111,111.1 meters is reliably 1 degree of latitude
gis.stackexchange.com
gis.stackexchange.com
It then follows straightforwardly that 1° ≡ 1/90 × 10^7 m = 111 111.111... m.
It also follows straightforwardly that the circumference of Earth is approximately forty million metres, or 40 000 km.
[0]: Edit: the initial definition of the metre was the length of a seconds pendulum, i.e. the length of a pendulum with a period of two seconds.
Given the formula T ≈ 2π√(L/g), letting T = 2 and L = 1, we have 1 = π√(1/g), and 1 = π²/g.
This is also why g is so close to the value of π²—because the former is expressed in units that are defined that way. It's also not a coincidence that 1 cm³ of water is 1 g—for a long time, that was the definition of the gram.
Since the metre was previously defined by the seconds pendulum, it was entirely defined by the definition of a second and the value of g. From the equations, 1 m = 1 s² × g / π².
While this makes g ≈ π² straightforward, it seems coincidental that the Earth's circumference was close enough to 40 000 km that the redefinition of the metre was a nice power or 10 without too much change to the metre.
[0]: Late 16th century, based on https://en.wikipedia.org/wiki/Second#Fraction_of_solar_day
If the Earth's circumference wasn't a nice number, people would have chosen another one.
> In 1675, Tito Livio Burattini suggested the term metre for a unit of length based on a pendulum length, but then it was discovered that the length of a seconds pendulum varies from place to place.
Assuming the second was also quite accurate, the seconds pendulum wouldn't be too far from its current definition given that g ≈ π² to within ~1 % in modern units.
One problem with degrees is that hard to convert to useful distances. This tricks help a lot, but it would be better to have no conversion.
Are you advocating for the use of Manhattan distances for everything?
In a previous life I had to implement conversions between ECEF and WGS84. If you do it, make sure to use at least 64-bit floats, the Earth is so big that 32-bit arithmetic will introduce errors on the order of meters.
“I’ll just automate this mapping task in Python, how bad could it be?”
- A very-new-to-everything me, years ago.
Most places in world also have local coordinate systems that reproject smaller geographic areas to cartesian coordinates with meter units for making easier to work in those areas.
There also MGRS https://en.wikipedia.org/wiki/Military_Grid_Reference_System , the NATO military variant of UTM.
360° = 400 gon, so 1 gon = 100 km of arc length
But I guess they were using the stars or something so maybe it's not as hard as I'd imagine. Also (2) and (3) are great points.
The meter was also standardized at a weird golden period for units -- we had global trade and travel (and so it was getting inconvenient to have different standard unit length sticks in different countries, let alone cities), we had enough science to have the notion of basing it on physical constants instead of random sticks, but we also weren't yet in a world where precision mattered all that much. You could change the length of your units by 3% and it wouldn't really matter as much it would today, where every bolt and manufactured part would instantly become a nightmare.
It's kind of a shame, because now we could pick so much cooler definitions for our units, because our science is so much better. Take restandardizing the foot as 1 ns * c -- so much more elegant than the mean circumference of the Earth, or an ugly number of wavelengths of a caesium atom. But changing the foot by 1.5% -- half as much as the difference between the meter and 3 Paris feet -- would be devastating today in a way that it wasn't in 1800. Hell, it'd probably be easier to change the definition of a second than the definition of a foot.
Doesn't sound like a good idea. Circumference of earth around Paris is not unchangeable.
The definition has been updated after that. https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_ba...
Which is why the CGPM changed the definition of the metre to:
- the length of the International Metre (a 9:1 platinum-iridium bar) in 1889;
- and then to 1650763.73 wavelengths of the orange-red emission line in the electromagnetic spectrum of the krypton-86 atom in a vacuum in 1960;
- and finally to the modern definition, the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second in 1983.
This means the realisation of the metre depends on the definition of the second.
As a sailor, I wish that all miles were nautical miles because they have a real meaning. What good is 5280 feet?
In fact, 1 nmi ≡ 1.852 km exactly.
Also from the original definition of the metre: 1/60 × 1/90 × 10^7 = 1851.85185185... m.
