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Obsolete German Units of Measurement (wikipedia.org)
84 points by zeristor on April 11, 2021 | hide | past | favorite | 105 comments

I wonder why Zentner is not on the list. People still used that in colloquial talk in the 1970s. Well, being exactly 50 kg it was already kind of ISO.

Measures of area are missing. I still remember very old people talking of Morgen, whithout having any clue how much that would be. Used to describe the size of a farm. I guess it was somehow metric already, but I'm sure farms where measured centuries before.

Yes, people still sometimes use the Morgen (=morning).

It's the area "tillable in the morning hours of a day by one man behind an ox or horse dragging a single bladed plough" (about 2500 m^2, though regional variations were 4000 or even up to 10000 m^2).

Interestingly, the acre was also historically determined as the area that can be ploughed in one whole day by a team of eight oxen, namely 1 furlong x 1 chain or 4047 m^2.

Not sure what that says about German vs Anglo-Saxon working hours or oxen...



> Hide Park is a park in Ankh-Morpork with a small lake. Its unusual name comes from old times, when a hide was the measure of land a man with a bullock could plough on a wet Thursday

I should have known Terry Pratchett had based this on some kind of real-world equivalent https://wiki.lspace.org/mediawiki/Hide_Park

FWIW, I've never heard the word "Morgen" used in that meaning outside of poems. Maybe this is a regional thing? I'm in East Germany (born and raised in Mecklenburg, now living in Saxony).

Never heard it either, born and raised in Stuttgart, living in Berlin

fwiw, heard it used regularly (NRW, "Bergisches Land") - in the late 70s, by people 70+.

I (GGP) have also heard it in NRW/Rheinland-Pfalz (Eifel) e.g. from older relatives. It is obsolete, and used less than the Zentner, Pfund.

heard it used in NRW where the size of a plot of land to be sold was still specified in Morgen

Because it's not obsolete. It's still in colloquial use.

Pfund (500g) is on the list and also still in use. I think it's more common than Zentner.

Depends on whether you tend to buy meat (only use case for Pfund for me) or you work in construction / gardening etc. where Zentner is still commonly used. At least where I live.

(This is a bit weird)

50 year old Brit here. I lived in a land called West Germany for several years in the '70s and '80s.

Pfund (pound) was routinely used in markets ie street markets but not generally in supermarkets but it was understood. If you asked for ein pfund pfeffer salami you got 400g or so of peppered salami. Back then Germany was pretty much fully SI and decimalized but just like any other country had some old units still left hanging on.

Yes, they are hanging around, while values typically have been rounded to bears "round" SI number. A more traditional pound is 454g, nowadays it's understood as 500g.

The reason why you don't typically see it in supermarkets etc. is that law requires SI units and written language often differs from spoken.

Has its own page though https://en.wikipedia.org/wiki/Morgen

Not even linked... (Reminds of other Wikipedia projects I have "ongoing" (which is really: haven't done anything for a while) Cleaning up some confusing article splits, it's a tedious task.)

Seemingly used the most these days in the Zungenbrecher ,,Zehn Ziegen zogen zehn Zentner Zucker zum Zoo.'

I also wondered about Fahrenheit, since Zoll (inch) is on the list.

In south asia traditional units of measurement are still in use for gold jewelry and similar:


In Afghanistan the ser and kharwar are still commonly used for purchasing firewood for cooking stoves and heating stoves in winter.


In Thailand, the baht is both a unit of currency and a unit of weight for gold. As of today, a baht of gold (approx 15g) is worth 26,844 baht of fiat currency, which explains why gold continues to be very popular for dowries.

Well, pound sterling was once indeed a pound of sterling silver (Ag).

IDK if it meant "normal" pound or "troy" pound (almost 20% lighter).

Well, the western countries also use an obsolete weight unit: the carat

Some of these are so obsolete that even the awesome Frink [0] doesn't handle them

  From: 10 Wegstunde
  To: metres
  Result: Warning: undefined symbol "Wegstunde".
  Warning: undefined symbol "Wegstunde".
  Unconvertable expression:
  10 Wegstunde (undefined symbol) -> 1 m (length)
[0] https://frinklang.org/fsp/frink.fsp?fromVal=10+Wegstunde&toV...

