Forgotten terminology and units of yesteryear - Page 1
Forum section: electronics / general

author: CNe7532294
author_rank: Regular Contributor
timestamp: December 28, 2017, 10:25:00 am
content: Before the 1960s prefixes like Giga, nano, and pico among others did not exist. When flipping thru old HP catalogs I come across things like kmc or mmf which means kilo mega cycles and micro micro farad. Both translate to Gigahertz (GHz) and picofarad (pF) respectively. I have so many questions about this. These are what I can think about at the moment.Was this the standard for anything scientific? I ask because even though tech was limited back in the day, I'm sure people were thinking about this stuff. For example, was this type of terminology used for say biology, chemistry (used Angstroms same with biology), or keeping track of time? How about in papers?Also where have I've seen an explanation for this before? I remember seeing a site explaining this in detail before which is why I kinda know about this but I can't find it again.

author: IanB
author_rank: Super Contributor
timestamp: December 28, 2017, 10:49:01 am
content: It is tempting to think that SI units have been used in science for ever, but this is not apparently true, at least not in the USA. For instance I came across a reference to a scientific publication from 1941 concerning the solubility of chlorine in water, where the data were given in units of (lb-mol)/(cu.ft.)/(atm).In fact the very first thing covered in my university engineering studies was an introduction to units of measure old and new, what they mean and how to convert between them.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 28, 2017, 11:39:11 am
content: In the US circa 1960, "metric" units were usually used in chemistry, biology, and medicine for length, concentration and so forth both in practice and in publicatons. However, in physics and thermodynamics both metric and "English" units were used. Of course,"metric" does not equate to SI. Some examples of "metric" that are not SI:mu = millimicron = nanometercc = cubic centimeter = milliliterdl = 100 ml"lambda" symbol and word = microliterOf course, foot-lbs (and equivalent expressions in ounces), mm Hg, torr ( = 1 mm Hg) are still used in practice, but much less so in publications.

author: German_EE
author_rank: Super Contributor
timestamp: December 28, 2017, 07:12:20 pm
content: Try these for units of length:Yard Three feet or 36 inchesEli Fingertip of outstretched arm to opposite shoulder or 45 inchesFathom Fingertip to fingertip of outstretched arms or six feetRod (A.K.A. Perch or Pole) 16.5 feetChain Four RodsFurlong 40 Rods or 660 feetAnd this will make your head hurthttps://upload.wikimedia.org/wikipedia/commons/c/c8/English_length_units_graph.pngSo THAT'S why the UK went Metric!!!

author: Tepe
author_rank: Frequent Contributor
timestamp: December 28, 2017, 07:26:31 pm
content: Quote from: IanB on December 28, 2017, 10:49:01 amWe had Gauss's cgs system.

author: amirm
author_rank: Regular Contributor
timestamp: December 28, 2017, 07:57:10 pm
content: An interesting change in audio has been move away from cycles to Hertz. I wonder why Hertz was considered more proper than the more descriptive cycles. The wiki explains the what, but not the why:https://en.wikipedia.org/wiki/Hertz"HistoryThe hertz is named after the German physicist Heinrich Hertz (1857–1894), who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission (IEC) in 1930. It was adopted by the General Conference on Weights and Measures (CGPM) (Conférence générale des poids et mesures) in 1960, replacing the previous name for the unit, cycles per second (cps), along with its related multiples, primarily kilocycles per second (kc/s) and megacycles per second (Mc/s), and occasionally kilomegacycles per second (kMc/s). The term cycles per second was largely replaced by hertz by the 1970s. One hobby magazine, Electronics Illustrated, declared their intention to stick with the traditional kc., Mc., etc. units."Anyone was around then, and knows the motivation?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 28, 2017, 08:27:18 pm
content: Well, to honor a pioneer in the field (pun intended), of course.Why is the SI unit for magnetic flux density the tesla, and not magnetic lines of force per inch?Tim

author: chris_leyson
author_rank: Super Contributor
timestamp: December 28, 2017, 08:41:20 pm
content: In the E.S.U. system capacitance was measured in centimeters where 1 F = 9x10^11 cms (approx), the British Royal Navy used jars as a unit of capacitance where 1 jar = 1000 cms = 1.111 nF or 1 F = 9x10^8 jars (approx). From the Admiralty Handbook of Wireless Telegraphy, 1938 "The jar is now obsolete as a Service unit, having been replaced by the Farad and its sub multiples". Those being milli-micro and micro-micro back then.The capacitance of a parallel plate capacitor is C = A*K/(4*pi*d*9*10^11) Farads = A*K/4000*pi*d jars = A*K/4*pi*D centimeterswhere A and d are area and plate separation respectively and K is "Specific Inductive Capacity" or relative permitivity.

author: chris_leyson
author_rank: Super Contributor
timestamp: December 28, 2017, 08:55:32 pm
content: I think grads (metric degrees) were in use until relatively recently, you could still buy theodolites graduated in grads, no pun intended. The French term centigrade was in use for one hundredth of a grad (EDIT: grade) and that is one reason why centigrade was renamed Celsius.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 28, 2017, 09:20:32 pm
content: I had to look up the SI unit for wavenumber. It is m^-1 instead of cm^-1 (after all, I am just a chemist).@German_EE : Talk about being an ideologue and ignoring reality.John

author: IanB
author_rank: Super Contributor
timestamp: December 28, 2017, 10:32:38 pm
content: Quote from: chris_leyson on December 28, 2017, 08:41:20 pmWouldn't that have been centimetres rather than centimeters?

author: Tepe
author_rank: Frequent Contributor
timestamp: December 28, 2017, 10:40:40 pm
content: Quote from: chris_leyson on December 28, 2017, 08:55:32 pmAnother might be that everybody else calls them Celsius and it gradually seeped in.

author: coppice
author_rank: Super Contributor
timestamp: December 28, 2017, 10:54:27 pm
content: Quote from: CNe7532294 on December 28, 2017, 10:25:00 amGiga and nano were introduced in the 1960s, but pico was already old. I remember seeing some capacitors described in micro micro farads in the 1960s, but I never understood why. Most were described in pico farads long before that.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: December 28, 2017, 11:00:16 pm
content: Actually, good practice is that only multiples of round thousands should be used. There is no real reason to have any other multiples, and they just complicate matters, by making the intervals between multiples inconsistent.This means that each multiple is always 103different from the previous one, and in physics when you are sometimes dealing with very large numbers that regularity of meaning reduces the chance of mistakes.Although the SI standard doesn't actually prohibit them, most labs consider the use of centi, deka, deci, hecto or the like to be bad practice. An exception might be made for centimetres since they are so widely used, but there is very little excuse for the others.The whole purpose of the metric system is to simplify things, but human nature seems to be to find ways of making things as complicated as possible in spite of that.

author: Tepe
author_rank: Frequent Contributor
timestamp: December 28, 2017, 11:21:16 pm
content: Quote from: IanMacdonald on December 28, 2017, 11:00:16 pmHere deciliters are a common measurement and in Sweden candy, for instance, is sold by the hectogram.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 28, 2017, 11:28:46 pm
content: I disagree about the use of 10^3 multiples as being better. Why add extra zeros when they aren't needed? An obstetrician might indicate that a woman's cervix is dilated to 8 cm (indicating an impending delivery), why write that as 0.08 m or 80 mm?Admittedly, it is unlikely the decimal will be misinterpreted in that example. But I don't see that any clarity is added. Of course, misinterpretation of 0.01 m vs 0.1 m could lead to a disaster. 10 cm versus 1 cm is less likely to be misinterpreted. (The JCAHO in the united states has tried to eliminate reporting trailing zeros, as in 1.0 for laboratory tests that are typically reported to 2 or 3 significant figures. I am not current enough to know the status of that regulation. Personally, I think it is stupid.)

author: chris_leyson
author_rank: Super Contributor
timestamp: December 29, 2017, 12:07:18 am
content: QuoteGood question, metre and centimetre is the spelling adopted by International Bureau of Weights and Measures. However. the American spelling is meter and I believe some Germanic languages spell metre as meter. I had a look at the 1938 Handbook of Wireless Telecgraphy and it's spelled centimetre. Thanks for pulling me up on that one.Units of yesteryear, well some engineers still use the cgs system of units like Oersteds Webers ergs dynes etc and conversion to SI units is not a problem, I guess it's what you're used to. A lot of people still use imperial units, PCB design for example, thou mil micron or mm ? A classic example of making a dogs breakfast of things is Howard Johnsons High Speed Digital Design where everything is in SI units except for distance.

