Metrication

[kkt]

My point with this research is simply to highlight that India and China, with populations far larger than even the US has today, was able to adopt metric. Whether the metric system played a role in their economic growth, I could not say. But both likely benefited from a uniform measurement system that matched those countries with which they traded not only goods, but also workers. This is likely where the US would benefit most: people coming to visit or work not being confused by our system of measurements; Americans themselves are unlikely to see any particular benefit...but then that isn't the point per se.

The big difference here (and with France in the 18th century) is the lack of an internal system of measurement that is consistent throughout the country.  In France, the foot was different, north versus south.  China and India lacked any coherent internal measurement system.  The US, by contrast, has a consistent internal measurement system, using both customary and SI (with customary, oddly enough, based off SI).

Are you saying Britain didn't impose Imperial measures throughout India in the 1800s?

[Duke87]

But maybe that's because I am a meteorologist, where customary and metric units both see a huge amount of use depending on what quantity you're talking about and what it is you're measuring.

This is a feature of having multiple systems that I experience in my field too and it helps keep clarity of what you're talking about because units from different systems are used to describe physically distinct things that nonetheless are dimensionally the same. A motor for example will have a rating in horsepower which is the amount of mechanical power it can put out... which is different from how much electricity it consumes which will be rated in kilowatts. Meanwhile if you have a heating or cooling system its output will be measured in BTU per hour. All three of these things are units of power, but which is used makes it immediately clear whether it's mechanical, electrical, or thermal energy involved.

Likewise, the speed of something physically spinning will be measured in RPM while Hertz is used for the frequency of anything electromagnetic.

When I stumble across foreign spec sheets and see a motor with its output expressed as something like "40 kW at 50 Hz" while the electrical input will be measured in the same units it somehow seems flat and bland in comparison. I like having the diversity of units.

[NWI_Irish96]

If the metric system is based on 10, why are its time measurements based on 60?

The earth rotates 365 1/4 times for each time it revolves. There's nothing anybody can do about that.

There are 86,400 seconds in a day. You'd have to redefine the second in order to base the parts of the day entirely on tens. Doing so would cause confusion on a level that is magnitudes higher than converting the US to metric distances.

[kalvado]

If the metric system is based on 10, why are its time measurements based on 60?

The earth rotates 365 1/4 times for each time it revolves. There's nothing anybody can do about that.

There are 86,400 seconds in a day. You'd have to redefine the second in order to base the parts of the day entirely on tens. Doing so would cause confusion on a level that is magnitudes higher than converting the US to metric distances.

On the next level, neither of those 2 numbers is fixed. Noon to noon timing changes throughout the year a bit; revolution around sun also fluctuate. So what was a well defined calendar 200 years ago became an approximation.

[Rothman]

We're circling into DST...

[jeffandnicole]

You would think liquor drinkers would be very interested in metrication.  After all, vodkas, rums, gins, etc are mainly sold in 750ml, 1L and 1.75L bottles. 

[Henry]

If the metric system is based on 10, why are its time measurements based on 60?

The earth rotates 365 1/4 times for each time it revolves. There's nothing anybody can do about that.

There are 86,400 seconds in a day. You'd have to redefine the second in order to base the parts of the day entirely on tens. Doing so would cause confusion on a level that is magnitudes higher than converting the US to metric distances.

On the next level, neither of those 2 numbers is fixed. Noon to noon timing changes throughout the year a bit; revolution around sun also fluctuate. So what was a well defined calendar 200 years ago became an approximation.

Ah, 365 1/4, the reason we have a leap year every four years.

Canada and Mexico may have been metric, but for the sake of familiarity in America, the imperial system simply works better, although once upon a time, we did use metric units as well, like when car engine displacements were measured first in cubic centimeters, and then in liters (the former is still used for motorcycles).

[SSOWorld]

I am of the opinion that there shouldn't be any issue with having multiple measurement systems out there.

But maybe that's because I am a meteorologist, where customary and metric units both see a huge amount of use depending on what quantity you're talking about and what it is you're measuring. Meteorology is perhaps one of the most confusing fields in this regard, because you have to give your output in a form that the people reading it are going to be able to understand. If you're making a public forecast in the US, that means customary units. If you're in research or around scientists from other fields, almost entirely metric. But the #1 application is aviation, which was a huge influence on the development of the field as a whole, and so a lot of their preferred units carried over. And sometimes what's used is simply a matter of what looks good on a map.

