> An obliterated corner would be when no original evidence remains of connecting monuments, no references or no other relative information that is available for use to locate or restore that corner with any certainty.
Andy, I'm pretty sure that's the definition of a lost corner, and not one that is obliterated.
A little difference
A little difference
Perhaps splitting of hairs is the issue? The ties I compute, based upon a least squares correlation with all position values having a weight of unity, reveals missing monument point with north and east coordinates of N0.00 E0.00 in your system as measured (000 N0.00 E0.00 in the 1949 surveyor's system also) would have coordinates of S0.085 E0.061 in the 1949 system coordinates subsequent to transformation. Your coordinates, transformed to the 1949 surveyor's position for points 231, 232, 233 and 000 are:
Pt: N E
231: 4.7178 - 2.4851
232: 0.1545 - -17.4177
233: 28.3328 - -14.3659
000: -0.0849 - 0.0606
Inversing between each point and point 000
dN & dE
231: dN = (4.7178) – (-0.0849) = 4.8028
dE = (2.4851) – (0.0606) = 2.4245
232: dN = (0.1545) – (-0.0849) = 0.2395
dE = (-17.4177) – (0.0606) = -17.4784
233: dN = (28.3328) – (-0.0849) = 28.4178
dE = (-14.3659) – (0.0606) = -14.4266
Brg dist
231: N26°47'06"E 5.38ft
232: N89°12'54"W 17.48ft
233: N26°54'54"W 31.87ft
The rotation I compute between the two systems is 03°04'06"
Wondering why the differences between your solution and mine? . . :-S
The value of the experience or knowledge of transit and compass reading conventions is invaluable in this case. I do agree that it would be very easy to make the mistake of reading N33W when the actual reading is N27W. Personally, I disliked the quadrant and bearing compass dials. They were a continuous source of mistakes for me.
Imagine the sighting error looking at a tree 5 ft away or 30 feet away looking at a compass. I would use the direction to only verify the trees or stumps that fall in that direction. How do the distances on the other bondary lines fit your measured distances if they are reasonably close. Distance-distance in a corner and then see if fits the references resonably. And moove on. Hopefully you have calibrated your plumb bob. I bet you could have 10 surveyors measure similar reference trees and get .20-30 maximum error differences. One they are measuring to the side of the tree and if it has any size estimating the center. Thats why we would always set nail and bottle caps and then later on disc with numbers on the references.
A little difference
I solved the former position of the Stake and Rock Mound by least squares using (what else?) Star*Net. That way, I could separately examine the effect of distances and directions on the solution.
After correcting the one bearing that definitely looks like a misreading of the compass, I treated the compass bearings as directions with standard errors of 0°10' since they were taken to the nearest 0°30'.
I relaxed the weights of the distances that the 1949 surveyor reported by putting standard errors of 1.0 ft. on them just to see what a solution based upon the directions would look like. As it turned out, the distance residuals from that solution looked perfectly reasonable. Recomputing the solution with standard errors of 0.5 ft. on the distances just shifts the position by a couple of hundredths.
This is the output from the adjustment:
[pre]
Adjusted Measured Distance Observations (FeetUS)
From To Distance Residual StdErr StdRes
234 231 5.5671 0.0671 1.0000 0.1
234 232 17.3964 -0.1036 1.0000 0.1
234 233 31.9851 0.5851 1.0000 0.6
Adjusted Measured Geodetic Direction Observations (DMS)
From To Direction Residual StdErr StdRes
Set 1
234 231 26-29-54.65 -0-00-05.35 600.00 0.0
234 232 270-59-24.98 -0-00-35.02 600.00 0.1
234 233 333-00-40.36 0-00-40.36 600.00 0.1
[/pre]
For most of us "metes & bounders", lost or obliterated means "it ain't there".
> Imagine the sighting error looking at a tree 5 ft away or 30 feet away looking at a compass. I would use the direction to only verify the trees or stumps that fall in that direction.
