Kent McMillan, post: 376534, member: 3 wrote: What I'm interested in is how the Sanborn's surveyors were instructed to (a) determine the boundaries of lots in cities and (b) measure setbacks of structures to those same boundaries. For example, some Sanborn's maps show street widths that differ significantly from what the public records reflect and the question is whether the width shown on the map represents the right-of-way as fences (which seems most likely) or was arrived at by other means. Same for setbacks. I'd assume that they were measured from fences, but it would be nice to know what the instructions actually provided.
Kent,
I'm VERY interested in these same questions. Please let us know if you actually find a copy.
Glenn Breysacher, post: 376540, member: 188 wrote: I'm VERY interested in these same questions. Please let us know if you actually find a copy.
Will do. The most important Manuals of Instructions to Surveyors, of course, would be the earliest ones that the maps of the same period would reasonably be presumed to have followed.
Kent McMillan, post: 357414, member: 3 wrote: Yes, the KU Library copy is the 1936 edition. The original published in 1905 is what I'm really after.
Apparently the Illinois State Library has one in their Map Room also, but it too is a '36 addition.
paden cash, post: 376552, member: 20 wrote: Apparently the Illinois State Library has one in their Map Room also, but it too is a '36 addition.
Yes, but I'm not so sure what one could conclude from it about how the surveys upon which the earlier maps were based were made. A person could probably make some good guesses, I suppose, but would ideally want something better.
paden cash, post: 376552, member: 20 wrote: Apparently the Illinois State Library has one in their Map Room also, but it too is a '36 addition.
Looking at the library info, both books are photocopies. A call to either library would likely get you a copy at a nominal cost. There may be some problems with copying the sample maps. The copy costs could be shared by other interested surveyors like Mr. Breysacher. Also, it may be that there are minimal changes to the 1905 "edition" in later "editions". I found this on Google books using the search term, "Surveyors' manual for the exclusive use and guidance of employees of the Sanborn Map Company".
Surveyors' Manual for the Exclusive Use and Guidance of Employees of the Sanborn Map Company (New York: 1950, reissued in 1911, 1923, 1925, and 1936)
I presume that "1950" should be "1905". If the manual was reissued four times (a probable scenario given that it was likely published by the company in small quantities) there may not be very many changes (if any) to later "editions" of the manual.
The Sanborn Map Co. is still in business, so you may find additional information from them regarding the various editions and perhaps even be able to obtain a copy or copies from the company.
For those not that familiar with Sanborn maps, here is an article entitled, Sanborn Fire Insurance Maps: History, Use, Availability
Kent McMillan, post: 376556, member: 3 wrote: Yes, but I'm not so sure what one could conclude from it about how the surveys upon which the earlier maps were based were made. A person could probably make some good guesses, I suppose, but would ideally want something better.
I looked at some of my "not so well known search sources" and struck clean out.
In the midst of my having seventeen windows opened I had a pdf written fairly recently that mentioned the exact title. I remember thinking an email to the author might shed some light on, if nothing else, how he knew the exact title. But business intervened and I closed all the windows before I wrote anything down; sorry.
You did pick a duesy for sure. Probably aren't three or four documented copies in the hands of all the 350 million folks here in the US. Good luck.
I've often wondered about their procedures when they collected their data. I remember one map here in Norman and there was an irregular lot on the corner of a block. The original plat (pre-Statehood) had an error with a distance and someone over the years (a good long time ago, it was faint) had penciled in the correct distance on the original plat at the courthouse. An early Sanborn Map of that block showed the correct distance also.
This led me to believe the "control" utilized in their initial blanketing of the area for graphic data had at least taken into consideration the legal boundary and probably was evidence that the "surveyor" had consulted recorded documents. I also remember one where the entire block length was shown on the Sanborn as significantly different than the plat. I later realized due to the location of the RR and a few other things that the block was indeed shorter than the plat indicated. I believe the maps were put together with some sort of 'ground measured integrity', albeit probably rudimentary.