Obligatory link to the Frink data file: https://frinklang.org/frinkdata/units.txt

Any source code where the simple declaration "candela := cd" comes with a 171 line comment ranting about the inadequacies of various international standards organisations is a must-read.

Note that Frink is proprietary, and that data file is directly taken from the GNU Units project in violation of its GPL license, including many of the textual descriptions.

Germany was not unique in this. From Ian Mortimer's book The Time Traveler's Guide to Medieval England:

"There are considerable complexities attached to other measures. It is not so much that they vary as they may be differently interpreted, according to what you are trying to measure. A foot in length is the same as your modern foot of 12 inches but if you are measuring cloth you use the ell, normally 45 inches--but 27 inches if the cloth is Flemish. Probably the most complicated measures are those involving liquids. A gallon of wine is not the same volume as a gallon of ale. A standard hogshead contains 63 wine-gallons or 52.5 ale-gallons. Except that there is no such thing as a standard hogshead; there is a standard for wine, another for ale, and a third for beer (which is imported). If you are buying beer in London, a hogshead amounts of 54 ale-gallons; if you are buying ale, it amounts to 48."

And so on.


The whole reason why French invented the metric system was because they had similar mess of various local measurement units all over the place, which notably made taxation and regulation complicated.

England was better off than France in the 1700s: in England there were national standards for the various measures, but in France they were local and differed from place to place. This opened up all sorts of opportunities for arbitrage and petty fraud.

American customary units are a simplified version of the old English measures: the main remnant of different measures for different goods in America is the Winchester bushel for volume of dry goods, and the Queen Anne wine gallon for volume of liquids.

The main difference between US customary measures and non-metric British measures is due to the reform of volume measures in the 1800s, which abolished the various old bushels and gallons, and replaced them all with the imperial gallon. (America does not use imperial units.)

England also went stone crazy and redefined the hundredweight as an even 8 stone (112 lb), while changing the pint to 20oz, making a pint no longer a pound anywhere in the world.

and the reason most of continental Europe started using metric was thanks to napoleon and the Napoleonic wars.

And in modern times we have made Mega and Giga mean different numbers when applied to memory, computer files, or hard drives... I find this embarrassing and disturbing as an engineer/technologist.

That has been fixed with mebi/gibibytes for the power of 2 variants - although it doesn’t seem to catch on very fast

Japan has several. Not sure if they are obsolete. Rooms are often measured by tatami mats. a 6 mat room, an 8 mat room, etc... I also once bought a tape measure assuming there was only one kind and it was metric but it turned out there are at least 2, metric and the shaku and I bought the wrong one.


In a way, we all do this.

A 4-person tent can hold about 4 teenagers travelling with nothing.

An airline seat is built to the “standard” person, but the average person is overweight/obese in USA.

A “lunch” can vary from 500 to 2500 calories.

A medium coffee = ???. When a Canadian coffee chain expanded to USA, an order for a medium was put into their L cups.

A Tetra Pak of Tropicana has gone from 2L to 1.89L to 1.75L.

Don’t even get me started on clothes.

Surprisingly, the government has done a great job at maintaining standards in the tobacco industry. Nobody is selling packs of cigarettes with 19 slightly-shorter cigarettes.

Imagine my surprise when I designed my first tree house then discovered that 2x4 lumber was actually 1.5x3.5.

If you get lumber from the Amish, the lumber measures the actual units.

nothing makes me angrier then slightly-shorter products. I.e sandwiches packets etc. It's cheating and wrong.

Taiwan (former Japanese colony) still uses 坪 (2 tatami mats) to measure the size of homes. Street markets often use 斤 to measure weight and price items. It’s .6 kg and the English term is “catty”

>Street markets often use 斤 to measure weight and price items. It’s .6 kg and the English term is “catty”

In Mainland 斤 = 0.5kg = metric pound. Apparently 台斤 is used to disambiguate the catty from the pound.

