This is a part of a plat that was made in 1837 to represent various lots bordering on an arm of the Gulf of Mexico. The lots were conveyed by the Republic of Texas by reference to this plat. While it doesn't give the dimensions of the lots, there is plenty of evidence that Lots 10, 11, 30, 31, 50, and 51 shown on the plat were 330 ft. wide and that Lot 502 was 660 ft. wide.
The lines extending beyond the shore of the tidal waters indicate where 50 ft. wide roads were laid out between the lots. and the numbers such as "11.50", "12.", "13.50" etc. are the acreages of the lots to the right of the numbers.
So:
1) How would one reasonably conclude from the map that the areas of the lots were determined? and
2) How would one best estimate the distances from the rear corners of Lots 10 - 502 to the bayshore as it was in 1837 based upon the information on the map?
Location of the shore should be simple. Just find some 1837 aerials of the area...
> Location of the shore should be simple. Just find some 1837 aerials of the area...
There is ample reason to think that the shore has gradually moved inland by hundreds of fee since 1837, even without the Montgolfier Daguerrotypes. :>
Oh, one relevant detail that I neglected to mention is that as nearly as I can determine, the scale of the map is 1" = 1/2 mile.
rate of change in area....
> rate of change in area....
If you put yourself back in the 1837 surveyor's shoes, though, how does the plat indicate that he calculated the areas to begin with? (To my mind, this is an essential fact to the reconstruction, i.e. what he actually measureed and what he did not.)
Why Is The Gulf Of Mexico West Of Texas ?
I would assume it is a bay and not the main body.
Paul in PA
No need to assume
> I would assume it is a bay and not the main body.
No need to make assumptions since the first sentence in the OP stated:
> This is a part of a plat that was made in 1837 to represent various lots bordering on an arm of the Gulf of Mexico.
No need to assume
I see no substantial arms to the Gulf and many named bays and lagunas.
Just wondering why the name was not given.
Paul in PA
No need to assume
> I see no substantial arms to the Gulf and many named bays and lagunas.
I'm trying (and failing) to see, whether the fact that the Gulf of Mexico may be called an arm of the Atlantic and a bay of the Gulf of Mexico an arm of the gulf (see Black's law dictionary under "bay") assists one in working this problem. Would you care to share your thought process? :>
Area by weight.... it could have been calculated by weight Are there any clues from the rest of the map? Do you already know what the answer is or the answer you will use?
> Area by weight.... it could have been calculated by weight Are there any clues from the rest of the map?
There are two main possibilities given the methods commonly used by surveyors in 1837 in Texas. The first is that the surveyors surveyed the meanders of the shoreline and plotted it on the map, then scaled distances to the shore from the rear lines of the lots. The subdivision was evidently laid out with a 2-pole (33 ft.) chain to facilitate the calculation of areas. The lot widths of 5 and 10 chains indicate that.
However, at a scale of 1" = 40 chains, it's not realistic to think that distances would be scaled with a precision of +/-0.5 chains (i.e. +/- 2 poles), which is what would have to be done to get a lot area of 13.85 ac., such as that of Lot 31.
While it is possible that larger sketches could have been made from which to scale distances more accurately, it seems much more likely that the shore was mapped by running a stair-step traverse along it consisting of lines parallel with the rear or side lot lines. That would accomplish two things:
- it would allow the survey to mark lot corners near the shoreline on the side lines of the lots as he mapped the shore, and with a minimum of calculation, and
- it would allow the ready calculation of fairly accurate lengths of side lines of lots without having to run and measure them.
I'd say it's nearly a certainty that the stair-step traverse was used and that distances were taken in 2-pole units (given the calculated areas). So, with that in view, how would a surveyor go about calculating the lot dimensions?
10 square chains = 1 acre. If you know the acreage and one side you can back out the average of the other side (assuming rectangles). Pretty standard stuff from the English measurement system using the chain.
> 10 square chains = 1 acre. If you know the acreage and one side you can back out the average of the other side (assuming rectangles).
And considering that the plat doesn't show rectangles, what would an alternate approach be? :>
> So, with that in view, how would a surveyor go about calculating the lot dimensions?
While apparently it isn't obvious, if you arbitrarily pick a length for any side lot line, the rest of the side lot line lengths follow if the contents of the lots (calculated by the trapezoidal rule) are be the values given by the plat. The plat shows a relatively smooth, monotonic curve for the shoreline and it turns out that there are only a couple of different sets of side lot line lengths that come closest to meeting those criteria.
My guess would be that they started on the land side of the subdivision. Surveyed that exterior boundary first then turned down one of the side lines and ran to the meander line,ran the meander line to the last side line, then run the side line to close on the exterior boundary line where the survey was commenced. The lots were calced as rectangles from the land side to the last tier before the tier of lots on the shore.Fot the last tier area was calced for a rectangular lot and the area beyond the meander line was treated as a triangle and that triangle's area was subtracted from the rectangle area of the lot. I do not believe they would have bothered with the sinousity of the shore line. That boundary line is ambulatory and suggect to change so why bother with a percise calulation that wil be invalid 5 minuted after it is figured. If the lots on the other boundarys are fairley regular then, I think that would support my theory. Sort of like looking at a tiled bathroom and figuing out where they started with the layout of the tile....
let me know if ai win anything
> My guess would be that they started on the land side of the subdivision. Surveyed that exterior boundary first then turned down one of the side lines and ran to the meander line,ran the meander line to the last side line, then run the side line to close on the exterior boundary line where the survey was commenced.
