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friartuck (Mechanical) (OP)
27 Oct 04 18:01
Does any body know how 'metric' came about.

I think the metre was supposed to be the circumference of the earth divided by 100,000 or something like that. But where did the kG come from and the Celcius.

We seem to have a real mish mash of units and knowbody sticking to them.

For instance, we have the kW for power as well as HP (Horse Power) and PS (Pferdestarke) which is a 'metric' horse power...(How can you have a metric horse power.)

I know that there is a thread on Metric already, but I don't think it was clear on who started it all. Any clues out there?

Sorry if this question has been raised already.

Friar Tuck of Sherwood

NozzleTwister (Mechanical)
27 Oct 04 18:16
Friar Tuck,

Try this link:
http://www.unc.edu/~rowlett/units/metric.html

and this one for more than you ever whated to know about any units of measure:
http://www.unc.edu/~rowlett/units/index.html

NozzleTwister
Houston, Texas

SlideRuleEra (Structural)
27 Oct 04 18:28
Friar Tuck of Sherwood - According the article in Fall 2002, issue of "American Heritage of Invention & Technology" the Revolutionary French govenment launched the expedition in June 1792. Outstanding French scientists of the time, such as Lavoisier and Laplace, were the driving force.

The individuals who lead the field work were:
Jean-Baptiste-Joseph Delambre and
Pierre-Francois-Andre Mechain
Took them seven years.

If you like the combination of history and engineering, like I do, this magazine is the one to subscribe to. I have been with it for over 15 years - here is a link to the web site:
http://www.inventionandtechnology.com
DrillerNic (Petroleum)
28 Oct 04 13:16
So there you go: metric and driving on the right- it's all Napoleon's fault........
TheTick (Mechanical)
28 Oct 04 13:25
As I recall...

The current official meter is x number of wavelengths of light emitted by excited krypton gas, though it used to be a fraction of the Earth's circumference along the prime meridian.

One cubic centimeter of water at 0°C(?) is one gram.  1 liter of water is thusly 1 kg.

Centigrade (Celsius) is set 0° for freezing and 100° for boiling at sea level atmospheric pressure.

"When everyone is thinking alike, no one is thinking very much." --Eckhard Schwarz (1930--2004)
http://www.EsoxRepublic.com

johnwm (Computer)
28 Oct 04 17:50
<fraction of the Earth's circumference along the prime meridian.> It may have been the Paris meridian, rather than Greenwich

<One cubic centimeter of water at 0°C(?) is one gram> ? 4°C?

Good Luck
johnwm
________________________________________________________
To get the best from these forums read FAQ731-376 before posting

UK steam enthusiasts: www.essexsteam.co.uk

mattis (Automotive)
29 Oct 04 5:53
one cubic centimeter of water@4°C =0.99997 g Water has the highest density @4°C...
to be picky.
gearguru (Automotive)
1 Nov 04 21:01
As I recall:
meter = distance from equator to north pole (following the Paris' meridian, of course) divided by 10 millions.
Later they defined it as a length of a "prototype" kept somewhere like Sevres (town?) close to/in Paris. Then they tried to define it by the wavelength of some chemical element(?).
For a gram - we were taught in the school, that 1 kg = mass of 1 liter (= 1 decimeter cube) of 4 deg C water.
But since then the whole Europe changed n times, so I am not sure about anything anymore...
PSE (Industrial)
2 Nov 04 15:55
I do believe the French can claim the "invention" of the metric standard of measurement.  I do recall some variant "standards or systems" MKS, SI etc. and I think that SI is now the "standard".  Perhaps the method of communicating the units varies between scientific and engineering communities.

Regards,
Skogsgurra (Electrical)
2 Nov 04 17:03
I am proud to inform you about Celsius and also how the relation between inches and millimeters came about.

Anders Celcius (see http://www.astro.uu.se/history/Celsius_eng.html) was a scientist in eighteenth century Uppsala, Sweden. He used freezing and boiling water as fix points on his thermometer scale. He divided it into 100 divisions - very modern at those times. He also let the freezing point represent 100 degrees and the boiling point represented 0 degrees. It was only after his death that this was changed to what we know to be the Celcius scale of today.

