Talk:Litre

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A fact from Litre appeared on Wikipedia's Main Page in the Did you know? column on 7 January 2013. The text of the entry was as follows:

... that even though it is commonly used, the litre is not an SI unit?

Wikipedia

Original metric system.[change source]

Fenna actually wrote "In fact it was not in the original metric system of 1791, being introduced two years later ...". Nothing in the article says that it part of the 1791 system, only that it was part of the legislation passed in 1795. Your comment therefore adds nothing to the article, so I removed it. Martinvl (talk) 22:26, 2 March 2014 (UTC)[reply]

Your reason for saying that the addition of that fact "adds nothing to the article" is not clear to me, so I have reinstated it. Please provide a better explanation if you think it is a worthless fact. Centaur (talk) 19:47, 3 March 2014 (UTC)[reply]

What was in the "original metric system of 1791"? Why was the litre not included in the 1791 system? Should it have been in the 1791 system? You are not telling the reader even though it is all in Fenna's book. Without an adequate explanation, it is a totally worthless comment. Martinvl (talk) 21:29, 3 March 2014 (UTC)[reply]

It is a referenced fact. Sure it can be expanded upon, by anyone with the time, at any time, but that is not a good reason to remove it. Centaur (talk) 21:40, 3 March 2014 (UTC)[reply]

Please reread Fenna and understand why he added that fact. Don't just pluck a sentence and quote it out of context. Unless you go into the philosophy of the definition of the litre, the fact by itself it is a totally useless. Simple Wikipedia is not the place for such a philosophy - the philosophy is too complex to explain in simple language. The fact and its underlying philosophy might have a place in English Wikipedia, so please do the decent thing and remove it. Martinvl (talk) 22:47, 3 March 2014 (UTC)[reply]

The fact stands alone. The pragmatic reason for it is less important, but can be added in a few simple English words by anyone with the time. Centaur (talk) 22:54, 3 March 2014 (UTC)[reply]

I have now added the reasoning for you. Centaur (talk) 23:00, 3 March 2014 (UTC)[reply]

Your reasoning is original research. I want the reason given by Fenna. Martinvl (talk) 23:10, 3 March 2014 (UTC)[reply]

The simplified English, one-sentence reason, that I wrote for why the litre was added to the metric system ("It was added because the public were not happy with the new units.") is supported in the cited Fenna book at the top of page 158 with this: "In fact it [the litre] was not in the original metric system of 1791, being introduced two years later, as sop to public demand and (with the are for area) the first example of official concession in the fight to establish what we now call metrication. Initially it was named the pinte, the cadil, and the litron (oddities in the context of post-revolutionary France, being relics from monarchist days, while the other units had been accorded original names), before acquiring its now-familiar name two years later." The pinte, cadil and litron being French units of volume from before the metric system was introduced. Now please explain which reason "given by Fenna" you want to see. Centaur (talk) 20:16, 4 March 2014 (UTC)[reply]

OK, you can cut-and-paste. But why did you stop where you stop there. The next sentence states "Of more concern to measurement ....". The rest of the Fenna's article details to differences at whether the litre was one kilogram of water or whether it was the volume of a cube with side 10 cm long.

The point that Fenna was making was the conflict between "philosophical perfection" (my words) and practicality, something which, while interesting in its own right, is hardly appropriate in the Simple Wikipedia. If you do want to be useful, why don't you write up the conflict that I described in Simple English? Martinvl (talk) 21:13, 4 March 2014 (UTC)[reply]

Firstly, you still haven't justified (or withdrawn) your assertion that: "[my] reasoning is original research". I gave the proof, the supporting quote from the reference I cited, that it was not original research, so now it is over to you to justify or withdraw.

Secondly, I stopped there because that is where the explanation (that you asked for) of why the litre was added, ended. Or do you think that the discovery, nearly a century later, that the definition was ambiguous, also had a bearing on that earlier event?

Thirdly, please don't patronize me, and leave out the sneers. Centaur (talk) 22:12, 4 March 2014 (UTC)[reply]

┌─────────────────────────────────┘
If you read Fenna's book and Hellman's paper you get very different views about the "public were not happy" (as you put it). First of all, Fenna fails to define the "metric system of 1791". According to Hellman, all that was agreed in 1791 was that the unit of length should be based on the earth's meridian, not on the pendulum. Furthermore, in 1792 the committee who were in charge of units of measure were debating whether the unit of length should be one metre or 10 cm (as we now know them). A base unit of length of 10 cm would be consistent with the litre and the grave (now known as the kilogram).

It was certainly not out for public debate until 1793 when the first document was produced so where does Fenna get the term "public" from? Who is correct - Fenna or Hellman? Given that I can find no reference anywhere else to the "1791 metric system", I am inclined to dismiss Fenna in favour of Hellman.

