111,111.1 meters is reliably 1 degree of latitude(gis.stackexchange.com)
gis.stackexchange.com
111,111.1 meters is reliably 1 degree of latitude
https://gis.stackexchange.com/a/2964/5599
262 comments
Given that the second is an older unit [0] than the redefinition of the metre, and defined based on "nice" subdivisions of the day, it would seem that there's still a bit of a coincidence there.
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
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
Well, it's not much of a coincidence. There are all kinds of constants around us, and one of them is prone to be close to a round number.
If the Earth's circumference wasn't a nice number, people would have chosen another one.
If the Earth's circumference wasn't a nice number, people would have chosen another one.
[deleted]
Was the meter based on the length of the pendulum similar to the length of the meter today? This doesn't necessarily say they were similar:
> 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.
https://en.wikipedia.org/wiki/Metre#Pendulum_or_meridian
> 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.
https://en.wikipedia.org/wiki/Metre#Pendulum_or_meridian
The period is also not independent of the amplitude. That is only the case of you approximate sin x ≈ x in the differential equation
My understanding (which could be wrong) is that actual clocks use a fancier pendulum than just a weight on the end of a string.
The difference in gravity around the Earth is small enough that the pendulums would be within a couple percent. (Wikipedia claims a measured difference of 0.3% from the time.)
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.
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.
And a 32-bit integer can represent latitude or longitude to an accuracy of around 1 centimeter :D.
Call that a long long.
That’s up there with buffalo buffalo buffalo
If you are serious, 32 bit is a more specific term, therefore better.
Can't be serious, because long long is 64 bits on most platforms.
Right, a 64 bit longitude would be a long long long.
‘long long long’ is to long for GCC, but not for the Beatles who may be made to sing it a long long i; // = todo time
Note that the meter is also basically 3 Paris feet, which comes out to about 0.97m (compared to 3 English feet, which is only around 0.91m). They weren't working in a vacuum to derive the most principled or cosmically beautiful unit length, just trying to find a way to define the unit they already used that wasn't "the length of this stick we have over here".
But in practice the meter ended up being "the length of this special metal stick we keep in Paris".
Yeah, because measuring the mean equatorial and longitudinal circumference of the Earth on a line passing through Paris is a pain in the ass.
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.
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.
I’m surprised that there isn’t GPS coordinate system which is just kilometers. Instead of 360 degrees uses 40,000 km. The real calculation would use the real distances but the approximation is close enough. This means don’t have to do any conversion to distances, at least for metric folks.
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.
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.
https://en.wikipedia.org/wiki/Earth-centered,_Earth-fixed_co...
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.
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.
You’ve brought memories of dealing with NAD83 (for local maps) and WGS84 (for everything else) crashing back. The error between those is tiny at the distances I was dealing with, but it was enough that it bothered me.
“I’ll just automate this mapping task in Python, how bad could it be?”
- A very-new-to-everything me, years ago.
“I’ll just automate this mapping task in Python, how bad could it be?”
- A very-new-to-everything me, years ago.
The main difficulty is that for ease of calculation you'd like a cartesian grid, which maps poorly to the spheroid shape of the earth. One solution is UTM https://en.wikipedia.org/wiki/Universal_Transverse_Mercator_... which divides the earth into 60 zones, and then inside each zone you have a cartesian grid with meters as the unit. So a UTM coordinate consists of the zone designator, and then distances in meters from the equator and the zone's central meridian.
There also MGRS https://en.wikipedia.org/wiki/Military_Grid_Reference_System , the NATO military variant of UTM.
There also MGRS https://en.wikipedia.org/wiki/Military_Grid_Reference_System , the NATO military variant of UTM.
The perfect sphere approximation of Earth is not at all close enough for GIS applications. Geoid data (the actual ellipsoid-ish shape with height variance) is an important factor in accurate GIS software.
There is a 'metric' coordinate system, it's called EPSG:3857 and uses meters as its units. Although it is not valid close to the poles and can give error of up to 0.6% so it's not useful for when you need high accuracy or to cover the entire globe.
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.
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.
Isn't that what gradians do?
360° = 400 gon, so 1 gon = 100 km of arc length
https://en.wikipedia.org/wiki/Gradian#Relation_to_the_metre
360° = 400 gon, so 1 gon = 100 km of arc length
https://en.wikipedia.org/wiki/Gradian#Relation_to_the_metre
Do you have an example in mind? A problem that you may encounter, how do you calculate now, and how could you calculate with a GPS system that is just kilometers?
> ...don’t have to do any conversion to distances...
Are you advocating for the use of Manhattan distances for everything?
Are you advocating for the use of Manhattan distances for everything?
The French also applied decimalization to angle measurements, so it's really 1 gon = 100 km, and 1 km is just 1 centigon.