It's even worse than that: Tokyo, Nagoya and Kyoto all have their own incompatible tatami sizes.


Even earlier didn’t they have different counting systems fo different items?

Like a brace of birds.

My country (Slovenia) was under Austrian domination for a long time, so we informally still use klaftra (Klafter in German) for firewood. It now means 4 m3, but I guess it was defined by the particular region in the past.

Sounds close enough to a cord in North America.


What bothers me is that it, of course, depends how you cut/stack it. Different woods = different density.

Firewood should be sold on based on dry weight, not volume.

A lot of American recipes assume scales are for cocaine dealers and inappropriately use volume and dumb measures at that “a teaspoon???” While European recipes appropriately use grams.

I have precisely one teaspoon which actually measures a teaspoon. The rest of my teaspoons are spoons used for making tea, but don't actually measure a teaspoon.

However, none of my cups are actually cups. they're just cups.

It amuses me that these are actual (and accurate) sentences.

Different crystals will pack differently, so a teaspoon of table sugar from brand1 will be different than brand2. Same between icing and table sugar.

And different syrups will have different surface tensions, so a 5mL flattish teaspoon will hold more than a 5mL deep-well

And if you own cookbooks, check the intro to see if it notes what kind of salt to use. Most recipes use coarser kosher salt for measure, at least with professional recipe writers.

Table salt is made of finer crystals and will make your dish far saltier if you substitute them unknowingly. (Fine table salt packs about 2x the salt into 1tsp than Diamond Kosher -- 2 tsp Diamond Kosher == 1 1/2 tsp Morton Kosher == 1 tsp regular table salt.

I use a scale at home but, for many purposes, it really is easier to use measuring spoons for things like spices and baking soda than to use the scale for everything.

Even my cookbooks that do give weights as well as volumes for ingredients like flour, tend to just give measuring spoon amounts for the small additions.

To your cord example, precision just isn't a big deal and I'm sure it's just easier for people selling to throw an approximate volume in their truck than weighing everything.

A lot of people don't really measure things out. And except for a few items, you don't need to be precise.

I mean, how would you measure eggs, down to the gram? Oh, I'm off by 5 grams, let me crack another one.

Sugar, you can usually use half of what the recipe calls for without much consequence.

Etc, etc.

Measuring firewood is fun too. Here we have 3 different ways to measure it. Roughly: loose, piled and solid. And differences aren't small. Really matters what are you talking about, loosely piled, properly piled or actual amount of material minus all air...

On this topic, I recommend reading "Measure of All Things" by Ken Alder. It is a book about the origins of the metric system and how it is partially based on forged data. Méchain did not trust his own excellent surveying observations (the meter was defined as a 1/10^7 from equator to N. pole so they surveyed a fraction of the prime meridian) and modern error analysis did not exist yet thus he made up results to make himself look good. You can get it for $4 used at Abe Books.

Note the german version of this page, https://de.wikipedia.org/wiki/Alte_Ma%C3%9Fe_und_Gewichte_(d...

has a bunch of more units, like the various "hunderts" counting units that are not actually 100s.

In Indonesia especially the island of Java, many people use "Ons" that means 100 Grams. The unit used for rice, flour, eggs in small retail store.

My father said that the unit adapted from Dutch's metric system.

The pronunciation is the same to standard unit "Ounce" that I got confused when I first learn about units in elementary school.

The "metrification" of Dutch customary units is a fascinating subject on itself. The "ons" was in fact quite close to the ounce, but it was set to 100 grams during metrification. The step from 1 pound to 1 metric pound = 500g was less noticable.

> Elle (ell) - Distance between elbow and fingertip.

This exact measurement is used by flower garland sellers in several parts of India. In Karnataka, this measure is called the "mala" and represents the distance from the elbow to the fingertip and is actually used by measuring that way using the sellers own hand.

The horror of having to manage all those different competing measurements from town to town. This definitely played a role in the advancement of technology and industrialization. Precision is critical to most modern engineering challenges like jet engines and rockets and long lasting cars.

Or Mars Climate Orbiters, to state the obvious.

