Some scholars, however, hold that the cyclic dactyl had approximately the value 1½ + ½ + 1, or
, and mark it –⏑ ⏑. In like manner they mark the cyclic anapaest ⏑ ⏑–. The true nature of these cyclic feet is very uncertain.
[Irrational Syllables and Feet.]
[2524.] A long syllable sometimes stands in place of a short. A syllable thus used is called irrational (marked >) because it destroys the normal ratio between arsis and thesis. The foot which contains such a syllable is itself called irrational. The most common irrational foot is the irrational spondee (– > when it stands for a trochee; >– when it replaces an iambus), which is found in iambic, trochaic, and logaoedic rhythms.
Probably the irrational long suffered a slight correption ([2517]), so that its duration was between that of the ordinary long and that of a short syllable.
[2525.] The different rhythms or metres are named trochaic, iambic, &c., according to their fundamental feet.
[2526.] Much of the Latin poetry (though not by any means all) was written to be sung. The Greeks and Romans employed in their music not only common (or 2/4) time and triple (3/8, 3/4) time, but also 5/8 time, which last is very rarely used in modern music.
[2527.] The Greek and Roman metricians divided the rhythms into three classes, according to the ratio between arsis and thesis in their fundamental feet. These classes were:— (a.) the Equal Class (γένος ἴσον, genus pār) in which thesis and arsis are equal in duration, as in dactylics, anapaestics, &c.; (b.) the Double Class (γένος διπλάσιον, genus duplex) in which the thesis has twice the duration of the arsis, as in trochaics, iambics, &c.; (c.) the Hemiolic Class (γένος ἡμιόλιον, genus sēscuplex) in which the thesis has one and a half times the duration of the arsis, as in bacchiacs, cretics, etc.