[Id. ib. p. 32.] K et q supervacue numero litterarum inseri doctorum plerique contendunt, scilicet quod c littera harum officium possit implere.
The grammarians tell us that k and q are always found at the beginning of a syllable:
[Prise. Keil. v. III. p. 111.] Q et k semper initio syllabarum ponuntur.
They say also that the use of q was more free among the earlier Romans, who placed it as initial wherever u followed,—as they placed k wherever ă followed,—but that in the later, established, usage, its presence was conditioned upon a vowel after the u in the same syllable:
[Donat. Keil. v. IV. p. 442.] Namque illi q praeponebant quotiens u sequebatur, ut quum; nos vero non possumus q praeponere nisi ut u sequatur et post ipsam alia vocalis, ut quoniam.
Diomedes says:
[Keil. v. I. p. 425.] Q consonans muta, ex c et u litteris composita, supervacua, qua utimur quando u et altera vocalis in una syllaba junguntur, ut Quirinus.
R is trilled, as in Italian or French:
[Mar. Vict. Keil. v. VI. p. 32.] Sequetur r, quae, vibratione vocis in palato linguae fastigio, fragorem tremulis ictibus reddit.
S seems to have had, almost, if not quite, invariably the sharp sound of the English s in sing, hiss.