My experience in Texas is generally that the common practice was to actually take the bearing to the mark on the tree. In this case, the 1949 surveyor didn't call for any marks, but the one standing tree, the 9 in. Live Oak, had a slightly flattened face and some scarring on the side facing the corner, so I'd guess at least a hack or small blaze was left in it. That would also explain the mortality of the other two Live Oaks.
Even on surveys made in the 1840's, the bearings to trees were clearly taken with the compass while distances sometimes were evidently paced.
>How do the distances on the other bondary lines fit your measured distances if they are reasonably close.
The 1949 surveyor reported that a marked Cedar Elm at a tract corner was 1244.6 ft. + 1426.7 ft. = 2671.3 ft. Northerly from the corner that is the subject of this thread. The actual distance is 2662.22 ft. (Surface). I wouldn't compare the accuracy of taping over half a mile in rough terrain to the accuracy of taping less than 31 ft. because other errors, such as eyeballing plumb or making a slant measurement, probably figured into the latter more prominently.
>I bet you could have 10 surveyors measure similar reference trees and get .20-30 maximum error differences.
I'd think it would be more like 2 to 3 ft. if RTK is involved. :>
:good: YEP, that is right
Those monuments that are gone and missing are obliterated - yet replaceable from known original references
Mostly around here, monuments are either there or they are lost.
Not many known original references. Monuments are getting replaced by poles, fence corners and for some reason many surveyors left their monuments about a foot high and brushhogs and other clearing implements sent them into the netherworld long ago. Today, not many surveyors will insert references into public records.
Not uncommon around here for references to actually be one's hubs and object ties of posts, tposts, power poles becauese trees are a commodity and are cut and sold every day.
😉
Did they have a fancy compass like this? Compass Notice the statement of accuracy. Did they use a directional theodilte and just assume a bearing with the compass early on in the survey and turn angles to the trees? if so what is the minumum focus distance of their instrument. Or were they using an instrument with a built in compass? Have you tried GPR yet to see if you can detect any voids in the ground where the old corner may have been?
> > How dos Texas law define the word 'obliterated' as it pertains to corners and accessories monuments?
>
> There is no statutory definition of 'obliterated' I'm aware of other than that contained in the Alcoholic Beverage Code.
Ah so that explains the beer can evidence you have found. That would possibly be an obliterated corner.
So there is no definition of lost or obliterated corners in Texas as opposed to the PLSS.
> Did they have a fancy compass like this?
No, when the 1949 survey was made, almost certainly the compass used was that of the transit, probably a mountain transit. Surprisingly good work can be done just "by the needle" in areas free of local attraction.
> So there is no definition of lost or obliterated corners in Texas as opposed to the PLSS.
In Texas, the rational policy is followed of searching for the best evidence of the location in which a corner was originally established. If there is no evidence other than the original record, that is the best evidence.
How would an engineer do this?
OK, so this is how a land surveyor uses the math to resolve this problem. Typically land surveyors are hard on engineers for just using the math, plug and chug.
So based on that theory, if an engineer were to solve this problem he'd use some sort of SUPER COMPUTER. Is that right?
How would an engineer do this?
> So based on that theory, if an engineer were to solve this problem he'd use some sort of SUPER COMPUTER. Is that right?
I'd think that an engineer would just turn it over to his surveying department or CAD technician.
A common practice with transit
Kent has alluded to this, but a common practice with a transit with a compass was to not only use the transit to measure angles, but to take a reading of the needle on every foresight (and occasionally on every backsight as well). This would give some idea of local attraction, but more importantly give a blunder check on the circle readings.
A common practice with transit
> Kent has alluded to this, but a common practice with a transit with a compass was to not only use the transit to measure angles, but to take a reading of the needle on every foresight (and occasionally on every backsight as well). This would give some idea of local attraction, but more importantly give a blunder check on the circle readings.
The other practice that was not uncommon in Texas at one time was to actually use the compass needle to determine the bearings of lines. It's easy to forget that good quality compasses were a fixture on most transits sold for surveying.
One surveyor who worked in the period around 1920 was in the habit of clamping the upper motion at a circle reading of 0-00 and then freeing the lower motion to orient the transit so that the compass was indicating 0-00. Having done that, the lower motion was clamped, the upper freed, and bearings could be read off the plate with an apparent accuracy of 00-01.