The work to measure the meridian with the highest possible precision was in itself a fascinating multi-year ordeal: https://en.wikipedia.org/wiki/Arc_measurement_of_Delambre_an....
A nice novel about it is Denis Guedj's "La Méridienne". https://en.wikipedia.org/wiki/Denis_Guedj
[deleted]
Why did they change the definition from the length of the pendulum to the circumference of the Earth?
Couple reasons 1) why use seconds when you can just measure a segment of a known distance? 2) pendulums swing faster or slower depending on altitude, 3) Problems with accurate measurement of seconds, swing time etc.
I guess for (1) I would imagine it was easier for an independent group of scientists to accurately measure a pendulum, than to travel all the way to the north pole in a straight line through Paris.
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.
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 metre was re-defined[0] in 1791 as one ten-millionth of the quarter-meridian
Doesn't sound like a good idea. Circumference of earth around Paris is not unchangeable.
Doesn't sound like a good idea. Circumference of earth around Paris is not unchangeable.
Exact geographic measurements where the high technology of 18th century. Each society uses the highest precision measurements available to them. Also, plate tectonics were scifi fantasy until 1950's.
The definition has been updated after that. https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_ba...
The definition has been updated after that. https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_ba...
> Doesn't sound like a good idea
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.
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.
This stuff why the SI units system really is a system. Rather than the collection of unrelated units that was used before.
[deleted]
1 nautical mile (~6076 ft) is exactly one minute of arc at the Earth's equator.
As a sailor, I wish that all miles were nautical miles because they have a real meaning. What good is 5280 feet?
As a sailor, I wish that all miles were nautical miles because they have a real meaning. What good is 5280 feet?
A mile is 5280 feet because it is 80 chains (survey chains) long. The chain's length is a byproduct of English land tax laws which were by the acre.
The roman mile was 1000 paces, or 5000 feet, which made a bit more sense.
https://en.wikipedia.org/wiki/Gunter%27s_chain
The roman mile was 1000 paces, or 5000 feet, which made a bit more sense.
https://en.wikipedia.org/wiki/Gunter%27s_chain
For those of you marvelling at Romans having a five foot (1.5 m) stride, a Roman pace was two steps, counted from the left foot down to left foot down again.
In my experience many people define pace the same way today. We were taught in Boy Scouts how to pace off a distance measuring 5 feet per pace, or every other footfall.
That's to account for possibly different (average) left/right steps.
Averages out better.
Averages out better.
I have seen this argument before, but I'm not sure that I buy it. Even if you count every footfall, you are not magically going to somehow use, say, only your left foot. At the end of a km, you will have 600 double paces or 1199, 1200 or 1201 single paces. Well within the margin of error.
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.
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.
Same reason people count things out in twos. "How many shells did you collect on the beach?" "Let's see... two, four, six, eight.. I got nine shells"
They're both shortcuts to count things with half as much counting.
They're both shortcuts to count things with half as much counting.
Maybe because you were kids and adult paces are a single stride?
Nope. Boy scouts, not cub scouts, so a lot of us were closer to adult stride than kid. If you measure a typical adult pace (same foot to same foot) it's probably just under 5 feet unless they're deliberately pacing to measure something. You get a feel for what it takes for your own pace to hit 5 feet so you can repeat it.
I used to teach orienteering and scout skills when I was a teenager. One of the first things we did was measure how long each kid's natural pace was so they could know how to pace out a distance. If the course said 600ft and the kid knows their pace was 3 feet then they would take 200 paces or 400 steps. Typically, unless you were a runt like me it almost always came out to 5 feet. Just kind of the way people work. 2.5 feet a step. Roughly 5 feet or 1.5 meters per pace.
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.
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.
You’ve ruined my mental image of the Romans all walking like John Cleese.
Like the marching hammers in Pink Floyd’s The Wall music video
I think more importantly would be how do pirates mark paces?
That's still how we pace in the military today, left foot to left foot and (while it differs for everyone) normally about 60 paces per 100m.
Don't worry, we've come full circle and defined the Data Mile to be exactly 6,000 ft.
Most other 'mile's are derivatives of the Roman mile which developed somewhat independently of the English units (foot, yard, inch, barleycorn, etc), ergo the weird conversion factors. The original Roman mile was 5000 Roman 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.
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.
> Most other 'mile's are derivatives of the Roman mile which developed somewhat independently of the English units (foot, yard, inch, barleycorn, etc), ergo the weird conversion factors. The original Roman mile was 5000 Roman feet.
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
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
> American influence (and to a lesser degree British) led to the adoption of the Anglo-American foot as the unit of altitude in aviation
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.
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.
The early US came tragically close to adopting the metric system, and on more than one occasion.
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!
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!
