Sonitus, qui graece phthongi dicuntur, in unoquoque genere sunt x et viii, e quibus viii sunt in tribus generibus perpetui et stantes, reliqui x, cum communiter  modulantur, sunt vagantes.
Sounds (which in Greek are called phthongi) are eighteen in number for each kind. Of these, eight are perpetually fixed in the three kinds; the remaining ten, when they are modulated in common, are found to vary.
final_alignments\Vitruvius_Architecture_Book_5.json