Ending the Era of the U.S. Survey Foot (opens in new tab)

If it helps, the miles-to-kilometers ratio is approximately the golden ratio... (1.609 vs 1.618.)

So, as a level N nerd, you can convert miles to kilometers by rounding to a nearby fibonacci number, and then finding the NEXT fibonacci number (and maybe fudging a bit in the direction of rounding).

Then, as a Level N+1 Nerd, you can realize that the Fibonacci Base exists, in which any integer can be represented as a collection of distinct fibonacci numbers. (for example, 43 = 34 + 8 + 1, or, using a binary string to show which Fibs are involved, 42 = 10010001.) The conversion of miles to kilometers is then just a bit-shift operation.

Well, almost, anyway.

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.

Just FYI, a 'factoid' is something believed to be true, when it probably isn't. I assumed you meant 'fact', but otherwise your comment could be confusing.

Sometimes the benchmark for northing/easting/elev is many miles away from the actual site. This is especially true with gps surveys.

It only takes a few inches to wind up with a substantial drainage problem.

How often does a "should" translate into reality?

Which feet?

This seems the only reasonable way to do it except for terms deemed unenforceable (which is why you see a lot of boilerplate about severability)

In practice, since the difference is so small it does not matter in almost all cases, because no one was in a position to measure accurately enough. If you ask for 100 feet of rope, the difference between the two definitions of "foot" is much tinier than the smallest possible roundoff error you or the sales person will make.

My calculation shows 12 * 0.0254 = 0.30479999999999996 meters. That may be off a little due to IEEE floating-point inaccuracy.

Surveyors almost always use tenths (of a survey foot), which is one dead giveaway to which one you're using.

The International one (i.e. Non Survey Foot)

> In 1959, the relationship of the foot to the meter was officially refined as 1 foot = 0.3048 meter exactly.

So 0.0254 * 12.000000 == 0.3048

0.3048 meters / 12 = 0.254

I was referring to the content of the post on nist.gov. But I think the title has changed, and may have been simply "U.S. Survey Foot" when I first commented.

US cars have had dual speedometers for decades. One example: https://www.ebay.com/itm/NOS-1980-1981-FORD-MUSTANG-85MPH-SP...

It's called "US Customary", not "imperial".

> the "2 x 4" has never been 2 x 4 inches.

Well, it used to be pretty close, until lumber manufacturers and builders cheaped out. They've been gradually "shrinkflating" by reducing the thickness, conveniently requiring less wood. This went along with the switch to fast-growing garbage pine. I lived for a long time in an early-fifties house, and the quality of the wood was vastly superior to what you'd find today. Though, the newer measurements did make things a pain.

The Comanche helicopter was subject to this dictum. The original drawings specified all metric fasteners. They found out nobody supplies aircraft grade metric bolts so everything had to be redesigned for the next size up in freedom-units with a corresponding weight penalty.

83 was also defined in metric, but most states chose to use feet for their actual grid.

I think that's what they did in Canada and it worked out great as far as I can tell (except that they had a silly clock based on 10 hours instead of 12 IIRC which had little to do with metric units and nobody wanted it nor was it compatible with the rest of the world).

Saw this here somewhere previously: Sweden did something more insane: Högertrafikomläggningen. Do it once, get it over with?

https://en.wikipedia.org/wiki/Dagen_H

My wife's family, who almost all have university degrees, who were all born and raised in the US, and who are very familiar with the imperial system NEVER seem to be able to do math with it. They ask me, a European raised with the metric system, for help.

Find out how many fl oz of milk are in a measuring cup graduated in units of cups? Ask mrb.

Convert my daughter's height from feet/inches to inches? Ask mrb.

Convert a package's weight from oz to lb/oz? Ask mrb.

Need to know how cold it needs to be outside in farenheit for water to freeze? Ask mrb.

I lost count of the number of times they accidentally mix up for example 1.3 feet with 1 ft 3 in. Sometimes it's due to miscommunication, eg. I have seen "six pound five" interpreted as 6 lb 5 oz by one when the speaker meant 6.5 lb. Or vice versa.

It's just comical to see someone trying to argue that the imperial system is "sometimes easier."

I do agree with you that base-12 is easier to work with, but I think it's worth pointing out, appropos of the article, that U.S. surveyors actually talk about feet in "tenths" and "hundredths" - so, quick, what's one third of a foot? About 33 hundredths of a foot. ;)

Feet and inches aren't really in "base twelve", because it's not a positional number system. For example, what's 1/3 of an inch?

I think we'd be better off using dozenal numbers, but that ship sailed a long time ago.

Agreed. If you have ever done any type of construction you are very thankful that you can divide a foot evenly by 2, 3, 4 and 6.

> Quick, what's 1/3 of a meter?

33.3 cm?

"Quick, what's 1/3 of a meter?"

About a foot.

> Quick, what's 1/3 of a meter?

33 cm

333 mm

333 333 micrometre

333 333 333 nm

... and so on ...

   $ units
   You have: 1|3 m
   You want: ym
    * 3.3333333e+23
    / 3e-24

> politicians

Oooooookay.

Yes, as an Australian I find the idea of using fractional measurements to be super weird.

People in these threads talk about 1/3rd of an inch as if that’s a real number :)

But seriously I think you are right. I never use fractional notation or thinking when I’m building something, while it seems very common when reading US sites. I have a socket set which US Customary sizes in fractional inches and mm; I cant tell which of the US sockets is bigger without comparing them, but 11mm is obviously larger than 10mm (to me).

I think your observation about cultural identity is spot on, but as always it goes both ways - I think the US system is nuts because of all these crazy fractions.

Until now I didn’t realise that this was my own cultural bias against fractions leaking in.

And base-2, rather than the computer-unfriendly base-10. Aaaaactually ... with a bit of squinting the U. S. customary volume system(s) define a complete set of base-2 nouns (which could be used as prefixes):

    tbspn
    oz
    jill
    gill
    cup
    pint
    quart
    half
    gallon
    peck
    kenning
    bushel
    rundlet
    barrel
    hogshead
    butt
    tun

Where each item below the next item is exactly 2x the previous one. It turns out there's also some base-3 stuff (for measuring simplicity), like the teaspoon, etc.

I've always imagined we could redefine a few things to make a "completely rational" U.S. customary measure. That'd be:

    1 in == 2.5 centimeters (as Thomas Jefferson wanted)
    256 in^3 == 1 gallon (water at 32° F)

1 in is a bit awkwardly small. A cup-inch is ~1.3ft. A pint-inch is exactly .8125m. Luckily, a 'tun-tun-inch' (65536in) is 1.0343 miles, so we could define a a 'tun-tun-inch' to be a mile, etc., etc.

What you want is metric, so 10 inches to a foot and so on. Switching makes of units isn’t so bad so long as the multipliers are 10,100,1000

Next you want your units to make sense across dimensions. You want your volume units to ALL be based on your length units. A cubic foot is ok. It then contains 1000 cubic inches. There are no quarts, gallons, pints (unless they are names for decimal quantities of cubic units).

IDK, if you're going to be non-standard might as well go all the way.

The boiling point of water may not be useful on a day-to-day basis, but the freezing point certainly is. 0C is a lot less arbitrary than 32F. Other temperature mileposts are just a matter of getting used to them; 100F is pretty hot, as is 35C.

I think you underestimate the usefulness of powers of 10.

A milli-inch (thou) is actually a commonly used unit in precision manufacturing: https://en.wikipedia.org/wiki/Thousandth_of_an_inch

I have actually worked with people who didn't notice this about their 100' tapes. Even better are the tapes divided by 12 on one side and 10 on the other...

Well this was a false memory I may now remember as false. No, it wasn't tenths. I think more likely it had to do with the claw at the start of the tape for attaching to your starting point, which does not stay at a rigid 90 degrees. My memory is that over several tens of feet I was off by 1/8 inch.