It’s not ironic, it’s economic. People had other things to worry about during the Revolutionary War, and then afterwards there was an industrial revolution. (The tax on tea might have been the straw that broke the camel’s back, but the protectionist taxes on goods manufactured in the colonies was the real killer.) Once that was in full swing changing the units was impossible.
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.
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.
> People had other things to worry about during the Revolutionary War
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.
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.
> People had other things to worry about during the Revolutionary War
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.
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.
Industrial revolution had nothing to do with it, given that the inch USA uses today is an inch created by a pissed off engineer (gauge block Inventor Carl Johansson) in European company making gauge blocks, who defined an inch to be 25.4 mm @ 20 degrees Celsius in 1912 - created by taking a reasonable metric approximation in between British and American inches.
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.
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.
> It’s not ironic, it’s economic.
> 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
> 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
I just checked and one of my tablespoons is 4 of my teaspoons, but none of them is imperial :-)
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.
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.
Base ten is an unfortunate numeric choice and responsible for much of the hesitation to switch to metric. Maybe someday when we have millions of O'Neill Cylinder colonies, one of them will adopt base twelve instead, at which point the main reason against metric would go away.
> Base ten is an unfortunate numeric choice and responsible for much of the hesitation to switch to metric. Maybe someday when we have millions of O'Neill Cylinder colonies, one of them will adopt base twelve instead, at which point the main reason against metric would go away.
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?)
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?)
A lot of traditional units are based on random reference points that were an issue from antiquity - consider how pretty much every market town kept their own measure references even if they used same terminology.
That said, Fahrenheit use of brine solution for 0 and his wife's armpit for 100 remains among most WTF for me.
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 traditional units are based on random reference points that were an issue from antiquity - consider how pretty much every market town kept their own measure references even if they used same terminology.
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)
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)
When it comes to precision machining, even Americans seem to prefer to use "thous" (1/1,000") and "tenths" (1/10,000"). Isn't it strange that the preferred measurements aren't fractional: 1/1,728" and 1/20,736"? Why do you think that is?
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.
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.
Or base 16 if the machine overlords have their way.
The biggest argument against base 10 is that one day our descendants will have to explain to aliens, "because the monkeys that built us had ten fingers".
Positively mortifying.
Positively mortifying.
And those aliens would shrug "the slugs that built us had no fingers at all, that's why we're using binary, not because of electronics."
English dragged their feet on doing that
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.
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.
Footer to your footer. At least in the Netherlands, ounce is still used as well, it's defined to 100g.
That's over three times too big though.
in the end, who cares? It’s just a name on a unit. There is no law of nature that puts a limit on its value. There always have been many definitions for an ounce (one of the reason for going metric in the first place); this one is just a bit on the large side.
And everyone measures TVs in inches, somewhat bizarrely.
Are they actually designed and manufactured in inches, or only marketed in inches?
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???)
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???)
Strictly speaking, this is also a consumer-oriented thing, using the diagonal. The diagonal is also misleading, because it gives no information about the dimensions and aspect ratio of a given panel. Consider a 15.6" 16:9 display, versus a (now increasingly more common) 16" 16:10 display.
Panel manufacturers are all based in Asia, and measure only the edges in millimetres, as they should. Even xrandr outputs EDID data in millimetres.
Panel manufacturers are all based in Asia, and measure only the edges in millimetres, as they should. Even xrandr outputs EDID data in millimetres.
CRTs were 4:3 and tiny, they could fit basically everywhere. The diagonal was more than enough for consumers. Computer monitors started to have different ratios but they were not as widespread as today, even in a world of laptops and mobile devices.
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.
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.
Gas and water pipes are often in inches too (Italy) probably because it's an old and critical infrastructure and nobody wants to risk mistakes by trying to fit a 1 inch pipe with a 25 mm one, or 1 1/4" with a 32 mm. Close but not close enough.
However I guess that even American engines are measured in liters or cc, cubic centimeters.
However I guess that even American engines are measured in liters or cc, cubic centimeters.
> Gas and water pipes are often in inches too (Italy)
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)
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)
English inches.
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.
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.
My Italian begins and ends with ciao. I’m just going by what Wikipedia says on the topic:
https://en.m.wikipedia.org/wiki/Italian_units_of_measurement
https://en.m.wikipedia.org/wiki/Italian_units_of_measurement
Thank you. It seems that it was a customary unit in my area of the country as well. Never heard about it.
We do measure TVs in Zoll here in German speaking countries, which has been redefined to exactly 1 in.
In the Netherlands we also colloquially use the 'ons' (ounce) which is defined though as 100g.
In Germany we've got 'Unze' (ounce) which is defined as ~30g which we only use when talking about precious metals.
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.
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.
China had their own mile. “The journey of a thousand miles begins with a single step” was actually only around 300 English miles long.