Some reference material I read also discussed the actual cost and length of time preparing the maps. I don't remember actually being impressed with that info. Something like a week per City. And at that time the average populated city with any commerce probably had a population of 500 to 2000 folks. This meant they either worked really fast or had a good amount of boots on the ground.
Did they actually apply surveying principles and locate corners? Who knows. I would be interested if you came up with anything. Keep us informed as to what you find.
paden cash, post: 376563, member: 20 wrote: I've often wondered about their procedures when they collected their data. I remember one map here in Norman and there was an irregular lot on the corner of a block. The original plat (pre-Statehood) had an error with a distance and someone over the years (a good long time ago, it was faint) had penciled in the correct distance on the original plat at the courthouse. An early Sanborn Map of that block showed the correct distance also.
The classic question of retracement....What was the surveyor supposed to do (i.e. what's in the manual) vs. what the surveyor said they did vs. what you found the surveyor to have done.
These are the editions of the Sanborn Surveyors Manual:
1898, 1905, 1911, 1923, 1936.
All other references are transpositions (1950), updates (1911,1914 and probably 1925) or errors.
Later today I will explain myself in the "introduce yourself" forum, and add an avatar.
paden cash, post: 376563, member: 20 wrote: Did they actually apply surveying principles and locate corners? Who knows. I would be interested if you came up with anything. Keep us informed as to what you find.
The best general history of the Sanborn Fire Insurance maps that I've seen thus far is this from the Library of Congress:
https://www.loc.gov/rr/geogmap/sanborn/san4a1.html
You'll note that D.A. Sanborn, the founder, was a surveyor who decided to create a brand for himself and succeeded. As to how the mapping effort was done, I think it is a safe bet that the Sanborn surveyors began by compiling some base sheets of blocks from whatever sources were available. Nearly all the Sanborn's mapping was done in cities, I'd suspect, and so the City Engineer or City Surveyor would have been a natural first stop for basic information. Having gotten a theoretical picture of a certain block, though, the surveyors almost certainly were faced with the practical necessity of generating maps that contained the information needed for fire insurance purposes, but without spending the time to make anything very much better. Distances between structures and accurate description of character of buildings, distance to fire hydrants. size of water mains? Important. Exact determination of whether yard fence is set back a foot from right-of-way of street or encroaches a foot into it? Maybe not so much.
Per the passage quoted in the above link:
"The information reported," the Sanborn surveyor was advised, "is technical to the fire insurance world, and you should master the technicalities and ever bear in mind the use to which the map you are producing will be applied." 14
Maps were drawn at the scale of 50 feet to an inch, on sheets 21 by 25 inches, which were cross ruled in one-inch squares. The manual instructed surveyors to map all the builtup part of the town or city. "Information," they were told, "is generally available at the Court House, or . . . some real estate agent may have the necessary data. [However] if records are not easily obtainable do not waste too much time, but proceed to measure up the territory with tapeline, and plot sheets from notes so secured. In plotting put on the street names and widths and real estate description." 15
EDIT: All other references are transpositions (1950), updates (1914,1917 and probably 1925) or errors.
This insurance plan of Charlotte Amalie is by Charles E Goad, London 1897. I have one in my personal reference library.
MapsOnFire, post: 378897, member: 11789 wrote: This insurance plan of Charlotte Amalie is by Charles E Goad, London 1897. I have one in my personal reference library.
Am I missing something? I don't see it. I and lots of people here would be interested.
Another source of Sanborn Maps
City of Johnstown in 1886 before the terrible flood of 1889. Penn State is usually a great source for maps and orthos.
@kent-mcmillan Hi Kent, any luck in the 6 years since these posts in finding the 1905 copy of the Surveyors' Manual for the Exclusive Use and Guidance of Employees??ÿ
Kent no longer participates here.?ÿ I'm told you can find him active on Facebook, though.