His maps and descriptions lead one to think he was doing real transit surveys, but the retracements show otherwise.
If there is no evidence other than the original record, that is the best evidence.
Nicely put.
Don
A little difference
II would be reluctant to use a standard error that assumes pointing to a tree within 2 hundredths. In most cases I would tape it in on the spot as a test. My assumption is I would likely introduced the same types of errors as the original. Of course I would also play with it in StarNet. It's fun:^)
A little difference
> II would be reluctant to use a standard error that assumes pointing to a tree within 2 hundredths.
Actually, the s.e. of 10 minutes would amount to +/-0.09 ft. at 31.4 ft. to a tree that was 8 in. diameter in 1949. That doesn't seem too far out there. A transit can be pointed by eye (unaided by the telescope) at a tree like that with about that uncertainty. The s.e. values are much less important for the tree that was 5.5 ft. away and whether the s.e. is 10 minutes or 50 minutes isn't as critical to their contribution as it is for the one at 31.4 ft.
Assuming Original Ties Were To Face Of Bearing Trees
and Kent surveyed to the center of found trees or remainders, I find the original ties accurate to 0.3'.
From Kent's points I constructed three circles of radius = tie + ties tree radius, then found the center of the intersecting area.
From Kent's random point my selected coordinates are Az 206°58'32" 0.13'
I have little concern for 3° or 6° errors in tie bearings as the swing distance is little affected by that error.
Paul in PA
A little difference - now understood
Ah ha, now I see and understand the discrepancy. It is a difference in methods. Your solution is dependent upon a least squares adjustment of observations. My solution is a function of a transformation that correlates the 1949 surveyor's positions and those of yours. For sake of brevity, in the following discussion I'll refer to the 1949 surveyor's system and that of yours as [49] and [km] respectively.
When I compute the translation and rotation, no scaling, between the [49] and [km] positions of the three trees, being the common points, the results are as follows:
First, the computed coordinates
[pre][49]:
Pt Brg dist N E
0: 0.0000 0.0000 - the stake and rock mound
1: N26°30'E 5.5 4.9221 2.4541
2: N89°W 17.5 0.3054 17.4973
3: N33°W 31.4 27.9776 14.2553
[km]:
Pt Brg dist N E
234: 5000.0000 1000.0000
231: 23°43' 5.38 5004.9256 1002.1639
232: 267°43' 17.48 4999.3036 982.5339
233: 330°01' 31.87 5027.6049 984.0730
Results:
Origin translation N = 11.0684
E = -9.7662
Rotation = -03°04'06"[/pre]
Transformation of [49] coordinates to [km] is accomplished using the equations[pre]
N[km] = N[49]?cos(-03°04'06") - E[49]?sin(-03°04'06") + 11.0684
and E[km] = N[49]?sin(-03°04'06") + E[49]?cos(-03°04'06") - 9.7662[/pre]
Results, including residuals are as follows:
[pre]Pt N[49->km] E[49->km] vN vE
1: 5005.1280 1002.1220 0.2024 0.0018
2: 4999.4500 982.4463 0.1464 0.0077
3: 5027.2561 984.2025 -0.3488 0.0168
0: 5000.0816 999.9349 - referenced stake and rock mound probable position[/pre]
Inversing, as a function of the [km] positions for the three trees and the probable position, 0[49->km], for the stake and rock mound yields the following:
[pre]0[49->km] to:
Pt az[km] dist
231: 24°42'35" 5.33
232: 267°26'24" 17.42
233: 330°02'41" 31.77[/pre]
Using only the information provided, I'd place a monument at:
[pre]Pt N[49->km] E[49->km]
0: 5000.0816 999.9349 - only a tenth from pt 234[/pre]_________________
Note in my post of yesterday, I had transformed [km] coordinates to [49] and erroneously copied from my solution. To prevent this type of mistake again, I assigned the coordinates for 234[km] as N 5000 and E 1000. In a sort of a sense, I made a mistake comparable to the N27W and N33W conundrum!
Interesting to observe how different people approach the same problem using differing solution methods.
