Found it

Never had one opportunity to survey in West Texas, although I hope to one day. I would be interested to hear the difference between your measurement with modern technology vs called for distance on finding those old rock mounds

TXSurveyor, post: 431044, member: 6719 wrote: Never had one opportunity to survey in West Texas, although I hope to one day. I would be interested to hear the difference between your measurement with modern technology vs called for distance on finding those old rock mounds

Monte's holding his cards close to his chest, but I can tell you a bit about the sort of errors that are typical in that area, not specifically those in the work he's following. The original surveys fall into four different categories :

- surveys located by protraction from connecting lines run between corners of senior grants to which a block of surveys was to be fit up,
- surveys located by protraction from traverses run along the river,
- surveys made by chain and compass,
- surveys made by transit and stadia,
- surveys made by transit and triangulation,
- surveys made by transit and chain,
- surveys made with theodolite and EDM.

The surveys made with chain and compass probably ordinarily don't have errors much larger than 20 varas per mile along lines actually run, but much larger errors are possible along lines not directly run. The original surveys made in that area between about 1876 and 1884 were all based upon an assumed variation of 11?ø30'E, which was wrong by between roughly 0?ø45' and 0?ø56'. So, to begin with, the bearings as reported are typically in error by about that amount. 0?ø56' amounts to an error of about 86 ft. per mile in alignment.

Add in the further complication that a significant number of later surveys were made without taking into account the erroneous variation used in the surveys upon which patents were based, considering, say a call for "NORTH" to mean N0?ø00'E Astronomic, or as nearly as they could run it and you have, in effect, competing theories about how the various surveys were to be laid out on the ground to begin with.

The stadia surveys probably don't have errors much larger than about 20 varas per mile unless there was a major blunder and typically the errors may well be closer to less than 10 varas per mile on average.

The transit and tape surveys will have the same bearing errors mentioned above, depending upon whether or not the variation in the original framework from which the block was located was taken into proper account. Distance errors are likely less than maybe 2 varas. per mile.

The surveys by transit and triangulation depend upon the skill of the surveyor. The very good ones have errors less than about 2 varas. per mile and the very poor ones are ridiculous.

Yep, Kent hit it real well on his answering for me! Thank ya sir!

Monte, post: 431368, member: 11913 wrote: Yep, Kent hit it real well on his answering for me! Thank ya sir!

One of the more interesting surveys that I've worked on was one about 20 years ago that involved retraceing two transit and stadia surveys, one by R.S. Dod and one by his son, James Potter Dod. I was able to locate the actual field books of both surveys and so could see exactly what had been done and, more importantly, what had not been done.

None of the distances contained ridiculous errors, except for one line of one section that was wildly wrong (more than 100 varas, as I recall) and entirely as a result of it having been the side that had not actually been measured, but which was calculated entirely from a compilation of transit and stadia measurements made at various times over about 10 years by the two surveyors. The key to following the work was to actually retrace it in the same order in which it had been run and the field books were the key to that.

Has anyone ever followed Ken Barnes? From what I gather, he came out to Terlingua to work on the Terlingua Ranch survey done by Urban Engineering in 1969 and never left. He was not a registered but was the County Surveyor until the laws were changed to require registration to hold the office. He prepared Brewster County Rolled Sketch No. 133 in conjunction with corrected field notes and surveyor's report for Section 67, Block 341, G.H. & S.A.Ry. Co. Survey. Both the sketch and the report seem adequate but I have not followed him on the ground. He was nice enough to reply to my email inquiry and tells me that his records are all with the current Brewster County Surveyor, Steve Walker.

I'm looking at the Urban Engineering surveys that retraced some of the R.S. Dod sections and as Kent says, the stadia distances between monuments are very close to the called for 1900 varas by their measurement except where the terrain is very tough and then it can be off by a substantial amount. I hope to be back in Terlingua in October to retrace the same points with modern equipment.

Kent, you say that you have inspected Dod's field books. Are those in Mr. Walker's possession too?

I am of the understanding Mr Walker is away from his office, for reasons he may not want known to the public. He was in possession of Dod's records when we were in the area in May, but Mr Walker was not very available then.

Monte, post: 442279, member: 11913 wrote: I am of the understanding Mr Walker is away from his office, for reasons he may not want known to the public. He was in possession of Dod's records when we were in the area in May, but Mr Walker was not very available then.

Yes, when I was in Alpine in March (I think it was), I spent some time in Steve's office going through the records of both Dods pertaining to some surveys in a part of Presidio County I think you know well by this time. Among the Dod papers were also a couple of field books of another earlier surveyor (ca. 1900 - 1910) whose name doesn't come to mind at the moment, but whose books were excellent, much more readily intelligible than the somewhat haphazard form that both Dods favored.

Andy Nold, post: 442271, member: 7 wrote: Kent, you say that you have inspected Dod's field books. Are those in Mr. Walker's possession too?

If a surveyor were to plan to visit Steve's office to examine the RS Dod and JP Dod records (as well as those of the important Presidio County Surveyor whose name I can't yet recall), he should plan to devote a day to that at least. The records have a quirky organization that depends upon finding aids that aren't present in the collection. For example, one important indexing tool would be the contents pasted on the covers of the field books as seen below on RS Dod's FB 12:

However, to really use that index, you may need to have abstracted the title back to the time when one of the Dods made the survey in order to know the name of the landowner who was likely Dod's client.

The maps and correspondence are another matter entirely. That involves the brute force method of just looking at everything.

It's easily the work of a day to research the Dod records.

It's a who's who of Texas surveyors down there. I just ran across Dennis Corwin's resurvey of Block 16, G.H. & S.A. Ry Co Survey. His map is wonderfully drawn but Dod and company had to do a 2nd resurvey in the first decade of the 20th Century to place more corners and verify conflicts with Gano's Block G4. Thanks for the pic. I have nothing but good wishes for Mr. Walker to resolve whatever keeps him from his office and hope to be able to review the Dod materials in person.

Well, just be sure to plan to spend a day or two going through the Dod records because that is what it will take. I would definity start with enough abstracting to identify most or all of the relevant names since many of his projects are indexed by name.