I think of the world before 1840 as a place where dimensions were not constant, where people didn't expect a foot or an acre to always be the same size. There was machinery, but all hand made. No mass production, no interchangeable parts. (On the other hand, everything could be fixed! No obsolescence!)
So when I think about using geometry to design, layout, and build before 1840 I am thinking about how to transfer information and keep it 'true'.
So here is an hypothesis:
Modern renovation contractors know to "measure 3 times, cut once". The same could be said about the houses built before standard dimensions. So what were the house wrights, masons, and joiners using as the 'measure'? The regulating lines could all be laid out by a length of rope and a piece of charcoal - and a point held tight. But that could be unwieldy: that taunt string got in the way. Or it had to be hung with a weight - not so easy for measuring the height of a unbuilt wall.
Story poles are the answer, I think. A story (or 'storey') pole as currently used is a 2x or a piece of strapping 'marked': the window and door openings noted by a mark, not a number. The length of the pole is the height of whatever is being recorded, a room, an exterior wall, etc. It is set against the place to be laid out and the important points are noted.
Today story poles are used for house framing, for clapboard and brick coursing, for constant dimensions for windows and doors, paneling. That is probably how they have been used for centuries.
Historic restoration carpenters told me they have found story poles in the attics of houses they are working on. That makes sense: What to do with a story pole when the house is finished? Leave it for the next guy!
Thinking of this I went to Wikipedia - which did describe 'storey poles' used in the past, and said they were not used today. However, I know about them because I've seen contractors use them.
Considering that my knowledge is concentrated in one particular geographic area and a certain group of contractors, I posed the question of the use of story poles to a contractors' group to which I belong, on-line: "Do you use story poles? If so, how?" 10 contractors, working from the Atlantic seaboard to Kansas, replied that they did. They use story poles for siding, stair layout, shelving, cabinetry, tile work, paneling, windows, chairs, clapboard and brick coursing. In Kentucky they are also called 'preacher boards'.
So, I will add that information to the entry on Wikipedia. The on-line encyclopedia needs a 'source', a footnote that refers to documentation of the idea, to show that it wasn't just one person's opinion. This post, documenting my research and the information provided by the contractors, is that source.
One contractor suggested I check out Lee Valley Precision Story Tapes. With permission from Lee Valley and Veritas Tools I will post them as a source as well.
Note to John Leeke, David M. Lyons, Mark Ratte, as well as the other contractors: Thank you!