The book by Coriolis Du calcul de l'effet des machines is usually translated in English literally: “Calculation of the Effect of Machines”.

Is it possible to stretch the translation to “efficiency” or “effectiveness” without forcing the original French meaning?

Larousse gives an example: être sans effet : rester OU demeurer sans effet (to have no effect, to be ineffective).

That encouraged me to ask: what is the best word in English in your opinion? What is the exact meaning in French?

Update after the answers: If you read wiki about it, Coriolis defined the new unit of work that would after be called Joule, substituting the British HP.

So what he did was to provide a unit of measurement of the output of a steam machine, as compared to real horses. What about “performance”?

What about output ? – mannaia

Thanks for your wonderful response, I am not able to judge if this option is acceptable, but I wanted to submit an element to your reflection:

Coriolis was just following ins Watt's steps, providing a measurement of the 'effect-iveness- of a steam engine as a substitute of the work done by horses. Could you help you find the right contemporary term, just thinking of which word you would use for a horse? I imagine that even in old French you would not talk about the 'effet des chevaux?

  • Performance somewhat imply you are comparing the effect with some others. Effet does not.
    – jlliagre
    Nov 29, 2014 at 13:39
  • What about output ?
    – mannaia
    Nov 29, 2014 at 19:01

3 Answers 3


Translating effet by “efficiency” or “effectiveness” would narrow down the meaning somewhat. Efficiency and effectiveness relate to the quantification of useful consequences resulting from the use of the machine, relative to the effort that went into making the machine work. Effet in French, like effect in English, more broadly covers the consequences resulting from the use of the machine as a whole.

In the preface by Navier, Girard and de Prony, I think effet means what physicists today call work (travail, which is the term introduced by Coriolis in this very book and used by physicists today).

While effectiveness is basically work divided by input energy, this is a social consideration in that only certain effects are considered useful. Coriolis's book is about physics, and analyses physical measurements: work, energy, etc. I would say that effect is as effective a translation as any, and efficiency or effectiveness would be wrong — if the author had meant to write efficacité in French, he could have done so.

If you need to choose a word in a language that isn't etymologically related to French, the gist of the word effet is, what happens when the machine is used. It doesn't carry any implication of usefulness. A secondary consideration for translation would be to tie the use of the word to physics vocabulary, but this is somewhat difficult: readers in Coriolis's time may have understood a physical meaning of the word effet, but modern French readers don't, so even a translation into modern French would have to choose between respecting the everyday language meaning (so retain the word effet) and choosing a physical term (which could be travail [work] or possibly even energie). I would go for the everyday meaning, i.e. keep the title as it is.

  • @bobie I don't see how performance would be any better. You seem to be trying to write a different title, rather than trying to translate the title. In this case, [en] effect is a straightforward translation of [fr] effet, there is no false friend. Nov 29, 2014 at 13:39
  • As you said, it was written 200 years ago in non-scientific terms, so that everybody would understand. Now, what is the nearest thing we can imagine to give it a physics sense, knowing what it really mean? isn't 'work' to far?
    – user5582
    Nov 29, 2014 at 13:44
  • @bobie You use "work" in your ow question. And "work" is the word we learn in secondary-school physics. Wikipedia says, "The joule (/ˈdʒuːl/ or sometimes /ˈdʒaʊl/), symbol J, is a derived unit of energy, work, or amount of heat in the International System of Units."
    – ChrisW
    Dec 6, 2014 at 3:21

Both "Efficiency" or "effectiveness" add some kind of judgment of value (i.e. quality, performance) while the French "Effet" is neutral.

Both "Effet" and "Effect" are just about observing and measuring the results of what the "machine" produces without judging whether it is better than something else or not.


ADDED Dec. 6 to try to address the OP's comment to my original response (see far below for my original, unedited response):

So it seems that you want a suitable synonym for « Effect » that wasn’t specifically used by physicists to describe machines and their power prior to Coriolis’ innovation. Maybe that’s why Coriolis arrived at the seemingly curious choice of “Effet” because he didn’t want to be accused of using/borrowing a “better” word already used by his predecessors/competitors, and maybe it would be wise to accept/respect his choice and stick with “effect.’

But if you’re still searching, I would offer some final suggestions based on the “produire/to produce” sense of the word “effet”: “Ce qui est produit par une cause.”
So working with “to produce/product,” you could get to “the productivity of machines,” but like ‘Efficiency’ and ‘Effectiveness,’ ‘productivity’ could still imply a value judgment, although perhaps a bit less than the two “E” words.
To remain completely neutral using the “product” sense of “Effet,” you could perhaps use:

“the production capacity,” “the production capability,” or “the production potential” [of machines].

(Finally maybe adding “potential” before “productivity” [or even before “efficiency” or “effectiveness”] would help resolve the value judgment issue and retain neutrality in the translated title, i.e., “Calculation of the potential effectiveness/efficiency/productivity of machines.”)

(Original Response)

The more I read your question, the more I understand your desire to replace/"change" effect in the English title.
There's a meaning of effet, the French noun, that is "puissance transmise (par une force, une machine)" in my Le Robert-Micro and therefore, I think "Power" would be a suitable replacement that would convey in English both the (^)effect sense and the above physics sense conveyed by effet in the original French title.
(^)(Effect arguably could mean Power in the sense that:"She has an effect on me/She has a power over me)

(BTW, in checking the meaning of puissance, I actually found force and efficacité (!efficiency/effectiveness!) as synonyms under definition #3 (still in my Le Robert-Micro), but I agree with others that efficiency/effectiveness would be changing the meaning and adding a value judgment. "Calculation of the power of machines," however, would seem to maintain the neutrality found in the French title [and it would work for horses, too!]).

  • Thanks for your reply, you are right. But power is a definite physics unit and that is what Watt used and described. The innovation by Coriolis was to substitute that concept and unit of energy * second, the concept and unit of sheer energy, which at the time was expressed in Volt*Coulomb and after the 'Exposition Universelle' in 1889 was changed to Joule
    – user5582
    Dec 6, 2014 at 6:28

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