author: Jr460
author_rank: Regular Contributor
timestamp: December 29, 2017, 12:17:38 am
content: I know of an operating system that has a kernel parameter in microfortnights. I suspect they still have that in place today.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 29, 2017, 12:37:28 am
content: Quote from: coppice on December 28, 2017, 10:54:27 pmIn Australia, picoFarads ( pF) were widely used in the 1950s .The "Radio & Hobbies" ( later RTV&H, & still later, Electronics Australia) used pF & decimal parts of uF, with the swap over being at about 0.0001 uF.The "Giga" prefix was in use in the Radio Communications field in the 1950s, with frequencies quoted in "Gigacycles per second".Well before I was working in Electronics, I remember my older brother using the above term."pico" for time durations was definitely used, maybe, not so much "nano".The S.I. Units were only a bit of a reorganisation of the older versions of the Metric System, which welearnt along with the Imperial system back in the day.The "Exercise Books" we used at School had a back page of useful information, one part of which was an outline of the "C.G.S" version of the Metric System.The Metrication Board in Oz were paranoid about the use of "centimetres", which might be understandable, but what was really silly was demanding that if I wanted to buy 1.8m of wooden dowelling, say, I had to ask for "1800mm".We were apparently too dumb to be trusted to use use decimal points!Never mind that we then paid in Dollars & Cents, with a decimal point between them.

author: HighVoltage
author_rank: Super Contributor
timestamp: December 29, 2017, 01:50:51 am
content: In the 1970s Germany switched from Horsepower (Pferde Stärke) (PS) to kW for engines but even today, most people prefer to ask about horsepower.It seems it is very difficult to change some units, even if it make so much sense from a science point of view.

author: Inverted18650
author_rank: Frequent Contributor
timestamp: December 29, 2017, 02:13:14 am
content: Quote from: Jr460 on December 29, 2017, 12:17:38 amClassic

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: December 29, 2017, 02:37:01 am
content: I'm surprised no one has mentioned the "jar". According to my 1939 copy of the Admiralty Handbook of Wireless Telegraphy, Vol 1 (published by His Majesty's Stationary Office and costing 4s 0d) The jar was the original unit of capacitance. The official exchange rate was 1 uF = 900 jars. I have included a scan of the pertinent page.

author: xrunner
author_rank: Super Contributor
timestamp: December 29, 2017, 02:38:43 am
content: Quote from: blueskull on December 29, 2017, 02:26:07 amSure is - if you watch a football game it's gonna be one of the main words.

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 29, 2017, 03:20:46 am
content: Quote from: xrunner on December 29, 2017, 02:38:43 amAmerican football that is. Football is soccer in the rest of the world.

author: tautech
author_rank: Super Contributor
timestamp: December 29, 2017, 03:31:38 am
content: Quote from: HighVoltage on December 29, 2017, 01:50:51 amHP ~= PS.Back in the 80's most Japanese equipment was in kW or PS.https://www.convertunits.com/from/ps/to/horsepowerQuote

author: vk6zgo
author_rank: Super Contributor
timestamp: December 29, 2017, 04:05:28 am
content: Quote from: Cyberdragon on December 29, 2017, 03:20:46 amNot in Australia--- we have four popular "codes" of football."Australian Football", which is what the AFL play.Rugby LeagueRugby Union& last but by no means least, the " World Game", whose supporters just callFootballThey hate the name "Soccer"."Australian Football" changed to Metric years ago, as I think the two "Rugbys" did.Metric would be pretty obvious for the "World Game".By the way, we mostly call American Football "Gridiron"!

author: coppice
author_rank: Super Contributor
timestamp: December 29, 2017, 11:20:18 am
content: Quote from: tautech on December 29, 2017, 03:31:38 amThere have been several slightly different definitions of horse power used since James Watt originally came up with the idea. Because they only vary by 1 or 2% people tend to ignore the differences.

author: tooki
author_rank: Super Contributor
timestamp: December 29, 2017, 11:48:21 am
content: Quote from: Cyberdragon on December 29, 2017, 03:20:46 amWhat’s funny is that the word “soccer” itself is British in origin, created using a linguistic pattern that isn’t even present in American English!“Association football” ->soccerRugby ->ruggerAnd so on.Indeed, American football is formally known as gridiron football. Maybe we should call it gridder? :p

author: HighVoltage
author_rank: Super Contributor
timestamp: December 29, 2017, 01:31:27 pm
content: Quote from: coppice on December 29, 2017, 11:20:18 amEspecially, when you consider how the HP or PS was measured in those days this small variance did not matter at all.When I grew up in Germany, we still used pounds for weight in a grocery store. Interestingly the changeover to kg was accepted by the public without any big problems.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 29, 2017, 01:43:31 pm
content: Quote from: tooki on December 29, 2017, 11:48:21 amIn fact, that what American football players were and in some cases still are called.http://www.dictionary.com/browse/gridder

author: AndyC_772
author_rank: Super Contributor
timestamp: December 29, 2017, 02:38:12 pm
content: Does anyone know why the 'nano' prefix seems, in some places, out of favour?When I'm looking to buy capacitors, I frequently find I'm having to navigate catalogues which list (say) a 10,000pF capacitor, which would be much more clearly labelled as 10nF.For example, Farnell here in the UK:http://uk.farnell.com/c/passive-components/capacitorsTheir parametric search uses pF all the way up to 82,000pF, then jumps to 0.1uF.

author: Tepe
author_rank: Frequent Contributor
timestamp: December 29, 2017, 02:48:14 pm
content: Quote from: HighVoltage on December 29, 2017, 01:31:27 pmDid those pounds happen to be exactly 500 g? They did in Denmark.

author: NottheDan
author_rank: Frequent Contributor
timestamp: December 29, 2017, 03:26:29 pm
content: Quote from: Tepe on December 29, 2017, 02:48:14 pmYes, they did. Since the 1st of July 1858 in Prussia.

author: coppice
author_rank: Super Contributor
timestamp: December 29, 2017, 03:56:43 pm
content: Quote from: AndyC_772 on December 29, 2017, 02:38:12 pmThe capacitor world moves slower than the silicon world. Eventually they will catch up with 1960s innovations, like the prefix "nano".

author: Tepe
author_rank: Frequent Contributor
timestamp: December 29, 2017, 04:14:26 pm
content: Quote from: NottheDan on December 29, 2017, 03:26:29 pmIn 1683, the Danishpundwas defined (by Ole Rømer) as the weight of 1/62 Danish cubic foot of pure water (499.7 g).1pund= 16unser= 32lod= 128kvintin.In 1839 the definition was changed to 1pund= 500 g.In 1861 the system was changed to 1pund= 100kvint= 1000ort.The metric system was introduced by law in 1907 with a transitional period until 1916.

author: IanB
author_rank: Super Contributor
timestamp: December 29, 2017, 07:17:54 pm
content: The trouble is that the metric system works terribly at the delicatessen.It is was fine and easy to ask for 4 ounces of ham, or a quarter pound of ham, or similar.In metric it doesn't work. You have to ask for 100 g of ham, or 125 g of ham, or some crazy large number like that. In Europe, do people ask for 1/8th of a kilo of ham?

author: tautech
author_rank: Super Contributor
timestamp: December 29, 2017, 07:44:20 pm
content: Quote from: Tepe on December 29, 2017, 02:48:14 pmIt took NZ ~30 years after metric introduction for our 'pound' of butter to change from 454g to 500g.....and of course it was good reason to further lift pricing.

author: HighVoltage
author_rank: Super Contributor
timestamp: December 29, 2017, 07:52:21 pm
content: Quote from: IanB on December 29, 2017, 07:17:54 pmNo.Fractions are not used in Europe like in the USA.It seems normal for people from the US, to use fractions everywhere and that is also why most Americans are used to calculating fractions in their head. Germans / Europeans are used to the decimal point.Even more weird at first sight in the USA:Buy a two by four and expect it to be 2 x 4 inches.Well, a "2x4" piece of wood really is only 1.5 x 3.5 inches.Go figure.And that in 2017!

author: glarsson
author_rank: Frequent Contributor
timestamp: December 29, 2017, 08:51:06 pm
content: Quote from: IanB on December 29, 2017, 07:17:54 pmIf I ask for 3/10th of a kilo they will just look funny at me. No problems asking for "3 hekto" or "300 gram".

author: coppice
author_rank: Super Contributor
timestamp: December 29, 2017, 09:08:49 pm
content: Quote from: IanB on December 29, 2017, 07:17:54 pmIn the UK people will ask for 1/2 a kilo of cheese or 1/4 of a kilo of cheese at the deli counter. I don't think many people ask for other fractions.

author: matseng
author_rank: Frequent Contributor
timestamp: December 29, 2017, 09:27:15 pm
content: Quote from: coppice on December 29, 2017, 09:08:49 pmIn the UK people will ask for 1/2 a kilo of cheese or 1/4 of a kilo of cheese at the deli counter. I don't think many people ask for other fractions.When during the years I lived in Kuala Lumpur I could never get my Chinese butcher or his assistants to understand how much a "half kilo" of ham or sausages was. But if I asked for 500 grams (or any other weight in grams) it was not a problem...

author: boffin
author_rank: Unknown
timestamp: December 29, 2017, 09:30:17 pm
content: Quote from: blueskull on December 29, 2017, 07:59:36 pmLocal Home Depot here in Canada sells plywood 4ft x 8ft x 19mm

author: coppice
author_rank: Super Contributor
timestamp: December 29, 2017, 09:33:31 pm
content: Quote from: boffin on December 29, 2017, 09:30:17 pmCar tyres all over the world have sizes like 17 inches by 175 mm.

