Hi.

According to the "Description and Utilization of the Sanborn Map" these are thicknesses of exterior walls in inches. Sometimes "party walls" will also have thicknesses indicated. Number at the bottom of the stack is the lowest floor, that on the top of the stack is the thickness of the upper floor. This information appears only for buildings with brick/masonry construction.


jmj
UIUC
maps

From: Maps-L: Map Librarians, etc. [mailto:[log in to unmask]] On Behalf Of Stephen Robert Appel
Sent: Tuesday, November 21, 2017 3:19 PM
To: [log in to unmask]
Subject: Sanborn Map Mystery

Hi All,



We had a patron contact us asking about some symbols on Sanborn Maps and I'm hoping someone can give us more information.



I've attached 2 images for examples and circled all the symbols I could find in red.  (I have more examples but there is a size limit for the list.)



As far as I can see, the symbols only appear on Brick Veneered buildings.  Most often they look like a 4 but sometimes there are two "fours" 44, or even three.  I also have seen an occasional 8, 88, and even 12 12.  From what I've found, the 8s and 12s only show up on brick dividing walls.



A standard brick is roughly 4 by 8, so numbers like 4, 8 and 12 make sense.



Thanks!



Best,

Stephen

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Stephen Appel | [log in to unmask]<mailto:[log in to unmask]>

Geospatial Information Specialist

American Geographical Society Library
University of Wisconsin-Milwaukee Libraries