My grandfather’s folding rule reads from right to left, while my tape measure reads from left to right. I never thought much about it, though I always did like using my folding rule when measuring the distance between the table saw’s rip fence and the blade because of this characteristic.
Then last week a reader pointed out that a new folding ruler from Holland reads from left to right , like a modern tape measure. Argh. It was a mystery that only a tool collector could unravel.
So I picked up a copy of “A Sourcebook for Rule Collectors” (Astragal Press) by Philip E. Stanley. What a delightful geek-fest. I have been consuming the thing all evening. (I even got a little chicken piccata on the cover, which explains its lemony-fresh smell.)
If you are even mildly interested in the history of measurement, this 286-page book will delight you. Not only does the book cover the different kinds of rules (carriagemaker’s rules, gear rules, glazier’s rules), it also discusses in detail how they were made. (It’s a very involved process.) And there are interesting articles on the origin of historical measurement systems, including the European units of length before the metric system.
But does the book have the answer to the question? An article by Kenneth D. Roberts in the book has this to say:
“A peculiar difference between American and English folding rules is that the former read from right to left; whereas the latter read from left to right. No known authoritative explanation has yet to be found to account for this difference. It is suggested that it was simply a matter of custom, similar to driving on different sides of the road.”
Another writer in the book notes that some English rules read from right to left.
So really, this is one for Leonard Nimoy to figure out.
– Christopher Schwarz
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