But your inclusion of long lasting cars is a very good one, tiny differences that seem good enough but aren't can have extreme impact on durability whenever you deal with moving parts. If we had a large number of competing units (like all those pre-metric German foot variations) we'd have a huge number of possible translation pairs of questionable precision and an absurd lack of dimensional conventions (try procuring a ball bearing with a dimension anywhere between full-numbers in mm), leading to lots of "it did fit without noticeable play when I set it up, why is it broken now?" situations. Compared to that, the American duality of imperial and metric is mostly harmless.

I think that long lasting cars was a reference to how Ford was notoriously early adopter of gauge blocks, which eventually became the standard references for inches.


Thank you. As an industrial engineer, I geek out about things like this. The video is immensely interesting and well presented.

> I geek out about things like this


Though I "blame" my father ("Schiffbauingenieur" ^= "ship/naval engineer") for my interest in engineering in general, my late grandfather for my interest in electrical engineering and my discovery of "This Old Tony" on YouTube for my recent interest in (manual) machining.

Ah, much less obvious, at least for us non-Americans, thank you.

I feel like the Mars Climate Orbiter could have been lost even in an all metric setup because they did not label their units. Using centimeters instead of decimeters or meters would result and just as much problem as using inches or feet.

But endless arbitrage opportunities!

Yojana and many other units in Sanskrit, from older Indian times:


> Wegstunde

> One hour's travel, used up to the 19th century.

Funny. There is still (colloquially) a thing called a Wegbier which you drink on your way to have another drink. Used in Dresden with friends once ;-)

I still use Pfund at the market, because it’s easier and clearer than asking for half a kilo. Everybody seems to use it

Hopefully someday there'll be a page like this for the US, referencing the pound or mile as obsolete measures.

Let's not have a hellwar about this please. Anything so repetitive (and likely so nasty) is off topic here.


Sorry, I meant it a bit tongue in cheek (as a German I only ever heard of most of these measurements in old cooking recipes), didn't expect it to turn into... this.

I agree, I very much hope we’ll switch to metric in my lifetime.

That said, I do think but it’s worth knowing that one of the reasons metric had a harder time catching on is that the US had already standardized its units a full fifty years before the metric system was developed. So, while our systems aren’t mathematically consistent or elegant as the metric system, by the time metric came about they were at least geographically consistent, so the painful business problem this Wikipedia page illustrates - of not knowing “what is a foot” from town to town - didn’t exist anymore.

One final note, a common misconception I encounter with non-Americans online is that Americans have no idea about metric. That’s not true. Metric is taught in schools and is the exclusive unit system for scientific work. We only have metric for electrical units. Certain other metric units are also common, for example liters, milliliters, grams, and centimeters are all used relatively commonly. Other units are frequently presented side-by-side with metric: mi/km or temperatures in f/c. So most Americans understand and can reason about metric units (perhaps with some discomfort), but unfortunately usage of the “American Customary Unit System” remains predominate.

>Metric [...] is the exclusive unit system for scientific work.

Lockheed Martin and the Mars Climate Orbiter beg to differ.

Which was over 20 years ago. I'm sure it's not 100% but it's certainly fair to say that the metric system is used extensively in science and engineering.

It's certainly used extensively, but exclusively is a big stretch, even nowadays. I've come across research papers from the last couple of years using feet and inches.

>Metric is taught in schools and is the exclusive unit system for scientific work.

Not in astrophysics and cosmology. You almost never hear of meters or grams. We use a hodgepodge of different units depending on what is most convenient and sensible. Working in the solar system? AU. In the galaxy? Light-years or parsecs. And in theoretical work, you often will encounter mass measured in electron-volts, distances measured in solar masses, or temperature measured in square meters, or (more often) everything measured in unitless quantities with no dimensions at all.

It really does feel a lot like the traditional medieval measuring systems, messy but once you learn them, useful and comfortable in the mind.