Inter-convertability was a defining trait of SI (or more precisely, its predecessors, MKS and CGS) from the very outset, which is why we have 1 m ≡ 1 s ≡ 1 kg ≡ 1 N ≡ 1 Pa ≡ 1 J ≡ 1 A ≡ 1 C ≡ 1 V ≡ 1 Ω ≡ 1 F ≡ 1 W ≡ 1 Wb ≡ 1 T ≡ 1 H ≡ 1 Hz (I use '≡' loosely here to suggest conversion factors, rather than its usual meaning of equivalence).
The only outliers in the SI are the kelvin, the mole, and the candela (and derived units from these). The former two are dealt with straightforwardly with the Boltzmann and Avogadro constants. I have issues with the presence of the candela in the SI.
Pre-metric Europe was full of units with weird conversion factors, based on a shared heritage (mixture of Roman and Germanic), but with lots of divergent evolution subsequently. England didn't really stand out; France, Spain, Italy, Germany, etc, were really no different.
Then the Continent did away with most of that complexity by adopting metric, and for whatever reason the English dragged their feet on doing that, and their American offshoots even more so. But the fact that people have forgotten that the French/Germans/etc used to have feet/inches/miles/pounds/etc too, [0] albeit with somewhat different definitions, makes people think English units were somehow unique. They never were. The uniqueness is in the slowness in replacing them with metric, not the units themselves.
[0] They still have some of these units for certain purposes. In France and Germany, the pound is still used, albeit redefined to be exactly 500 g. Nautical miles are used in maritime and aviation applications; American influence (and to a lesser degree British) led to the adoption of the Anglo-American foot as the unit of altitude in aviation – the foot French pilots use to measure altitudes is the English foot not the old French foot; etc
There are a few notes I have regarding this. The Airbus consortium initially set up the Airbus A300 cockpit entirely in SI units, but they realised this wouldn't sell well in the US, and they switched to feet and flight levels.
Airfield weather data, including pressure and temperature readings in everywhere but the US are given in hectopascals and degrees Celsius.
Many post-Warsaw Pact countries (Russia, China, Uzbekistan, Belarus, Ukraine until recently) used to have a completely metric unit setup for their air traffic controls. Both Boeing and Airbus cockpits have settings to output altimeter readings in metres.
> Then the Continent did away with most of that complexity by adopting metric, and for whatever reason the English dragged their feet on doing that, and their American offshoots even more so.
If there's one export of the US I despise more than anything else, it is making legacy non-SI units relevant again because of its outsize influence in traditional and social media.
I live in a country that metricated half a century ago, but I have Gen Z friends who measure their heights in feet and inches, and their gym weights in pounds. What the absolute hell.
The SI units are the pinnacle of standardisation and the culmination of a three-hundred-year long effort to make life easier for everyone. I have no idea why the richest country in the world can't metricate properly.
Get rid of legacy units, and we save billions in not printing the (XX fl. oz), (XX lbs), or (XX oz) on food packaging alone.
It is ironic that a country that did away with colonialism, a whole lot of tea, and embraced the French and their revolution, never embraced the French units, but stuck with the English units.
I've heard this argument many times before, but I don't think it makes much sense. The US customary / British imperial measurements are not consistently based on base 12. Yes, there are 12 inches to a foot; but there are 16 (not 12) ounces in a pound, and 128 (not 12 or 144) US fluid ounces in a US gallon (versus 160 UK fluid ounces in a UK gallon). Fahrenheit has 180 degrees between the freezing and boiling points of water, with water freezing at 32 degrees – none of which has much to do with base 12 either. There is no widely used unit corresponding to 12 feet or a twelfth of a mile. If you really want a system of units based on base 12, the US customary / British imperial system ain't what you are looking for.
Also, it ignores the fact that you can metricate while keeping a foot of 12 inches, if you define a new "metric foot" composed of 12 "metric inches". This has been done before – as I mentioned in an earlier comment, many European countries kept the pound when metricating, by defining a new "metric pound" of 500 g. Given the current standard US-UK inch is exactly 25.4 mm, one option would be to have a metric inch of 25 mm (= 2.5 cm), twelve of which would give a metric foot of 300 mm (= 30 cm, versus 30.48 cm exactly for the standard US-UK foot). Sure, having two different foots and inches (old and new) coexisting for a while might cause some confusion; but if the confusion isn't worth it, maybe base 12 isn't really worth it either. And to avoid the confusion, you could always give the new metric units different names ("moots and minches", maybe?)
