so what are you trying to do...investigate the existing shoreline from 177 years.
It is evident that you do not have plats/records to do that.
There been some good advice here .
Have you tried other sources for maps? If there was a 19th fort or garrison in the area protecting the harbor, you may find some pretty decent military topographical maps of the area. They would be in a military library. Texas A& M?
May lead to a dead end.
There are some nice old maps and design plans of Louisiana coastal forts that were updated through the years with geodetic info.
> so what are you trying to do...investigate the existing shoreline from 177 years.
> It is evident that you do not have plats/records to do that.
Well, how much better does it get than a survey made on the ground in 1837? It really doesn't. What is neat about this exercise is that the acreages were obviously calculated from survey measurements (which the scale of the map prevented being noted on it) and offer a means of reconstituting the measurements. While it does require some thought, the technique is one that is generally applicable for most of the shoreline lots in the entire 18,000+ acre subdivision.
> > If I were forced, with a gun to my head, to note the location of the shoreline in 1837, it would be per scale from the old map, AFTER I located with parent lines and built it out.
>
> That would not be a very good choice considering the condition of the original map, its scale (1 in. = 40 chains = 1/2 mile) and the fact that the acreages noted both on the original, and two early copies are unquestioned.
So what you're saying is that you're not actually doing real surveying, just some exercise, presumably for some client and it's O&G related (my supposition).
Well, in that case, you do have a drafting arm somewhere that you can protract the original shore line and make your theoretical computations a little less of heaving lifting, right? 🙂
> > That would not be a very good choice considering the condition of the original map, its scale (1 in. = 40 chains = 1/2 mile) and the fact that the acreages noted both on the original, and two early copies are unquestioned.
>
> So what you're saying is that you're not actually doing real surveying, just some exercise, presumably for some client and it's O&G related (my supposition).
So, is the idea that a surveyor should always give up when he or she has to apply logical reasoning to a surveying problem? Amusing, to say the least. :>
> > > That would not be a very good choice considering the condition of the original map, its scale (1 in. = 40 chains = 1/2 mile) and the fact that the acreages noted both on the original, and two early copies are unquestioned.
> >
> > So what you're saying is that you're not actually doing real surveying, just some exercise, presumably for some client and it's O&G related (my supposition).
>
> So, is the idea that a surveyor should always give up when he or she has to apply logical reasoning to a surveying problem? Amusing, to say the least. :>
No. The idea that the surveyor should have a hobby instead of playing brain games with a 177 year old survey isn't amusing at all. I worry about you sometimes. 🙂
> No. The idea that the surveyor should have a hobby instead of playing brain games with a 177 year old survey isn't amusing at all.
Okay, we'll mark you down as not interested in the problem, regardless of whether it is relevant to a lawsuit or not. Next. :>
I had assumed you had already resolved the question seeing as how the case was resolved for now.
I have had some success in the past backing into a solution using CAD involving plats with limited calls and acreage shown. It was a largely a curvilinear subdivision and about drove me mad until I realized that the distances were on the chord instead of the arc.
(If you haven't already done it) if you go with the theory that they only held to the nearest whole unit of measurement for the length of the sidelines, there should be some method of working with all the lots to come up a workable solution but the only method I can think of is trial and error. I am kind of thinking about a mathematical solution like a least squares program to look at all the lot areas at the same time.
> I had assumed you had already resolved the question seeing as how the case was resolved for now.
Actually, this is a question that applies to nearly all the shoreline lots of the more than 18,000-acre subdivision on Galveston Island that Trimble & Lindsey surveyed in 1837. I haven't been in any hurry to offer a solution since it takes all the fun out of it.
I do realize that there are lots of surveyors who like nice and neat problems which can be solved by button pushing, but why would anyone need a surveyor for that? :>
> > I had assumed you had already resolved the question seeing as how the case was resolved for now.
>
> Actually, this is a question that applies to nearly all the shoreline lots of the more than 18,000-acre subdivision on Galveston Island that Trimble & Lindsey surveyed in 1837. I haven't been in any hurry to offer a solution since it takes all the fun out of it.
>
> I do realize that there are lots of surveyors who like nice and neat problems which can be solved by button pushing, but why would anyone need a surveyor for that? :>
Unless this some esoteric exercise in number conjuring, I don't believe the solution can be found in only looking at the specific acreages and plat dimensions in order to determine the location of the original 1837 shoreline and most probable length of the lot side lines. I think you hinted at the real solution by your above reference "this is a question that applies to nearly all the shoreline lots of the more than 18,000-acre subdivision on Galveston Island that Trimble & Lindsey surveyed in 1837". As such the only solution that would seem even half plausible would be to look at the entire subdivision plat and all of the evidence and not just a snapshot of just a small portion. The big picture so to say. Some kind of pedigree field evidence would also be critical in constructing a satisfactory solution. In short, approaching this as some simple exercise, or as you put it, 'what button do I push', is a bit of a fools errand. But likely, you already know that and just really enjoy yanking on other surveyor's chains. 😉
Are the areas calculated assuming rectangles with your stair step line being the shoreward side?
Disregarding the little triangles between the shore and the perpendicular traverse line?
Maybe,
5 chains wide. So add the two sides (in chains) and divide by 4 to get the acreage. So the length of the two sides is 4 times the acreage. But without a side chainage here and there you can't know the actual value of the individual sides. Might be there in the puzzle somewhere but I ain't spending that much time on it.
There is a similar thing in the PLSS when solving for lots. Add the two opposite sides of the lots (or average) to get the acreage (as long as one dimension is twenty chains). That's how you solve for the sides when all the dimensions are not shown but the lot acreage is. Just one of those things.
The mixture of units is weird. I guess they measure 5 chains then 50' then 5 chains then 5 chains then 50', etc.
Offsetting as they go because the shore isn't perpendicular to the lots.
Or maybe it's 5 chains then 76 links?
Which Button? The Answer
> Here's a moderately interesting exercise. The detail below is a portion of a plat showing a part of the Gulf of Mexico side of Galveston Island on the Texas coast.
>
> The map shows the lots and their acreages as laid out by a survey made by R.C. Trimble and Wm. Lindsey in 1837 under contract with the Republic of Texas. The lines extending to the right, into the Gulf of Mexico, indicate where 50 ft. streets were laid out between the lots indicated. The numbers to the right of the lots are their contents in acres and decimal fractions of an acre.
>
> The map gives a scale of 1 in. = 40 chains, which suggests that the 1837 survey was made in chains and there is no particular reason to doubt that to be the case since it it only makes sense given surveying practices of the day. The Lots are recognized as having widths of 5 chains and there is no particular reason to doubt that to be true in that the regular lots such as 153, 165, 168, 181, 184, & cet. are stated to have contents of 10 acres and scale as 5 chains x 20 chains.
>
> The 5 chain lot widths are recognized as not including the 50 ft. wide streets between the lots.
>
> So, here's the question: "What were the most probable lengths of the side lines of the lots fronting on the gulf and is there a button I can push to calculate them?" :>
>
> 
And this is what I think is the obvious answer:
[pre]
Line Acres Length
(chains)
1 20.5
10.50
1&20 21.5
11.02
20 22.6
road
21 22.6
11.58
21&40 23.7
12.04
40 24.45
road
41 24.45
12.55
41&59 25.75
13.06
59 26.5
road
60 26.5
13.60
60&75 27.9
14.10
75 28.5
road
76 28.5
14.60
76&89 29.9
15.10
89 30.5
road
90 30.5
15.65
90&101 32.1
16.25
101 32.9
road
102 32.9
16.65
102&113 33.7
17.15
113 34.9
road
114 34.9
17.70
114&125 35.9
18.20
125 36.9
road
126 36.9
18.70
126&139 37.9
19.25
139 39.1
road
140 39.1
19.80
140&151 40.1
20.12
151 40.4
road
152 20.5
10.5
152&166 21.5
11.0
166 22.5
road
167 22.5
11.5
167&182 23.5
...
[/pre]
> Unless this some esoteric exercise in number conjuring, I don't believe the solution can be found in only looking at the specific acreages and plat dimensions in order to determine the location of the original 1837 shoreline and most probable length of the lot side lines.
See below. It's essentially an exercise in resolving integer ambiguity where the basic unit is 0.1 chain.
> Are the areas calculated assuming rectangles with your stair step line being the shoreward side?
>
> Disregarding the little triangles between the shore and the perpendicular traverse line?
No, the lot areas are calculated as parallelograms. It would be slicing the balogna too thin for the road corners on the shore not to both fall on the same line of the traverse, though. That is, the stairstep traverse would have begun at the upper right corner of Lot 1, run perpendicular to a point on the line of 1 & 20, over to the shore for a corner of 20 and then perpendicular, making the upper right corner of 21 at 1.5 chains (nominally 50 ft.) and continuing on the same line for 5 chains more to a point on the line of 21 and 40, and so on.
> The mixture of units is weird. I guess they measure 5 chains then 50' then 5 chains then 5 chains then 50', etc.
>
> Offsetting as they go because the shore isn't perpendicular to the lots.
>
> Or maybe it's 5 chains then 76 links?
For 1837, almost certainly it was 0.75 chains = 50 ft. for all practical purpose. The 2-pole chain had a swivel at 0.25 chains, so it was an easy one to lay off.
Kent Kent Kent
1.5 chains is nominally 100'. 🙂
Kent Kent Kent
> 1.5 chains is nominally 100'. 🙂
Sorry, I meant 1.5 2-pole chain lengths, of course. :>
Which Button? The Answer
So where is it on the Island, address?
I suppose the four pole chain theory would sound right. If i'm not mistaken pre-Republic instruction for surveying included a vara equal to three geometric(?) feet which would divide evenly into the four pole chain, though i think i remember it being just less than a foot.
I have seen some odd road row from the very early 1900s that had me wondering if the surveyor had just placed the excess from the parent tract (less the lots) into these oddball row, until a fairly sharp registered explained that oddball distance was equal to a twenty vara chain. Just some thoughts on row.
