I have recently come across a very compelling and rather shocking document on Latin pronunciation, quoting the Latin grammarians themselves, on exactly what the Romans had to say about the sound of consonantal u, which is most often spelled as v in contemporary texts. I have taken great pains to transfer the section dealing with consonantal U in full, with my own BBord italicizations, emphasis, and transliterations to add clarity. Notate: if I make a parenthetical comment, it will appear thus: {*L.E.: (comment)}:
· · ·
U (consonant) or V.
That the letter U performed the office of both vowel and consonant all the grammarians agree, and state the fact in nearly the same terms. Priscian says that they (I and U) seem quite other letters when used as consonants, and that it makes a great difference in which of these ways they are used:
[Keil. v. II. p. 13.] Videntur tamen > I > et > U > cum in consonantes transeunt quantum ad potestatem, quod maximum est in elementis, aliae litterae esse praeter supra dictis; multum enim interest utrum vocales sint an consonantes.
The grammarians also state that this consonant U was represented by the Greek digamma, which the Romans called “vau” also.
Marius Victorinus says:
[I. iii. 44.] Nam littera > U > vocalis est, sicut > A, E, I, O> , sed eadem vicem obtinet consonantis: cujus potestatis notam Graeci habent > V> , nostri “vau” vocant, et alii “digamma”; ea per se scripta non facit syllabam, anteposita autem vocali facit, ut > Vαμαχα, Vεκαεβολος > et > Vελεναε> . Nos vero, qui non habemus hujus vocis nomen aut notam, in ejus locum quotiens una vocalis pluresve junctae unam syllabam faciunt, substituimus > U > litteram.
Now it is contended by some that this “digamma,” or “vau,” was merely taken as a symbol, somewhat arbitrarily perhaps, and that it did not indicate a particular sound, but might stand for anything which the Romans chose to represent by it; and that therefore it gives us no certain indication of what the Latin U consonant was. But we are expressly told that it had the force and sound of the Greek “digamma.”
In Marius Victorinus we find:
[Keil. v. VI. p. 23.] > F > autem apud Aeolis dumtaxat idem valere quod apud
nos “vau” cum pro consonante scribitur, vocarique > [size=134]βαυ
et “digamma.”