author: IanB
author_rank: Super Contributor
timestamp: December 29, 2017, 09:35:01 pm
content: Quote from: coppice on December 29, 2017, 09:08:49 pmWhen I want to be wicked I ask for 337 g of cheese and then I ask them to add a bit/remove a bit until the scale says exactly 0.337 kg

author: boffin
author_rank: Unknown
timestamp: December 29, 2017, 09:38:20 pm
content: Quote from: Jr460 on December 29, 2017, 12:17:38 amIIRC in VMS MicroFortnights are approximated to seconds -- it's in there deep somewhere in the manuals, but then hey, I can barely remember the 12 parameters to SYS$QIOW(), I could be wrong.

author: mc172
author_rank: Frequent Contributor
timestamp: December 29, 2017, 10:58:17 pm
content: Quote from: coppice on December 29, 2017, 09:08:49 pmEr, you sure about that? Most people I come across in life can't figure out what a quarter of one is in decimal, let alone figure out how much 0.25 is relative to one. Is 0.25 even less than one? It's just too confusing. Handily, cheese comes readily packaged in blocks whose masses are decided by supermarkets. The unit of measure is either ASDA or Waitrose. If you're hosting a really big dinner party with cheese and crackers to finish, you buy three ASDAs of cheese. If you live alone and just fancy some cheese and know you probably won't finish it all, you buy one Marks and Spencers of cheese.Much like car fuel tanks. They are not sized according to volume but are sized in GBP of fuel, where for most cars like, say a VW Golf, £20 is remarkably bang on half a tank regardless of fuel cost per litre. Strangely, £45 is a full tank.Anyway, you can still buy an 8oz steak from the meat counter at any supermarket and at any small, family-run butcher, since this seems for some bizarre reason to be the convention on every menu, everywhere. The person doing the weighing probably has a scale with a "g/oz" button. It's hardly a precise science, knowing where to cut a 20 kg lump of cow in order to end up with a slice weighing precisely 226.796 g anyway.I remember as a kid growing up in the 90s that we would ask the man that would dish out the sweets from the jars behind him for 100 g of mishaps (for example). Not ounces. I wasn't familiar with pounds and ounces until, well, I'm still not apart from when comparing some mass in ounces to uncooked steak.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 29, 2017, 11:13:34 pm
content: Surprised that no one has mentioned one of the oldest and weirdest units still used in much (maybe most) of the world - the barrel. Widely used in petroleum industry. Virtually unused anywhere else that I know of. Related to other old standards of measurement found mostly in ditties and songs today. Bushels and pecks.For all you metric proponents, splain to me how so many of you measure torque in kg-m, or gm-cm. It throws the whole benefit of metric units out the window. Should be Newton-meters or dyne-cm and then all of the dimensional analysis and unit consistency works.

author: mc172
author_rank: Frequent Contributor
timestamp: December 29, 2017, 11:18:22 pm
content: We do measure torque in N-m and not kg-m (or derivations thereof, like kg-cm).Some olde-worlde things I've come across are in kg-cm, for instance a fairly old but not olde torque gauge at work. It's just 9.81 per 10. Simple!

author: tautech
author_rank: Super Contributor
timestamp: December 29, 2017, 11:29:04 pm
content: Who here still uses grains (gr) or 1/10ths of grains. (1 gr = 1/7000th/lb)I do regularly, who can guess why ?

author: glarsson
author_rank: Frequent Contributor
timestamp: December 29, 2017, 11:35:56 pm
content: Quote from: CatalinaWOW on December 29, 2017, 11:13:34 pmWe use Nm.Never seen kg-m, nor gm-cm. By kg-m I assume you wanted to write kgf m, but we don't use that one any more.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 29, 2017, 11:38:00 pm
content: Quote from: tautech on December 29, 2017, 11:29:04 pmReload?

author: CNe7532294
author_rank: Regular Contributor
timestamp: December 29, 2017, 11:55:40 pm
content: Well this thread blew up in ways I didn't expect. I have to go back and read. This question has probably been answered in an indirect way but at the time I was about if something like the Giga- prefix wasn't available was it a standard in the scientific community to just mix prefixes that would make sense for that day and age ("kilomega-").Quote from: IanB on December 29, 2017, 07:17:54 pmWhat IanB said I have to agree with in some ways. In my own personal experience. Weight does not bother me. I'll know what you mean by 68kg or 150Lb. However alot of things were born of practicality.Here's an example I explained to a buddy of mine. Although I do have to mention that I was born into imperial vs metric.So say you were to say to me its 0 degrees C. To me thats nothing. I've been in a tank top with shorts for 5 minutes in that. But now tell me its 0 degrees F. Well in that situation I know I wouldn't last. Celsius was literally born from science since chemistry has concerned itself with the univeral solvent dihydrogen monoxide. Fahrenheit however had a different up bringing. It was born out of when saltwater freezes. It was used more especially for travel which back in the day was only by ship. It was practical to know when sea water would freeze and avoid getting stuck in ice or slammed by an iceburg. To this day I believe F is still practical over C since your body has solutes with the water that mostly makes up you. The opposite can be said but I think its more psychological/being born in one unit of measurement. If you were to tell me its 40 degrees C. I'd say that was nothing. If you were to tell me if it was 104 degrees F I would say THATS  HOT! However an interesting thing occurs with me in the lab. Again due to practicality. If you were to warn me that this object is 2000 degrees F I wouldn't think thats too hot but if it was 2000 degrees C then I would think thats very hot. Either way I would take precautions but the point I'm making is the impact due to practice and psychology.I haven't even begun on foot and meters. With foot it makes sense in everyday use. For example I'm trying to guess how big a package I will receive will be. I have absolutely nothing available to me except the information and myself. So what do I use? A length of some body part of mine's. I don't know if the story of a king measuring his own foot is true but it is practical. Now they wouldn't have been concerned with receiving packages back in the day but distance was highly important. Especially on ground. If you happened to just measure 12 inches on your foot, saying the distance from town A to town B is a 10,000 feet would imply 5,000 steps. Unless you're something other than a biped. The meter however is different. In those times sailing became a huge priority over foot travel. Living in an age of expansion so to speak. They had to come up with a new unit since, unless you're divine, using a foot was impossible. Using the stars and mainly the earth itself the meter was born.Anyways I hope this explains a bit as to "the why". I do not know how accurate all of this is so feel free to correct me.Now for other units and conversions try going into a pharmacy. You'll have fun with "drams", "gtt", "grains", "minims", and of course household measures like teaspoon and tablespoon. Loads of fun to be had there. EDIT: I forgot to mention CC aka cubic centimeter and tablet as well.

author: IanB
author_rank: Super Contributor
timestamp: December 29, 2017, 11:59:51 pm
content: Quote from: CatalinaWOW on December 29, 2017, 11:13:34 pmGotta be precise, though. The oil barrel is different from the wine barrel, or the grain barrel. It's the oil barrel that remains in common use.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 30, 2017, 12:04:07 am
content: Quote from: CNe7532294 on December 28, 2017, 10:25:00 amSome of my old military attenuators were calibrated into the early 80s. Some were on a 27 day calibration cycle.

author: CNe7532294
author_rank: Regular Contributor
timestamp: December 30, 2017, 12:15:08 am
content: Quote from: joeqsmith on December 30, 2017, 12:04:07 amThis is why I brought this thread up in the first place. I managed to obtain some old stuff. Along with that I've been viewing jeff quitney's youtube videos. The old military training videos are very helpful in explanations but sometimes use very old terms that didn't make sense to someone much younger. Also its interesting to go back into what mindset they had back in the day and see how it evolved.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 30, 2017, 02:55:06 am
content: Quote from: glarsson on December 29, 2017, 11:35:56 pmI can't speak to current usage, but in the period from 1985 to 2005 I was working with Europeans from several countries regularly and ran across these "mixed" units often. Apparently even those brought up in the metric system develop some confusion over the difference between force and mass since the universal experience of mass is the force in a 1g field. I have continued to encounter it in web sites and product catalogs to this day. I suspect the usage is more prevalent in the "trades" such as auto mechanics, fabricators and the like, and less prevalent in university researchers. The ones I was working with were in between - engineers. I never encountered the notation kgf though that would at least be technically correct. I have seen gm-cm in writing, and recall a kg-X but substitued kg-m since I don't remember the length unit.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 30, 2017, 02:58:57 am
content: Quote from: IanB on December 29, 2017, 11:59:51 pmIt is strange that any kind of barrel is standardized since the old wooden barrels came in so many sizes. For a couple of hundred years they filled the same role that amphora filled in classical times - the universal packaging method. But it is kind of like saying the standard "cardboard box".