The relation between inch and millimeter was discussed for many years in the NBS and the Congress. Since there were many different inces in the different states of America, it was difficult to come to a decision. Carl Edvard Johansson was a metrologist in Sweden and his principle invention were the gague blocks aka Jo-blocks after Johansson. See http://www.medibix.com/company.jsp?company_id=9992...

Henry Ford was in great need for a gauging system that could be used in all his factories. Without such a system parts from one factory wouldn't fit parts from another factory. So he asked Johansson to produce gauge blocks for him. And Johansson tried to get the numbers to work with from NBS. He never got them.

So Johansson decided to make one inch equal to 25.400000 millimeters. He delivered the gauge blocks to Ford. The rest is history.

Why proud? Well, I live in the same country as did Celsius and Johansson. And I actually worked for some time at the Johansson company in Eskilstuna.
epoisses (Chemical)
9 Dec 04 9:31
The introduction and propagation of the USE of metric units (which is not the same as having invented them) was done to a great extent by the French. But netric which is all about equations linking different properties of objects that were discovered little by little, and the French obviously can't claim to have discovered them all.

Celcius is a good example. Newton contributed a lot to relating force with mass and acceleration, and force and distance with energy; that's why Newtons, kilograms, meters, seconds, Joules and Watts can be converted back and forth so nicely. Certain funny numbers like g = ~9.8 m/s2 are funny because they are inherent properties of the earth or of other objects. Not every property of the earth can be a beautiful number when expressed in a consistent system of units. That's why the meter defined (in hindsight) as x number of wavelengths of light emitted by excited krypton gas, or a fraction y of the Earth's circumference along the prime meridian, looks as ugly as an inch being 25.4 mm. But so what..?
sreid (Electrical)
22 Dec 04 18:50
My 1960's physics book said 1 inch = 25.400009 mm (or something like that).  I have always assumed that this was rounded off sometime later.
25362 (Chemical)
24 Dec 04 12:47
Kindly refer the centigrade temperature scale to Celsius, not Celcius.
Skogsgurra (Electrical)
5 Mar 05 6:04
sreid,

The "rounding off" took place in 1920 - 30.
0707 (Petroleum)
23 Mar 05 9:14
“The word meter, which comes from the Greek word for "measure," refers to the regular pattern of stressed and unstressed syllables in a poem”.

“Over 300 years ago, the need for a single worldwide coordinated measurement system was recognized. Gabriel Mouton, Vicar of St. Paul's Church in Lyons (France) and an astronomer, proposed, in 1670, a decimal measurement system based on the length of one minute of arc of a great circle of the Earth. Mouton also proposed the swing length of a pendulum with a frequency of one beat per second as the unit of length. A pendulum with this beat would have been fairly easily to reproduce, thus facilitating the widespread distribution of uniform standards. Other proposals were made, but more than a century elapsed before any action was taken.
In 1790, in the midst of the French Revolution, the National Assembly of France requested the French Academy of Sciences to "deduce an invariable standard for all the measures and all the weights." The Commission appointed by the Academy created a system that was, at once, simple and scientific. The unit of length was to be a portion of the Earth's circumference. Measures for capacity (volume) and mass were to be derived from the unit of length, thus relating the basic units of the system to each other and to nature. Furthermore, larger and smaller multiples of each unit were to be created by multiplying or dividing the basic units by 10 and its powers. This feature provided a great convenience to users of the system, by eliminating the need for such calculations as dividing by 16 (to convert ounces to pounds) or by 12 (to convert inches to feet).
British industry converted successfully to the metric system in the 1960s. But with continued legal validity of inch-pound units, take up of the metric system by the British public remained a slow process for three decades, which is still in progress. The pound finally lost its status as a legal unit of weight in the United Kingdom on 1 January 2000, but dual labelling will be permitted until 2009.”

I suppose that the English people will never change to the Euro, will never change to the metric system, will never drive on the right.  
DrillerNic (Petroleum)
24 Mar 05 7:09
0707- the English may not make the changes you list, but you never know about the Welsh or the Scots or the Northern Irish......!
UKpete (Electrical)
25 Mar 05 8:13
0707, I'm english and I can tell you we are getting there slowly.  Our weights and measures are metric, it is illegal for shops to sell comodities measured in pounds and ounces; petrol/gas is sold in litres, timber is measured in mm and metres.  About the only things that haven't gone over are pints of beer and the road signs and speed limits, which are still in miles (and yards) and miles/hr respectively.  I don't think there is any plan to change them yet, they are purely internal to the UK although they may confuse visitors.

