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0 pointsp1mrx6y ago0 comments

At least you can't blame Johansson for that; 25.6mm would've been so far off (0.8% versus 0.0002%) that people wouldn't have bought his product.

Now I'm wondering how the ratio landed so close to 25.4 in the first place; 25.4000508 and 25.399977 have too many 0s and 9s for random chance.

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beerandt6y ago

Johansson rounded the inches, but previous legal definition was in yards. The Mendenhall Order was the US agreeing to define it's units in terms of the metric pegs, instead of the UK's (which were unreliably changing). The US survey of the coast (today the national geodetic survey), defined conversion values for the yard and pound.

1 (survey) yard = 3600⁄3937 meters

Reduces to:

1 (survey) foot = 1200⁄3937 meters

1 (survey) inch = 1/39.37 meters ~ 25.4000508 mm

https://en.m.wikipedia.org/wiki/Mendenhall_Order

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