That said, Fahrenheit use of brine solution for 0 and his wife's armpit for 100 remains among most WTF for me.
A lot of that was because keeping the definition of units consistent across time and space was very hard in ancient and mediaeval times, even the first few centuries of the modern period. Units were defined in terms of physical artefacts (as long as this metal rod, as heavy as this particular stone), which tended over the centuries to be lost or stolen, or slowly decay. Issues such as expansion and contraction of metals at different temperatures were also not widely understood, and accurate/reproducible thermometers didn't exist until the 18th century. As we improved our knowledge of natural science, we became more and more aware of these issues – but the initial solution was often just to make the whole country adopt the standard of the national capital, and empires were made to adopt the standard of the imperial capital (the British don't call their traditional units "Imperial" for nothing)
What would a machine shop say if you called out a dimension as (5,081/20,736")?
I think they'd stare at it for a while, chuckle at your sense of humor, and then punch it into a calculator to work it out in decimals.
Positively mortifying.
I invite you to watch this amusing and relatively short video by History Maters on the subject: https://youtube.com/watch?v=BtKbq_zAr-A&pp=ygUWaGlzdG9yeSBtY...
As an American I will say this, almost nobody genuinely thinks that our measurement system is superior. I suspect the majority of us know it’s a janky system but it’s so difficult to change.
That being said, I switched over to Kilometers on my iPhone because of Pokémon Go. I’ve actually gotten to the point where I think of walking distance in metric more readily than in fractions of a mile, so metrification is making progress in unexpected and exciting ways!
Every machine in every machine shop was geared towards manufacturing dimensions and tolerances specified in inches, tenths, and hundredths. Changing to metric would have required rebuilding or replacing all of them. England had the same problem. They had the most manufacturing capability in the world, and they weren’t about to spend all that money replacing all of that machinery.
Worse, the SI system isn’t really easier. The SI units were designed to make unit conversions easier, but in practice nobody actually converts units. In the US Customary system (as in the English Imperial system before it), every common activity has it’s own units.
Houses and furniture are measured in feet and inches, and you never ever convert those to miles. Why bother? Miles aren’t useful for measuring cupboards or rocking chairs.
Cooking uses teaspoons, tablespoons and cups, but you never need to convert between spoons and cups let alone cups and gallons or barrels or hogsheads. It is handy to remember that a tablespoon is three teaspoons though, because that can save you some time at the holidays when you have to scale your recipes up to feed all of your relatives.
The SI system is not really any different in practice.
> and then afterwards there was an industrial revolution.
> Every machine in every machine shop was geared towards manufacturing dimensions and tolerances specified in inches, tenths, and hundredths. Changing to metric would have required rebuilding or replacing all of them.
I don't think this argument makes anywhere near as much sense as you think it does: the part of the US which lags the most in metrication isn't industry, it is in everyday life, K-12 education, and consumer products/services; the US manufacturing industry is significantly ahead of US consumers in the adoption of metric. Entire industries in the US have adopted metric (most notably the US automotive design&manufacturing industry has switched to mostly metric). If the real issue were about industry, you'd expect industry to have the biggest lag, not to be ahead of consumers.
I think the real reason is actually cultural. Almost every country which successfully metricated, did so with some degree of government coercion – "you are going to start using metric now, and we aren't giving you a choice about it". The US cultural emphasis on individual freedom led it to refuse to go down that path, insisting that metrication be voluntary only – which is a large part of why, decades later, so little progress has been made. Similarly, the UK's insistence on retaining miles for road distances is due to cultural and political reasons, not any practical concern – Australia successfully converted all its road distance and speed limit signs to kilometres, despite having much longer roads than the UK does
Also, for all that US insistence on "freedom", it actually engages in anti-metric governmental coercion – consider the Fair Packaging and Labelling Act (FPLA), a federal law which makes metric-only packaging illegal for many categories of consumer goods.