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 30, 2017, 03:14:54 am
content: Quote from: CNe7532294 on December 29, 2017, 11:55:40 pmI can't speak for the whole scientific community, or how it developed, but when I first started paying attention to this stuff in the 1960s tutored by those in the amateur radio community capacitances were done in mmf and mf, or mmF and mF. Some people were using the pF, but nF were unheard of. Similarly cps was the standard for frequency. kcps and Mcps were common usages. No one I had contact with used frequencies high enough to go beyond these.In school exposure to the whole range of prefixes was treated as something new (Initial version of SI was published in 1960) and there was much dithering between those who preferred cgs over the SI (not to mention the traditional unit holdouts). So from this I would infer that before roughly 1960 people did what felt right in their own field of endeavor. Hence units like the Angstrom and electron volt. During the 1960s the gradual adoption of these terms began, and roughly three decades later as the careers of those who learned before this transition ended the transformation was complete.

author: coppice
author_rank: Super Contributor
timestamp: December 30, 2017, 03:19:33 am
content: Quote from: CatalinaWOW on December 30, 2017, 03:14:54 amThe SI units we know today didn't all appear in one go in 1960. They gradually dribbled out over a number of years.

author: AndyC_772
author_rank: Super Contributor
timestamp: December 30, 2017, 08:52:47 am
content: Quote from: tautech on December 29, 2017, 11:29:04 pmI use grains. It's the standard unit for measuring the weight of an arrow.

author: tautech
author_rank: Super Contributor
timestamp: December 30, 2017, 09:08:24 am
content: Quote from: AndyC_772 on December 30, 2017, 08:52:47 amI have great fun in teasing bow hunters.......where do you find 'bows' to hunt ?But seriously now, what game to you hunt Andy ?

author: AndyC_772
author_rank: Super Contributor
timestamp: December 30, 2017, 09:37:31 am
content: Paper targets

author: tautech
author_rank: Super Contributor
timestamp: December 30, 2017, 09:50:16 am
content: Quote from: AndyC_772 on December 30, 2017, 09:37:31 amShite Andy, you can't eat them.

author: Tepe
author_rank: Frequent Contributor
timestamp: December 30, 2017, 10:12:11 am
content: Quote from: mc172 on December 29, 2017, 10:58:17 pmWorks fine with fractions in Denmark:

author: AndyC_772
author_rank: Super Contributor
timestamp: December 30, 2017, 10:21:40 am
content: Quote from: tautech on December 30, 2017, 09:50:16 amIf it were a choice between that or the foam boss it's pinned to, I suspect the target itself would be preferable.Bow hunting is illegal here, though there are some rabbits living on our outdoor range just beyond the 100 yard line. I'm sure if a random gust of wind carried an arrow a little further than usual, someone would be able to make a nice stew in the clubhouse.

author: tautech
author_rank: Super Contributor
timestamp: December 30, 2017, 10:54:45 am
content: Quote from: AndyC_772 on December 30, 2017, 10:21:40 amReally ?I was aware a few years back firearm rules were toughened up for you guys but no hunting with arrows ?Where's their sense of adventure ?Crossbow better for the long range rabbit ?

author: glarsson
author_rank: Frequent Contributor
timestamp: December 30, 2017, 10:55:16 am
content: Quote from: CNe7532294 on December 29, 2017, 11:55:40 pmPure fantasy.Sea water freezes at 28 degrees F, -2 degrees C.Fresh water freezes at 32 degrees F, 0 degrees C.Water that is a saturated salt solution, which has as much salt as the water can hold, freezes at -6 degrees F, -21 degrees C. Ships never experience this.In what way is F better for someone traveling by ship?

author: Vtile
author_rank: Super Contributor
timestamp: December 30, 2017, 10:58:20 am
content: A few usefull search words are Giorgi system and mksa system. Until about 1950 there were no electromagnetism in metric system. Italian physicist Giorgi proposed iirc ampere as new unit for metric system and this not yet standardised system were known giorgi system and (iirc) mksa when it were later standardised. From memory.Some pre-SI units are really nice.. Like the kg/cm and kg/cm^2 (or meters of H2O in heating system pressure gauge) .. Nice realworld engineering units. Much more expressive than Pascal or Newtonmeters. Shame kind of.To above tempetature discussion. There is also Raumore unit. Which I really know anything about.

author: HighVoltage
author_rank: Super Contributor
timestamp: December 30, 2017, 11:30:01 am
content: Quote from: glarsson on December 30, 2017, 10:55:16 amA few years back I read an Englisch book on Newton and Alchemy and in this book, they had a very different, far fetched explanation of the relationship between Celsius and Fahrenheit.I am not sure, if I remember it all, but it was something like this:1. The two scales meet at -40°C (Pair) because the number 40 always shows up as a pair in history2. Freshwater freezes at 32 °F, because Fahrenheit was 32 degree mason3. Water boils at 212°F because 212 * Pi = 6664. The normal human body temperature is 98.6°F because 98.6 -32 = 66.6Probably a few more ...In science the benefit of the Fahrenheit scale is simply the higher resolution.I think this is the reason why airplanes use Fahrenheit instead of Celsius.

author: NottheDan
author_rank: Frequent Contributor
timestamp: December 30, 2017, 01:02:13 pm
content: Quote from: IanB on December 29, 2017, 07:17:54 pmExcept, that is complete and utter bullshit.Customers in Europe quite happily buy 100g or 150g or 200g of ham. Or even 7 slices. They have no innate need to ask for 1/8 kg or some such.And you know what? This is easy!

author: Tepe
author_rank: Frequent Contributor
timestamp: December 30, 2017, 02:21:51 pm
content: Quote from: HighVoltage on December 30, 2017, 11:30:01 amWe have decimals for that.Quote from: HighVoltage on December 30, 2017, 11:30:01 amI think it has a lot more to do with the US winning WW2.

author: ciccio
author_rank: Frequent Contributor
timestamp: December 30, 2017, 05:07:56 pm
content: Quote from: NottheDan on December 30, 2017, 01:02:13 pmI usually ask for one and halfhectogramsof ham, and even if the hectogram (100 grams, or 1/10 of a kilogram) is not included in the SI system (and in theory not allowed by Italian or EU laws) everybody understands.. The same for a "quintale" (100 Kg).Other older metric units, such as the Dam (decameter = 10 meters) or the Hectometer (100 m) have disappeared from normal use. A square Hectometr is an Hectar (10000 square meter) that is still thestandardunit for ground surface areas, for measuring wineyard or fields.

author: Tepe
author_rank: Frequent Contributor
timestamp: December 30, 2017, 05:18:30 pm
content: Quote from: ciccio on December 30, 2017, 05:07:56 pmThe hectogram (hg) is indeed valid. All the prefixes can be used with any of the units in SI. Meteorologists seem to be quite fond of hPa.

author: timb
author_rank: Super Contributor
timestamp: December 30, 2017, 05:30:15 pm
content: Quote from: Tepe on December 30, 2017, 02:21:51 pmI think he meant that Fahrenheit provides better resolution, in everyday use, for the various climates that humans live in.0f = Cold as Eskimo Shit60f = A Lovely Day100f = I’m Sweating in Places I Didn’t Know I HadThat’s a nice, 0-100 linear scale of temperature for most of the places people live at. It’s a more useful scale in that regard than one based on the freezing point of some arbitrary liquid.

author: helius
author_rank: Super Contributor
timestamp: December 30, 2017, 05:35:39 pm
content: Quote from: timb on December 30, 2017, 05:30:15 pmLikewise, the well-establishedFurlongs per fortnight systemis a more useful scale than one based on the length of an arbitrary meridian that most people will never travel.

author: timb
author_rank: Super Contributor
timestamp: December 30, 2017, 05:40:18 pm
content: Quote from: helius on December 30, 2017, 05:35:39 pmNotice I qualified that by saying it was practical as a unit in casual, everyday use. For precision or scientific uses, Celsius is great.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 30, 2017, 05:44:02 pm
content: Quote from: timb on December 30, 2017, 05:30:15 pmYou mean the liquid we all know intimately, have vast empirical experience with and upon which our lives depend in the most profound sense possible? The liquid which is by far the most abundant on the surface of Earth, and which commonly shows itself naturally in all three states, providing a very natural defined and limited scale with extremes which most of us encounter on a very regular basis?I guess instead a scale between the temperature of brine and our body temperature, which isn't quite as fixed as you would think makes a lot more sense.

author: timb
author_rank: Super Contributor
timestamp: December 30, 2017, 05:49:19 pm
content: Quote from: Mr. Scram on December 30, 2017, 05:44:02 pmPersonally, I use my own unit for everyday temperature measurement, and it’s based on Si standards! You don’t even need any sophisticated measuring devices: Just a cm ruler and a pair of balls. Each drop of 1cm is equivalent to rise in temperature of 5c. I call the unit Tempicles. It’s a portmanteau, you see.

author: Tepe
author_rank: Frequent Contributor
timestamp: December 30, 2017, 05:53:10 pm
content: Quote from: timb on December 30, 2017, 05:30:15 pmThe 0 on the water based scale marks a state change of water that has implications in traffic, both on foot and when moving on rubber wheels.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 30, 2017, 05:59:20 pm
content: Both Fahrenheit and Celsius are arbitrary, and don't have any real physical basis. Even given that water is common and important, why not 200 divisions between freezing and boiling? The best unit is clearly the one you grew up with. Celsius is the clear winner now since most of the world uses it, but a better science unit would be Kelvins. Which is another arbitrary scale, but at least has the virtue of working well in formulas like Wein's displacement law since it is always positive. Just like the thermal energy in anything.

author: glarsson
author_rank: Frequent Contributor
timestamp: December 30, 2017, 06:03:41 pm
content: Quote from: timb on December 30, 2017, 05:30:15 pmWater is not some arbitrary liquid. Our world changes dramatically when the temperature falls below 0 degrees C.Mr F defined his scale based on a salt and ice mix for 0 and the armpit of his wife for 96. Not something most people are interested in.