Conversation I had with a US guy a decade ago: „Hey now that I‘ll stay in Europe here for some time, I want to get a real feeling for the temperatures here...“ - „Sure!“ - „So what temperature is freezing water in Celsius?“ - „Zero.“ - „Wow, that‘s funny. Like, exactly?“ - „Yeah, it‘s the definition.“ - „Cool, but what temperature is boiling water?“ - „100 degrees.“ - „That... makes a lot of sense!“ - „Doesn‘t it? You‘re welcome :)“

Interesting tidbit, the original definition for Celsius set 0 as boiling and 100 as freezing. It was swapped in 1743.


Celsius is not that practical for everyday life though :

1.) The 0-32-96 °F range covers much better the range typically experienced by humans than 0-100 °C.

2.) It's more dozenal than decimal allowing for easier mathematics (even when stuck in a decimal number representation system like we are).

3.) For "non-human" fields, you are probably better off anyway using a scale starting at the absolute zero. (The triple point of water seems like a good candidate for 100 degrees ? Or maybe a value directly related to log 2, e, kB ?)

For room temperatures or air temperatures, integer °C is exactly the right amount of resolution. The difference between 20°C and 21°C is pretty much exactly what I would be able to tell apart.

And on the other hand, for body temperatures, tenths of °C as a level of resolution is just right, whereas integer °F would be too coarse.

>For "non-human" fields

In those cases, Kelvin is customarily used with the same degree size as Celsius with 0 Celsius corresponding to 273.15 K. (There is a corresponding scale for Fahrenheit degrees but it's rarely used.)

Hmm, yeah, it might be better to just keep the same degree "width" for both scales (whether Celsius or Fahrenheit).

"practical for everyday life" involves cooking, and I encounter 0°C and 100°C regulary, with ice and boiling water.

To be honest, humans are likely able to adapt to scale when talking about the weather, or how hot the room is.

The reasons the US should move to metric are: - The rest of the world is on metric - It's better for science and engineering

I'm not suggested moving is easy, just that I for one would like it to be attempted.

Metric might be good for scientific measurements, but it's a trash system for day-to-day human usage.

This most stark in Celsius, where the useful range of temperatures where humans can live is compressed into roughly -20 C to 40 C, versus 0 to 100 in Fahrenheit.

I hear this again and again from Americans, but it is simply a matter of what you are used to, e.g. what you grew up with.

Its funny how it is so important to have a wider range of temperatures whereas I most often hear Americans use ranges. And instead of saying "today temps will go up into the 70s" you just give the actual number, "it will go up to 23C", what is the problem with that? You could also say because a celsius degree is greater, the number matters much more and it is often not necessary to give a range like that. Ranges or not, it does not matter. A celsius is certainly small enough that decimals are not necessary for humans day-to-day.

What I also often hear from Americans is that the inch is such a perfect unit and "2.5cm" is so awkward but then I hear "6/8 of an inch" and similar units or the mixing of feet and inch and I just don't get it.

This is pretty much where I'm at. Below 30 I put on a t-shirt. Below 20 I put on long sleeves. Below 10 I put on a jacket. I have absolutely no idea what I'm expecting when the Americans say 65.

This isn't a feature of either system, it's straight-forward familiarity. I'm sure if the weather man used Kelvin, it wouldn't take me long to figure out how to dress for it.

Shame you're downvoted, because it's a comment that shows why this imperial/American vs metric "competition" is silly.

It's like saying Cyrillic is better than Latin script. Or driving on the left is better than on the right. In reality, it just doesn't matter. Whichever you grow up with will seem like the easier one.

When I think -5C, I know how the temperature will actually feel. Someone who thinks "25F" will feel the same in their head. Same for 25cm, 5 inches, 10kg, 40lbs, 9 stones, 7 shaku, etc. Whatever you grew up with will feel better.

Metric just seems to have won in most of the world, including in countries like the US and Japan which use it in science/industry. It just makes sense to have one standard for communicating with as many other people as possible.

> It's like saying Cyrillic is better than Latin script. [...] It just doesn't matter.