> The SI units were designed to make unit conversions easier, but in practice nobody actually converts units
I can remember doing lots of unit conversions in science and maths classes in high school. If I'd gone on to study physical science or engineering at university, I'm sure I would have done plenty more. From an educational viewpoint, I think it is easier to teach students how to do science with SI units if they have already been taught basic metric units at the primary/elementary level, and are used to using them in everyday life. Whereas, students in the US start out with less familiarity with basic metric units, which makes learning to use SI units in science class more work for them
And every time I visit the US I find myself constantly trying to remember stuff like "what is an ounce, again?" "what's 60 degrees Fahrenheit in Celsius?". If the US finally finished adopting the metric system, it would eliminate the need for many unit conversions which are now required by international visitors, immigrants/emigrants to/from the US, journalists, businesses engaged in product localisation, etc
> Cooking uses teaspoons, tablespoons and cups, but you never need to convert between spoons and cups
Some countries (Australia I know is one, there are probably others) have defined metric cups, teaspoons and tablespoons. So this isn't really the argument against the metric system that you think it is
Well, the metric system was devised in France mostly during the Revolution, with the size of Earth surveyed while at war with most of Europe in order to get a good basis for the length of the meter.
> Cooking uses teaspoons, tablespoons and cups
Or millilitres and grams, which are basically equivalent for liquids, so you only need a kitchen scale to do most cooking as long as it's not an American recipe, and it's extremely easy to scale recipes.
Actually there are plenty of examples of countries adopting metric after a revolution or gaining independence, so perhaps the US didn’t adopt metric in spite of the revolution rather than because of it.
On the other side, 1 liter of water is 1000 grams so if I need 100 cc I can put water in a glass and weight it.
The popularity of Johansson's blocks is Brits changed their definition of inch in 1930 and USA followed in 1933. Most countries that still used inches started to use "industrial inch" of 25.4mm in 1930s, the rest went metric.
What we do use is 'Pfund' (pounds lbs) which is defined as 500g.
I am amazed the nations of the world actually came to an agreement about what to use as base units and I can't even fathom what shit show it must've been before that.
I live a 30min drive away from the Netherlands and your ounce is already 230% more then my ounce.
Almost everyone called 90 mm floppy disks "3.5 inch", despite the fact the formal standard which defined their dimensions was metric. I believe the same was true of the "5.25 inch" disks which preceded them. (I think the original 8-inch floppy disks were non-metric though???)
However I guess that even American engines are measured in liters or cc, cubic centimeters.
English inches (now 25.4 mm) or Italian inches? (“once”/“oncia”-varied in definition between different parts of Italy, but was always at least a fraction more or less than the English one)
I'm not sure I ever heard the Italian word oncia as a unit of length. I thought it was a translation of the imperial unit of weight, ounce. However all is possible in the world of the old semi forgotten traditional units.
https://en.m.wikipedia.org/wiki/Italian_units_of_measurement
Panel manufacturers are all based in Asia, and measure only the edges in millimetres, as they should. Even xrandr outputs EDID data in millimetres.
The last time I had to buy a TV set I was more interested in the width of the appliance (screen plus bezel) than in its diagonal because I had to fit it into a set space. I went to a shop with a tape ruler.
Pun intended? ;-)
It's also worth noting that English and American units also differ slightly --- one of the more common examples being that the US gallon is not the same as the Imperial gallon.
To be specific, 5280 feet = 1 mile didn't happen until 1959 and the United States needed higher precision and remove all the fuzziness out of the units. It might be inconvenient on some aspects, but it was also "close enough" to what miles were already established to be.
uh what? are you sure you're not mixing that up with the international geophysical year or something? the mile has been 1760 yards since before the US even existed. it's called the imperial system because of the british empire. they couldn't have done the great trigonometrical survey of india without an accurate mile.
(8 prime factors, 4 distinct)
So 5280 is better if you want to divide by 11, I guess! What a strange thing, how on earth did it end up with a factor of 11 in there...
Edit: it's complicated: https://math.ucr.edu/home/baez/inches.html
Going the other way, 2 yards in a fathom and 3 feet in a yard. That accounts for all the factors above.
90: 2, 3, 5, 6, 9, 10, 15, 18, 30, and 45
100: 2, 4, 5, 10, 20, 25, and 50
If we used grads, it would be a nice even 100,000 meters per grad, vs 111,111.111 per degree.
