# Talk:History of the metric system

History of the metric system has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
Article milestones
DateProcessResult
September 12, 2013Good article nomineeNot listed
October 28, 2013Good article nomineeListed
A fact from this article was featured on Wikipedia's Main Page in the "On this day..." column on December 10, 2011.
Current status: Good article

## Metre and Kilogram des archives & The first metric system: France, 1799

These sections are wordy, wordy, wordy, even though I've whittled them down to just relevant material. Only two things happened here: prototypes were fashioned and entered into the archives, and a law was passed making the metric system the official system of France. 5 dates in 1799 appear in the sections; maybe we don't need them at all, since the section head tells us the year. Other details appear or should appear in prior sections, so they're superfluous here. I think two sentences, one section of one short paragraph, is more than enough here. How about:

In June of 1799, platinum prototypes were fabricated according to the measured quantities, the metre des archives defined to be a length of 443.296 lignes, and the kilogramme des archives defined to be a weight of 18827.15 grains, and entered into the French National Archives. In December of that year, the metric system based on them became by law the sole system of weights and measures in France from 1801 until 1812.

Sometimes details of history matter, and there's a place for them. Scientific details (like the broad-brush statement that the metric system is a <this>, <that>, and <next thing>) might be more properly placed in the companion article Metric system about the science. Sometimes history is just about the end result; we only say what we need to say.

Sbalfour (talk) 21:00, 15 January 2018 (UTC)

Done. Sbalfour (talk) 03:26, 16 January 2018 (UTC)

## Electrical units

Answer these two questions, based only on what you read here: 1) why did the ampere unify the EMU/ESU/Gaussian/International systems of units? 2) what is the dimensional manifestation of electricity?

The mechanical dimensions have intuitive notions: length because things have size; mass because they are heavy; time passes as events happen, we age, clocks tick, etc. Why isn't it good enough to define the ohm as meters/second? As long as we stay within the system (EMU), things actually work rather well. The Kelvin and candela are both definable in terms of the MKSA system. Why do they remain base units? It's intuitive that we have a base unit of one spacial dimension; it's just as useful and intuitive to have a base unit of two spacial dimensions, i.e. area, and one of three spacial dimensions, i.e. volume (litre). Why don't we? None of these questions can be answered in the article, and probably some of them shouldn't be. But we spend a lot of column space on fragmented electrical systems of units, and then don't provide any closure. Some science is needed. There is absolutely a defined dimensional manifestation of electricity, and it is necessary. The original editors didn't have a fundamental grasp of that, so they wrote a whole lot of stuff and said nothing. It doesn't matter that we know it was called an abohm (actually, it wasn't called that until much later), or that it was named for Georg Ohm. That's worth a footnote. Those hairy equations are utterly inaccessible in an article about history. I think we need to start over here. Sbalfour (talk) 04:10, 16 January 2018 (UTC)

Defining the ohm as meters/second would have the drawback of reintroducing fractional exponents in units. If [R]=m/s, and P=I2R, then [I]= kg1/2 m1/2 s-1. Ceinturion (talk) 17:52, 16 January 2018 (UTC)

## The units of weight and length

The section 'The units of weight and length' contains a nonchronological sentence that should probably be removed: While Méchain and Delambre were completing their survey, the commission had ordered a series of platinum bars to be made based on the provisional metre. When the final result was known, the bar whose length was closest to the meridianal definition of the metre would be selected. These two sentences are unclear and they do not seem to make much sense. They can be removed because a later section, 'The French metric system', already says what needs to be said: 'In June of 1799, platinum prototypes were fabricated '. Ceinturion (talk) 19:54, 18 January 2018 (UTC)

Yeh, I know. Bzzzzt. I haven't read anywhere what must've happened, but it's pretty clear: a number of prototypes were made around the established value of 443.44 lignes, probably varying by only a few hundredths of a lignes. When the surveyed value came in well more than a tenth of a lignes shorter, they had to discard the prototypes and make a new one exactly 443.296 lignes. I've since combined the sentences to make sense of them. Sbalfour (talk) 05:31, 19 January 2018 (UTC)
I think the French description by Delambre is somewhat like: in 1795, the provisional metre was calculated to be 0,513243 toise, and they tried to create a prototype with an accuracy of 10-6 toise. The length of objects could be measured on a subdivided toise scale with Lenoir's 'comparator', presumably a kind of vernier calipers. Lengths of up to 4 meters could be measured, with an accuracy of 10-5 toise. Four approximate metre bars were made, from brass (not platinum). By measuring the bars together, in different combinations, the accuracy of each bar improved. The bar closest to 0,513243 toise was chosen as the prototype provisional metre.
In 1798 Delambre and Mechain concluded that final metre was 0,5130740740 toise. Twelve approximate metre bars from iron were made. By measuring the twelve iron bars together, in different combinations, the accuracy of each bar improved. The iron bar closest to 0,5130740740 toise was used as reference for making two bars from platinum. One became primary standard, and was called "mètre des Archives". The other one became a secondary standard, and was called "mètre de l'Observatoire". Delambre, Base du système métrique
So I would think the two sentences should be something like: After Méchain and Delambre had completed their survey, the commission ordered a series of bars to be made based on the final metre. The bar whose length was closest to the final metre would be selected. Ceinturion (talk) 02:17, 20 January 2018 (UTC)

## GA status

I am checking on Good Articles with cleanup tags and have just arrived at this. I see there is a lot of talk page activity aimed at improving the article, which is excellent. Hopefully you can get the article cleaned up and resolve any outstanding tags. Let me know if you need any help regarding GA criteria or anything else. AIRcorn (talk) 02:58, 27 March 2018 (UTC)