Nate, when you're reduced to double proportioning it's really just a big guess.?ÿ Doing it the "wrong" way or reducing to cardinal equivalents doesn't make that much of a different in my opinion...especially in the light of it being a wild ass guess anyway.?ÿ While I respect our friend Dennis Mouland, there is little to no public lands in Oklahoma...meaning we pretty much get away with doing things however we like.
The early guidance in the 19th century suggested single proportioning along north-south lines only. Proportioning to be reasonable depends on original measurements and original monuments (or known perpetuations) relatively nearby; perhaps the early re-surveyors were aware the east-west measurements were a fairytale and could unreasonably warp the solution. The modern analogy is a filed survey map with directions and distances, nowhere on the map is a note that the measurements were not made on those lines yet everybody knows they aren??t.
Yes, I only do it with cardinal directions, more importantly cardinal equivalent distances. Cause a distance/distance intersection simulates cardinal directions.?ÿ
If you are dealing with "regular" sections, ones that are close to square, it isn't going to make any practical difference.?ÿ The cardinal equivalents thing comes into play when sections are irregular.?ÿ
Nevertheless, it is the BLM proscribed way to do a DP, so it isn't really a choice, IMO. Oregon law says that you do things in conformance with the Manual. I'm pretty sure that there are similar statements in the statutes of my other states as well.?ÿ
This said, I am not a CFEDS, and I have never done a DP for a final monument placement.?ÿ?ÿ
The cardinal equivalents from the W1/4 of 5 and the S1/4 of 6 change 2640 to slightly shorter distances. It makes about .8' of difference. Not a big deal, but it's how we do it. This is also an illustration of how plats in the same area might be quite different. Normally I will see closing bearings very close to "true", however this plat has more slanted ones which should be looked out for.
In the middle of the township cardinal equivalents will be 2640 north-south and whatever is shown east-west within hundreths.?ÿ
The cardinal equivalents from the W1/4 of 5 and the S1/4 of 6 change 2640 to slightly shorter distances. It makes about .8' of difference. Not a big deal, but it's how we do it. This is also an illustration of how plats in the same area might be quite different. Normally I will see closing bearings very close to "true", however this plat has more slanted ones which should be looked out for.
In the middle of the township cardinal equivalents will be 2640 north-south and whatever is shown east-west within hundreths.?ÿ
And don't forget to consider the east-west odd chainages which result in .3' from the mean.?ÿ
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Our early Plats and Notes go east on the random line, state the falling, then go west on the true line. The slightly off cardinal bearing isn??t shown like newer townships. So do you reduce or just use the record distance?
I do reduce everything to cardinal equivalents, usually as you can see on the above plat for everything except for the closing lines it's irrelevant.?ÿ
10 minutes causes .01' in 2640 so it's not really an issue.
Pay attention to the return distances also, they can change the dimensions from what the plat shows. For the south line of Section 4 it shows a total of 79.75, they return 39.87 which leaves a distance of 39.88. So the east 1/2 of the line is 39.87, the west 1/2 of the line is 39.88.
@mightymoe Since distances are reported to the link, it is possible that the quarter corner was set midway and the distance is reported accurately to the nearest link. Now we see the same with accumulated lot distances not matching up with the overall boundary distance by hundredths on a plat.
Regarding the original question, if you are going to do it you might as well do it by the book. It is easier to explain that way.
No one will ever complain if you mid point the 1/4 corner.
For this discussion I will use 39.88 between the S1/4 and SW corner, then reduce it to cardinal which for this one will still be 39.88 since it's 1 minute from being WEST.?ÿ
If you DP a corner by prorating eastings and northings (like it's often taught) your coordinate system needs to be true north, or if grid the central meridian needs to be close to the site you're working in. It can really get messed up in a Lambert system far from the central meridian.?ÿ
I find it easy to prorate Lat and Long's and then all the questions are taken care of automatically. Still for that prorate to be correct cardinal equivalents need to be calculated.?ÿ
I??m probably going to DP a corner at 3/4/9/10. 4/5/8/9 is a pipe set by the CS in 1950. It is in a north-south county road. His method was unconventional. A UPRR Track runs NE??ly through 9 & 4. He turned the calculated angle off the C/L tracks and ran west for 630.9 feet to where the RR map shows found stake and mound. Nothing there. The county road is another 300??. The RR Map (1912) probably has a drafting error. He runs west until he can turn 90?ø to a fence running south on the other side of the tracks where they cross the 8/9 line.
A month later he measure south about 1/2 mile to ??old stake and flag? then he runs west about 1/2 mile and 1 mile to north-south fences. He uses this information to justify his pipe. There is a found scribed stake in mound S 2?ø W about 1 mile which he never found, a later CS found it and perpetuated it in 1960.
@mightymoe I??ll have to look at it again. Pretty sure they are R/W maps. The County Surveyor has a lot of RR maps but they are on microfilm. He said the printer no longer works so he sent photos of the screen. They aren??t easy to read. There is more than one generation.
Val maps are easy to spot since they're asbuilt maps showing improvements. I've even got competing val maps showing different ROW's depending when they were issued.?ÿ
It depends what you mean by "improve" and what you are double proportioning. Double proportioning only makes sense when proportioning in a corner that was established by the standard (pre GPS) GLO/BLM method. It makes absolutely no sense in most other situations.
Double Proportioning sort of makes sense (least squares would be better) if:
1. the GLO Deputy actually did what is in the field notes
2. the GLO Deputy did a reasonably decent job of measuring, tough when they had to do 126 miles of lines in a week and a half
3. There is a decent number of nearby original monuments or known perpetuations
4. not much has happened in the township or locale of the double proportioned corner.
The prescribed double proportioning procedure arbitrarily leaves out most of the data to arrive at a solution. A least squares solution (assuming good original data inputs) would use all the data and produce a better solution. The problem most of the time is we don??t have good original data inputs. If there is nothing else then it is better than nothing.
The township I??m currently working in has a history of farming. The original notes call for charred post in mound with trench pits (1856). The presumed originals (mostly found on the fringes in hills or places that the plow missed) are a scribed stake in rock mound. Is that the original or a later in the 19th century unrecorded resurvey? I don??t know. I think we often fail to realize there was surveying going on immediately after the original survey for decades before recording and tagged pipes became a thing. We also have federal ownership but they reacquired their holdings in the 1930s by deeds. Due to the drought of the 1930s the farmers on the west side of the valley couldn??t make it any more so the feds reacquired the land and the soil conservation service managed it as grazing land. It is now FS national grassland. DP solutions look really bad, they distort the obvious grid pattern and corners fall into field plowed for decades. The corner should be in the section line road.