author: Tepe
author_rank: Frequent Contributor
timestamp: December 30, 2017, 06:07:06 pm
content: Quote from: CatalinaWOW on December 30, 2017, 05:59:20 pmWhich is of course also why it is used in science. Celsius remains more practical than Kelvin in everyday life. Luckily conversion between them only requires the ability to add and subtract.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: December 30, 2017, 06:22:02 pm
content: Kelvins would be perfectly practical in everyday life if you grew up with them. Just as both Fahrenheit and Celsius are practical. Those in the Fahrenheit world have absolutely no difficulty in realizing that things get slippery at 32 degrees. Just as those who live in the Celsius world have no difficulty realizing that body heat rejection gets seriously more difficult when temperature gets above 37 degrees. Zero is a little easier on the cold end for the Celsius guys, and 100 is a little easier for the Fahrenheit guys, but most humans can remember one number pretty easily. I suspect that the need to remember two numbers wouldn't be too much of a challenge for most of the world. Slippery at 273 and hot at 310. Fahrenheit guys might complain about the poor resolution, but the Celsius guys should do just fine. Even the number of digits in the display isn't an issue since all three systems need 3. A sign and two digits on the cold end for the F and C systems, and three digits on the hot end for F and C. Three digits on both ends for K.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 30, 2017, 06:38:39 pm
content: Quote from: CatalinaWOW on December 30, 2017, 06:22:02 pmKelvin is obviously less convenient in every day life, simply due to 15 degrees being more concise than 288. Every day life has a way of striving for concise ways of expressing itself, rather than fully accurate or well defined ways.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 30, 2017, 08:10:17 pm
content: Quote from: glarsson on December 30, 2017, 06:03:41 pmIf it weren't arbitrary, the triple point of water wouldn't be 0.01C. Close, sure, but just as much an arbitrary, historical accident as F, or any other unit.Except Planck units, but they are noticeably inconvenient for anything human sized.Indeed, the arbitrariness is that some arbitrary self-declared life form (humans) is using those units. I don't get how that counts as reason to denigrate one arbitrary system over another.One might save their accusations of arbitrariness for a domain which is much more critical of irrational decisions, like mathematics, or computer science; but even in the latter, instruction sets know no bounds on complexity and lack of orthogonality. Indeed it would seem the only universal truth is that nature abhors an orderly system; very few if any complex systems we have studied show any kind of meaningful order in their design, from biological cells to computer operating systems to international economic systems of trade.Tim

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 30, 2017, 08:36:44 pm
content: Quote from: T3sl4co1l on December 30, 2017, 08:10:17 pmIn the end everything is arbitrary as you have to just pick some point of reference, but we both know that's not the point people are making. It's about a system that's consistent with itself, and if possible convenient. In the case of Celcius, it's picking something that's both common and familiar to people.That being said, I have no interest in having another imperial versus metric discussion.

author: rollatorwieltje
author_rank: Unknown
timestamp: December 30, 2017, 08:46:27 pm
content: Quote from: German_EE on December 28, 2017, 07:12:20 pmFathom is still regularly used in the maritime world to measure depth. Speed in knots was also based on Fathoms, they used to drag a rope behind the ship with a knot every 8 fathoms. 1 kt = 8 fathom in 30 seconds. The "modern" definition has changed a bit though.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 30, 2017, 11:09:31 pm
content: Quote from: Mr. Scram on December 30, 2017, 08:36:44 pmHm, what's inconsistent about any of the units being discussed? Multipliers I suppose, not that anything's keeping you from writing "kiloyards per hour".If anything, C and F are the least consistent of all units, having a zero offset(!). The argument should then be Rankine vs. Kelvin. I can't think of any other units in existence which require any kind of correction beyond a scale multiplier (possible exception for dB and other logarithmic units, but they're measuring ratios, so, that's arguable).Tim

author: IanB
author_rank: Super Contributor
timestamp: December 30, 2017, 11:13:58 pm
content: Quote from: T3sl4co1l on December 30, 2017, 11:09:31 pmGauge pressure might be one, but that is particularly troublesome since the offset may depend on local atmospheric pressure and need not be a constant.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 30, 2017, 11:32:47 pm
content: Quote from: T3sl4co1l on December 30, 2017, 11:09:31 pmAn example I've seen elsewhere is probably a good illustration. Try to do it without using a calculator or doing calculations on paper. A swimming pool is 165 inches wide, 25,5 feet long and 0,0015 mile deep. How many gallons go into the swimming pool and how much stone does this water weigh?Now do the same with a pool 415 cm wide, 7,65 m long and 0.0025 km deep and tell me how many litres are in it, and how much kilogram the water is.Need a hint? Thou, inch, foot, yard, chain, furlong, mile and league respectively relate to each other 1 to 1000, 12, 3, 22, 10, 8 and 3. Millimeter, centimeter, meter, decimeter, hectometer and kilometer relate to each other 1 to 10, 10, 10, 10 and 10.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 30, 2017, 11:50:03 pm
content: Quote from: IanB on December 30, 2017, 11:13:58 pmAh, good one!Tim

author: IanB
author_rank: Super Contributor
timestamp: December 31, 2017, 12:17:07 am
content: Quote from: Mr. Scram on December 30, 2017, 11:32:47 pmBut that is a daft question, and one that would never exist except if someone were deliberately being silly.The realistic question would have a pool 75 ft long, 30 ft wide and 6 ft deep, and the question would be how many cubic feet of water does the pool contain? The weight of the water would readily be found knowing that the density of water is 62.4 lb/cu.ft.The question is of just the same nature as the pool being 25 m long, 10 m wide and 2 m deep.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 31, 2017, 12:41:01 am
content: Quote from: IanB on December 31, 2017, 12:17:07 amHow much stone is that water when it has a density of 62.4 pounds/cubic feet?I assume you understand that the example is not about this literal question, but that it's a simplification of the much more complex calculations you see in real life that mix and matches all sorts of units. In real life, you don't always get your units conveniently in the same format, as they can come from a variety of sources. Even just comparing two datasheets can yield the same data in quite different formatting. The imperial system can be rather cumbersome in such a case, while the point of the metric system is to do away with conversions as much as possible and to have related units conveniently coincide. That's how it's more consistent, in no small part because it was specifically designed to be so. It is quite literally the reason it was invented.And sure, I'll admit that kilometers and centimeters aren't commonly used alongside each other, but millimeters, centimeters and meters certainly are.Bonus fact: the computers that landed on the moon actually calculated things in metric units. Because they didn't want to increase the cognitive load of the pilots even further, they made sure displaying and entering units was done in the imperial units the pilots were used to, but that was basically just a convenient GUI.

author: tooki
author_rank: Super Contributor
timestamp: December 31, 2017, 03:18:50 am
content: Quote from: Mr. Scram on December 30, 2017, 11:32:47 pmAnd that non-powers-of-10 relationship isn’t necessarily a bad thing. You have to do careful math, and it’s obvious that an operation has been done at a given step. With metric, where it’s just 10, 10, 10, it’sextremelyeasy to lose track of the decimal and be off by an order of magnitude or two.

author: helius
author_rank: Super Contributor
timestamp: December 31, 2017, 03:33:26 am
content: Quote from: tooki on December 31, 2017, 03:18:50 amDecimal arithmetic is currently the most widespread, so this is a problem that everybody deals with anyway.It used to be different: base-60 arithmetic was used all over the world starting in ancient Babylonia. That's why there are 360 degrees in a circle (along with 60 minutes in a degree [or hour] and 60 seconds in a minute): a confoundingly irregular number that isn't, on the face of it, any less so than 12 inches to a foot. I'm in favor of metrification if and only if we also abandon degrees and hours.However, it would be much cleaner from a mathematical perspective if we could agree to use units with a natural base instead of the malignantly arbitrary base 10.e(or Euler's other constant, gamma) would be ideal from the natural unit perspective. I confidently await the day that we discard all this historical baggage and adopt truly futuristic irrational units.

author: IanB
author_rank: Super Contributor
timestamp: December 31, 2017, 08:33:23 am
content: Quote from: Mr. Scram on December 31, 2017, 12:41:01 amI assume from your writing, e.g. "how much stone" and "pounds/cubic feet", that you are not a native English speaker, and that you therefore have not used or worked with traditional units. One should be careful criticizing what one does not understand.QuoteYes, in engineering it is a mess, for example having Btu/h for thermal power and hp for mechanical power, or using lbmfor mass and lbffor force in the same calculation. But this is nothing to do with powers of ten and everything to do with physical consistency. That is the real advantage of the SI system

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: December 31, 2017, 08:46:43 am
content: The obvious problem with Fahrenheit in the lab is that it does not directly relate to absolute temperature.Kelvin and Celsius have the same unit size, so only an offset need be applied.

author: richard.cs
author_rank: Super Contributor
timestamp: December 31, 2017, 10:49:34 am
content: Quote from: IanB on December 31, 2017, 08:33:23 amIt's this kind of thing that I find gets people lost and leads to mistakes, particularly that a lot of people interchange lbmand lbfwithout realising the implications, and end up with something that is bollocks dimensionally and/or off by g.In comparison the thermal units are just an annoyance (though remember to include ton as a unit of refrigeration, and account for the fact that electricity is measured in W). Don't get me started on circular mils though.

author: Circlotron
author_rank: Super Contributor
timestamp: December 31, 2017, 11:12:48 am
content: Quote from: CNe7532294 on December 29, 2017, 11:55:40 pmThe king's foot is 1 foot long.That's also probably why we have a 1 foot ..... ruler.

author: Circlotron
author_rank: Super Contributor
timestamp: December 31, 2017, 11:19:11 am
content: Quote from: glarsson on December 30, 2017, 10:55:16 am32 deg to 212 deg is a span of 180 deg.You could use a protractor scale with the pointer ranging from 9 o'clock to 3 o'clock.

author: Circlotron
author_rank: Super Contributor
timestamp: December 31, 2017, 11:24:47 am
content: Quote from: T3sl4co1l on December 30, 2017, 11:50:03 pmHumidity, so the need to to express it as relative humidity?

author: tooki
author_rank: Super Contributor
timestamp: December 31, 2017, 01:00:03 pm
content: Quote from: IanMacdonald on December 31, 2017, 08:46:43 amWell that’s not true — it does relate directly to something. It’s a span of 180 degrees between the boiling point of water and the freezing point of saline. (Why he didn’t use the freezing point of plain water, I don’t know...)FYI, there is Fahrenheit equivalent to Kelvin (that is, the same unit size, but based on absolute zero instead): the Rankine scale.

author: Vtile
author_rank: Super Contributor
timestamp: December 31, 2017, 01:05:06 pm
content: The pro imperial units do forget to mention at which kings feet they are using as reference. As before the current imperial units were referenced to metric system (and US & UK systems were equalized) every damn corner of the non-metric world had their own "imperial units" without direct equility. Preussian, Swedish, English, Russian etc. inch...

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 31, 2017, 04:59:07 pm
content: Quote from: IanB on December 31, 2017, 08:33:23 amDon't assume I don't understand because I used units that don't suit your story. The point being made is that SI units are easily translated into each other and you don't get yourself stuck in the units you're used to. Your remark confirms the pointEasily moving from one unit to the next is a huge boon.It does have to do with power of ten, as many units aren't just related to each other within themselves and easily converted, but also to each other in a way that makes sense to humans. A cube of water 10 by 10 by 10 cm is 1 liter, and weights about 1 kilo. That's no coincidence. Added to that is the physical consistency you speak of and the ever refining of standards so they are universally true, rather than based on people's feet. As soon as the kilogram gets redefined, all the units are based on constants rather than objects and you could even transmit the definition across the galaxy and they'd still hold true. Done are the days of pointing to a specific object and going "about ye long".

author: helius
author_rank: Super Contributor
timestamp: December 31, 2017, 07:12:30 pm
content: Quote from: Mr. Scram on December 31, 2017, 04:59:07 pmWell from just that example you can tell that consistency and practicality are conflicting goals and some level of compromise is required. I had to memorize that the litre was (1 dm)^3 and not (1 m)^3, which would have been more consistent, but less practical for measuring the volume of products in the store.Then you have hectares (1 hm)^2, why isn't it the same prefix as the cube? There are little irregularities everywhere because people don'twantsomething fully consistent since the world we live in isn't.The definition of the gallon, 128 fl.oz., is a nice power of 2 and very nice and easy to remember. It is defined as exactly 231 in^3, which is not that easy to remember. Unit conversions are easily handled with advanced calculators, so part of me wonders if the whole issue isn't obsolete.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 31, 2017, 07:21:17 pm
content: Quote from: helius on December 31, 2017, 07:12:30 pmI'll be the first to admit that the metric system isn't entirely consistent. That irks me more than it probably should. Most of it has to do with legacy issues or convenience, your litre example being the latter. Something like having the kilogram as a base unit is also slightly annoying. Some other units seem inconveniently large or small too, at least for some common uses. This is evidenced by us dealing with picofarads and microhenries all the time. Ohms seem to be reasonably well chosen, though.I don't think people want irregularities in this case. It's surprisingly similar to software development, where choices of the past come back to bite you. I've though about this before, and whether it would be better to start over with SI 2.0 or that it's better to adjust what we already have. We have redefined certain things in significant ways in the past, like ohms, so it doesn't seem impossible.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 31, 2017, 09:23:18 pm
content: Quote from: Mr. Scram on December 31, 2017, 07:21:17 pmTechnically it should be milli-kilogram, not gram. I think the SI recognizes this and makes the exception to cross out the prefixes.Language ultimately is the most arbitrary imposition, in all technical domains. Even in math, we have a nightmare of notation and terms, some being reused for similar (and not very similar) things, others being invented that only made sense to the person who first published it! I would love to rename "real" and "imaginary" numbers, reverse numeral writing order, and a hundred other things I don't have on my mind at this time; but alas, we are stuck with things as they are.Tim

author: TimFox
author_rank: Super Contributor
timestamp: December 31, 2017, 09:42:09 pm
content: When I turned 32, many years ago, I started converting my age to degrees Celsius.Eight years later, I started converting to Réaumur.Finally, I started converting to radians.Very few people have heard of the temperature unit in the second sentence, but it was popular in the 19th century for popular, seafaring, and thermodynamic applications.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: December 31, 2017, 09:48:30 pm
content: https://en.wikipedia.org/wiki/Foot-lambert

author: glarsson
author_rank: Frequent Contributor
timestamp: December 31, 2017, 10:09:27 pm
content: Quote from: Mr. Scram on December 31, 2017, 07:21:17 pmCan't change this. We do not wan't extra constants everywhere LC and RC appear in formulas.

author: Vtile
author_rank: Super Contributor
timestamp: January 01, 2018, 12:41:50 am
content: Quote from: glarsson on December 31, 2017, 10:09:27 pmIIRC actually that were one of the driving reasons of the SI system. Atleast in the old 1950s electrophysics books which still refer to the Giorgi system outlines this that the all formulas are of new "type free" format.

author: bw2341
author_rank: Regular Contributor
timestamp: January 01, 2018, 06:42:37 am
content: Is this the thread where we gripe about units?It makes sense that cycles per second has been left in the past. Hertz is an easy single-syllable proper noun and has a short two letter abbreviation. Any form of "cycles per second" is clumsier to say and write. I guess "cps" was often shortened to "c" but that just makes it nonsense term. What does "cycles" mean by itself? And it still needs two syllables anyways.In a similar vein, BTU per hour (BTU/h) is often shortened to BTU alone in the marketing text for air conditioners. Does that mean that the AC unit is empty once you move that much heat?It'd be nice if the SI hadn't used the same letter M for milli (m) and mega (M). Also, the "µ" symbol is a pain for micro.My own weird personal complaint is that "kilometres" is pronounced ki-LOM-etres. It never made sense to me and I've always said KIL-o-metres since I was a kid. I know I'm alone on this. The standard pronunciation is inconsistent with all other usage. We don't say mil-LIM-etres or cen-TIM-etres. Or ki-LOG-rams and ki-LO-hertz.

author: helius
author_rank: Super Contributor
timestamp: January 01, 2018, 07:04:00 am
content: Quote from: bw2341 on January 01, 2018, 06:42:37 amBut we do say al-TI-meters, cy-CLO-meters, spee-DO-meters, seis-MO-meters, etc.There's even an instrument that is also a unit: the mic-RO-meter.

author: IanB
author_rank: Super Contributor
timestamp: January 01, 2018, 10:37:39 am
content: Quote from: bw2341 on January 01, 2018, 06:42:37 amOn the British side of the pond the standard pronunciation is KIL-o-metre. That's how I say it and how I hear it.There are two possible pronunciations for kilometre: one with the stress on the ki- and the other with the stress on the -lo-. The first is traditionally considered correct, with a stress pattern similar to other units of measurement such as centimetre. The second pronunciation, which originated in US English and is now also very common in British English, is still regarded as incorrect by some people, especially in British Englishhttps://en.oxforddictionaries.com/definition/kilometre

author: AndyC_772
author_rank: Super Contributor
timestamp: January 01, 2018, 11:25:18 am
content: Top tip: don't trust any source of information on the English language that refers to something called "British English".The clue is in the name. English is the language that comes from, and is spoken in, England. A qualifier is neither necessary nor correct.The correct pronounciation for units of distance in England is, of course, "miles"

author: richard.cs
author_rank: Super Contributor
timestamp: January 01, 2018, 02:15:02 pm
content: n inQuote from: helius on December 31, 2017, 07:12:30 pmOr 160 fl.oz. in much of the world.Gallons (either size), fluid ounces, and litres, are all an unnecessary complication. Once you have a unit of length defined, be it inches or metres, it makes more sense to use cubes of that for volumes (and squares for areas). Part of the point of SI is to remove the complexity associated with unrelated units. If you always measured length in inches, area in square inches and volume in cubic inches then converting to to acres or gallons is never required. You would then find cubic inches an inconvenient size for measuring oil tankers, so you'd end up adding prefixes.My point is that the main advantage of SI doesn't come from the choice of base units (metre, kilo, etc.), it comes from defining all the other units (area, volume, power, whatever) in terms of these base units. There's then never any conversion needed and formulas are neither full of magic numbers nor need an accompanying statement about what units it expects or outputs in. People who argue one or the other is better because they find the base unit more intuitive have missed this.

author: IanB
author_rank: Super Contributor
timestamp: January 01, 2018, 03:16:16 pm
content: Quote from: richard.cs on January 01, 2018, 02:15:02 pmThis is in fact what engineers have traditionally done with traditional units. For example, volumes in cubic feet have always been very standard (consider for example cfm, cubic feet per minute, a very common unit).In general, if you work in feet for length, then you work with feet and fractional feet. If you work in pounds for weight, you work in pounds and fractional pounds (or multiples).

author: bw2341
author_rank: Regular Contributor
timestamp: January 01, 2018, 04:43:06 pm
content: Quote from: helius on January 01, 2018, 07:04:00 amThat only reinforces my claim. The instrument names are always pronounced with stress on the second syllable. We always say mic-ROM-eter for the instrument. The unit is MIC-ro-metres. This leaves kilometre as the odd man out.