The roman mile was 1000 paces, or 5000 feet, which made a bit more sense.
Averages out better.
My hypothesis is this: Actually try to count every foot when you’re out. If you count only every second footfall, you can mentally go "a-one-a-two-a-three" and so on, but counting every foot, there are just too many of them. At least I get brain overload from it.
They're both shortcuts to count things with half as much counting.
It always got complicated with obstacles though. Especially since most of them didn't know how to do trigonometry yet. We usually just had them estimate which they got pretty good at after a few hours of counting paces.
nm are great because charts and speeds are in units of nm and kt of course, but what does "real meaning" give you exactly?
Now, of course, in principle charts could have a separate scale for distances in km, and we could use km for navigation just fine. But, well, I've never seen a nautical chart with such a scale.
The equivalency with knots is great and all but it too is just a convention
These days, everybody has plotter or phone to measure position and speed and calculate distances.
Could you define 'real' here please?
This feels like one of those 'customary is better because you can't divide 10 by 3 using only integers' claims.
You seem to be asserting that once you divide a circle into 360 arcs, then at a a certain distance from the focus, one of those arcs has a certain meaning.
I would say that because ~ 2 millennia ago the Greeks pinched the Babylonian's use of 360, and the Babylonians came to that number by perfecting a rough days-in-a-year measurement used for astronomy over the previous 2 millennia, a nautical mile now has a derived / coincidental meaning, more so than a 'real' one.
EDIT: And this is before contemplating the complications of living on an oblate spheroid - the NM's length depends on where you are.
The actual length of a nautical mile only makes sense because we have this weird way of measuring earth (based on how we measure circles).
NM's were obviously defined using that weird numbering system - 360 degrees in a circle, 60 minutes in a degree, 60 seconds in a minute - so it shouldn't be a surprise that they 'feel real' within that system.
Given a quarter of the circumference of earth is ~ 10,000km, it seems ripe for using base-10 and metric units ... but for the fact, obviously, that these arc-based-at-6-thousand-km-from-the-centre measurements are highly variable and not hugely useful.
> The point of calling nautical miles 'real' is that you can do easy mental math with them to express a distance in terms of latitude and longitude.
And that's not true either.
At best it works for latitude -- even a small way from the equator you'll suffer the effects of longitudinal meridians converging.
But at that point, why not just do your mental math in minutes rather than (yet another) mile variant?
If you're using a plotter, then actual length is presumably irrelevant - any unit would do, yes?
I was not asserting that nautical miles don't have meaning - just that their meaning is even more arbitrary than most other units of measurement, except in this case they're extra useless because they align to what they ostensibly derive from only at or near the equator.
If you want to use something 'around that size', and you're very keen on avoiding metric at all costs, then why not just use the 'upstream' unit - a minute? Obviously it still suffers from converging meridians if you measure from a plane through the sphere, but I'm not sure what number of measurement problems you're happy to contend with.
The coordinate grid may be arbitrary (though having a lot of factors is nice), but the derived nautical mile is not.
Yes. We may be misunderstanding each other.
It's convenient to have nautical miles per hour if you're using a base unit of nautical miles, and your map grid is nautical miles based. This isn't a surprise at all.
Estimating wind, tides, drift, etc, would be equally as easy if everyone was working in kilometres, and your maps were showing grids based on multiples-of-kilometres, and all speeds were given in kilometres per hour. Again, wouldn't be a surprise.
Inches using base 2 for the fractions is useful.
The building code(s) only get you so far. There's also aesthetics.
About the only example of imperial being easier I can think of is that the thin-kerf saw blades he buys are American, and thus are measured in inches - 1/16” to be precise. It’d be tremendously annoying to deal with 1.588 mm. If he had a 1.5 mm blade, of course, it would be the other way around.
Why? You can't just say that without a reason.
(The numbers you cited above don't count, because you'd instead use 6.1 and 14.4 (or maybe 14.45) centimeters)
Let's say you are centering a 2 1/4" board on a 22" frame.
The edges need to be 8 3/8" apart.
It's a lot more common to divide lengths in halves (and quarters, etc) than tenths.
But if I did that would indeed be difficult.
It’s also easier to add up 10 different decimal numbers than the same number of mixed numbers.
That's why I like to do things that are easier.