The modern Chinese li is defined as exactly 500 meters.
Laozi had some foresight to use meters in 500BCE.
And, similarly, the 斤 (jīn) is defined as 500g.
Kilogram is also an outlier, as it is the only base unit that comes with a magnitude prefix.
The base unit is gram, not sure what you mean
The base unit is indeed the kilogram, see https://www.bipm.org/en/measurement-units/si-base-units.
Interestingly, a mile was originally the less surprising 5000 feet. But in the 1500s the English changed the mile to be 8 furlongs, as that made for much easier math around the agricultural measurements of the time.
https://en.m.wikipedia.org/wiki/Furlong
https://en.m.wikipedia.org/wiki/Furlong
I wish those medieval people had defined it as 5040 feet, then it would be divisible by 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 28, 30, 35, 36, 40, 42, 45, 48, 56, 60, 63, 70, 72, 80, 84, 90, 105, 112, 120, 126, 140, 144, 168, 180, 210, 240, 252, 280, 315, 336, 360, 420, 504, 560, 630, 720, 840, 1008, 1260, 1680, and 2520.
For reference, 5280 = 2^5 × 3 × 5 × 11
(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
(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
There are 11 fathoms in a chain, 10 chains in a furlong, and 8 furlongs to a mile.
Going the other way, 2 yards in a fathom and 3 feet in a yard. That accounts for all the factors above.
Going the other way, 2 yards in a fathom and 3 feet in a yard. That accounts for all the factors above.
Is that why we have 90 degrees in a right angle, instead of 100?
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.
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.
Connecting 1 mile to 5280 feet happened many centuries after the medieval period. Such precision wasn't really possible nor desired before the 18th century.
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.
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.
>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.
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.
1959 must be referring to this: https://en.wikipedia.org/wiki/International_yard_and_pound
> I wish that all miles were nautical miles because they have a real meaning.
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.
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.
Each of those arcs do have a meaning, they're called 'degrees' and any human being whose not being obtuse for the sake of argument would tell you that they're 'real'. 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.
I think you may have missed my point.
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?
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?
The math is not done in ones head but using a plotter on a chart. As long as latitude is defined as it is, nautical miles have meaning.
I didn't say 'in one's head', merely used the same phrasing as nmilo.
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.
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.
You need some reference. The latitude grid is available anywhere on your chart, with multiple subdivisions, so even when your boat is shaking like crazy you'll be able to draw a course ad hoc (which requires estimating drifts due to wind and tide etc., which are conveniently given in knots (so nautical miles per hour)).
The coordinate grid may be arbitrary (though having a lot of factors is nice), but the derived nautical mile is not.
The coordinate grid may be arbitrary (though having a lot of factors is nice), but the derived nautical mile is not.
> which are conveniently given in knots (so nautical miles per hour)).
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.
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.
Right, but what’s the point of arguing about the real-ness of something you’re using without verifying it ever. The equator (or the 45th parallel, or any meridian) is not a circle; nobody ever said anything like “man, it’s so much more natural that the equator is 21638.778 nmi instead of that ugly 40,075.017 km”.
Well, latitude, or longitude at the equator.
What good is converting miles into feet anyway? I've never found a reason to perform that conversion, or reverse. A mile is just an arbitrary unit of distance that doesn't need to be related to any other. Even in sports, swimmers may casually call a 1650 yard swim 'a mile' but if you do the conversion it isn't. That doesn't matter to anybody though.
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.
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.
The most simple example is adding or subtracting distances. You might say you don't need that, but I'd wager most people need to at some point.
Agreed. When I learnt about nautical miles and knots (nm/h) which is both used by aviation and sailors, I feel we should be using nautical miles for all travel distance.
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.
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.
What good is a mile to begin with. Just use kms and then we have a nice round figure. Being from the US and as someone that does a lot of woodworking, I’m very used to inches but I can’t do anything beyond basic calculations in inches and always have to pull out a very specific carpenters calculator. It’s not trivial to add up 2’13/32” + 5’11/16”, there’s too much carrying over and doubling to equalize the denominators to do easily in your head. That’s just addition, dividing is a whole other beast.
Nautical miles are used in sailing because they correspond (nearly) directly to an arcminute of latitude which simplifies chart navigation.
IDK if 2.40625 + 5.6875 is any easier :)
Inches using base 2 for the fractions is useful.
Inches using base 2 for the fractions is useful.
> Inches using base 2 for the fractions is useful.
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)
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)
Certainly.
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.
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 say you have to divide a 8 3/8” board into 5 parts. That turns into an ugly 771/40. What do you even do with that using an imperial measuring tape?
I have never needed to divide a board into 5 parts.
But if I did that would indeed be difficult.
