The great thing about Star*Net is that its flexibility allows the solution of many unusual problems.
I've previously mentioned that at one of the corners established in 1875 on a hilltop, the surveyor took bearings with his surveying compass (or plain transit) to three distant peaks known as Lone Man Mountain, Lone Woman Mountain, and the West Peak of the Twin Sisters, all in the general vicinity of Wimberley, Texas. In 1875, the top of the hill was probably mostly bare of trees (the nearest live oak large enough to use as a bearing tree was evidently 30 varas from the corner, which is 83.3 ft. American).
If the hilltop were still open, that would have been me setting up the total station on the rock mound and proceeding to measure directions to the peaks and to a reference target from which I could compute the actual bearings to the peaks. However, the hilltop is anything but open and the problem was how to determine the bearings +/- 0°01' to the peaks from the rock mound to compare to them to what the 1875 surveyor reported.
Just opening up lines of sight from the mound to the peaks wasn't feasible for various reasons, not the least of which was the necessary landowner's permission. So I ran through various schemes for locating the peaks by triangulation from stations as near to the corner as possible so that the aspect presented to the observer was as similar as possible to what the 1875 surveyor would have seen.
To get rough estimates, I digitally scaled the positions of the peaks from the USGS quad sheet that showed them after transforming the map datum to NAD83 and computed inverses using those estimates, but I still wanted to get estimates that would be as close to what direct observation of the peaks from the rock mound would yield.
As I was set up at a station on the highway 1595.01 ft. from the corner, I realized that I could actually see all three peaks and proceeded to turn angles to them from a backsight of known azimuth.
I entered the ties to the peaks in the Star*Net adjustment, using the actual observed angles and the distances computed from the positions of the peaks as shown in high-quality NAIP digital orthophotos with 0.5m pixels. The position that Star*Net computed using the observed direction to the peak and the distance +/-5 ft. taken from the orthophoto was then overlaid on the orthophoto to make sure that it looked reasonable.
so, using those estimates of the positions of the peaks computed by Star*Net, I then queried Star*Net for the bearings from the rock mound to those points, which Star*Net computed as follows:
[pre]
From To Grid Azimuth Grid Dist 95% RelConfidence
Azimuth
122 LMAN 21-15-29 55607 40.26
122 LWOMAN 15-36-58 53222 40.20
122 WTWIN 17-14-33 29740 41.03
[/pre]
Note that the uncertainties in the computed azimuths took into account:
- the estimated standard error of +/-5 ft. in the distances to the peaks scaled from the orthophotos,
- the actual directions taken to the peaks at the control point No.19 (plotted in the image above), and
- the (small) uncertainty in the NAD83 position of Rock Mound No. 122.
It was simple enough to compare the very good (standard error of +/-20") grid azimuths computed by Star*Net from Rock Mound No. 122 to the bearings reported by the 1875 surveyor.
[pre]
Grid Az Record Grid-Record
122-LMAN 21°15'29" 23°00' -1°44'31"
122-LWOMAN 15°36'58" 17°00' -1°23'02"
122-WTWIN 17°14-32" 19°00' -1°45'28"
-----------
Mean -1°37'40"
[/pre]
So, that shows that the 1875 surveyor had his compass or plain transit adjusted so that at Rock Mound No. 122 it indicated NORTH when oriented Grid Azimuth -1°37'40" (= -1°38')
From Rock Mound No. 122, a corner that the 1875 surveyor reported as bearing SOUTH actually has a Grid Azimuth of 178°19'15" (or was evidently run in relation to a NORTH with a Grid Azimuth of -1°40'45"). Coincidence? It would definitely appear not.
Then the surveyor needed at least a modicum of scientific and legal knowledge. The possession of this learning alone was sufficient in frontier times to make a man notable.