If you examine the whole plat of the subdivision showing the more than 500 lots (which I haven't posted), it's fairly clear that some baselines were almost certainly run to locate the regular (non-littoral lots) and the littoral lots were platted in the space that was left over.
It isn't particularly plausible that the littoral lots (at least in the area shown on the detail of the plat I posted) weren't actually surveyed and marked. The plat of the subdivision is typical of other subdivisions made in the late 1830's and early 1840's for the Republic of Texas in not showing lots of survey data other than numbers and acreages of lots. Thousands of acres of land owned by the Republic of Texas known as the "Government Tract" surrounding the City of Austin were subdivided into Outlots in roughly the same manner by a surveyor who actually did the surveying and left marked corners, but transmitted his sketches to a draftsman who prepared the plat of the whole business.
I would pretty much say that the areas of the lots were definitely calculated from survey measurements, so the question is what the most efficient way for the 1837 surveyor to have determined the lengths of the side lot lines would have been. The stair-step traverse was widely used for meandering rivers in the 19th century. I've seen surveys made as late as 1884 that used it along the Rio Grande in West Texas.
By "stair-step traverse", in this case it means a traverse that runs the full width of the lot, parallel with the back line of the lot to intersect where the side line of the lot will be, and then runs along the future side line to intersect the shoreline where a corner is made. Then the traverse turns and continues across the next lot, parallel with the rear line, and so on.
The length of the next side line is just the length of the last plus or minus (depending upon direction) the offset to reach the shoreline. For simplicity's sake, using a 2-pole chain we'd probably just record chaining to the nearest 2 poles since the shoreline would be along tidal flats.
While it may be easy to forget, the advantages of a stair-step traverse were that it hugely simplified computations. If we were doing the same work with the same technology today,we'd probably want to do things the same way.
> I do not believe they would have bothered with the sinousity of the shore line.
Well, they had to get reasonably accurate values of the areas of lots since the lots were to be advertised by acreage as well as shore frontage. So, the easiest method to do that would in all likelihood have been what was followed. From examining the map, you can conclude that the lengths of the sidellines of the littoral lots were known to the nearest 2 poles.
Good luck. My Corp office wants me to get license in Texas. Here is a good example why I tell them look at someone else.
> 2) How would one best estimate the distances from the rear corners of Lots 10 - 502 to the bayshore as it was in 1837 based upon the information on the map?
Ken I would say the distance (not sure how is was determinded in 1837) was 2046' from the ne corner 503.
The lots are 660' wide and the acreages on the plat are 502 = 31 acres, 503 = 20 acres, 531= 26.75 acres. This area of Trimble and Lindsey Section One is located between two water bodies and you need to go to lot 52 to find a corner common to the rest of the subdivision.
The tax map overlaid to the current aerial photo gives some idea of how the shore has changed.
The lot to the west (Lot 506) is interesting - in 1954 it was almost wiped out by erosion and sometime before 1969 it was completely recovered from what would generally been considered State of Texas Submerged Lands.
> > 2) How would one best estimate the distances from the rear corners of Lots 10 - 502 to the bayshore as it was in 1837 based upon the information on the map?
>
> I would say the distance (not sure how is was determinded in 1837) was 2046' from the ne corner 503.
Except if you look at all the areas of the littoral lots, you pretty much have to conclude that they were calculated as trapezoids, which is what you'd expect. The oddball area of Lot 31. i.e. 13.85 acres, was probably calculated from an average side length of 27.75 chains rounded down to 27.7 chains.
Considering that the rest of the lot areas appear to have been calculated from side lengths measured to the nearest 0.5 chains (= 2 poles = 33 ft.), I'd conclude that means that 27.75 chains wasn't measured directly, but was the average of either:
- 27.0 chains and 28.5 chains or
- 27.5 chains and 28.0 chains
The two main candidates as series of side lot line lengths determined by Trimble and Lindsey in 1837 are both within 0.5 chain on all lengths in the series from Lot 10 to Lot 502, with the East line of Lot 502 being either 29.0 or 29.5 chains in length (1914 ft. or 1947 ft.) per their plat.
> The lot to the west (Lot 506) is interesting - in 1954 it was almost wiped out by erosion and sometime before 1969 it was completely recovered from what would generally been considered State of Texas Submerged Lands.
Yes, that filled-in land in an area of the bay part of which had once been part of Lot 506 was the subject of a lawsuit decided in 1976 in which the State of Texas sued to recover the filled-in land. The adjoining upland owner had to purchase the land from the State and the State retained the minerals.