Define "Customary" - part of "Usual and Customary" in the insurance world for them trying to screw you over

Just to get an idea of the huge variety of units and systems we use regularly in American meteorology:

Temperature - Fahrenheit for surface temperature, Celsius for anything upper air. For any sort of thermodynamics equations, we'll use Kelvin, which sometimes gets converted back to Celsius and sometimes does not. I can convert C to F and vice versa to within a degree or two in my head very quickly because I have a bunch of equalities memorized beyond just the freezing/boiling points: 50F=10C, 77F=25C, 104F=40C, etc...

I'm confused, For a profession that calls a tornado different terms depending on where it is....

Speed - miles per hour when talking about surface wind that's going to affect populated places that aren't airports. Pure science contexts will use meters per second everywhere. Otherwise, the general unit of wind speed is the knot, which is equal to a nautical mile per second and was the usual aviation unit before being essentially adopted by most aspects of meteorology. 1 kt is a little more than a mph, and 2 kt is about 1 m/s. I have no concept for how fast a km/hr is.

A knot is used to hold a swing bench up or to keep your shoe from falling off.

Height - usually in meters, unless you're talking about snow levels, which are usually in feet because they reference surrounding topography and we usually think of topographic elevation in customary. Stuff like the height of cloud tops or cloud bases are also often in feet because that's what the aviation industry likes. Even at the international scale today, they prefer to measure height in hundreds of feet. Sometimes you'll get decameters because that requires one less digit on an upper-air map when you're rounding to the nearest 10 m anyway.

Snow levels can be in meters

Horizontal distance - for visibility, statute miles, or feet if you're talking about visual range on a runway in highly impaired visibility conditions. Nautical miles for hurricanes or aviation - a nautical mile is a little more than a regular statute mile, and is supposed to be the distance covered by a minute of latitude (1/60th of a degree) at constant longitude. Kilometers in more pure science contexts.

Keep them at 200. 

No, feet </airplane!>

Pressure - The usual unit in almost all contexts is the millibar, which the general public only seems to ever hear about when the news is talking about hurricanes. In more pure science you'll usually hear of a hectopascal, which it turns out is exactly equal to a millibar by definition, but because the pascal is the official SI unit of pressure it's considered more acceptable to use that name for those contexts. Might be one of the only actual uses for the hecto- SI prefix. In rare cases you might hear of kilopascals. You've probably seen inches of mercury on weather reports, but nobody in the field actually uses them...except our good old friends in aviation, who use it to set their altimeters. There's likely issues with updating instruments or technology in older planes that make metricating altimeter setting a tall order in the US, but I have no concept for what anything in inHg is and I hate when displays make you use them if you want other units to be in customary.

Hence why no 5G at airports...

And the list goes on...

[US 89]

Just to get an idea of the huge variety of units and systems we use regularly in American meteorology:

Temperature - Fahrenheit for surface temperature, Celsius for anything upper air. For any sort of thermodynamics equations, we'll use Kelvin, which sometimes gets converted back to Celsius and sometimes does not. I can convert C to F and vice versa to within a degree or two in my head very quickly because I have a bunch of equalities memorized beyond just the freezing/boiling points: 50F=10C, 77F=25C, 104F=40C, etc...

I'm confused, For a profession that calls a tornado different terms depending on where it is....

Huh? I guess Uncle Bob on his family farm of five generations in Kansas might call them " twisters"  or " cyclones" , but those are not terms any real meteorologist under the age of 70 would ever use unironically.

[GaryV]

Just to get an idea of the huge variety of units and systems we use regularly in American meteorology:

Temperature - Fahrenheit for surface temperature, Celsius for anything upper air. For any sort of thermodynamics equations, we'll use Kelvin, which sometimes gets converted back to Celsius and sometimes does not. I can convert C to F and vice versa to within a degree or two in my head very quickly because I have a bunch of equalities memorized beyond just the freezing/boiling points: 50F=10C, 77F=25C, 104F=40C, etc...