That some "jack-legs" offered their services as surveyors is not to be doubted, considering the speculative trade in land. Lieutenant Marcy encountered a surveyor evidently of this class. To quote him: "I encountered a deputy state surveyor traveling on foot with this compass and chain on his back. I saluted him politely, remarking that I presumed he was a surveyor, to which he replied, 'I reckon Stranger that I ar that thar individoal.' I had taken the magnetic variation several times always with the same results (about 10° 20'); but in order to verify my observations, I was curious to learn how they accorded with his own working, and accordingly inquired what he made the variation of the compass in that locality. He seemed struck with astonishment at the question, took the compass from his back, laid it on a log nearby, then facing me and pointing with his finger toward it, said, 'Stranger, do you see that thar instrument? I've owned her well nigh going on twenty year. I'be put her through the perrairies and through the timber, and you can just bet yer life she never varied any time, and if yer foller her sign she'll knock the center out of the North star.' "
~ One League To Each Wind ~
Texas Surveyors Association
> He seemed struck with astonishment at the question, took the compass from his back, laid it on a log nearby, then facing me and pointing with his finger toward it, said, 'Stranger, do you see that thar instrument? I've owned her well nigh going on twenty year. I'be put her through the perrairies and through the timber, and you can just bet yer life she never varied any time, and if yer foller her sign she'll knock the center out of the North star.' "
That is one of the tales that can be discounted as early BS. There is no evidence whatsoever that I have ever seen that the early Texas county surveyors and their deputies were oblivious to the variation. To the contrary, the county surveyors usually instructed their deputies as to which variation to adjust their compasses for. I have seen exactly one survey that was ever made in Central Texas without any regard to the variation. That was a very early survey made in the 1840's around present day Wimberley that was actually run in relation to magnetic North.
'Stranger, do you see that thar instrument StarNet Least Squares? I've owned her well nigh going on twenty year. I'be put her through the perrairies and through the timber, and you can just bet yer life she never varied any time, and if yer foller her sign she'll knock the center out of the North star.'
Dave
In all actuality, the starnet exercise was redundant and probably performed just to get starnet out of the barn for an afternoon to stretch its legs. In the photo it is clear that all of the "[msg=286485]Pointer Stones[/msg]" dutifully set by the 1875 Texas surveyor are still extant. All that is needed is to wrap angles to the pointers and you have the lines to Lone Man Mountain, Lone Woman Mountain, the West Peak of the Twin Sisters and, apparently, a couple hundred other nearby peaks.
> In all actuality, the starnet exercise was redundant and probably performed just to get starnet out of the barn for an afternoon to stretch its legs.
Naw. Here's the view of the features as seen from the control point.
The exercise of actually pointing at a peak is necessary to see what the 1875 surveyor was really looking at in profile that he directed his instrument to. Even though the point I was set up on was more than a thousand feet from the corner where the 1875 surveyor took bearings, the peaks themselves are far enough away that their aspect would have been virtually the same at the corner.
Oh, just so you know, the floating letters above the peaks weren't really in the scene at the time. Likewise, the AT&T tower on Lone Man Mountain was not there in 1875, either. You're welcome.
>the floating letters above the peaks weren't really in the scene at the time –
Right. There you go trying to snooker us again by covering up the fact that early Texas surveyors constructed smoke signal “Sky Brands” above corners and/or prominent peaks they triangulated to.
You are not doing the profession any favors by keeping the obscure knowledge of “Pointer Stones” and “Sky Brands” in your vest pocket. Although not well documented in survey texts or field notes, research reveals that “Pointer Stones” have been placed by surveyors “prior to fences being built” for millennia.
An early example of Pointer Stones placed by Qin dynasty surveyors circa 150 BC in northern China:
A McMillan of Pointer Stones placed by Roman surveyors almost 1900 years on a large rancho survey in the British Isles for Hadrian Ltd. of Rome, Italy (note that at a later date of convenience or pasture fence was built near the pointer stones):
(in both photos the Pointer Stones are very discrete, so it may take you a while to recognize them)
Sky Brands over a pin cushion of 1/4 corners outside of Rock Springs Wyoming. The center brand was fired in 1870. The others came about in 1888 (left) and 1892 (right). GLO surveyors typically made one hack mark as opposed to your example of Texas surveyors using an atmosphere scribe to spell out the feature’s name:
The recognition and acknowledgement of early Pointer Stones which were “placed before any fences were built” will shake the survey world to its very core. Personally, in the last week I have amended nearly a dozen PLSS corners which I had previously set without considering the (now) obvious Pointer Stone evidence, a few of which are shown in the following photos. Some of them were well over 500 feet from where the corner was erroneously set using less reliable evidence. Once you are aware of them you realize they are everywhere:
