Technically, the US has been using the metric system since 1893

US Pint

Thanks for the trick, very useful !
Anyway a map speak more than a thousands words : http://commons.wikimedia.org/wiki/File:Metric_system.png

A mile is short for ā€˜mille passuumā€™ which translates to a thousand paces, and a pace is two steps.

I fortunately live in a metric country, but knowing steps and paces help when you need to find treasureā€¦hehehe

Seriously though, Iā€™m almost 40 and I didnā€™t know that 1pace=2step.

Just a correction there, 1.02m is in fact 1020mm, 1m being 1000mm. So 3.05m/3 is actually 1016mm more or less and your estimation of 1020mm would in fact put you off by 4mm after one itteration and by 8mm for the next. Not much, but even so 1016mm is very measurable on all of the tape measures I have in my garage.

I live in a metric country(South Africa), so I spotted the problem easily being used to converting between meters and millimeters.

For interest sake, our country switched to metric long before I was born even, but I would still say something is miles away, or your off by miles. Itā€™s just a figure of speech. And when I race, I race the 1/4mile, not 400mā€¦wink

Conversion isnā€™t instant. When Canada converted, people (spurred on by things like AM radio stations, who stuck to F) converted back to Fahrenheit for several years before they got used to Celsius. Now most people would have a hard time visualizing temperature in degrees F. Doesnā€™t help that the government, who doesnā€™t want to lose votes, allowed both units (applies more to weight, especially things like groceries).

In the UK we just use both, if you drive down a motorway youā€™ll see road signs measuring distances in miles, and then another sign telling you that there is 400m to the next junction. Or I can turn to my dad and describe a bit of wood as being two inches by 10cm.
Generally we use metric though, and Iā€™ve not noticed any labourers having problems with the maths.

Mind you, for some reason drugs are often still sold in (fractions of) ounces.

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I recall working on my old '71 Volvo 144ā€¦I tried the 12mm socket and it was too small and then the 13mm socket was too bigā€¦ā€œNah, canā€™t beā€ I thought as I used the 1/2" socket and it fit perfectlyā€¦I wouldnā€™t have thought that a car designed in Sweden and manufactured in Belgium would use SAE fittings.

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Hardly a good enough reason to keep miles as a standard measure of distance. Thereā€™s enough variation in a human stride that a Kilometer would be a better approximation of 1000 paces for some people than a mile anyway.

I would agree with Fahrenheit being the superior temperature scale. See, for example:

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Usually 13mm and 1/2" sockets and wrenches are completely interchangeable. But it depends on how many points in your sockets, I guessā€¦ I actually have one set of wrenches that are marked in both metric and SAE (as well as full sets of both, down to 64ths and half-millimeters in the ignition wrenchs).

  1. I have given you the reason that colonial America purposely chose to use non-metric for some purposes and metric for others. Itā€™s because there are more whole divisors in the base 12 system. This is not something you need to berate me for sharing.

  2. Itā€™s wonderful that you are good at math, I am happy for you. I am not good at math and personally find that using SAE for construction helps people like me do a better job. I prefer actual correctness rather than mathematically calculating what level of approximation will not result in a 13mm gap on the last course supported by a given height of framing. You can berate me for that if you wish, but I have done it both ways.

  3. You are confused about my earlier post. This is no doubt my fault. When I said ā€œTell me the whole number corresponding to ten divided by three without using fractionsā€ this was intended to illustrate that no such number exists. One third of ten is not a whole number; one third of a foot is four inches. I thought perhaps you were pretending not to understand, my apologies.

  4. Off topic, but 2x4 lumber used to be 2x4. During World War II, US lumber became ā€œnominalā€ and itā€™s been shrinking ever since. I have 1926 2x4s that are two or three times the weight of modern 2x4s, and have corners you could practically shave with, at exactly 2x4 inches. I have 2x4s from the 1960s that are noticeably and measurably larger than 1976 2x4s, which are in turn larger than what you find at Home Despot today (and all these have rounded corners). When working on older homes, I routinely buy larger lumber and rip it down to match the existing studs.

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In his initial scale (which is not the final Fahrenheit scale), the zero point is determined by placing the thermometer in brine: he used a mixture of ice, water, and ammonium chloride, a salt, at a 1:1:1 ratio. This is a frigorific mixture which stabilizes its temperature automatically: that stable temperature was defined as 0 Ā°F

I think thatā€™s actually the second go-round (but Iā€™m working from memory) after he had the media worked out satisfactorily, by using mercury. He was trying to get rid of negative numbers in everyday usages, for several very good reasons. I believe the next step was to designate 180 intervals between boiling and freezing, because that would provide 18 whole number divisors. He got this idea from classical geometry - 360 degrees in a circle - and supposedly called his divisions ā€œdegreesā€ for that reason.

Wikipedia has a table of divisors. If you compare numbers like 10 and 100 to numbers like 12 and 180, you can see why mathematicians and carpenters might prefer the latter to the former. Not only does 12 have many whole divisors, those divisors themselves also have abundant divisors. Spiffy, huh?

So why do people fetish over metric systems? Simple. Youā€™ve got ten fingers. Our standard system of writing numbers is an anthropomorphic base ten system, and thereā€™s value in leveraging that notation for many (but not all) things. Caveman notation because weā€™re still cave people in our heads.

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You know where it gets all crazy-pants? Tires. When I bought tires for my first car, they were ā€¦ umā€¦ L-15s, I think. But by the second time I bought tires, theyā€™d switched to the current system. In the current system, the tireā€™s inside diameter (rim diameter) is measured in inches, its widest point (which falls at an unspecified place) is measured in millimeters, the sidewall height has to be calculated from the ā€œaspect ratioā€ or ā€œseries profileā€ which is specified as a percentage (so, a P205/70R15 has a sidewall height that is 70% of 205mm I kid you not) and the top load and speed ratings are specified by completely arbitrary number and letter codes, respectively. The positions of the ratings are fixed unless itā€™s a Z rated tire in which case the speed rating is moved over to the middle between the aspect ratio and the rim diameter, next to the construction rating (which is usually R for Radial these days).

I swear to God I did not make any of that up.

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Here is the secret about fractional versus decimal. The inch system has both.

So, fractions, right? You know you can use fractions with metric, right? You can talk about 1/12 of a kg. You can even talk about 1/17th of a cm, or 37/13 ml, or 14Ļ€ mĀ² or whatever kind of mathematical notation you like. It just strikes me as a super weird argument.

Show me your tape measure.

and by the way, I love you user name.

Haha, OK, you got me. But I hear that argument from people who donā€™t make shit, who use a tape measure once every 5 years to measure a sofa or cupboard. And I mean, even if you DO make stuff, try dividing 1 foot into 10 pieces with inchesā€¦ you end up with fractions again and somehow people cope with that.

Anyway thank you, I liked my username better when it was the full ā€œecholocate chocolateā€ but this ridiculous software only displays my truncated username. Ho hum.

I was on a standards committee that was designing a tabular-format spec sheet standard for digital copiers. (ISO, EU, sigh.) We wanted to include an entry for number of output dots per linear unit. All the companies on the committee (all the Big Names) used metric for everything but that; we all used DPI. We put that into our draft, defined as ā€œdots per 25.4mmā€, but ISO was not amused. We had to change it to ā€œresolutionā€, which is not the right term for output. Thatā€™s what you see in standard-format spec sheets now, although I see that Xerox is using ā€œoutput resolutionā€. (Example)

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