OK. I'm throwing in the towel on this one. It's not in the books.
I've hunted down the magnitude of errors associated with chaining...alignment, temperature, sag, wear on the links. None of them are coming close to 3.75' per 1/4 mile...unless I'm calculating typical catenary errors wrong. Sag is the only one that might do it.
Public disclosure: I've never used a chain; never held one or touched one, so I'm clearly out of my league here.
I remember reading of a boundary retracement that Kent did a while back, wherein I believe he found something similar, but can't find that thread. Could have been off by a different distance; can't remember.
I do know Nate the Surveyor knows the answer but am curious how many others do, and where to get more information on the subject (without chaining a few miles myself).
Most of them here are 1320'!
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Most of them here are 1320'!
Yep. That's where I set them at. No need to look first. Just set 'em. All day - everyday...:-P
Most of them here are 1320'!
It says 80 rods on the spool of bob wire.
DDSM;-)
Most of them are. Just like every month has 28 days in it.
It is more typical in many parts of the country to find long measurements because the very first surveyor added a link or two to be certain the future land owners would get at least what the record indicated.
Check out the history of the principal meridian running through Missouri and Arkansas. Some miles grew substantially over standard along the meridian intentionally.
Sounds like you have a good case for an Index Correction. Also, be sure you are reporting ground distances instead of grid.
I missed the source of the observation, and that might help with the explanation. Where do you find so many 1/4 miles that are that distance?
Maybe there's a loose nut at the zero end of the tape you're using.
> Where do you find so many 1/4 miles that are that distance?
My guess is that Arkansas would be a good place to look.
> ...but am curious how many others do, and where to get more information on the subject (without chaining a few miles myself).
I remember trying to follow the footsteps of an old timer (1920-40 era) who did lots of subdivisions in very hilly terrain and lots of lakes & streams in W MI. When comparing distances, things always measured short. Lots of head scratching.
In talking with a new old timer it seems that those who've also tried to retrace the original old timer realized all (or most) of his distances were slope distance. Factor in the slope and things came within reason of horizontal.
Slope chaining
I've come to suspect that the 1958 development plat our church is in, and I've scratched my head over for so long, was laid out with slope measurements and then the leftover lengths, when they came up against a previous line, reported back to the office and the plat changed to match.
There are several regions of the plat that just don't have room for the recorded distances to fit with other recorded distances, and these tend to be the hilliest regions.
I don't have measurements on the ground in those areas to support the idea (I've restricted myself to the immediate vicinity of the church), and as a non-LS I probably won't upset those folks to get data. Measuring seems to generate fear in a lot of people.
There's a lot of other weirdness on this plat, like some curve data that seems to be arc formula and others chord formula, lots on each side of one line don't add up by 0.8 ft, and the plat calls for some backyard monuments 0.9 ft and 0.1 ft apart - why not design the lot a bit wider or narrower?
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So how common was the practice of slope measurement in that era? Was it a rarity or do you run into it now and then? How common was updating the design from field data?
Is it any wonder why measurements, mathematics, stated bearings and distances in descriptions and on "plaques" are not the controlling factor in the location of most boundaries?
This thread only re-enforces the logic, reasoning, and LAW behind that simple principle.
Measurements are not "perfect" (no matter have many times or ways you may manipulate them), but the lines as run and marked on the ground are "perfect".
What are you talking about?
Are you referring to a single section? A Township? A County? A State? Need more info...
You might look at the 1881 Manual of Instructions - it details an interesting measurement technique.
Take a look at the resurveys in the powder river basin, lots of info there
> What are you talking about?
>
> Are you referring to a single section? A Township? A County? A State? Need more info...
>
> You might look at the 1881 Manual of Instructions - it details an interesting measurement technique.
I'm talking about a statement a wise sage here on BeerLeg made some time ago. I don't know the answer.
I've read those instructions and the ones that follow on. It's very interesting reading. I didn't realize they figured out a way to avoid the propagation of errors further than across a single section. But nothing in there suggests the precise distance noted.
I've also looked at "A" stability NGS data sheets (yes, in Arkansas, with nothing better to go on). I don't think the "Grid to Ground" correction could possibly account for that big a difference. I looked at a few and multiplied the convergence factor and came up with maybe .05' in some cases. This is huge. it's .28%.
Some of the responses suggest slope distance. But that pre-supposes that of all the measurements made, over many years, the slope distances are the culprit. If so, that would mean that ON AVERAGE, the terrain upon which all these measurements were made is 4.3199 degrees. I think that might be the case if you included the Rockies, but I'm thinking it might not. That leaves the vast stretches where the only thing that gets to 4 degrees is the temperature! But I'm not sure we can rule it out yet (slope distance).
What else is suggested? A systematic tendency to "throw a link in there every now and then" to make sure the land owners get their fair share. I'm not sure I can buy that one. Perhaps the 3.75' is a statistical summary, but I'm thinking the precise distance referenced has to do with the measuring equipment...the chain, but haven't found that link yet (Bad pun). Besides, if the old timers threw in an extra link, the distance WOULD be longer, not shorter. The only way that would happen is if they measured a full chain, but then just recorded an extra link...but then it'd be right on. That dog don't hunt.
I will say one thing: I'm feeling a lot better now that I'm not the only one who hasn't figured this out. Not giving up yet though.
Anyone?
Isn't that why we get paid the "big bucks" rfc? Just think if we could only read minds, or have a time machine... to go along with pulling rabbits from twixt thyne buttocks. Can't wait to break the bank myself, but still waiting. 😉
Speaking of bucks, hope you're getting paid for the shampoo to treat all that head scratching. Not to mention..... (fill in blank).
Question to ponder though - have you spoken with peers about your issue (aside from beerleg)? Maybe have one of your fellow surveyors go check something simple that you already measured, then compare notes? Just a thought. Good luck
It sounds like you've thought your way through this pretty well. I have figured it with all of the tools I can think of and no magic numbers pop up. It could well be things were done by a guy with a 2 pole chain that was .09 short. At the end of the day I'm ecstatic when I see consistency. At that point I know how to adjust my chain and move forward. Unfortunately (like you) I will spend the next three weeks trying to figure out 'why'...
Perhaps he is referring to Nate's comment in this [msg=91575]old thread[/msg]?
I took that comment to have picked an arbitrary number different from 1320, and not to say that there were a lot with that particular non-ideal value.
That Jogged my memory
O yes, the nefarious 1320.25' yes, Hmmm ok, now I get it.
That number is significant.
It is a number I made up. But, it is close enough to 1320, that it does not raise an eyebrow. But, it does make some of the deeds overlap.
To develop a 1:5000 closure, you would be allowed about 1' of error, per mile, while traversing around a Section of land. So, assuming it all happened at one place, then you have a total error, after traversing around a section of 4'. 3.75' is just under that. And, that is where that number came from.
We have met that old standard of 1:5000 for rural property, it is all piled in one place, and here, we found it, 3.75' off. And, we are ALL within min standards, for 1980. (See Arkansas Min standards)
Nate
Does anyone know what equipment they actually used? I know the distances are in chains; but I've heard they used a "2-pole" chain (which would be 33'). If that is the case, I would bet horizontal alignment would become an issue at long distances. Also, without calculators, how accurately did they offset around trees? I'd assume they used a 3-4-5 triangle method.; but, how accurate is that?
The back of every field book under "Survey Measurements" lists: 4 rods = 1 chain. Is there a chance that they weren't actually using a chain at all? How accurately do you think someone could measure a mile through dense forest with a 16.5' measuring rod?
I'd love to see a competition among modern surveyor's. Everyone get issued standard surveying equipment from the 1850's. Let's re-measure a Section line. Closest to the "actual" distance wins. I wonder how close we could get?