Seems like straight forward arithmetic, but if using a calculator is a must, the HP 35s (RPN daily driver) handles fractional calculations elegantly without being a "very specific carpenters calculator":
2.13.32 [Enter] 5.11.16 [+]
8.09375
[-->] [FDISP]
8 3/32I've always found it curious how Europeans pride themselves in speaking their native tongue + English...except its always a cultural flame war-inciting impediment when the communication barrier involves a mere arithmetic unit conversion. Doubly ironic when most of the world is consciously aware of what the prevailing USD exchange rate with their native currency is without complaint, whereas the average American simply doesn't have a clue how many Euros a US dollar gets them.
Similarly, if the Brits want to reference weight in stone, or Canadians want to sell me lumber in board-foot, I don't find that offensive in the least; I'm of the position that the impetus is on me to understand their measure, not for the one communicating to conform to my norms.
11 11
14.446
+ 6.789
--------
21.235> ...which probably even children can do in their head reliably.
You're moving the goalposts.
An indefinite number of applications exist where we can make meaningful decisions all day without ever needing to write results down.
Every single thread (both here and on Reddit) I've seen says 'oh, decimals are too hard'.
This is a terrible indictment of the American schooling system if your only defence against metrication is 'I can't do decimals'. It is you lot who have to catch up.
To the contrary, if you read into the full context of this thread, the underlying contention isn't that we're incompetent at decimal arithmetic, but that the rest of the world (and apparently some Americans too) believes our common fractional arithmetic is too much of a mental burden, and I don't blame those individuals either.
Indeed decimal arithmetic is trivial to most grown adults, but that wasn't the point; the example was merely to highlight how just slightly changing a few numbers in the same sequence of operations serves as an effective counterpoint to the grandparent's assertion that "even children can do in their head reliably".
Americans are taught and handle metric units in compulsory school just fine, but most of us also practice imperial units on a daily basis as well. We're just not culturally predisposed to complain when everyone else conveys measure in the SI mks/cgs framework.
I agree with the current of the thread, that mixed numbers are decidedly inferior to decimals. They're not harder, strictly speaking, but are more tedious, and this additional tedium introduces steps that people can make mistakes in. Fractions are also not easily parsed by standard desk calculators, and are not easily printed in a single line. They may even be mistaken by someone in a hurry as three separate numbers.
Decimals do away with all this unnecessary pain, and this really is the key point of metrication: it is a waste of time and effort to use non-SI units and convert back and forth or deal with mixed numbers. That's what people are complaining about: it is exasperating when Americans dredge mediæval units up in the 21st century, when we have a modern, simple, and unified system of units available.
A counterpoint to this is the fact that there are close to a million employed carpenter tradesmen in the US whose average level of education is a high school diploma[1], and yet their trade operates almost exclusively on fractional arithmetic, most of which occurs mentally on the jobsite.
The point being that tedium is a relative measure of training and experience, and it goes without saying that those trained in only decimal form are liable to struggle with unfamiliar systems.
And if you think that's bad, try purchasing lumber from any lumber yard in Canada or the US; the trade's board-foot system[2] will really tickle your metric attachment.
> it is a waste of time and effort to use non-SI units and convert back and forth.
It seems the story is more like it's a waste of time to those who find value in what Americans have to say but are unaccustomed and insistently resistant to performing conversions. I don't disagree that there's certainly value in having a globally common measurement framework, and indeed an American who conveys imperial units in a European setting is liable to be chastised. But old habits die hard and last time I checked, we're not having this discussion on a .eu gTLD.
Now try imagining how the typical American feels when engaging with the rest of the world: SI units, (,) and (.) symbols reversed, left-lane driving, etc. We tend to just adapt.
[1] https://www.bls.gov/ooh/construction-and-extraction/carpente...
Tell you what, just keep it on that side of the Atlantic and continue buying our natural gas, and since we're so biased to a fault towards "we've always done it this way", we'll keep buying your most excellent products that conform to Reinheitsgebot.
To be perfectly honest, I never remember how many feet are in a mile and the only times I've looked it up have been to calculate some meaningless trivia like how many tape measures it would take to stretch across the country, or some useless nonsense like that. Even then I usually just approximate 3 feet to a meter and 1.6 km to a mile, close enough.
