and 
marked the line of the parallel, as determined by astronomical 
observations and calculations for latitude, westwardly to the 109th 
meridian, a distance of over 331 miles. ...

Several years later, the Commissioner of the General Land Office 
employed John J. Major, a surveyor and astronomer, to survey and mark 
the remaining portion of the southern boundary of the Territory of 
Colorado, extending along the 37th parallel to the 102d meridian. Major 
made this survey in 1874, and marked the line of the parallel between 
the Macomb monument and that meridian. The field notes of this survey 
were filed in the Land Office and approved by the Commissioner.

and so on over the next 20-30 years

This kind of surveying was hard work: hostile native americans attacking 
survey parties, wildlife (lions, bears, etc.).  The wildlife problem 
wasn't quite as bad as tigers eating surveyors in India doing the Great 
Trigonometric Survey.

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