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 01, 2018, 05:31:52 pm
content: Quote from: HighVoltage on December 29, 2017, 01:50:51 amAnd let's not forget theCV: cheval-vapeur (French) or caballo de vapor (Spanish), which equals 1 CV~ 0,986 HP.

author: m98
author_rank: Frequent Contributor
timestamp: January 01, 2018, 07:04:46 pm
content: Quote from: T3sl4co1l on December 30, 2017, 08:10:17 pmHow does that mean that degrees Celsius are arbitrary? The melting and boiling point of water at standard atmospheric pressure is just about the only unit definition one can easily and very accurately replicate in any lab and at home.

author: IanB
author_rank: Super Contributor
timestamp: January 01, 2018, 07:17:18 pm
content: Quote from: m98 on January 01, 2018, 07:04:46 pmBut what is "standard atmospheric pressure" other than something arbitrary? There is absolutely no way I believe you can accurately achieve standard atmospheric pressure at home, even if you knew what pressure you wished to achieve and maintain.It is remarkably difficult to get water to boil at 100 degrees C at home, however hard you try, and I have tried quite a lot.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 01, 2018, 07:39:44 pm
content: Likewise the melting point is extremely sensitive to impurities and nucleation, and also slightly sensitive to pressure -- the triple point is ever so slightly off 0°C for the latter reason.The triple point -- assuming you have the materials to measure it adequately -- is characteristic of a substance, independent of lab conditions. In other words, one step less arbitrary. That the C scale is based on a different condition, is evidence of an arbitrary historical decision.Also, temperatures can be accurately measured to more than 3 decimal places, so it's not that I'm making a fuss about nothing -- that 0.01C error is negligible for every day use, sure, but strictly speaking, it is an arbitrary offset, it is statistically significant, and it is critical to the accurate calibration of a precision thermometer.That is, it's akin to noting a micrometer is off by several thousandths at full scale, or its scale is offset by as much (as the case may be). Such an error might be tolerable in many places, but strictly speaking, it is definitely out!Tim

author: Pack34
author_rank: Frequent Contributor
timestamp: January 01, 2018, 07:48:40 pm
content: I always rather enjoyed the bastardized metric-freedom hybrid units.When I did some work in Telecom the unit "kilo-feet" always made me chuckle.

author: m98
author_rank: Frequent Contributor
timestamp: January 01, 2018, 08:48:04 pm
content: Quote from: IanB on January 01, 2018, 07:17:18 pmSure it is a bit arbitrary, but since it roughly matches the average pressure at sea-level, nearly anyone not living in a mountain region is able to set up a barometer and wait till the day it reaches some value around 1013,25 hPa. Atmospheric pressure doesn't change quick enough to actually affect the measurement. Then with the right setup, you'll both get the accurate melting and boiling point.And since Fahrenheit is officially defined by the Celsius scale, why add an unnecessary lookup-table?I'd also state that while using the triple point as a reference might be a bit more elegant as a definition, try to determine and sustain the accurate triple point of water in your standard chem-lab.

author: IanB
author_rank: Super Contributor
timestamp: January 01, 2018, 11:00:47 pm
content: Quote from: m98 on January 01, 2018, 08:48:04 pmBut the water also needs to be very pure, with no dissolved solids or gases. And the conditions for the true boiling point are that the liquid and vapour need to be in equilibrium, which means that the water should not be boiling, since boiling is a rate process and as such implies a departure from equilibrium, and also that only water vapor should be in contact with the surface of the water (no air should be present). Both of these may seem overly fussy, but failure to account for such details may lead to an error in the measurement. It is truly quite difficult to get water boiling at 100 degrees.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: January 01, 2018, 11:34:23 pm
content: The same car in the US does more or less mpg than in the UK? And in Australia?

author: coppice
author_rank: Super Contributor
timestamp: January 02, 2018, 12:16:11 am
content: Quote from: GeorgeOfTheJungle on January 01, 2018, 11:34:23 pmA British gallon is significantly bigger, so of course a car does more miles per British gallon. The measures in British motoring are really silly, though. We buy fuel in litres, and burn it in miles per gallon. If your car's systems display the actual content of the fuel tank it will display this in litres, while the same computer shows your efficiency in miles per gallon.

author: tooki
author_rank: Super Contributor
timestamp: January 02, 2018, 02:35:39 am
content: Quote from: AndyC_772 on January 01, 2018, 11:25:18 amAs someone who has actually studied linguistics formally (and is the son of an English teacher), I respectfully declare that that’s nonsense, and respectfully ask that you leave your British arrogance at the door.“English” refers to all variants of English (as spoken by native speakers) as a whole. So we use that word for every aspect where all variants are the same (for example, the statement “The definite article in English is ‘the’.”) Anywhere where the variants differ, we specify. And the name ofyourvariant is “British English”. Your arrogance doesn’t change your wrongness on the issue. Full stop.

author: BrianHG
author_rank: Super Contributor
timestamp: January 02, 2018, 04:58:51 am
content: Quote from: IanB on January 01, 2018, 07:17:18 pmI was working on environmental thermometers 5 years ago. To test the waterproof sensors, I stuck them in a pot of boiling water on my stove. They all read around 99.2 deg C except 1 which read 98,8. Ok, there may be some error here, but unless you need lab grade dead on 100 deg C measurements you can get within 2 degrees of true 100 with relative ease.I wasn't able to test the freezing point as my patience would not allow such an endevour.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 02, 2018, 05:02:32 am
content: Quote from: tooki on January 02, 2018, 02:35:39 amWorse, it is "some people in England English"!People from London, Liverpool, Manchester, & other English cities all have difference pronunciations ( sometimes multiple ones in each city).This is before we add in Scotland, Northern Ireland & Wales!(all part of Britain).

author: Circlotron
author_rank: Super Contributor
timestamp: January 02, 2018, 08:40:01 am
content: Quote from: vk6zgo on January 02, 2018, 05:02:32 amWhy is it called the United Kingdom then?

author: tszaboo
author_rank: Super Contributor
timestamp: January 02, 2018, 11:14:14 am
content: Quote from: coppice on January 02, 2018, 12:16:11 amAnd the typical USA fuel octane rating is lower. Note they use a different scale. Here, 95 is the norm, there 87, which is 91 in the EU system.

author: IanB
author_rank: Super Contributor
timestamp: January 02, 2018, 11:30:36 am
content: Quote from: NANDBlog on January 02, 2018, 11:14:14 amInterestingly, the descriptions match between the UK and the USA (and possibly continental Europe as well), even though the octane ratings use a different numbering system.The USA has regular, mid-grade and premium fuel at most pumps, and most cars are designed to run on regular (low octane) fuel.The normal grade in the UK is equivalent to premium in the USA, and most cars are designed to run on premium fuel.The UK also has "Super" at some pumps which is for high performance cars. I have not seen super grade fuel in the USA.

author: HighVoltage
author_rank: Super Contributor
timestamp: January 02, 2018, 11:39:33 am
content: Quote from: NANDBlog on January 02, 2018, 11:14:14 amYes, not only a different scale, a completely different testing basis to obtain an Octane number.And a different energy density of the fuel between the US and EU.Therefor consumption numbers are really not directly comparable.

author: m98
author_rank: Frequent Contributor
timestamp: January 02, 2018, 07:26:39 pm
content: Quote from: IanB on January 01, 2018, 11:00:47 pmCheck this out:https://www.nist.gov/pml/mercury-thermometer-alternatives-verification-methods-alternative-thermometersIt's not like I've made that stuff up and have to try to justify something.

author: Mr. Scram
author_rank: Super Contributor
timestamp: January 02, 2018, 09:14:37 pm
content: Quote from: BrianHG on January 02, 2018, 04:58:51 amYes, it's quite nice that you can just have some melting ice and boiling water and being in the most unprofessional home setting more than close enough for most purposes.