All our engineering industry has been metric for decades.  I haven't seen a drawing in inches for about 30 years, except ones from the US.  Ironically, they call them "English Units" in the US but that is historical.

Driving on the right?  Well the Japanese do too, and they make more cars than anyone else.  I know the Swedes made the change, we are more conservative than they are.

The Euro currency - it will come eventually, it's just a question of us getting used to the idea.  Euros do change hands here, you can't go into Europe without them and we have a lot of Irish people (our largest immigrant community) using them.
DrillerNic (Petroleum)
28 Mar 05 5:18
The UK's Oil & Gas industry is still in feet and inches though (although these are actually part of units system called "Oilfield Units" which is a real dog's breakfast of a units system: volume in barrels or sacks or scf or somthing called an acre-foot)....
Imagineer (Structural)
5 Apr 05 12:44
Now to really stir the pot...  

At the risk of being called a heretic, why the big push for the metric system or SI or whatever the "official" name is? (Yes, I know there are technical differences but on normal human scale these are insignificant.)

I'm not trying to be a pain, but being a US engineer who has done work abroad, I really don't get why metric is easier or better.  I understand the history of the metric system, but I'm still at a loss as to the supposed advantages of it.  

It's supposed to be more rational.  As far as I can tell, it has only two "rationalities": everything uses base 10; and the relationships between units is by design rather than coincidence.  Are there more that are unknown to me?

We can discuss the various points later, but I thought I'd start with this.

Imagineer

UKpete (Electrical)
5 Apr 05 16:37
I'm not passionate about it but the two reasons you give are pretty strong ones - I was brought up with the old measurements but find the metric system easier to work with as a design engineer.  For example (ok, it is probably the worst one!) take thermal conductivity.  If I look up an adhesive product and find it quoted in BTU•in/ft²•hr•°F - I'd rather work with W/m•K.

A third reason is that if the whole world uses a common system this is better for everyone.  Converting between units is a pain, and a source of error.
Helpful Member!  carterinms (Marine/Ocean)
5 Apr 05 16:52
I'd prefer metric.  If I take measurements from a drawing, I usually have to do two conversions to get a consistent unit:  23'-7 13/16" = 23.65'.  Any conversion can be a source of error - at my last job, a drafter converted 1'-8" to 18" which caused all sorts of problems down the road.  

And one other reason - slugs.  Need I say more?

-erica
IRstuff (Aerospace)
5 Apr 05 17:30
> There's no reason you couldn't work in W/in-ºF.  Even in metric units, you often can get errors because someone is using W/m*K and someone else is using W/cm*K

> The problem with mixed fractions is that they're MIXED.  We use decimal inches in all our drawings with no problems other than normal addition and subtraction errors.

TTFN

Heckler (Mechanical)
18 Apr 05 14:06
I hope the pubs don't change over to the metric system.....that will really take away from the British history not forgetting in might confuse the drunks.

I agree with Erica....slugs.

Best Regards,

Heckler
Sr. Mechanical Engineer
SW2005 SP 2.0 & Pro/E 2001
Dell Precision 370
P4 3.6 GHz, 1GB RAM
XP Pro SP2.0
NIVIDA Quadro FX 1400
      o
  _`\(,_
(_)/ (_)

Do you trust your intuition or go with the flow?

0707 (Petroleum)
19 Apr 05 13:00
At which system measurement belongs the term pint? A pint has always the same quantity of beer? The foam wide shear above the liquid beer is included in the pint volume?

The Nederland Pint is equal to the English pint?

Are the beer drinkers being stolen because when they ask for a pint they also pay the foam?

luis
UKpete (Electrical)
19 Apr 05 15:55
Heckler, that's very considerate of you but it's probably a bit of history we could do without.

Er, on a pint beer glass there is a line near the top that marks the pint level, the liquid must reach this line and any foam is above this - and the pumps are usually push button so they dispense an exact pint.

