capitalized), and then by mentioning "the new Temperament" as contrasted with "the one that everyone uses". Accordingly, it does appear that for Huygens in 1691, "temperament ordinaire" was a phrase denoting just the temperament in ordinary use, with no sign that he was using this expression as a proper or conventional name or label; and it also appears that for him, the one in ordinary use was (quarter-comma) meantone temperament. 18th century The term was later used in the Encyclopédie of Diderot and D'Alembert, published in Paris in 1751–1772, which contains an article on temperament written by Jean-Jacques Rousseau. The article discusses the contrasting merits of equal temperament and of an arrangement referred to as "temperament ordinaire", "temperament" (without qualifier), and also as "the common rule of temperament", and gives practical instructions how to tune a keyboard to this temperament. In regard to the use of the expressions denoting the temperament in this article, it is noticeable that while all occurrences of the word 'temperament' in the original article stand italicized, the accompanying words, including 'ordinaire', never are. That seems to show that Rousseau was using the phrase just to denote descriptively what he regarded as usual, rather than as a proper name or conventional designatory label. As for the nature and identity of the temperament that Rousseau called the common one, the content of the article (see instructions reproduced below) leaves it clear that it was a circulating temperament, rather than the quarter-comma meantone referred to by Huygens about 60 years previously. It is relevant to reproduce here the actual instructions from the Encyclopedie (in translation) for tuning to "the common rule of temperament", so as to leave it clear where they are specific, and where they are vague: "To do this: 1st, start with the middle C of the keyboard, and narrow the first four fifths going up, until the fourth, E, makes a very true major third with the first note C; this is called 'the proof'. 2nd, Continuing to tune by fifths, as soon as one has arrived at the sharp notes, one then widens the fifths – even though the thirds suffer by it – and one stops when one has arrived at G#. 3rd, Return to C and tune the fifths going down, that is, F, B flat, and so on, widening them all the time, until one has arrived at D flat, which