I'm confused, For a profession that calls a tornado different terms depending on where it is....

Huh? I guess Uncle Bob on his family farm of five generations in Kansas might call them " twisters"  or " cyclones" , but those are not terms any real meteorologist under the age of 70 would ever use unironically.

How about hurricanes then? Cyclones, typhooons, ...

[Rothman]

I do like the term Super Typhoon and think that having different terms per ocean is helpful.

[Road Hog]

Metrification is happening slowly in the U.S., but it is happening in everyday life. Procter & Gamble held out forever but now either sells product in metric units or marks the metric equivalent. Liter Cokes have been around for as long as I can remember. And somebody mentioned the 750 mL liquor bottle, which is almost the equivalent of a "fifth."

The 400 km sign between Dallas and Houston won't happen anytime soon, but most products will eventually be sold in metric units (marketed in SAE units at first). The reason will simply be to reduce costs for marketing to U.S. consumers vs. the rest of the world. The last holdout will be gallons of gas.

[kkt]

Metrification is happening slowly in the U.S., but it is happening in everyday life. Procter & Gamble held out forever but now either sells product in metric units or marks the metric equivalent. Liter Cokes have been around for as long as I can remember. And somebody mentioned the 750 mL liquor bottle, which is almost the equivalent of a "fifth."

The 400 km sign between Dallas and Houston won't happen anytime soon, but most products will eventually be sold in metric units (marketed in SAE units at first). The reason will simply be to reduce costs for marketing to U.S. consumers vs. the rest of the world. The last holdout will be gallons of gas.

The liquor biz loved adopting 750 ml bottles, because they're a bit smaller than the traditional 1/5 of a gallon and they got away with selling them at the same price.

[andrepoiy]

This is true (and dividing by 5280 is such a pain in the ass nobody even attempts it; we just say things like "½ mile" rather than "2640 feet"), but the thing that makes km usage in the US unlikely isn't because of the division, but because the country was physically built using a mile-based surveying system.

Take a look at this utterly typical section of rural land south of Woodward, Oklahoma:


That grid of roads is built exactly 1 mile apart. That means you can easily determine the distance between any two points on it just by counting the grid squares. Of course, you can't do that with kilometers, you have to actually measure.

Canada was also surveyed using customary units. Canada only adopted metrics in the 1970s.

However, something funny happened in the Toronto area, where the surveyors decided that each "square" would be 1 1/4 x 1 1/4 miles.
Funnily enough, that translated to 2 km x 2 km when metricated. Therefore metrication actually made it easier to estimate distances simply because surveyors chose a random number back in the day.

[US 89]

Just to get an idea of the huge variety of units and systems we use regularly in American meteorology:

Temperature - Fahrenheit for surface temperature, Celsius for anything upper air. For any sort of thermodynamics equations, we'll use Kelvin, which sometimes gets converted back to Celsius and sometimes does not. I can convert C to F and vice versa to within a degree or two in my head very quickly because I have a bunch of equalities memorized beyond just the freezing/boiling points: 50F=10C, 77F=25C, 104F=40C, etc...

I'm confused, For a profession that calls a tornado different terms depending on where it is....

Huh? I guess Uncle Bob on his family farm of five generations in Kansas might call them " twisters"  or " cyclones" , but those are not terms any real meteorologist under the age of 70 would ever use unironically.

How about hurricanes then? Cyclones, typhooons, ...

I do like the term Super Typhoon and think that having different terms per ocean is helpful.

It's not really per ocean, though, it's per ocean basin. Storms that form in the Northwest Pacific (Pacific north of the equator, west of the international date line) are typhoons, while Central (180-140W) and Eastern (east of 140W) Pacific storms north of the equator are called hurricanes just like the ones in the Atlantic. They're called Cyclonic Storms in the Indian Ocean north of the equator, and Tropical Cyclones (or just Cyclones) in the South Pacific and South Indian oceans.

Why the different terms? Mostly because areas in East Asia and North America already had their own local names that had gained too much traction in those regions. The scientific umbrella term that covers all of them, by the way, is "tropical cyclone" , often abbreviated to TC. In meteorology, a cyclone is any large scale low pressure system, and tropical cyclone refers to the type that form over warm ocean waters usually at tropical latitudes.

