I think the solar compass the GLO surveyors used in the 19th century would've automatically followed the curve except for their errors. At least as I understand how they did it. They probably didn't worry about it IF they moved the temporary corner which a lot of them were most likely stubbed in despite what they wrote in the notes. I love how the second half mile just seems to commonly miss the topo calls; it was perfectly flat with no ravines LOL.
If you calculate the azimuth of a point at the same latitude one mile west (or east)and then the azimuth to a point at the same latitude 1/2 mile west, the difference is about 12 seconds for a mid-latitude region like 42 degrees.
The question then, is when did the GLO or BLM start using instruments/methods with a probable error on the order of 12 seconds, so that the question of a curved line becomes meaningful.
And, of course, if you don't account for the curve but have several setups along that half mile at which you use the 270 or 90 degree azimuth, you have mostly followed the curve without trying, so the result at that level of precision still depends on the sight distances used.
If you have an opportunity, sometime study an entire township where many of the original quarter corners on east-west lines have been perpetuated. You will often see a pattern where the west half mile is very close to 40 chains and the east half is long or short. There are many quarter corners out there that have wrongly been reset at the midpoint because the search area did not find them at the midpoint area. The east half mile on the western tier of the township is also close to 40 chains. Time was money in the 1800's just like it is today. By the time someone could ever prove them wrong, which they rarely even attempted, they had their money and were long gone.
Jerry's article on the Shortcut Method:
http://www.profsurv.com/magazine/pdf/archives/shortcut_method.pdf
and his web site page introducing a PDF of historical writing on the subject.
http://www.penryfamily.com/surveying/shortcutmethod.html
The link on his page appears to be outdated. Try this for the old document:
www.sso.nebraska.gov/pdf/harvey1914.pdf
What I don't understand is that the solar compass wasn't invented until 1836 and the first solar transit didn't come into existence until after 1867, so how were all of the rectangular survey performed before then? And after the solar devices were actually put into production, weren't the solar devices used predominantly on township boundaries and the subdivisions measured using plane compasses?
Also, even in more modern times, say in the 50's-70's, the solar devices were only useable during a small window of the day (with any accuracy), a few hours before noon and a few hours after noon, depending on the latitude. Wasn't traditional transit methods (or compass methods) used during the "off" solar periods? Also on rainy and cloudy days, I doubt the crews sat around in camp picking their toes waiting for the sun.
Although all attempts were made to put lines on the curve, the accuracy of the surveys performed with transit and tape, especially 8 chain tapes, would have made that attempt a pure novelty especially since taping corrections were probably never taken into account.
Can any of you old timers explain how that all worked?
The times that I used the solar transit, there were several hours that it could not be used over the mid-day and during that time, a transit line was run and then continued on the solar line when the sun was again available.
Obviously, the line run with the solar transit was a curved line and the accuracy was not that great to actually worry about the less then a link difference at the 1/4 sec. cor., but the procedures automatically put the line on a curved line.
And it is easy to determine that a section line that was run with two solar transit setups, would be different than if it was run with many setups.......but didn't matter, as long as the section closed within the limits at the time and that difference was inconsequential.
The problem with running lines with a solar transit was, if the section did not close, the error was almost impossible to determine where it was, and usually the entire line had to be rerun. Could not tell from the books, if the error was with the solar transit or chaining.
It may be hard for some to understand, but running a solar line, you don't look back! In fact points ahead could be set on the other side of a tree, and then the line was prolonged ahead from there. The line would actually bounce back and forth and it would never be as accurate as a precise transit line.
The surveyor usually did not run the solar transit and had to have a lot of trust in the instrument man who had to have experience running the gun. The GLO and BLM land surveyor hardly ever ran the gun and was usually an extra guy on the crew that could do the necessary duties like looking for corners, talking to the land owners and doing the calculations of the lats and deps of the days work.