Surely it's more efficient to drink by the litre, this means less visits to the counter, less glasses to collect and wash.
GregLocock (Automotive)
19 Apr 05 19:05
I think Guinness is/was the only beer where the head is part of the volume, in the UK. Doubtless that has changed.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

UKpete (Electrical)
20 Apr 05 3:08
Greg, I'm sure there is an EU directive that doesn't allow that any more.
Helpful Member!  dpc (Electrical)
20 Apr 05 19:08
Just to make things more confusing, a US pint (liquid) is NOT equal to a British pint.  So when you Brits come to drink our fine microbrews in the Pacific Northwest, don't feel cheated when your Pint seems a little short.

UKpete (Electrical)
21 Apr 05 16:13
dpc, I'm not sure I'd notice.  Unfortunately for most Brits when they go abroad they ask for beer but get something different and very cold.  Lager aside (a relatively recent introduction) there is no cooling involved over here.
dpc (Electrical)
21 Apr 05 16:34
Pete:  Plenty of British-type ales in the US.  Getting a pint served at room temperature could be a little difficult.  A few links to wet your whistle:  

http://www.bridgeportbrew.com/home.html

http://www.rogue.com/

http://www.redhook.com/ales.html

Seriously off-topic, I know.  My apologies.
UKpete (Electrical)
21 Apr 05 16:51
Yes that's the sort of stuff, probably an acquired taste.  However all I remember from my brief visits about 30 years ago being available was B*******er (I don't think we are allowed to advertise the name on Eng Tips) which is now sold over here too.
IRstuff (Aerospace)
21 Apr 05 20:51
Unless you were going to give an ringing endorsement or opposite, it's not advertising.  Even then, it might still not qualify as advertising, unless you also have vested interest in the product selling.

Brand names are not prohibited, per se, since many forum names include a brand name.

TTFN

davidbeach (Electrical)
21 Apr 05 21:23

Quote (UKpete):

Yes that's the sort of stuff, probably an acquired taste.  However all I remember from my brief visits about 30 years ago being available was B*******er (I don't think we are allowed to advertise the name on Eng Tips) which is now sold over here too.

But Filtered Horse P!$$ starts with an 'F', not a 'B'.

Come to Portland Oregon and enjoy the vast variety of beers available, the majority of which are brewed within 200 miles.  You could probably enjoy a different, good, beer every day all year.
UKpete (Electrical)
22 Apr 05 3:11
IRstuff - thanks for the clarification.  I don't intend to endorse one way or the other (each to his own!).

davidbeach - I didn't have a high quality experience but perhaps I was misusing the product.  I am very confident too that suitable alternative products are available in Oregon, but unfortunately I'm scared of volcanoes.
friartuck (Mechanical) (OP)
24 Apr 05 14:53
I recently had the great pleasure of visiting Dusseldorf and Dortmund in Germany. I have never seen so many breweries...I think over 200. And the beer is superb. Incidentally it was a technical visit to a large pump manufacturer.

Well worth going on if you can wangle it.  (Wilo Pumps in case you were interested)

Friar Tuck of Sherwood

friartuck (Mechanical) (OP)
26 Jun 05 18:57
Somebody mentioned the US pint being different to the Inperial Pint. How did this happen?
Are there any other units that are different, i.e. US gallon, (Is there a US inch or is it the same as an Imperial Inch--25.4mm)

Friar Tuck of Sherwood

GregLocock (Automotive)
26 Jun 05 21:25
gallon, ton, dram , fl oz, gill, pint, qt , barrel, peck,cwt, and bushel, are all different in the UK to the customary US units.

Doubtless there are others

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

zeusfaber (Military)
27 Jun 05 16:55
And how did they come to have both short and long tons in the US - neither weighing 1000 kg?