[TXtoNJ]

This is true (and dividing by 5280 is such a pain in the ass nobody even attempts it; we just say things like "½ mile" rather than "2640 feet"), but the thing that makes km usage in the US unlikely isn't because of the division, but because the country was physically built using a mile-based surveying system.

Take a look at this utterly typical section of rural land south of Woodward, Oklahoma:


That grid of roads is built exactly 1 mile apart. That means you can easily determine the distance between any two points on it just by counting the grid squares. Of course, you can't do that with kilometers, you have to actually measure.

Canada was also surveyed using customary units. Canada only adopted metrics in the 1970s.

However, something funny happened in the Toronto area, where the surveyors decided that each "square" would be 1 1/4 x 1 1/4 miles.
Funnily enough, that translated to 2 km x 2 km when metricated. Therefore metrication actually made it easier to estimate distances simply because surveyors chose a random number back in the day.

Similar thing happened in BC. The Lower Mainland is entirely divided up by section-line roads outside of Vancouver. Those sections are numbered eight per mile - so the US border is 0 Av, 660 ft north is 1 Av, 660 ft north of that is 2 Av, etc. You'd think this would become nonsense with metrication, but in fact it didn't - because 660 ft is almost exactly 201 m. It's actually easier to approximate how far away in km you are from the base line, because you've just got to multiply the road number by 2 and divide by 10, and you've got a pretty good estimate, within a few hundred m.

Turns out when you're using metric on a daily basis, there are a lot of these.

[Scott5114]

Are those equivalencies pure luck, or is there some sort of property of the 5:8 mile:km ratio that makes them more likely to happen?

(I might regret asking this, because I suck at math...)

[Big John]

Are those equivalencies pure luck, or is there some sort of property of the 5:8 mile:km ratio that makes them more likely to happen?

(I might regret asking this, because I suck at math...)

old surveying had 66 feet to a rod, and an acre being 1 rod by 10 rods  aka 660 feet

[andrepoiy]

Are those equivalencies pure luck, or is there some sort of property of the 5:8 mile:km ratio that makes them more likely to happen?

(I might regret asking this, because I suck at math...)

I dug a little deeper (meaning I looked at Wikipedia) into the ones in Toronto 1 1/4 mile was chosen because the square would form 1000 acres.

Here's the extract from Wikipedia:

"In a common square grid layout known as a 1,000-Acre Sectional System, adjacent parallel roads were 100 chains or 1+1⁄4 miles (2.0 km) apart, and arranged as ten 100-acre lots each 20 chains by 50 chains[7] so that two consecutive concession roads and two consecutive side roads enclosed a square of 1,000 acres (4.0 km2)."

A chain is a historical unit used by the Brits at that time.

Article: https://en.wikipedia.org/wiki/Concession_road.

As for the math part, I don't know. But I think that these equivalencies are pretty interesting.

[1995hoo]

I thought of this thread yesterday while watching the Hungarian Grand Prix because David Croft was grumbling about an FIA graphic that used solely km/h (some of their graphics also use mph, but this one didn't). He then said something along the lines of supposing that there are places around the world that don't use mph and Martin Brundle then interjected that some people use furlongs.

[US 89]

Are those equivalencies pure luck, or is there some sort of property of the 5:8 mile:km ratio that makes them more likely to happen?

(I might regret asking this, because I suck at math...)

All in the math. If you plan and survey a city with 8 blocks to a mile, each of your blocks is 1/8 of a mile long. If you assume 5 mi = 8 km, then that means that block is also exactly 0.125 mi * 8 km/5 mi = 0.2 km, or exactly 1/5 of a kilometer - so 5 blocks is 1 km.

Of course, this is limited by the accuracy of the 5 mi = 8 km equivalency is, but it's pretty close. 1 mile is equal to about 1.609 km, where the simple 5:8 conversion would give 1.6 km. So for every mile you assume this, your km conversion gets further off by only 9 meters. Not bad.

[kalvado]

Are those equivalencies pure luck, or is there some sort of property of the 5:8 mile:km ratio that makes them more likely to happen?

(I might regret asking this, because I suck at math...)