Miles really don’t have much meaning.
If someone goes at 60 nautical miles per hour (111.112 km/h), for 360 hours (15 days), they cover the circumference of the planet around the equator. I.e go around the planet.
1cm = 10mm
1m = 100cm
1km = 1000m
1kg = 1000g
1ton = 1000kg
1in = ???
1ft = 12in
1yd = 3ft
1mile = 5280ft
1lb = 16oz
I would be surprised if more than 50% of the population knows how many ounces are in a cup of water. Same for feet per mile, etc.
Thank goodness even in the US the metric system is used as standard within the science community.
The British fluid ounce was defined to be the volume of an ounce of water, and the Imperial gallon was defined to be the volume of 10lb of water. This vague nod towards decimalization happened to match the pre-Imperial beer gallon fairly well, and it’s also why the Imperial pint has 20 fl oz instead of 16.
25.4 mm, ever since 1959 when we redefined it.
In the 1800s when Britain and the USA stopped keeping their units in alignment, they both defined conversion factors in terms of inches per metre (the inverse of the modern definition). However the conversion factors were slightly different. In the 1920s and 1930s, Carl Edvard Johansson used 25.4mm as a compromise between the two definitions when making his guage blocks, and this became a de facto standard that was later blessed as the international standard inch.
https://en.wikipedia.org/wiki/Carl_Edvard_Johansson#Johansso...
What do you need to convert those inches into? Why would you ever need to convert those inches into miles? Nothing you will ever do in life requires you to convert between inches (or feet and inches) and miles.
I assure you people regularly figure out how many small things fit in a large thing. I places where those things are measured in feet and miles, that's what they'd use.
Others have given other examples, such as printers who divide the inch into points and picas. They do this because it makes figuring out how many characters fit in a line of type easier than if they measured the type in fractions of an inch. It lets them work with integers instead of fractions all day. Of course these days it’s all computer–driven and it hardly matters what units printers use; the computer does the counting and could just as easily do it in fractions of an inch.
Weird real-life unit conversions come up all the time, often when you need to calculate a net weight or price, and you have some big surface area (eg. a road, with width in yards + feet, thickness in inches, and length in miles), and your gravel supplier prices by ton, and you look up the density in a conversion table and see something like lbs/ft^3, and now you have a whole bunch of opportunities to make a mistake.
You have 4 square mile of land with dense forest. Trees grow 5 feet apart and are 10 inches thick on average. How many trees are there? How much wood can you expect?
There's 5 inches of snow on your 5000 square feet roof. How much does it weight? Can it break the roof? Should you clean it up or can it stay?
These things are mental-math in metric and notebook-math in imperial, and that sucks.
Of course you can work around that. People always avoid the bad parts of the tools they use and find workarounds. Like not using exceptions in C++ or comparisons in javascript. If it's a widely used tool you know it has to work somehow.
Thus Americans never convert between units unless absolutely necessary and write press articles like "Asteroid the size of 3 elephants missed Earth by 1000 football stadiums" :)
But let's not pretend it's not a problem.
You might as well complain about meter measurements from 100 years ago not being exactly the same as a modern meter.
I notice it most when things here by chance are done in metric, but the units still aren't converted. E.g. I might see something listed at 1000mL, instead of just writing 1L. Or 3500g instead of 3.5kg.
Sometimes a European might say "This way is 600m, but that way is 1.2km", an American would never say "This way is 800 yards, but that way is a mile". A European might say "I had to carry 4L of water, so my bag got 4kg heavier". An American might say "My bottle is 24 (fluid) oz, so it's about 24 (weight) oz", but if it's a gallon, they probably just say it weights around a gallon.
All I'm saying is that the conversion problem has turned out to be less of an issue than I imagined. Simple because Americans don't run around converting their units every sentence.
Like if you say to use 300g of flour, the response will automatically be « How many cups is that ? ». And the answer is that you can’t measure flour correctly by volume.
Suffice to say, we had tons if very similar obscure systems in medieval Europe, even my tiny eastern country had at least 6 with various absurd conversion schemes for lengths, volumes and weights. These days we go to museums or medieval wiki pages if we want to see that. The thing is, we moved to modern era and absolutely nobody looks back.