Furthermore nobody mentions cubic metres, so your inclusion of cubic metres is original research. Martinvl (talk) 11:11, 6 March 2014 (UTC)[reply]

I don't want to pay for access to Hallman's work, so cannot access it. I'll take your word for what is said there. We need to get the consensus amongst reliable sources for this, if it isn't clear from these two, and not be tempted to use our own personally preferred account.

As the metric system only had the metre and grave (later the kilogram) defined at the beginning, it isn't really original research to deduce which one of those was intended to be used for capacity and volume measurement. Centaur (talk) 22:56, 6 March 2014 (UTC)[reply]

I have found an authoritative source (in French) which states that the cubic metre was inconvenient unit of measure for everyday use. The same source makes no mention of a 1791 version of the metric system, rather it speaks of a three year investigation. This is clearly the period 1790-1793. I have taken the liberty of rewriting the section to reflect the views of the authors of the book (who were also the authors of the metric system). Part of this rewrite was to remove the reference to "the public". Martinvl (talk) 07:44, 7 March 2014 (UTC)[reply]

By all means add content from a new reliable source, but don't just delete other reliably sourced content. --Centaur (talk) 09:32, 7 March 2014 (UTC)[reply]

I have reinstated the earelier version. I have also completed the citation regarding Fenna's book. Martinvl (talk) 10:09, 7 March 2014 (UTC)[reply]

Please restore the content you deleted too, as deletion of content still under discussion may be seen as disruptive. --Centaur (talk) 10:26, 7 March 2014 (UTC)[reply]

I wrote a good deal of the text that I deleted. In particular, after reading this, this, this and this I am convinced that there was no "1791 metric system". The 1791 document was an outline brief that was put together to authorize the measurement of the meridian. The document also authorized the setting up of five working parties to study various scientific fields. One of these fields was the density of water at different temperatures. This was almost certainly a precursor to the definition of the unit of mass. The name "metre" and a few prefixes were proposed in 1792. In short, Fenna's description of the "original metric system of 1791" seems to contradict everything else that I have read. So unless you can give me details of the metric system as it was in 1791, I will not be reverting. May I further draw to attention that I have given you a citation which, if quoted, allows you to rebut my earlier claims of OR. I have also completed the citation of Fenna's book (I accept the bit about the litron and the pinte). Martinvl (talk) 18:22, 7 March 2014 (UTC).[reply]

Amended Martinvl (talk) 21:34, 7 March 2014 (UTC)[reply]

So you've taken ownership of the article, and unilaterally decided what should be included, and what not, and which sources are acceptable, and which not. This despite the fact that this discussion is still open, and no consensus reached. I call that blatant disruption. I'm not going to indulge in a battle of reverts, but am asking you to behave more collaboratively here.

And your "earlier claims of OR" have already been shown to be groundless, and need no further rebuttal. To restate them could be seen to be discourteous, even uncivil, even inflammatory.

I accept that the timeline isn't very clear in the literature, but there is plenty of evidence that the metric system was first implemented in 1791, even in the cites you list. And there is also plenty of evidence there that the litre (as the cadil) wasn't introduced until 1793. This leaves a 2 year gap, which Fenna fills nicely. Centaur (talk) 08:54, 8 March 2014 (UTC)[reply]

I think that you can stop arguing: the litre is not part of the SI system, so you will likely not find an authoritative mention of it in documents about the SI system. --Eptalon (talk) 09:10, 8 March 2014 (UTC)[reply]

The official unit of volume (derived) is the cubic metre, since the litre can be expressed in terms of cubic metres, there is no need for litres in the SI system; officiallly, the lire is an alternate name for the cubic decimetre, see here--Eptalon (talk) 09:19, 8 March 2014 (UTC)[reply]

see for example this page for the definition of 1795: "Article 5: Gramme, le poids absolu d'un volume d'eau pure, égal au cube de la centième partie du mètre et à la température de la glace fondante." (Art 5: Gram, the absolute weight of the volume of pure water, equal to the cube of the 100th part of the metre, at the tempearure of melting ice) --Eptalon (talk) 09:48, 8 March 2014 (UTC)[reply]

@Centaur: You wrote "This leaves a 2 year gap, which Fenna fills nicely." Fenna does not fill this gap nicely. In fact he fills it vary badly. A quick reminder of the chronology (as per Tavernor in Smoots Ear.

29 March 1791 - The proposal to use a decimal-based system based on constants of nature approved by the National Convention. The unit of length would be defined using the earth's meridian rather than the pendulum. Five committees set up to look at various aspects of a new system of weights and measures
7 August 1791 - Funding for the meridian expedition approved.
11 June 1792 - Preliminary report on metric system published by the commission for weights and measures. The name "metre" and a few prefixes defined.
1 August 1793 - Draft metric system published.

I do not see how Fenna's explanation "fills" this 2-year gap. Martinvl (talk) 14:35, 8 March 2014 (UTC)[reply]

I've done some more research, and have now updated the article to reflect the balance from many references. Centaur (talk) 20:51, 9 March 2014 (UTC)[reply]