All in the math. If you plan and survey a city with 8 blocks to a mile, each of your blocks is 1/8 of a mile long. If you assume 5 mi = 8 km, then that means that block is also exactly 0.125 mi * 8 km/5 mi = 0.2 km, or exactly 1/5 of a kilometer - so 5 blocks is 1 km.

Of course, this is limited by the accuracy of the 5 mi = 8 km equivalency is, but it's pretty close. 1 mile is equal to about 1.609 km, where the simple 5:8 conversion would give 1.6 km. So for every mile you assume this, your km conversion gets further off by only 9 meters. Not bad.

Remember to add width of the road between blocks, and inevitable effect of earth curvature...

[TXtoNJ]

Are those equivalencies pure luck, or is there some sort of property of the 5:8 mile:km ratio that makes them more likely to happen?

(I might regret asking this, because I suck at math...)

All in the math. If you plan and survey a city with 8 blocks to a mile, each of your blocks is 1/8 of a mile long. If you assume 5 mi = 8 km, then that means that block is also exactly 0.125 mi * 8 km/5 mi = 0.2 km, or exactly 1/5 of a kilometer - so 5 blocks is 1 km.

Of course, this is limited by the accuracy of the 5 mi = 8 km equivalency is, but it's pretty close. 1 mile is equal to about 1.609 km, where the simple 5:8 conversion would give 1.6 km. So for every mile you assume this, your km conversion gets further off by only 9 meters. Not bad.

Remember to add width of the road between blocks, and inevitable effect of earth curvature...

Nice thing about the meter is that the effect is pretty much baked in. Nice thing about the mile is that it's based on the meter.

[kalvado]

Are those equivalencies pure luck, or is there some sort of property of the 5:8 mile:km ratio that makes them more likely to happen?

(I might regret asking this, because I suck at math...)

All in the math. If you plan and survey a city with 8 blocks to a mile, each of your blocks is 1/8 of a mile long. If you assume 5 mi = 8 km, then that means that block is also exactly 0.125 mi * 8 km/5 mi = 0.2 km, or exactly 1/5 of a kilometer - so 5 blocks is 1 km.

Of course, this is limited by the accuracy of the 5 mi = 8 km equivalency is, but it's pretty close. 1 mile is equal to about 1.609 km, where the simple 5:8 conversion would give 1.6 km. So for every mile you assume this, your km conversion gets further off by only 9 meters. Not bad.

Remember to add width of the road between blocks, and inevitable effect of earth curvature...

Nice thing about the meter is that the effect is pretty much baked in. Nice thing about the mile is that it's based on the meter.

I am talking about the fact that since the earth is not flat, you cannot use simple Euclidean geometry for land surveying. Works fine for the backyard, but starts to glitch on a city level.
As for miles, you may add that a nautical mile used to be 1 arcminute. That should mean 10 000 km = 5400 nm (the modern definition of a nautical mile is 0.01% different, though)

[Rothman]

Are those equivalencies pure luck, or is there some sort of property of the 5:8 mile:km ratio that makes them more likely to happen?

(I might regret asking this, because I suck at math...)

All in the math. If you plan and survey a city with 8 blocks to a mile, each of your blocks is 1/8 of a mile long. If you assume 5 mi = 8 km, then that means that block is also exactly 0.125 mi * 8 km/5 mi = 0.2 km, or exactly 1/5 of a kilometer - so 5 blocks is 1 km.

Of course, this is limited by the accuracy of the 5 mi = 8 km equivalency is, but it's pretty close. 1 mile is equal to about 1.609 km, where the simple 5:8 conversion would give 1.6 km. So for every mile you assume this, your km conversion gets further off by only 9 meters. Not bad.

Remember to add width of the road between blocks, and inevitable effect of earth curvature...

Nice thing about the meter is that the effect is pretty much baked in. Nice thing about the mile is that it's based on the meter.

I am talking about the fact that since the earth is not flat, you cannot use simple Euclidean geometry for land surveying. Works fine for the backyard, but starts to glitch on a city level.
As for miles, you may add that a nautical mile used to be 1 arcminute. That should mean 10 000 km = 5400 nm (the modern definition of a nautical mile is 0.01% different, though)

But the world is just a bunch of backyards put together, so just go from one backyard to the next.