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603. The following are General Rules of Quantity (cf. §§ 9-11):

Quantity of Vowels

a. Vowels. A vowel before another vowel or h is short: as, vĭa, trăhō .


  1. In the genitive form -ius,ī is long: as, utrīus , nūllīus . It is, however, sometimes short in verse (§ 113. c).
  2. In the genitive and dative singular of the fifth declension, e is long between two vowels: as, diēī; otherwise usually short, as in fidĕī , rĕī , spĕī .

    Note.--It was once long in these also: as, plēnus fidēī (Ennius, at the end of a hexameter). A is also long beforeī in the old genitive of the first declension: as, aulāī.

  3. In the conjugation of fīō , i is long except when followed by er . Thus, fīō , fīēbam , fīam , but fĭerī,fĭerem; so alsofĭt (§ 606. a. 3).
  4. In many Greek words the vowel in Latin represents a long vowel or diphthong, and retains its original long quantity: as, Trōes (Τρῶες),Thalīa (Θαλεῖα). hērōas (ἥρωας), āēr (ἄηρ).

    Note 2.--But many Greek words are more or less Latinized in this respect: as,Acadēmī˘a,chorē˘a, Malĕa , platĕa .

  5. In dīus , in ē˘heu usually, and sometimes inDī˘āna andō˘he, the first vowel is long.
b. Diphthongs. A Diphthong is long: as, foedus , cui ,1 aula .

Exception.—The preposition prae in compounds is generally shortened before a vowel: as, praĕ-ustīs (Aen. 7.524), praĕ-eunte (id. 5.186).

Note.-- U following q, s, or g, does not make a diphthong with a following vowel (see § 5. N. 2). For â- , -ior , pê-ior, etc., see § 11. d and N.

c. Contraction. A vowel formed by contraction (crasis) is long: as, nīl, from nihil; cōgō for †co-agō; mālō for mā-volō.

Note.--Two vowels of different syllables may be run together without full contraction ( synizēsis , § 642): as, deinde (for deinde ), ms (for meōs ); and often two syllables are united by Synæresis (§ 642) without contraction: as when părĭĕtĭbŭs is pronounced paryĕtĭbus.

d. A vowel before ns, nf, gn, is long: as, īnstō , īnfāns , sīgnum .

Quantity of Syllables

e. A syllable is long if it contains a long vowel or a diphthong: as, -rus , ō-men, foe-dus .

f. Position. A syllable is long by position if its vowel, though short, is followed by two consonants or a double consonant: as, adventus , cortex .

But if the two consonants are a mute followed by 1 or r the syllable may be either long or short (common); as, alacris or alăcris; patris or pătris .

Vowels should be pronounced long or short in accordance with their natural quantity without regard to the length of the syllable by position.

Note 1.--The rules of Position do not, in general, apply to final vowels before a word beginning with two consonants.

Note 2.--A syllable is long if its vowel is followed by consonant i (except in bĭiugis, quadrĭiugis): see § 11. d.

Note 3.--Compounds of iaciō , though written with one i, commonly retain the long vowel of the prepositions with which they are compounded, as if before a consonant, and, if the vowel of the preposition is short, the first syllable is long by position on the principle of § 11. e.

    obicis hostī (at the end of a hexameter, Aen. 4.549).
    inicit et saltū (at the beginning of a hexameter, Aen. 9.552).
    prōice tēla manū (at the beginning of a hexameter, Aen. 6.836).

Later poets sometimes shorten the preposition in trisyllabic forms, and prepositions ending in a vowel are sometimes contracted as if the verb began with a vowel.

  1. (1) cūr an|nōs ŏbĭ|cis (Claud. iv C. H. 264).
  2. (2) reīcĕ că|pellās (Ecl. 3.96, at end).

Note 4.--The y or w sound resulting from synæresis (§ 642) has the effect of a consonant in making position: as, abietis (abyetis), fluviōrum (fluvyōrum). Conversely. when the semivowel becomes a vowel, position is lost: as, sĭlŭae, for silvae .


1 Rarely dissyllabic cŭĭ (as Mart. 1.104.22 ).

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