§ 523. _Measures._--For every accented syllable in the following line, write the letter a, and for every unaccented one, the letter x, so that a may stand for an accent, x for the absence of one-- The wáy was lóng, the wínd was cóld.--SCOTT. or expressed symbolically x a x a x a x a, where x coincides with _the_, a with _way_, &c. § 524. Determine the length of the line in question.--It is plain that this may be done in two ways. We may either measure by the syllables, and say that the line consists of eight syllables; or by the accents, and say that it consists of four accents. In this latter case we take the accented syllable with its corresponding unaccented one, and, grouping the two together, deal with the pair at once. Now, a group of syllables thus taken together is called a _measure_. In the line in question _the way_ (x a) is one measure, _was long_ (x a) another, and so on throughout; the line itself consisting of four measures. § 525. _Trisyllabic measures._--The number of measures consisting of two syllables, or dissyllabic measures, is necessarily limited to two, expressed a x and x a respectively. But beyond these there are in the English language measures of three syllables, or trisyllabic measures. The number of these is necessarily limited to three. The first of these is exhibited in the word _mérrily_ (a x x). Mérrily, mérrily sháll I live nów, Únder the blóssom that hángs on the boúgh.--SHAKSPEARE. The second is exhibited by the word _disáble_ (x a x). But vaínly thou wárrest, For thís is alóne in Thy pówer to decláre, That ín the dim fórest Thou heárd'st a low moáning, And sáw'st a bright lády surpássingly faír.--COLERIDGE. § 526. The third is exhibited by the word _cavaliér_ (x x a). There's a beaúty for éver unfádingly bríght, Like the lóng ruddy lápse of a súmmer-day's níght.--MOORE. When grouped together according to certain rules, measures form lines and verses; and lines and verses, regularly arranged, constitute couplets, triplets, and stanzas, &c. § 527. The expression of measures, lines, &c., by such symbols as a x, x a, &c., is _metrical notation_. § 528. _Rhyme._--We can have English verse without _rhyme_. We cannot have English verse without _accent_. Hence accent is an _essential_; rhyme an _accessory_ to metre.