But if I did that would indeed be difficult.
I regularly need to divide to build bookshelves out of 4x8 plywood sheets.
Are you visually or mentally impaired? I don't mean it in any condescending way. I can add those on the spot by just looking at the numbers and tell you result immediately, that's primary school level math in Europe.
Yes I'm mentally impaired.
That's why I like to do things that are easier.
That's why I like to do things that are easier.
2405.25 + 5687.5 is easily 8092.75. But in both cases not using a calculator and not doing an operation on it at least twice (if it has no log) is a recipe for wtf, imo. An expensive mistake requires only one miscalculation.
It isn't easier, but 6.112cm + 14.446cm is fairly easy. Especially if you drop thousandths, which you can only maybe get when measuring with a caliper...
Inches only use base-2 fractions down to 1/64", then they switch to thousandths of an inch (thou), with base-10.
Easier to type into any general purpose calculator. It’s also so much more accurate when trying to enter into any CAD/CAM software.
It’s also easier to add up 10 different decimal numbers than the same number of mixed numbers.
It’s also easier to add up 10 different decimal numbers than the same number of mixed numbers.
Yeah, I don’t think woodworking is the best example for arguing that metric is better than imperial. In fact, it’s one of the few disciplines where the imperial system as a decent argument for superiority.
Sorry, I dabble with woodworking and disagree heavily. I usually don't care for bigger precision than 1mm (so between 1/16" and 1/32"), and adding things up is a nightmare ("umm... 7 3/16" + 2 1/8" + 5 1/4" is... where's a goddamn pen & paper..."). Same with figuring out which line is which fraction of an inch on measuring tools. Things became tolerable once I got metric measuring tape.
Once you get past the dabbling stage it starts to get pretty natural. I don't think either system is better, the value is mostly tied up with what's on the shelves at the local home center and how your measuring tools are marked.
It's already natural when using metric, so I'll stick to it.
The stuff on the shelves is rarely sized precisely enough for the units to matter. I've bought 1/4" ply that measured much closer to 6.0 mm than to 1/4".
Sure, if tools are dirt cheap you can just sacrifice to Benford's Law and use base 10. If tools are not cheap, you'll learn to use base 2, one way or another.
I doubt I'll ever be able to quickly add fractions in base-2 (it doesn't happen often enough to train this), so pen+paper will always be a necessity if I wanted to stick to imperial. I could see getting the intuition for "which line is the eights vs sixteenths" over time though, but if the one-off calculations are going to be such a pain, I don't really see a point.
Metric woodworking just uses integer millimeters for everything.
My FIL is a fine art woodworker (makes stupidly nice furniture, canoes that are functional art, etc.), and he uses both. He’s done it so long that he can work with fractions instantly in his head, but he also fully admits that metric is way easier for a lot of it, and so uses both as needed.
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.
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.
Woodworking measurement has two forms: lumber, which is notional, pre drying, shrinkage and rough handling, and cut, which is required to be beautiful. Sometimes, it isn't about feet and inches as much as "the same"
Plumbing is another example where imperial works and is even used in Europe. It doesn't matter that a pipe is 3", it may as well be called "type B", since all you care about is if it's big enough for the purpose (you look that up in building code) and if the parts match together. The moment you need to perform calculations is when imperial becomes a total PITA to use.
Minimum radius is much more important in plumbing I think than metric/Imperial. And screw-thread.
WDYM by minimum radius? Are you referring to the part of my post where I wrote that you just look it up in the building code (as opposed to trying to calculate it), or when actually designing where the pipe runs?
The intersection of both. I did a very bad job of plumbing an electric shower into my flat in York back in the 80s and working out how to route the pipe to meet both ends requirement of where I could connect it into supply, and where it had to be to deliver water to the heater, was massively confusing. I am sure a plumber would understand this innately, but I wasted 2+ m of copper pipe trying to "route" it, without understanding the limits of how I could bend it, or cut and use a fitting.
The building code(s) only get you so far. There's also aesthetics.
The building code(s) only get you so far. There's also aesthetics.
Ah, well, I only did PEX and ABS for my reno, very idiot-proof so I managed. ; )
I made the mistake of watching (as a kid) a plumber use his own body to form the curves, and assumed "it's that easy" without taking in that he was 25 years past his apprenticeship and had bent thousands of pipes, and used a former almost all the time. It's a different game when its you, the pipe, and twenty needle-jets of water streaming out of the badly fitted olives, lack of PTFE (or too much) tools which don't fit, pipe with ugly crinkles in them, splits along the length...
> It’s not trivial to add up 2’13/32” + 5’11/16”, there’s too much carrying over and doubling to equalize the denominators to do easily in your head.
