Straight lines
> What procedures would Abe use to run a line of constant bearing?
One thing is certain. He didn't have a mile-long piece of monofilament in his pocket.
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JBS
Straight lines
Abe would have ran a curved line east and west with his compass. I think we could agree that a compass line would be on a curved line?
Keith
Straight lines
Come to think about it, I have yet to see a section subdivision east-west center line that has multiple bearings that would indicate a straight instrument line?
Keith
Keith
WELLLLL.....
I see LOTS of them on "private surveys," but that's because MOST folks play on a "flat Earth," and compute, survey, and plat EVERYTHING using GRID bearings (whether they realize it or NOT).
The same goes for MOST surveys of Sections, Township Lines, and all too often, EVEN Standard Parallels.
Of course IF they "platted" the way the GLO/BLM does (and always have), then the Real Estate, GIS, Engineers, and Attorneys would pitch a fit!
It has only been in recent years (last 10 or so), that I have been "doing it right," but luckely I haven't done a lot of PLSS (sectional) work since the mid-1980s. Mineral Surveys are a different critter, and SMALL enough that it doesn't generally matter one way or the other.
🙂
Loyal
Loyal
I can understand the rationale of a real estate salesman or even an engineer, that can't grasp the concept that a line with a bearing of EAST is a curved line. Hell, even surveyors on here have asked the question; Why don't we show the curve information if the line is curved?
I do understand why and how many surveyors don't get it, when all they do is survey lot lines of 25 feet or so! The have missed out on seeing a 6 mile line where the curve is very visible.
Speaking of mining claims; I was just involved in a court case which was all about the rights of mining claimants and how the claims are described.
I have resurveyed many Mineral Surveys and yes, did not worry about the curve on the 1500 ft. side lines.
Hey, curved lines and junior corners bending senior lines are always favorites of mine to bring up. Lots more interesting to me than most threads on here!
😉
Keith
Abe
Wouldn't he have run a random line and corrected for the offset, weather he was using a compass or a transit? But this would not be on any curve. How could it be?
Anyways if your contention is true then all of BLM computer programs to compute center of section from current GCDB back to the old Bill Ball programs are incorrect.
A lot of recomputing will have to be performed.
Keith
William
"Wouldn't he have run a random line and corrected for the offset, weather he was using a compass or a transit? But this would not be on any curve. How could it be?"
Virtually ALL compass lines are curves of some sort or another, most are rather simple and very modest, some are quite complex and anything but modest.
Lines run with a “transit” can be either quite “straight” OR simple curves DEPENDING on the methodology used, and the procedures adhered to by the transitman. In cases where the Transitman is relying on the Compass, then it's a COMPASS line anyway.
I don't know exactly HOW the GCDB program works internally, but I doubt that what we are talking about would significantly influence to GCDB results.
Loyal
William D.
Then you don't believe a compass line or a solar transit line is run on a curve?
Anyways if your contention is true then all of BLM computer programs to compute center of section from current GCDB back to the old Bill Ball programs are incorrect.
I have no idea of the truth to that statement, but as we can see the new Manual emphasizes the curved east-west center line of the sections. See sec. 3-114 of the 2009 Manual, page 69. Last line of that section is: "In this application, "straight lines" implied "lines of constant bearing" (43 U.S.C.752(2)).
Are you saying that the new Manual is wrong?
Keith
Kris
AS you can readily see, not all surveyors believe east-west lines are curved!
Sort of a favorite topic with me.
Sorry if you don't like it.
Keith
William
Our State's BLM software has computed on the arcs since the mainframe days prior to Unix boxes and PCs. Our GCDB data is also calculated that way. Nothing new in the 2009 Manual or Keiths statements of the Federal way for Alaska. The world is round and not flat, and the PLSS datum has taken than in account for a long time.
Northern
Of course the curved lines would be much more prominent in Alaska!!
Keith
Loyal
The manual (1973 version) does discuss running straight lines from 1/4 corner to 1/4 corner to break a section into quarters (synopsis of congressional legislation).
This I have been told means straight lines are straight north and south and straight lines are curved east and west. The manual also discusses straight east west lines that are clearly straight. Such as the line run tangent to a township line to use as an offset line to the curved township line. And also the Secant Method for the layout of a township line includes a straight line.
So we are to assume some east-west lines called straight are really curved while other east-west lines called straight are really straight.;-)
As far as the GCDB goes; they show the section lines as curved and the interior east west section lines as straight where I have downloaded it. There really isn't enough accuracy in the GCDB to matter one way or the other in any of it that I've seen.
Of course, if I find a monument within 2" at either the center of a Section or the 1/4 corner on an east west line I'm too busy celebrating to care.
Major Issue
High latitudes really demonstrate why you have to take it into account. The PLSS founders were some visionaries, obviously they could not have contemplated use of the PLSS system at Alaska Latitudes.
I forget the exact numbers for offset in 1/2 mile at 70 Degrees North, and I am at home in recovery, but the offsets are impressive. Not dealing with them looks very odd too.
MightyMoe
Obviously, Loyal can answer for himself, but I just have to interject here and have you look at the 1973 Manual Figure 13 on page 54. It can't get any simpler to explain curved lines. You might notice that the instrument straight line (random line) changes bearings every mile! Whereas the true line is the curved line with a constant bearing of EAST.
Keith
MightyMoe
Yes, that's the way I see it also. The straight line (the tangent) changes bearings and the township line (the offset line or parallel) is east along its length. Which is my point about the confusing language in the manual. If the straight line in the figure on page 54 changes bearing, then why doesn't the straight line mandated for the east west centerline of a section change bearing?
I'm not saying I'm against the constant bearing e-w centerline; only that the terms used in the manual could be better presented.
Kris
Some people will argue the same points back and forth all day, and year after year, for that matter, on politics and that is all fresh and exciting....but discuss an extremely relevant survey concept that a lot of surveyors misunderstand on a surveyor board.....and your beating a dead horse.
Keep up the good fight there Keith.
adam
I will stipulate that I missed that part in Clarks on boundaries as "curved section lines" are not a hot topic in Texas. However, after 10 years of the same (I really think he's got it all typed up and cuts and pastes it) conversation, I couldn't resist.
I won't argue he's wrong, when in fact, he is 100% right, but he brings it up more than it comes up if you catch my drift.
MightyMoe
The east-west center line of the section has one bearing because it is a curved line!
Keith
MightyMoe
The east-west center line of the section has one bearing because it is a curved line!
Exactly! It's just that the manual on page 8 says "that the center lines of a regular section are to be straight". Thus the confusion.