I suspect with US its more an ego thing and swallowing pride that somebody else can he it simply better, rather than anything else. I mean whenever US actually needs to do some proper science and achieve great stuff, it turns quietly to metric/liters/kilograms. We have 10 fingers 100% of the time right in front of our face and everybody learns to count on them first, there is really nothing more natural.
I see things like this constantly in shops in Europe. I think it is part of a dark pattern to make price comparisons less intuitive and even misleading if you just skip over the prices trying to find the cheapest. What is cheaper, the product advertised as $X per liter or the one priced $Y per 100ml? There usually isn't a significant difference in packaging volume or usage that would otherwise explain why anyone would use different units for each.
In Germany they put the price of a unit on the price tag. So that you can clearly see that 0.33 bottle of Coke is more expensive (per liter) than the 1l.
In France it is always labelled in €/kg or €/L consistently through the shop.
Knowing the price of saffron for 1kg would be a really impractical information
Edit: Oh wait, I get it. It’s just that a price per 100 g is an order if magnitude less than per kg, so psychology kicks in and makes it look cheaper, even though the conversion is trivial. A bit like the 9.99 effect.
> I see things like this constantly in shops in Europe. I think it is part of a dark pattern to make price comparisons less intuitive and even misleading if you just skip over the prices trying to find the cheapest.
It doesn't really matter though, as conversion is so easy and automatic.
Meanwhile in the US, if I want to determine which product has more fat, my butter lists nutrition per tea spoon, my milk by the cup, my yogurt by 3/4 of a cup, another butter per 100g, yet other products per 24 ounces.
Honestly I don't know if anybody is able to extract useful information from those comparisons, without pulling out a calculator in the super market.
Derived from surveyors’ tools, a chain is 22 yards. (It is also 4 rods, making a rod equal to 5½ yards; go figure.) Ten chains make a furlong, and there are 8 furlongs to a mile. So there you are. Incidentally, an acre is 1 furlong × 1 chain. It may be madness, yet there’s system in ‘t.
It even was really useful when I was making patterns and molds for industrial ceramics. Half the orders would be in metric, half would be in imperial, but was 90% of the time converted to imperial by everybody whenever possible despite knowing both systems because it was much faster to get work done using ratios of standard fractional sizes. Need more precision? Divide your unit in half how many times you needed.
If you find it difficult, it is merely due to lack of experience in using fractional measures.
They made historical sense.
A foot is the distance in one step (ie, a foot placed after the other). A mile was the distance a person could walk in an hour. A pound was roughly a fist worth's of meat-- so if a piece of meat was fist sized it was roughly a pound in weight.
These were intuitive units that made sense when they were invented. It was only later on when we needed more accuracy that the metric system was invented
I don't understand this feigned "outrage".
$ units c ft/ns
* 0.98357106 Although a mathematician, Turing took quite an interest in the engineering side of computer design.
There was some discussion in 1947 as to whether a cheaper substance than mercury could not be found for use as an ultrasonic delay medium.
Turing's contribution to this discussion was to advocate the use of gin, which he said contained alcohol and water in just the right proportions to give a zero temperature coefficient of propagation velocity at room temperature.
https://sci-hub.ru/10.1145/321439.321440
https://en.wikipedia.org/wiki/Delay-line_memory
https://www.theregister.com/2013/06/28/wilkes_centenary_merc...
Digital signals (when using N/P balanced lines) also have this problem, to a lesser extent. Some CAD EE design software have ways to design squiggly traces to balanced impedances in traces that have to go around corners on the PCB and end up with different lengths.
Flash Boys, Michael Lewis
That's to say, 500000 + 25000 is very nearly 525600. It's only off by ten minutes!
Or does “reliably” just mean “close enough to be useful”?
Gah. I’ve been doing non-geography work for far too long. I used to know this stuff.
My use case which led me to discover this fact is sort of documented here: https://twitter.com/mholt6/status/1695685022710477043 -- even if my use case did have whole kilometers of displacement, it wouldn't likely be near the poles, and if it was, the answer would be, "Meh, we get it, you're at the pole."
It's like the Earth orbit: we learn in school that it's an ellipse, but we are never actually given a sense of the shape, and most of the drawings give a completely wrong idea.