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":
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 3/32Or you add 6.112cm to 14.446cm, which probably even children can do in their head reliably. But sure, you can do it using fantasy units, too :)
Now change that first number from 6.112 to 6.789 and watch that same child stumble.
I'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.
I'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.
Why would there be any stumbling? Because it's two 6s? Because there's two carries?
The child would clearly have to mentally carry four times all the way down the chain:
11 11
14.446
+ 6.789
--------
21.235Really, this is primary school maths. I learnt about carries when I was seven.
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.
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.
> 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.
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.
> common fractional arithmetic
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.
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.
> ...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.
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...
[2] https://en.wikipedia.org/wiki/Board_foot
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...
[2] https://en.wikipedia.org/wiki/Board_foot
It’s baffling to me how you twist and turn the perfectly clear explanation of the parent poster into some convoluted argument in favor of imperial units. Essentially, it boils down to ”we’ve always done it this way, we don’t mind pointless busywork, and doing stuff different to everyone else is a good thing“.
What’s so difficult with that? Just use pen and paper for calculations, you’re supposed to write down the result anyway. It’s a simple math.
The goalposts set by the grandparent was reliable mental arithmetic by a notional child:
> ...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.
> ...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.
Was that available on 48g perhaps?
Unsure with the 48g; trained myself since engineering undergrad days to not lean into graphing calculators. The feature existed since at least the 32sii, so it makes sense that successor 33s and 35s models also got it. Easily one of the most useful features that I've found for woodworking and converting arcmin/sec to decimal as the most common usecases.
I know of sexagesimal mode in 48g and used it, but haven't encountered anything for imperial units
I'm not a sea dog (or air dog), but even absent electronic calculation and navigation devices of the last half century or so, is there any real advantage to using nm vs any other unit? Other than for the presumably niche case of traveling exactly directly along the equator, that is.
nm are great because charts and speeds are in units of nm and kt of course, but what does "real meaning" give you exactly?
nm are great because charts and speeds are in units of nm and kt of course, but what does "real meaning" give you exactly?
Am sea dog, I think it's just a little bit of smugness. Because it doesn't generally help (besides quickly estimating latitudinal distance or near-equatorial distance), unless you are actually doing dead reckoning with a chart or similar, which is rare today.
The equivalency with knots is great and all but it too is just a convention
The equivalency with knots is great and all but it too is just a convention
To be precise, a nautical mile is always a minute of latitude, everywhere on earth. It is only a minute of longitude at the equator.
Ah, good point. In that case expand the niche cases to traveling due north or south.
In practice, when navigating by pen and paper, what you do is you measure a distance on the chart with a divider, then you put the divider (with the previously measured distance set) to the north-south scale on the side of the chart to read out the distance in nautical miles.
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.
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.
And, at sea level. At altitude this no longer applies either because the circumference at altitude is greater.
I think the only advantage is when using old navigation devices. You measure altitude of sun at noon and that is your latitude, time of noon is your longitude. It also only works when going east-west, it falls apart any other angle.
These days, everybody has plotter or phone to measure position and speed and calculate distances.
These days, everybody has plotter or phone to measure position and speed and calculate distances.
It fits with the other unit: 1 knot is 1 minute of latitude per hour
rant: I live in the US for more than 10 years and I still can't get used to the imperial system. I never will. It just doesn't make any sense to me. The metric system is pure gold:
1cm = 10mm
1m = 100cm
1km = 1000m
1kg = 1000g
1ton = 1000kg
1in = ???
1ft = 12in
1yd = 3ft
1mile = 5280ft
1lb = 16oz
What I've come to realize, also from living in the US, is that most Americans just don't convert between units. Unless they really have to. That way the issue does't really come up much.
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.
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.
... which is a natural result of such an obscure system that is needlessly complex for everybody involved. If you can't do conversions on spot as a population, you simply over time don't do it and this state becomes natural. Just like for us literally everywhere else in the world we convert and literally everybody with even very subpar intelligence can be discussed with in such units.
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.
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.
It seems like many Americans are really confused about weights and volumes, because of this unit system.
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.
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.
Measuring dry ingredients by volume is like a recipe brown M&M, at that point you know the recipe is bad and you should look for another one.
> 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.
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.
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.
> 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
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 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.
Germany is a big user of the trick "lemme change the unit from €/kg to €/100g in this part of the shop", for example at the cheese counter, which is what the parent is saying. It was the same trick used in the UK.
I believe it comes from a european rules which allows such labeling if the packaging is small.
In France it is always labelled in €/kg or €/L consistently through the shop.
In France it is always labelled in €/kg or €/L consistently through the shop.
>€/kg to €/100g
Knowing the price of saffron for 1kg would be a really impractical information
Knowing the price of saffron for 1kg would be a really impractical information
> > 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.
> 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.
> 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.
