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?" :>
Oh, the red button there kid, don't ever, ever touch the red button!
B-)
It's the "times 2" button, Kent.;-)
I wonder why..
In the lots along the north tier of section 5, it would be the "divide by 2" button to convert the acreage to chains.
Things that make you go "hmmmm" at this late hour.
> Oh, the red button there kid, don't ever, ever touch the red button!
Okay, so if get an enlargement of the map made and lay it out on the ground, can I "localize" with my RTK to solve the positions of the corners or do I have to actually think about what I'm doing?
> It's the "times 2" button, Kent.
Okay, I have tried that, but it gives me a very jagged looking shoreline that doesn't really resemble the map. Should I be concerned or do real pros not sweat that stuff? :>
I have only put it to pencil in my mind, but I'm thinking possibly an answer could lie in a "mean" of the chained distances for each side of the lot?
You only have one distance for each lot and the shoreline is definitely not square.
(I can't tell if I'm making sense, so it's best that I probably keep quiet...:'( )
> I have only put it to pencil in my mind, but I'm thinking possibly an answer could lie in a "mean" of the chained distances for each side of the lot?
(Well, I think that the straight answer is that if you seed the solution with any number for the length of the upper line of Lot 1, which is *approximately* 20 chains, the rest of the lot line lengths follow; and some sets of results resemble the map much more than others.) But surely there's a button for that, isn't there?
Possibly..
The acreages that are shown (out in the water) have every other lot line protruding out also. Every other lot line isn't "sticking out" in the water.
Possibly those not protruding are the line actually ran (measured) and the rest is craticulated creative draughting? Maybe that might take the jig-jag out of your plotting.
Possibly..
> The acreages that are shown (out in the water) have every other lot line protruding out also. Every other lot line isn't "sticking out" in the water.
The problem with that would be that the map shows a smooth shoreline. So, there really isn't any way of getting around the idea that the gulfward boundaries of the lots as laid out in 1837 by Mssrs. Trimble and Lindsey followed the (nearly linear) shore.
The other wrinkle is that Trimble and Lindsey were hired to make the survey and apparently one Andrew Phelan was hired to draw the map. In the early days of Texas, those were conceived as entirely separate activities. The surveyors went out and marked the corners with some recognizable somethings, gave their notes or sketches to a draughtsman and he turned out a jazzy-looking plat for posterity.
Does Not Matter, It Is Federal Land Now
Ain't you learnt nuttin yet?
Paul in PA
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Yeah, put all that into my trimble dc by coordinates I plotted in CAD from google and GIS, set on the first found point, press the "localize" button (not sure what that botton does but the salesman showed it to me) and I'm off and setting "missing" corners. And boy do they fit together!!;-)
Got to ask though, Gavelston? 1830's? ocean front? is any of it still there?
Possibly..
> The surveyors went out and marked the corners with some recognizable somethings, gave their notes or sketches to a draughtsman and he turned out a jazzy-looking plat for posterity.
Isn't this an 1800's procedure for the creation of toilet paper that has made a strong comeback in the past couple of decades?
Obviously, results vary depending upon the experience and level of collusion between draft person, party chief, and LS.
Steve
Does Not Matter, It Is Federal Land Now
Paul,
In Texas the state land goes to 3 marine leagues offshore.
Possibly..
> Got to ask though, Gavelston? 1830's? ocean front? is any of it still there?
There has been considerable change in the shorelines of Galveston Island since the 1837 survey. Had a seawall not been built in the early 20th century to protect what was left of Lot 1 shown on the plat above, it would no longer exist at all.
Possibly..
Looks like a fun one!!
Does Not Matter, It Is Federal Land Now
I always thought the State boundaries went out 3 nautical miles, or one league, from the farthest out salient point of the State's shoreline.
Hope Mr. McMillan will provide some details on his solution, if there is one beyond hitting the big red button marked 'easy'.
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> Looks like a fun one!!
Yes, there's ample evidence that Trimble & Lindsey did actually make a survey and mark corners on the ground in 1837. The pattern of lots sold at auction after the survey indicates that the buyers weren't just picking at random, but had some idea as to the location and quality of the land. As recently as 1900 (before the September hurricane that washed over most of the island), a surveyor reported finding wood posts at some lot corners with the lot numbers marked in Roman numerals, which would be consistent with what one would expect Trimble & Lindsey had done.
The Republic of Texas followed a similar scheme for selling off the remainder of several thousand acres of land it acquired around where the City of Austin was laid out in 1839. That survey appears also to have been made in chains, and corners marked with wood stakes into which lot numbers were cut. Likewise, the actual surveying and marking of lots was a contract separate from the drafting of the plan, as was apparently done on Galveston Island.
Area divided by width will give you the average depth of each lot. A linear regression should put you onto a pretty good guess. [sarcasm] That's about three buttons.[/sarcasm]:-P
> Area divided by width will give you the average depth of each lot. A linear regression should put you onto a pretty good guess.
Except the lot areas were plainly calculated from exact measurements, so the point of the exercise would be to calculate those actual measurements that yield the stated acreages. When you consider that some dimensions would be unlikely to have been measured with a 2-pole chain and that the shore has a particular shape, that would mean a different button would be the one to press. :>
