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Who 'Invented' Metric 2

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friartuck

friartuck

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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
 
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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:
 
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So there you go: metric and driving on the right- it's all Napoleon's fault........
 
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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.

[bat]"When everyone is thinking alike, no one is thinking very much." --Eckhard Schwarz (1930--2004)[bat]
 
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<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
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To get the best from these forums read faq731-376 before posting

UK steam enthusiasts:
 
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one cubic centimeter of water@4°C =0.99997 g Water has the highest density @4°C...
to be picky.
 
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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...
 
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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,
 
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I am proud to inform you about Celsius and also how the relation between inches and millimeters came about.

Anders Celcius (see 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
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.
 
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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..?
 
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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.
 
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Kindly refer the centigrade temperature scale to Celsius, not Celcius.
 
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sreid,

The "rounding off" took place in 1920 - 30.
 
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“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.
 
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0707- the English may not make the changes you list, but you never know about the Welsh or the Scots or the Northern Irish......!
 
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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.
 
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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)....
 
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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
 
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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.
 
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