Hand Tools Archive
William Duffield
Well, they didn't call it a "rule joint" (ref. Aug. 2012 issue of Popular Woodworking for more on the rule joint) for nothing. Rule joints have been incorporated in table tops since at least the 18th Century.
The Hay Cabinet Shop at Colonial Williamsburg uses reproduction 2 foot single fold rules that are period correct for mid-18th Century colonial America.
The inventory of the 1797 Tool Chest of Benjamin Seaton lists a rule, which is now missing, so we don't know any details of its design.
http://www.astragalpress.com/Benjamin_Seaton.htm
This book references the The Gabrial Ledger of 1797, which lists 7 types of rules.
In The Faithfull Surveyour in 1662, George Atwel wrote instructions for making a carpenters rule.
http://books.google.com/books/about/The_faithfull_surveyor.html?id=7NK1OwAACAAJ
These instructions have been reprinted in The Rule Book, Measuring for the Trades, by Jane and Mark Rees, Astragal Press.
http://www.astragalpress.com/rule_book.htm
Jane illustrates several rules in this book from the 17th Century. One illustrated 18th Century rule is graduated in 8ths. Two older slide rules have logarithmic graduations much finer than that. One of these, which would have used dividers instead of a slide for multiplication and division, is from 1623. She also notes a rule created pre-1545, recovered from the Mary Rose, and documented by Richard Knight in the journal Tools & Trades.
(And, yes, I use a slide rule in my shop in addition to a four-fold box & brass rule, but they are much newer than these references.)