Out of all the examples that you gave, this is the one that doesn't fit your argument. Cyrillic has a wider range of letters which makes it a better fit for certain languages with a specific phonology. I don't remember which language it was, but I remember reading about one of the countries between Russia, Turkey, Iran, etc. switched from their indigenous writing system to Latin script in the 1930s/1940s to enable usage of standard typewriters etc. And just a few years later, they switched again, to Cyrillic script, after finding that Latin script does not fit their language all that well.

The first point you're trying to make doesn't seem to hold.

You use a subjective opinion on one unit's range as a proxy for all other units. How is the meter (cm, mm, km, etc) trash compared to the foot (inch, yard, mile, etc)? They're objectively better in every regard, not just for scientific purposes but in everyday life.

Come to think of it, it's the first time I'm seeing someone making that sort of statement rather than the usual "it's too difficult to change now" excuse.

But if you actually need more accuracy (which I do not in my daily life) you can simply add a decimal point? Also, that's a difference between 60 and 100 data points, which is not really that much.

Americans don't seem to like decimal points. Everything has to be expressed in fractions.

5 kilometer = 5000 meter = 500 000 centimeter = 5000 000 millimeter. Now you do this for 5 miles (yard, feet, inches).

1/8 mile = 220 yards = 660 feet. Now you do t--actually wait.

1/110 mile = 16 yards = 48 feet. Now you do this for an one-hundred-and-tenth of a kilometer.


1/3 pound = 1/2 mark = 6 shillings & eightpence = 80 pence. Now you do this for a euro. 1/3 of a euro = , ummm?

The point is, the traditional measures are built out of very highly divisible numbers, which is very useful in certain applications, for example surveying, bartering, baking, etc. Just like the metric measures are built out of powers of ten, which is very useful in certain other applications, like seamlessly moving between scales of magnitude in scientific work.

1/8 km = 0.125km = 125m = 12500cm

So freaking what. Use decimals and you can easily convert anything into everything. And you don’t have to rely on those few cases where you can exactly divide.

6.8m = 680cm = 0.0068km, etc.

Who writes out prices in fractions?

Its even worse with baking. Scaling up units from recipes is really hard if you have fractions of different units like tee spoon, table spoon and cup and when ounces can both mean a volume and a weight. (“fl. is not always specified”) No thank you.

Also your examples are really poor, when the base systems keep changing in the same dimensions (e.g. length) there is not benefit at all, just confusion or reluctance to convert to other units because it would be too awkward.

When you need to partition a field using crude tools, there is nothing "easily" done with decimals. Integers are far easier to work with and measure out. This is simply proven by the most basic outdoor experience, which I suppose you don't have.

Being able to divide by 2, 3, 4, 5, 6, 8, 9, 10, 11, and 12 is not a "few cases", it's the chief part of the small integers into which stuff often needs to be divided evenly.

If you ever went to the market before decimalisation, you would meet many who write prices in fractions. Something would be priced at X pounds/crowns/marks per Y items/weights. Then, the cost of Z units/weights is XZ/Y. When the coins are highly divisible multiples of each other, you have a lot of choices to be able to pay the exact amount and don't have to bother with getting change back. Even better if we price by the dozens (Y = 12) instead of 10s: 12 has twice as many factors than 10.

I understand that this all requires a certain numeracy however. Thankfully nowadays we can just buy things using their credit cards on Amazon: makes mindless consumption much easier.

I grew up when metric was replacing "imperial" in Canada. The road signs had mph and kph, thermometers all have C and F, tape measures have both (lumber is still sold as a 2x4, its pre-finished dimension). Socket sets. God.

Anyway, metric just makes sense for most things. The attachment is cultural. My parents talked about my height and weight in the old units. I still use them and so do government forms.

But there's nothing "good" about the old stuff. It's just what you are used to.

In other words, it's Fahrenheit that doesn't make sense because it goes from arbitrary -20 C to 40 C. Even the originally targeted alignment with human body temperature to 96 F doesn't match.

On the other hand, freezing and boiling water makes sense, because you know that you have to drive carefully when the temperature is below 0 C.

