Definitions
Yes I should have further clarified that I mean the bearings to be essentially chord bearings. The bearing of an east-west line is constant in terms of geodetic north and constantly changing in terms of grid north.
Darrell
> I don't want to argue! I want to agree and drink beer!
I'm not sure what we're arguing about, but I agree.
Now, let's have a beer.
Don't ask, if ya doan wanna know!
W-1/4 to C-1/4 to E-1/4
Bollocks the math intersection and curvy crap.
Darrell
Heh, I am not arguing that with you!
I was actually putting my 2 cents in!
Arguing reminds me of this scene:
[flash width=640 height=390] http://www.youtube.com/v/LnLDMqPBeKQ?fs=1&hl=en_US&rel=0 [/flash]
distance on the curve
Now let's say you're a conscientious GLO surveyor and you're doing an original survey of a section line and dutifully mindful that the E-W lines are curved, so your line is not an instrument-straight line from Sec. Cor. to Sec. Cor. but on a line of constant bearing (curve), is it 40 chains as the crow flies from the Sec. Cor. to the 1/4 Cor. or a little bit shorter? If you could measure by an infinite number of traverse points correcting up your bearing at each one thereby defining a true curve rather than a series of segments, it would actually be less than 40 chains between corners wouldn't it? And if you were just tallying up chains until you got to 40, the more traverse points you used, the shorter it would be? Did the GLO worry about this? Not being a smart-ass (much) just asking.
distance on the curve
Where's that illustration of someone beating on a dead horse?
Steve
Are you missing the point to all this?
It should be obvious to all that the original GLO surveyors were not interested in the distance at the C 1/4 between a theoretical instrument straight line and their solar transit curved line.
I was in the field surveying with a transit and its straight lines and also with a solar transit and all east-west lines were on the curve, but we sure did not have the ability to measure as precisely as is done now.
The point should be remembered that now, surveyors are arguing about the width of my finger nail and therefore should also be interested in the actual survey procedure that will give them the correct position on the earth's surface.
It is a simple concept, all ya gotta do is listen and learn. I am well aware that many if not most surveyors on here will never see a C 1/4 sec. cor., but they still should be able to understand the procedure to get there.
We ain't talking about GLO surveyors!
Keith
It is posts like this, that get me started on curved lines:
by jlwahl, Friday, February 25, 2011, 21:55 (11 hours, 0 minutes ago) @ Keith
But the subdivision of section lines are defined by the act of 1805 to be straight. One of those little exceptions to the rule. Now Mr. Dahl has decided that is not true any longer, so we have the new manual applies to BLM but no one else. Really that is the truth, and it invokes a concept wherein past acts are forgiven. So any center quarter set by the BLM (darned few) at intersect of straight lines is still okay, but now what?
And that is from someone who should know better!
And where are the examples to prove his statement?
Keith
Most Blesséd Bovine
I understand and feel your pain. Sometimes enough really is enough.
Of course, I'm not a very good surveyor.
Don
I think that just to be sure about this curved 1/4 section line,
we better get out the chain and check the distances from the E 1/4 corner,
center of the section, and the W 1/4 corner to the the North Pole.
Keith
Sorry if I changed the subject. I was talking about a section line, not an E-W center line. Just one of those things that crossed my mind while pruning grapevines.
distance on the curve
Hey I never thought of that. The chord distance would really be 39.9999999999999chains. You've got a point there Steve 😉
distance on the curve
Is that based on a real computation of any kind? I thought it would make more difference than that, but didn't care enough to calculate it.
The Act of February 11, 1805 certainly used the phrase "straight lines" but we will need to look to later developments for clues as to how these were run on the ground.
There are other acts of this era which also contain clues as to how the Surveyor General was to determine things such as baselines, meridians, township lines, etc.
The Act of March 26, 1804 provides for "astronomical observations...as may be deemed necessary for the correctness of the surveys".
When we reach the First Meridian Survey, which would be the first part of the PLSS actually recognizable to surveyors working in later PLSS surveys, we have the first major survey done after the conclusion of the War of 1812, which was certainly an interruption in that region. This survey introduced the Surveyor General's Instructions of 1815. It also introduced the concept of a latitudinal baseline, instead of a river or other physical feature. It's important to note that the baseline for the survey was the 41st Parallel.