In almost every European country, stores must show the price per liter or kg.
At least in Germany shops play rather loosely with the units. Yes, you have €/kg but you also have €/100g, €/g, ... and they will switch between them even for near identical products. Can't cheat buyers out of money by selling them a 30% larger bottle if you make it too obvious that they are paying 40% more for it.
I’m puzzled by this. How hard is it to convert prices by powers of 10? Do the same thing with $/lb and $/oz, and I’d be lost.
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.
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.
But this could just be part of the pattern of Europeans being more lose with unit changing, because it's so easy to do anyway.
People just tend to use the units that keep the values in a reasonable range of 1-10.
I think there’s even a lot of people who grew up in America that don’t fully get our system.
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.
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.
In US customary units, a fluid ounce of water does not weigh an ounce avoirdupois, because US volume measures are not Imperial units: they are based on the pre-Imperial Queen Anne wine gallon.
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.
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.
You missed a few intermediate units, which might help somewhat to explain it:
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.
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.
This is one of those cases where I can’t tell if a comment is sarcastic or not.
Those cases are the best, are they not? But yeah, a large dose of sarcasm was intended. And a little bit of seriousness.
> 1in = ???
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.
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.
A reservoir is 3 sq miles, the level rises by 7 inches. How many acre-feet of water have been added :)
The owner of the reservoir doesn’t bother to measure it in square miles, he measures the acreage. Then the acre–feet becomes a trivial computation. Yes, if pressed he might dredge up the obscure fact that a square mile is 640 acres, but then he would have to do long division to convert it, and the whole point is to avoid that kind of complexity.
Bonus point: how many cubic yards of water added?
Do you buy gravel by the cubic mile then?
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.
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.
Gravel is purchased by the yard, not by the cubic inch or mile.
I'm certain it's by weight, but either way, I don't see that helping much.
Sellers price it by the weight, purchasers buy it by volume.
You have to lay 3miles of pavement, 5 feet wide, bricks are 5x10 inches. How many bricks to buy?
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 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 kind of mess it up from the beginning by assuming everything is based of 5 or 10 unit fractions for the math. Do it with 2,3,4,6,8 inch standards and metric becomes notebook and imperial becomes mental.
Do you mean because people just use metric in those contexts, or that everyone avoids math?
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.
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.
I mean that in every context where a person would ever have to convert units or do long division, we invent a new set of units instead.
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.
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.
Printing measures go smaller than an inch.
The width of printed columns is measured in “picas.”
12 “points” equal one “pica”; 6 picas equal 1 inch.
We still use those in image resolution measurements.
Yes, this is a great example of what I mean by everything having their own set of units!
Unit conversions are inconvenient for sure, but I think the worst part is actually fractional length measurements. It may make sense for woodworking and handicraft, which I assume is the origin, but for any other use? Try reading 2 3/16" on an imperial ruler as quickly as 5.6cm. Screw sizes also get affected by this.
As someone who uses imperial measures, it is incredibly fast and easy to read fractional inch measures on a measuring tape or ruler because each fractional unit is half of the previous unit size, and they are marked to differentiate each half size measure from the previous for quick reading. To speed things up I wouldn't count three ticks, I would use a 1/8th tick mark count up one more 1/16th tick.
If you find it difficult, it is merely due to lack of experience in using fractional measures.
If you find it difficult, it is merely due to lack of experience in using fractional measures.
As a European having watched many house framer videos on Youtube, the imperial system of in/ft actually somehow makes sense there. As far math, it's pretty annoying, but as far as communicating ratios or dividing distances into halves or fourths, it seems like a better fit to the human brain.
Yeah, a lot of people really don't get how useful fractional measures can be for building and construction, or other tasks. You can do like 99% of the math required to build a residential home completely in your head, even if you aren't great at math to start with. You could even forgo a tape measure completely and build the house using a piece of wood with a mark to give a standard length and then doing all the rest with a piece of string you fold over for ratios of that length.
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.
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.
> Jesus Christ, who the hell came up with this madness?
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
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
> 1in = ???
25.4 mm, ever since 1959 when we redefined it.
25.4 mm, ever since 1959 when we redefined it.
I believe an opportunity was missed some time ago in the past to define one inch to 25.6mm, which would make for much nicer conversions IMO, especially with the convention to use fractions of powers of two in the inch world (e.g. 15/16" would be 24mm exactly vs. 23.8125mm).
Usually the absolute value of units is preserved as much as possible when a unit is redefined.
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...
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...
Is it really novel to you that a more modern system is based on powers of 10 for ease of use? Were you just as mad when you discovered Egyptians used hieroglyphics as their method of writing?
I don't understand this feigned "outrage".
I don't understand this feigned "outrage".
And even the beer you are passing is a 16oz pint, not a 20oz pint, as in the UK.
