# Yet another question...about datasheets, this time!

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(I seem to be posting a lot here recently...)

When reading a datasheet, I have found quite a few that the only N/S measurement given is ".1 miles from farmhouse" or ".1 miles from road". What I haven't determined yet is if this is an actual 528 feet (.1 mile) or an estimate based on an odometer reading or being scaled from a map?

the E/W mesurements given are from "centerline of road" and "from fenceline". Of the ~23 miles of FM 359 (Texas), all but ~7 miles of it has or had a fenceline on one or both sides of the road. I can usually find a mark if I can get a reasonably close N/S reference.

Couple of marks to see what I'm talking about:

BM0150

Also, for some reason all the witness posts on FM 359 are gone...makes for a very frustrating time!

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quote:
Originally posted by RACooper:

(I seem to be posting a lot here recently...)

When reading a datasheet, I have found quite a few that the only N/S measurement given is ".1 miles from farmhouse" or ".1 miles from road". What I haven't determined yet is if this is an actual 528 feet (.1 mile) or an estimate based on an odometer reading or being scaled from a map?

From my old class in physics and signficant digits, I'd assume that ".1 mile" could be anything from ".05" to ".14" mile. It's most likely an estimate of some type or else they would have used feet to indicate a more exact position. Just my 2¢.
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If its given in miles it was measured with an odometer and not intended to be a precise measurement. If it was more precisely measured it would have been noted in feet or meters.

You can convert it to feet to locate but don't expect the accuracy, it could be in the 0.05 to 0.15 mile range. I have often found using my odometer is often off by this much.

Mike

Survey Tech (Retired)

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And my kids think I am crazy when I tell them that 2 plus 2 equals five for sufficiently large values of 2

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I have found that creating a GO TO out of the "Point" gives better distances from intersections,you can also do this for Reference marks and Azimuths this giving you Bearing and Direction and DISTANCEto the "Point",in feet to the .10 mi.= "528 feet".

In most cases the roads have been altered and this causes small changes in the odometer readings,and some that I have found the roads are completely gone now,no witness posts,which made me use this system that works real well for me.

Remember also that 1 degree East/West is 55.6mi.

1 degree North/South is 69 mi.

at 36 to 38 degrees and 90 to 94 degrees

so therefore:

69 divided by 60 = 1.15 mi.

55.6 divided by 60 = 0.9266666 1 min.

And correct me if I am wrong but this is where the least squares theory is used to get the Rectangular coordinate system.

Least Squares

WHEN ALL ELSE FAILS

*GEOTRYAGAIN*

TAKE PRIDE IN AMERICA

1803-2003

"LOUSIANA PURCHASE"

"LEWIS AND CLARK EXPADITION"

Arkansas Missouri Geocachrs Association

[This message was edited by GEO*Trailblazer 1 on October 09, 2003 at 11:01 PM.]

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