And from that concept we have the definitions of east-west township lines as being parallel to the baseline, so they are also laid out as parallels of latitude.
And the east-west section lines were to be "straight" and parallel to the east-west township lines.
And what was to be used to lay out the sections in the subdivisions of townships?
From General Instructions of Deputies, Part 1st, Instructions of 1815:
"You will provide a good compass of Rittenhouse construction, having a nonius division and movable sights..."
So the east-west lines of sections were laid out with a compass, using the local variation as determined by the Surveyor General astronomically. The concept of seeing clear across a section in Ohio in the time period of say 1820 is hilarious. Seeing a few chains before moving the compass up would be the norm, and would produce a latitudinal line.
And what about the interior quarter lines of the sections and the center quarter under the Instructions of 1815? There is no such concept. The quarter lines were never run on the ground by the GLO and appear as brown lines on the plats; protraction only.
Excellent post Carl,
Another factor that should be stated is that the Congress will pass a law that in their view is what is intended in concept, but with the full knowledge that the Administrative Branch will carry it out and issue instructions on how to do that.
The laws that are passed having to do with surveys, will be interpreted and regulations written by the "Land Department". That Land Department is the Bureau of Land Management, formally the General Land Office and are the only agencies that had/have Federal Land surveying authority.
Thus, the Manual of Surveying Instructions and its several additions. We now have the 2009 addition and represents the regulations of the Federal Government.
The lines have been curved from the get go and for somebody to question that fact is only sowing wild accusations.
One can only imagine the surveyors in the late 1800's and their compass's and how they carried out the law of the land.
But, that is history and the point is now, how those lines are located on the ground with the capability of measuring my finger nail.
Historical facts are wonderful and we know where are predecessors were and how they did their surveying, but now is now and your measurements are so precise that you really should wonder about where and how to survey!
If you can't learn a few facts, then find another profession.
Keith
Keith
You're probably a very nice person but I don't know why you are using this issue as though you're picking a fight. With whom? I assume most surveyors have a globe in their office or at home and can see that latitudinal lines are curved. Are there people arguing with you about that? Is there a good reason to tell people to find another profession if they don't agree with you when everybody does anyway?
These online forums tend to be confrontational and I have felt myself getting caught up in that mindset, but I try to resist it. You have a lot of depth of experience to offer the surveying community and I look forward to participating in many more discussions with you. Please consider this post in the conciliatory spirit in which it was intended.
What is BLM?
I've seen that before.
I don't have an example at hand. But I remember my boss called it a "broken back" section.
:coffee:
Don't ask, if ya doan wanna know!
Ding Ding Ding...Correct answer. The corner IS where it IS! The original surveyor noted this and it appears to have been accepted for the millenia. Just because you can measure more accurately than days past does not mean you are correct. Intent and acceptance overrides modern day accuracy.
We would be moving every state line if this weren't the case.
Steve
Thanks for your thoughts and sorry that you didn't like my closing statement above!
I get irritated at surveyors who should know better, about the BLM Survey Manual procedures and some simply refuse to learn any more that "that's the way it is done around here"! And of course some are just at odds with the Manual, for whatever reason.
Some refuse to acknowledge that they live on a globe and some lines are curved.
The whole point is, that there is a lot of postings about how close one can measure, but in my opinion, they then don't know what to do with those precise measurements. Some use them as the sole judgement call on where the "true" corner "should" be located.
This is true in the present case of the difference between an instrument straight line and a line of constant bearing on the east-west centerline of a PLSS section. The ability to measure that difference is now present and one should at least acknowledge the difference.
It may seem like a frivolous argument to some and maybe it is, but what better way of demonstrating how to use the precise measurements that are now present in the survey world.
Even those surveyors who never run lines any longer than the local subdivision lots should appreciate the larger world of the PLSS.
Just some thoughts.
And yes, I would like to have a BLM surveyor, retired or working now, who is aware of the survey/resurvey procedures in the Florida Appeals Court Case Rivers v Lozeau, explain it.
One would think that it would be a pleasure to explain a survey/resurvey that was upheld in a Federal Appeals Court Case!
Keith