The double line represents the cæsura, which in rare instances falls a syllable later.
The Alcaic is, like the Sapphic, a four-line stanza. Its scheme is—
Lines 1 and 2, —ᴗ — | ᴗ — | — || — ᴗ ᴗ | — ᴗ —ᴗ
Line 3, —ᴗ — | ᴗ — | — — | ᴗ — | —ᴗ
Line 4, — ᴗ ᴗ | — ᴗ ᴗ | — ᴗ | — —ᴗ
That is to say, it consists of two eleven-syllable, one nine-syllable, and one ten-syllable Alcaic lines (Alcaici hendeka-, ennea-, and deka-syllabici). Much of the success of the stanza depends on the flow of the third line, which, according to the best models, should consist of three trisyllables (or equivalent combinations, e.g. a dissyllable noun with its monosyllabic preposition).
When it is stated that Horace wrote in four or five-and-twenty lyric measures, it will be obvious that I cannot exhaust, or attempt to exhaust, the list of measures in a work like this. The reader will have acquired some notion of the nature of classic versification, from what I have stated of Latin composition applying with unimportant differences to Greek. Those who have the leisure or the inclination might do worse than study Greek and Latin poetry, if only to see if they can suggest no novelties of metre. I can recall no English verse that reproduces Horace's musical measure:—
"Mĭsĕrār' est | nĕqu' ămōrī dărĕ lūdūm | nĕqŭe dūlcī
Mălă vīnō | lăvĕr' āut ēx|ănĭmārī | mĕtŭēntēs
Pătrŭǣ vēr| bĕră līnguǣ."