Keith
Kieth, how you did it was not the question, how was it done for the thousands of miles ran before the Solar transit or attachment came along for the late comers like you to use. What you will get from the still living BLM surveyors is the firm statement that all longitudinal lines were ran on the curve because the solar transit made it so. Or you will hear that is the way I did it. Long before the solar tools came along the system was set up to survey and subdivide land quickly by using plane surveying methods with provisions to make corrections so that plane surveying methods used on a sphere would not force the distortion beyond acceptable limits. That is one reason why we have correction lines and closing corners, the real old timers knew about projection distortion. I am only one of the few who believe that the township subdivisions were done using plane surveying methods, but after the south township line was ran, that line being on the curve resulted in what appeared to be curved lines throughout the township as the lines were ran North because when you run North from a curve at equal distances, the original curve is reflected in the E-W direction at the section corners that were measured and set on N-S lines as they went those N-S lines were intended to be the East lines of sections to the East, that is why they closed on the previously corners set to the East, there are manuals written about the normal method and some vaiations. The old plats show the declination only at the section corners and knowing about the effects of local attraction did not determine it anywhere else, but having that local declination at the corner would allow them to later point a magnetic line for the return line and once determined project that line back to the West to the last section corner set. I also was wondering about the timing of and the late arrival of the solar attachment to the GLO work. Don't think it changed the intended method for internal township surveying, the goal was quick and acceptable surveys done in order to get the land into the hands of those who would use it. What I have said here is heresy to those who like the idea of curved lines, forgetting the original intent of the GLO work to begin with and that the solar attachment was not available in the formative years of the GLO. I know well the arguments against what I said above, just don't buy into it, I do not expect to change anyone's mind, nor do I feel the need to attempt doing so, ample to explain as best as I can, my reasoning for my belief. Lots of surveys done before the state of the art solar compass came along, so using that tool as the way to explain a curve that was never intended to exist would seem lacking in substance to those who subdivided many a township before the solar attachment was put into common use, probably in the mid 70's.
jud
Jud
I can't tell a lot more than what I know, and I have said that.
Prior to the solar transit and solar compass, they used the magnetic compass and I would suppose that you may agree that the lines run with it, were also curved.
They found out the errors of the magnetic compass and banned it and went with the solar compass. I don't know the dates of all that and right now, am not researching it.
Why do you refuse to believe me when I explain how we used the solar transit and how it automatically ran a curved line?
Obviously, short cut methods were done and I have wondered myself how some townships were surveyed in 6 days and most of the corner monuments were actually set.
I also know of townships that were done in 6 days and it would have been impossible for that task, yet was officially approved.
I am not here to accuse past Surveyor Generals of the States, that they could not know of these frauds, but it would seem like they should have!!
East-west lines are curved, whether you want to believe it or not.
Keith
Jud
I have no trouble believing what you say about how you did it. I just don't believe you did it the way those who preceded you by 70 years or so did it. Believe there were solar observations done in those earlier years, the North line was determined and projected North. By projecting that line North it was easy to determine the declination at the section corners as they set them. From those corners it was easy to determine a true line East from that point, project that line East, note the mis-closure and then using the declination recorded at that missed corner, determine the direction using the needle to determine the correct return line and follow the line back, must have been good at it, never saw any notes showing a closure for that one mile long line. I have found most of the GLO work fairly good except those Benson Syndicate contracts. I was taught by an 80 year+ old engineer in 1970 or 71 how the PLSS was intended to be accomplished and the methods, as he had been told by those who actually did the work in the 1860s and 70s did it. Internal E-W section lines were not ran on the curve according to him and it is easy to follow the reasoning for it, primarily it wasn't needed to obtain the results required. I have good reason to believe the way I do and my only intent is to write my opinion. Township South lines and correction lines were ran on the curve, setting corners as they went. We are destined to have differences of opinion about how internal section lines were ran long before our time, we have no disagreement on how you did it. Don't think either one of us is going to change many minds and I think my position is in the minority side of the coin and that's OK, I'm happy with it and not really bothered much by those who disagree.
jud
Before the solar compass, the township line surveyor was supposed to do a Polaris sight as often as he could to determine the local declination (then called "variation"). Then he would use that declination for the next day or several days until he got a new value.
The subdividing surveyor was, in some of the instructions, told to adjust his compass to match the township line on the east side of section 36, and use it for the whole township subdivision.
Careful interpretation of the field notes will often reveal whether they had a solar compass, by the change in "variation" they set on northward lines. The random line along the north side of a section may have been run at the same setting as the west side or may have been adjusted according to previous fallings from the section corners. The return on the "true line" (if they didn't shortcut) would use the calculated setting to return to the starting corner.
Solar compasses were manufactured after 1840, and recommended by the Surveyor General at Cinncinnati in 1841. They were beginning to be common enough by the mid 1840's that a lot of township lines were run with them. The initial practice was to use the solar compass in place of Polaris sights, but more often, to obtain the setting for the magnetic compass. Then they started just running the lines with them when they had good conditions.
The General Instructions of 1846 from the Surveyor General of Wisconsin and Iowa state
“Base, meridian, correction and township lines are to be run with an instrument that
operates independently of the magnetic needle, which is to be employed only to show
the true magnetic variation. Section, meander, and all other lines interior of a
township may be run either with the same instrument or with the Plain Compass...”.
It was much later that section lines were commonly run with them.