A
rb1957 (Aerospace)
28 Jun 05 8:34
i reckon they had tons before they had kgs ...
a long ton is an imperial ton = 2240 lbs (just about a metric tonne)
a short ton is 2000 lbs ... i guess they couldn't be bothered with the 240 lbs (maybe a comment on the education system in the US)
unclesyd (Materials)
28 Jun 05 12:08
Depends on whether you are buying or welling which ton you use.
rb1957 (Aerospace)
28 Jun 05 13:10
welease wodger
friartuck (Mechanical) (OP)
5 Jul 05 15:51
I bet you thought this topic had died a death, well, I've been thinking (I think real slow----just like the trees on Lord of the rings I hear you say)

I suppose metric makes sense since we have ten fingers. There isn't much logic to counting in twelves is there?? (Or is there?)

Friar Tuck of Sherwood

IRstuff (Aerospace)
5 Jul 05 18:26
But you're looking at it after the fact.

Start with the basic unit of 1 ft.  That had some rough correspondence to a body part that's always with you, as opposed to the tape measure that's either at home or in another room.

Now you want a smaller unit, so maybe you use the length of the big toe or the thumb.  It then turns out that there are roughly 12 of those to the foot.

The fact that you have 10 fingers is irrelevant, because the basic unit had a requirement to be something commonplace, and ideally, with you all the time.  One-millionth of the distance from the equator to the north pole is unrealistic and unmanageable at the personal level.

TTFN

notnats (Mechanical)
9 Jul 05 10:21
It's a shame we weren't born with 12 fingers. A base 12 number system has factors of 1,2,3,4,6 and 12, or more correctly, 1,2,3,4,6 and 10
25362 (Chemical)
11 Jul 05 6:35
Notnats, what do you infer from the fact that Jesus had 12 disciples, and Israel 12 tribes ?
IRstuff (Aerospace)
11 Jul 05 11:02
And:
12 signs of the Zodiac
12 animals in the Asian calendar
Minutes arranged as 12 groups of 5
12 hours in a half-day
12 months in a year

TTFN



notnats (Mechanical)
13 Jul 05 2:30
I don't know, 25362. Are you implying that Jesus and Moses had 12 fingers?
25362 (Chemical)
13 Jul 05 10:13

Notnats, when referring to the 12 tribes, although Moses guided them out of Egypt it was Jacob who was credited with their being born. Somehow, I entertained the illusion you'd find a divine nexus in the number 12 because of the biblical connotations.
ewh (Aerospace)
13 Jul 05 10:45
Why only ten commandments?
rb1957 (Aerospace)
13 Jul 05 12:26
boy, have we ever strayed from the OP !
notnats (Mechanical)
14 Jul 05 21:53
I'm not a symbologist. This is moving into Dan Brown's area.
cadcoke5 (Mechanical)
24 Jul 05 0:22
Friar Tuck asked about advantages to 12 instead of 10.

The common use of numbers like 12 or 16 to divide units predate the use of 10.

Despite the metric claim of 10 being more intuitive because of having ten digits on our hands, I think 12 is more intuitive.  This is because people think in terms of halves, not 10th.  This also

The question ,"Is the glass half full?" is never presented as, "Is the glass .5 full?" Also, dividing an inch into half, half again into 1/4, etc is very natural.

Since the metric system came from France (and the metric unit based on a measurement of the earth through France) it was an alternative to Great Brittan's world standard. I think the main motivation for metric was political, not scientific or an effort to unify units.  

Joe Dunfee
Skogsgurra (Electrical)
24 Jul 05 4:43
We had a king once (Charles XII of Sweden) that was going to introduce 12 instead of 10 as a basis for the number system. He got killed in action and we still have 10. Like all other countries.

Cadcoke, there is a very practical reason for measuring the Earth's quadrant the way the French did it. The measurement was done along a stretch of land that included Finland, the Baltic states, Prussia, Germany, France, Spain etc. It simply wasn't practical to do precision measurements across open water, which would have been necessary if England was included in the chain. Nothing political there.

Gunnar Englund
www.gke.org

TChronos (Automotive)
23 Aug 05 21:04
Surprisingly, base 12 originates from an ancient method of finger counting, first documented in Babylon, but probably much older. No, they didn't have more fingers back then. If you examine your fingers, you will see that each finger is divided into three joints. Using your thumb as a pointer, and each joint of each finger as a counter, you can count to 12 on one hand. Using the other hand to accumulate, and you easily see why numbers like 60, 360, and 144 come up so often in measurement systems.

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