Inférence de la mensuration

Subject of this page
Finding hints allowing to guess mensuration (including modes) in the absence of any explicit sign.

According to Blockland de Montfort
on his pages 28 and 29 :

	We've seen the external signs, let's now talk about the internal ones, namely the presence of some black notes, & the disposition of rests, by which can be deduced perfect mensuration. First, when one will come upon three black maximas, or double rests laying across three line spaces, inside the song; or immediately after the tempus sign, they will prove perfect major mode: & each [black] maxima will weight two longuas, loosing one third of its value, provided there's no perfection dot in their neighbourhood.
	Secondly, when one will similarly come upon three black longuas, or a rest over three line spaces, the song will be of perfect minor mode : & each [black] longua will weight two breves.
	Thirdly, coming upon three black breves, or double semibreve rests at same height, then the song will be of perfect time: & each [black] breve will weight two semibreves.
	Fourthly, coming upon three black semibreves, or double minim rests at same height, then the song will be of major prolation:&and [black semibreves] will loose one third of their value.

According to Jean Yssandon
on his page 20 :

Though mode, time & prolation have their own signs, if one is able to know about them without these signs, that's because of so called internal signs. Thus perfect minor mode can be known when coming upon a dot inside a sequence of two breves laying between two longuas: it's also known when coming upon three black longuas, or a rest extending over four lines.

Perfect time can also be known when coming upon three, six, or nine coloured breves, if not under hemiola proportion: and also two semibreve rests at same height, or two semibreves included between two breves, the former ones beeing separated by a dot; it's also known, and quite often, when several breve+semibreve sequences are found one after the other.

Perfect prolation is known when coming upon three or several blackened semibreves: or two minim rests standing up on the same line. or a dot between two minims themselves included between two semibreves.

Disclaimer : strange punctuation by the early authors, not by me :-)

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