author: boffin
author_rank: Unknown
timestamp: January 02, 2018, 10:48:59 pm
content: Quote from: coppice on January 02, 2018, 12:16:11 amIf you think that is silly, go flying here in CanadaAirplanes burn (US) Gal/Hr;which weigh 6lb/gal - you care about the weightBut you buy fuel in litresYou fly in hundreds of feetYou set your Altimeter in inches of HgDirection is in degrees magnetic for some things, degrees true for othersAs for weather reports (a Canadian and British example)METAR CYYJ 022200Z 29006KT 20SM FEW020 BKN170 OVC240 04/02 A3032 RMK SC1AC6CI2 SC TR SLP269=METAR EGLL 022220Z AUTO 21017G27KT 5000 -RA BKN009 BKN017 OVC026TCU 12/11 Q0990 TEMPO 3000 +RA BKN008CYYJ = ICAO code for Airport (which can be very different than the 3 letter IATA code)022200Z = date/time in UTC29006KT= wind speed /direction (06 Kts @ 290 degrees true)20SM = visability 20 statute milesFEW020 = few clouds (1/10) at 2000ftBKN170 = broken clouds (6/10th) at 17000ftOVC240 = overcast at 24000ft04/02 = temp 04, dewpoint 02 (deg C)A3032 = Altimeter 30.32" HgOf course note the differences in different countries, At Heathrow (EGLL / LHR) with altimeter 990 hPa (Q0990) instead of "Hg, and visibility in metres (9999) not Statue Miles.For added fun and excitement, when you call the airport for a wind check, you get the results in degrees magnetic (which is also how runways are numbered - divide bearing by 10)It's amazing that incidents like ACA143 don't happen more often (fuel loaded in lbs, entered into computer as Kg, ran out halfway there)

author: Tedro
author_rank: Unknown
timestamp: January 03, 2018, 12:17:18 am
content: Don't those Canuckistan's in the big Maple Leaf 8bit land still use the word "Colour" for the way that an object reflects or emits light?

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 03, 2018, 01:00:45 am
content: Quote from: Mr. Scram on January 02, 2018, 09:14:37 pmAnd absolutely none of this has any bearing on the relative merits of two temperature scales. Ice water and boiling water can be used to calibrate any temperature scale that has a reasonable number of measurement ticks between the two points. We could propose the EEBLOG scale which reads 0.00 at the freezing point and 1.00 at the boiling point. 0.23 degrees would be comfortable for most folks. Or the super human friendly scale which reads 0 at the freezing point and 100 at body temperature, and would read 270 at the boiling point.There is no denying the superiority of the metric system of units. But the temperature scale included has little if any advantage over any other unit of temperature. If water were to dominate the choice of units you might well choose to divide the degree C by 4.18 so that one Joule would heat one gram of water one degree. Very convenient if that class of calculations dominates your work. But just another arbitrary scale.

author: Mr. Scram
author_rank: Super Contributor
timestamp: January 03, 2018, 01:07:21 am
content: Quote from: CatalinaWOW on January 03, 2018, 01:00:45 amI won't claim it's the biggest advantage by a long shot, but it helps that people have a lot of experience with both ends of what was determined to define the scale. I think I mentioned this before.Quote from: Mr. Scram on December 30, 2017, 05:44:02 pm

author: boffin
author_rank: Unknown
timestamp: January 03, 2018, 04:12:48 am
content: Quote from: Tedro on January 03, 2018, 12:17:18 amYes, Canada has chosen to follow the UK, Ireland, Australia, New Zealand, India to name just a few, that use "Colour"

author: Circlotron
author_rank: Super Contributor
timestamp: January 03, 2018, 12:02:10 pm
content: Quote from: boffin on January 03, 2018, 04:12:48 am

author: HighVoltage
author_rank: Super Contributor
timestamp: January 03, 2018, 01:34:49 pm
content: The UK agreed to spell the airplane CONCORDEthe french way with an "e" at the end and convinced the public that the "e" stood forEngland.Everyone was happy.Little games are always palyed.May be one day we will have a worldwide English dictionary that everyone would agree on to use.

author: IanB
author_rank: Super Contributor
timestamp: January 03, 2018, 03:43:39 pm
content: Quote from: HighVoltage on January 03, 2018, 01:34:49 pmLOLIt doesn't quite work that way. We stole the word and assimilated into the English language, so now Concorde is a national symbol of Britain. We do hear the French may have had some Concordes as well, but we don't really care about that.

author: bw2341
author_rank: Regular Contributor
timestamp: January 03, 2018, 03:51:19 pm
content: A few years back when fuel prices were high and people worried about fuel economy, car ads promoted the MPG ratings in big text. The numbers looked really good because they were using Canadian gallons instead of USA gallons. An unexceptional car at 30 US MPG suddenly had 36 Canadian MPG. Since we're exposed to a lot of spillover media from the USA, the general public might have a better knowledge of typical US MPG values. Only enthusiasts knew the official L/100km ratings.Canadians have to deal with US customary units since we have a combined market with the USA for a lot of products. For example, all building materials are in feet and inches. In the grocery, packages are in a strange number of grams or millilitres because they correspond to US package sizes.A unit problem that's a bit more insidious is that blood sugar level is measured in mmol/L in Canada and mg/dL in the USA. While the values don't overlap in this case, I hope doctors don't have to deal with unit problems with closer ranges.

author: glarsson
author_rank: Frequent Contributor
timestamp: January 03, 2018, 04:37:11 pm
content: Quote from: HighVoltage on January 03, 2018, 01:34:49 pmSamuel Langhorne Clemens already had a plan for that.For example, in Year 1 that useless letter "c" would be dropped to be replased either by "k" or "s", and likewise "x" would no longer be part of the alphabet. The only kase in which "c" would be retained would be the "ch" formation, which will be dealt with later. Year 2 might reform "w" spelling, so that "which" and "one" would take the same konsonant, wile Year 3 might well abolish "y" replasing it with "i" and Iear 4 might fiks the "g/j" anomali wonse and for all.Jenerally, then, the improvement would kontinue iear bai iear with Iear 5 doing awai with useless double konsonants, and Iears 6-12 or so modifaiing vowlz and the rimeining voist and unvoist konsonants. Bai Iear 15 or sou, it wud fainali bi posibl tu meik ius ov thi ridandant letez "c", "y" and "x" -- bai now jast a memori in the maindz ov ould doderez -- tu riplais "ch", "sh", and "th" rispektivli.Fainali, xen, aafte sam 20 iers ov orxogrefkl riform, wi wud hev a lojikl, kohirnt speling in ius xrewawt xe Ingliy-spiking werld.

author: Vtile
author_rank: Super Contributor
timestamp: January 03, 2018, 05:53:14 pm
content: Quote from: glarsson on January 03, 2018, 04:37:11 pmSounds kuud.

author: boffin
author_rank: Unknown
timestamp: January 03, 2018, 07:03:56 pm
content: Quote from: HighVoltage on January 03, 2018, 01:34:49 pmen: coordiated universal timefr: temps universel coordonnéhowever the abbreviation is UTC in order to offend neither.

author: schmitt trigger
author_rank: Super Contributor
timestamp: January 03, 2018, 09:56:03 pm
content: Quote from: boffin on January 03, 2018, 07:03:56 pmWouldn't FIFA be a similar case?

author: tooki
author_rank: Super Contributor
timestamp: January 03, 2018, 10:09:26 pm
content: No, "FIFA" is fully French. (And based here in Zurich, go figure…)

author: Cubdriver
author_rank: Unknown
timestamp: January 05, 2018, 05:35:34 am
content: Quote from: boffin on January 02, 2018, 10:48:59 pmAnd don't forget the standard temperature lapse rate of 2 degrees C per thousand feet of altitude-Pat

author: Zero999
author_rank: Super Contributor
timestamp: January 11, 2018, 04:42:32 pm
content: Has anyone seen K pF being used for nF? I've found this site which lists its capacitors in K pF, which just seems odd. Is it just a Spanish thing?http://www.cetronic.es/sqlcommerce/disenos/plantilla1/seccion/producto/DetalleProducto.jsp?idIdioma=1&idTienda=93&codProducto=150272234&cPath=799

author: ciccio
author_rank: Frequent Contributor
timestamp: January 12, 2018, 01:18:31 pm
content: I've seen many times, but it seems to disappear in recent times-It seems that nano as a prefix needed a longer time for becoming of standar use.Best regards

author: boffin
author_rank: Unknown
timestamp: January 13, 2018, 08:25:27 am
content: Quote from: Cubdriver on January 05, 2018, 05:35:34 amI haven't forgotten, and officially it's much more ridiculous 1.98 degrees/1000', not 2. (The official definition is 6.49 K/km)It's always one of those questions the put on tests.

author: BrianHG
author_rank: Super Contributor
timestamp: January 13, 2018, 09:52:00 am
content: Quote from: glarsson on January 03, 2018, 04:37:11 pmAaaaaaaaaaaaarrrrrrrrrrrrrrrrrgggggggggggggggWhat did you do?I can no longer read english!!!It's going to take me a day to undo this!!!

author: Vtile
author_rank: Super Contributor
timestamp: January 13, 2018, 06:11:16 pm
content: Quote from: BrianHG on January 13, 2018, 09:52:00 amWelcome to my world.

author: BrianHG
author_rank: Super Contributor
timestamp: January 29, 2018, 12:54:45 am
content: 6 Weird Units of Measurement We're Still Using for Some Reason