Seated ín thy sílver chaír,
Státe in wónted spléndour keép.
Hésperús invókes thy líght,
Góddess, éxquisítely bríght.—Ben Jonson.
In all these lines the last measure is deficient in a syllable, yet the deficiency is allowable, because each measure is the last one of the line. The formula for expressing faír, sléep, chaír, &c. is not a, but rather a x followed by the minus sign (-), or a x-.
A little consideration will show that amongst the English measures, x a and x x a naturally form single, a x and x a x double, and a x x treble rhymes.
[§ 540]. The chief metres in English are of the formula x a. It is only a few that are known by fixed names. These are as follows:—
1. Gay's stanza.—Lines of three measures, x a, with alternate rhymes. The odd (i.e. the 1st and 3rd) rhymes double.
'Twas when the seas were roaring