A 'pint' in the UK is 568ml, still I think. Maybe REUL will undo that. Some places you get half-litres.
An inch is an inch.
Not so quick: One inch may be 1/12 of a foot, but a foot is not necessarily a foot. The international foot is 12×2.54 mm, but a US survey foot is 1200/3937 m. The ratio of the definitions is 500000/499999.
But nobody would ever use a survey foot outside of surveying, and if you are using survey foot outside of talking to other surveyors you would call it a survey foot, or be using it in a context where that tiny inconsistency doesn't matter. Something being 5 feet away in feet is still for all practical purposes 5 survey feet away, nobody is going to pull out a 5 foot set of calipers to measure that 1/100,000th of a foot difference. And nobody would use survey feet for anything that requires that sort of precision.
You might as well complain about meter measurements from 100 years ago not being exactly the same as a modern meter.
You might as well complain about meter measurements from 100 years ago not being exactly the same as a modern meter.
Not complaining really. I mentioned this mostly for entertainment value, besides pointing out that things are not always as straightforward as it might seem. (Also triggered by the absurd precision of the number in the title.)
And 1 nanosecond at light speed ≈ 1 foot
That's remarkably close to reality. I'm impressed :)
$ units c ft/ns
* 0.98357106Admiral Grace Hopper Explains the Nanosecond: https://youtu.be/9eyFDBPk4Yw
The first time I saw one of her demonstrations of a nanosecond, I was confused when she pulled out a length of wire. I don’t remember what class it was in or what context the video was being used, but this was 6th grade
Possibly an urban legend but there's a story about a company in India that ordered a Soviet made computer system that has an sloppy spool of wire attached to the main board. They contacted the Soviet institute that built the computer system and it was explained that the computer needed a timing delay between two components but didn't have the proper ICs on hand so they used a precise length of wire to introduce the needed delay to make the timing correct.
As a stone cold fact physical mediums with known delay timings were once used as memory storage for computers and as "echo removal" filters in radar installations.
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...
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...
They are still used to test networking equipment under long propagation delays. Spools of fiber hundreds of miles long.
There were a lot of delay–line memories back in the day. It wasn’t just that they didn’t have memory chips; memory chips hadn’t been invented yet.
https://www.youtube.com/watch?v=2BIx2x-Q2fE
https://www.youtube.com/watch?v=2BIx2x-Q2fE
This is the method used to add delays for HFT to ensure fair(er) markets for all participants on the IEX exchange.
Flash Boys, Michael Lewis
https://en.m.wikipedia.org/wiki/Flash_Boys
Flash Boys, Michael Lewis
https://en.m.wikipedia.org/wiki/Flash_Boys
Back in the old days of analog video, component video was three separate cables. When we made custom cables, we had to ensure the cables were the same length to ensure the timing was within tolerance. The day we got to switch to digital SDI which also included audio as like a gift from the gods
This was probably also due to impedance matching between all the lines involved.
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.
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.
This is still a problem for modern multi-lane digital connections, like PCI Express. The solution? Make each individual lane self-timing, and compensate for it digitally in the receiver buffer.
GNU units is one of my favorite tools.
kragen's recent HN comment is a gold mine:
<https://news.ycombinator.com/item?id=36988917>
<https://news.ycombinator.com/item?id=36988917>
You need bigger feet
If you like approximations, there is also https://xkcd.com/1047/
my favorite of these not on the xkcd is that there are pretty close to ~5e5 + (5% of 5e5) seconds in 365 24-hour days (a very naive "year")
That's to say, 500000 + 25000 is very nearly 525600. It's only off by ten minutes!
That's to say, 500000 + 25000 is very nearly 525600. It's only off by ten minutes!
Surely you mean minutes, not seconds. And it's off by 10 hours.
Yeah, I think it would be neat to change time to be defined as 1 chrono = how long it takes for light to go 1e9 meters. 1 kilochrono is 55 minutes. Useful enough for space travel type situations where you can’t rely on solar days for units.
And 1 googol femtobarns ≈ 1 square teraparsecs
But given the Earth is an oblate spheroid won’t the actual arc length of 1 degree of latitude be variable?
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.
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.
Reliably means close enough to be useful, but the estimation is also quite precise where most populations live.
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."
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."
The Earth diameter at the equator is 43 km larger than at the poles.
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.
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.
The title of the post could make you think that a degree of latitude varies by less than a decimeter, but that is of course not true. But close enough for many practical purposes, definitely.
This post also has a nice rule of thumb that 111,111 * cos(latitude) meters is 1 degree of longitude. I like the correction! In practice you can use some simple constants; 25° is about 100,000 meters. 44° is about 80,000 meters. 57° is about 60,000 meters.
How many football fields is that?
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.