Jud
As along with Keith and Jerry Knight I too can attest to the fact that all East West lines (including subdivision of sections) are and were run on the curve. As a BLM surveyor that was one of the necessary requirements that you learned in your formative years. Even though you might not be using a solar compass there are methods to compute where points would be on a curved line. Some methods are by making minor bearing ajustment on the straight line that you would be running depending on the Latitude; offsets that you would make, as along an East West township line; or offsets made to a straight line connecting adjacent section corners. Even without the solar compass or transit there are always calculations that can be made.
We spent many a weekends making sure that our solar instruments were in good adjustment, and providing the necessary accuracies that was expected.
Jud
I am sure that you did it that way, Our GLO surveys were done in the 1860's for the most part, Doesn't matter what you did, what matters is what they did. We retrace GLO work, we don't do original GLO surveys on un-surveyed government lands, little remains in government hands, so we must retrace the surveys completed by the GLO long before you were born.
jud
You need to realize that not many of us, if any, have run original lines of the PLSS!
Um Keith, I think you might want to rephrase that. I've seen scads of original lines run. They aren't authorized but that doesn't stop the resurveyor from pinning a new location for the improperly located one. 🙂
lol.....you are right1
We are working on that problem, maybe the Secretary's office will notice!
Keith
Jud
Ya know something.....
I think we know more about what the GLO guys did than you know!
KW
I'm sure you do. I feel fortunate to have received my most important training as a rodman on a PLSS retracemnt and restoration crew in the 70's. I was taught the way my mentors were taught in the 50's and the way their mentors were taught in the 30's. You tend to give more recognition to evidence of establishment when you are running random line adjacent to it one swing of the axe at a time. Our standard rule was tie in the fence every 5 chains plus any other notable features in between. Then plot it up at 1" = 500 ft along the RL and 1" = 10 ft rt and lt. Then get out the triangles and pick out the best fit path of established lines and dig a 6 x 6 for the stones. If no stone could be found use the best fit. Mostly a lost art. Try plotting evidence at an exaggerated scale sometime. It can be an eye opener. You will find that many time the established evidence is meandering its way toward the PLSS corner where the PLSS line bends, The exaggerated scale makes the location of the PLSS corner very evident. The textbooks spend way too much time teaching us how it should have been done and not nearly enough time teaching how to recognize how it was done. I've depended way more on my retracement skills over the years than my knowledge of original survey procedure although following the first surveyors notes can explain the location of evidence along a random line at times.
linebender
You had a great beginning with your mentors who knew what they were doing.
It just seems like some of these arguments just keeps going on and on and do not come to an end.
Back in my beginning days in the Montana State Office, I would listen to our boss, Jim Minnie and he would relate the arguments that were going on in their yearly get-to-gether, all State Office Branch Chiefs and the Washington, DC bunch.
As in; do line trees control line, how to establish the true point from witness corners, how to proportion missing Mineral Survey corners, were east-west center lines of a section curved, and some other such items.
In my time in the Washington, DC office, I attempted to "solve" these arguments and get on with more important arguments. Instruction Memorada from our office did in fact resolve some.
Then we have a problem, (I think major) with the ongoing argument now about subdividing sections in the PLSS and of course the bogus theory of only surveying these lines in strict conformance with the original protracted center lines, which of course ignores the existing corners that have been established by landowners or previous surveyors.
But I am working on it!
Stay tuned.
Keith
KW
:good:
I don't think the precision of how some of these lines were run in the 1800's, is very pertinent to where you find them, as the difference between the position of a monument in a half-mile is less precise than the difference due to curvature of the latitude.
I get the philosophical argument, but it is the least of my worries in finding the corner location and the best available evidence in reestablishing an oblitereated corner.
adamsurveyor
You are right of course and in my field days, I really was not concerned with a difference between a curved line position and a straight line position, as my error was more than that anyway.
But now in the days where surveyors are arguing about distances that are the length of my finger, then why don't we talk about the real world and correct procedures to establish those distances?
And of course, the bigger issue that I keep posting about, is how to run those subdivision of section lines on the ground and what evidence to accept or not. (Are the protracted center lines the only evidence to use?)
Keith
Limits of closure???
With the limits of closure of the 1947 and 1973 Manuals (1:640 and 1:1280 respectfully), I just don't see how curvature could be attained with any reliability at all. Sure, offsets would have been computed and the corners kicked over a few tenths here and there, but since the chaining was suspect how could curvature be truly determined. I have heard that BLM did not use plumb bobs back in the day (1950's and 1960's, 1970's?) when chaining; they usually dropped rocks, chaining pins or spit for that matter because the accuracy of the surveys was not that tight.
Did you Skip, or Keith or Jerry always chain using plumb bobs? Tell the truth.
