[28]. For the intermediate sound ([103]) between i and u, as in the first syllable of lubet, libet, it pleases, and in the second syllable of optimus, optumus, best (Quint. 1, 4, 8; 7, 21), the emperor Claudius invented a separate character. It failed of acceptance, as did also the sign which he attempted to introduce for ps.
[29]. The same characters were ordinarily used to denote both long and short vowels. But at different periods long vowels were sometimes indicated in inscriptions thus:
([1.]) Long a, e, or u was sometimes doubled: as, AARA, altar; PAASTORES, shepherds; LEEGE, by law; IVVS, right. This doubling, which was never frequent, seems to have been introduced into Latin from the Oscan by the poet Accius. It occurs most frequently in inscriptions about the year 150 B.C., but sporadically much later: as, CONVENTVVS, of the assembly; ARBITRATVV, by the decree; and in other stems in -u- ([593]).
([2.]) Long i was often denoted (a.) By the spelling ei (after the pronunciation of this diphthong had been changed to ī, [98]): as, DAREI, be given; REDIEIT, hath come back; INTERIEISTI, hast died. Some Roman grammarians prescribed this spelling for every long i; others tried to regulate the use of ei for ī by special rules. At the end of the republic, the spelling EI had given way to uniform I. (b.) Since the time of Sulla, by a taller letter (‘i longa’): as, fIxa, fastened ([23], [24]).
([3.]) A mark called an apex (
) was often put over a long vowel: as, FE͆CIT, made; HORTE͆NSIVS; DVV͆MVIRATVS, duumvirate. The apex was written ´ in the imperial age; the form -, which occurs in an inscription, was adopted by the grammarians, and is still in use to mark the long vowels. It may be mentioned that inscriptions which employ the apex are by no means consistent in its use, and that late inscriptions have it over short and long vowels, apparently for decorative purposes. Quintilian 1, 7, 2 prescribes it only for cases which otherwise might be ambiguous: as, MÁLVS (mālus), mast, to distinguish it from MALVS (malus), bad.
[30]. In schoolbooks, a long vowel is indicated by a horizontal line over it: as, āra, altar; mēnsis, month; ōrdō, series. A short vowel is sometimes indicated by a curved mark: as, pĕr, through; dŭx, leader; but this mark is unnecessary if long vowels are systematically marked. Usually the quantity of the vowels in each word is definitely fixed; but in a few cases the same vowel may be now short, now long, as in English the ee of been is pronounced long by some (bean), short by others (bin). Thus ([2446]) mihi, ibi were sometimes pyrrhics (⏖, [2522]), sometimes iambi (⏑-, [2521]). See for other cases [134], [2443], [2452], [2453]. Such vowels of variable quantity are termed common and marked ⏓ or ⏒: as mihī̆, to me ([2514]).
[PRONUNCIATION.]
[31]. The pronunciation of Latin sounds may be approximately determined: (a) from the description of the native grammarians and incidental allusions in other Latin authors; (b) from variations in spelling; (c) from the Greek transliteration of Latin words; (d) from the Latin transliteration of foreign words; (e) from the development of the sounds in languages derived from the Latin.