I'll actually defend Fahrenheit more strongly than other US units. 32 degrees is a single number it's probably worth remembering. Balanced against that, environmental temperatures are usually going to be positive unless it's really fricking cold and the degrees are about twice as granular. The main advantage of Celsius is just that it's what's used in most places (and that it's tied in with metric units).

The absolute scale of Celsius (as opposed to the size of the degree) isn't the most useful anyway because you tend to use Kelvin for a lot of purposes.

Metric works fine everywhere it is used. It's just what you are used to. American engineering isn't any better or worse than engineering elsewhere. There's no inherent advantage to using a different way to measure stuff that you can objectively point at.

The history of the Fahrenheit scale is actually quite fascinating. It's one of the less famous things to come out of the Dutch eighteenth century scientific community. Daniel Fahrenheit picked a few reference points to calibrate thermometers. None of these have anything to do with your level of comfort. That was never a thing or an intention.

Zero was the temperature of a particular mixture of ammonium chloride and water and ice (a brine basically) reaching an equilibrium. The second point (30) was picked as the temperature of water with ice floating in it. The main point was to make this somewhat of a repeatable process. Basically water with ice in it has a very stable temperature because the transition from ice to water takes a lot of energy. Tossing in some ammonium chloride in a known quantity gives you a second point of reference that is different enough that it is meaningful.

Daniel Fahrenheit was using those two points to calibrate mercury based thermometers. He came up with a third reference point: the temperature you get when you insert a thermometer into your mouth. This was originally supposed to be 90 degrees. Later it was determined to be 96 and we now know it is 98.2 degrees. In other words, he kind of messed up there by picking something a bit harder to measure.

The final reference point that Daniel Fahrenheit worked with was the boiling point of mercury. Which he put at 300 degrees. The scale was redefined several times according to progressive insights regarding e.g. the notion that there are about 180 degrees Fahrenheit difference between freezing and boiling water.

The latter is of course an attempt to reconcile the scale with the centigrade scale which is based on the freezing and boiling temperatures of water. That's technically also somewhat imprecise of course but quite easy to figure out. Basically take water, put ice in it, wait a bit. That's your zero point. Then put it on a fire, wait for it to boil. That's 100. Put two little markings on your glass tube with mercury where that happens and then divide that into tens and again into tens. That's a repeatable process for making a thermometer. Not super precise of course because it depends on air pressure (later of course factored into its definition). But if you are making thermometers, that's pretty easy to do if you are an eighteenth century instrument maker. You need ice of course but that would have been a commodity much of the year where Celsius was living (Stockholm).

For better or worse, the metric system actually uses Kelvin which simply is the Celsius scaling (or centigrade as it was called originally) but adjusted to absolute zero −273.15°. That last adjustment by .15 degrees happened only fairly recently actually. Fahrenheit only continues to exist as a derived scale from that. None of its original reference points are precise enough to matter these days. That's true for most remaining imperial measurements: they are defined very precisely in metric units. You can measure feet with your feet of course. But only if you don't care about precision. Any self respecting engineer uses more carefully calibrated instruments.

The important feature of the metric system, for day to day use at least, is that it plays nice with decimal numbers. I grant you that in this regard Celsius has no advantage over Fahrenheit. However for measuring lengths calculating in thousands of inches, power of two fractions of inches, and even tenths of feet (apparently excavator operators use that) seems more an opportunity to showcase one's mental arithmetic skills than something selected for ease of use.

Now do "Imperial units of measurement to be obsoleted".

Let's not have a hellwar about this please. Anything so repetitive (and likely so nasty) is off topic here.


Believe it or not, the US rod is a close relative to the Italian pertica, which is a traditional unit of length and surface, coming straight from the Roman Empire. It's still used to refer to the size of fields. I found it recently in some sales announcements. Of course every city had its own variant.


The survey foot is going away soon, and not a moment too early. Having two feet with a mutual ratio of 499999/500000 seems rather confusing. But to be sure, the survey foot has apparently not been used much since 1986.


They already are mostly obsolete!

(American units date from before the British volume measure reform that created imperial units.)


Please don't post flamebait or swipes to HN. It leads to tedious, nasty threads.


You're right, I'm sorry!

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