Compound measures are such as contain more than two or three beats, and they must always be multiplications, or groups, of a Simple measure; for whether so small as to comprise only the fundamental groups of two or three beats (as in 2-4, 3-8, 3-4 measure), or so large as to embrace as many as twelve beats or more (as in 4-4, 6-4, 6-8, 9-8, 12-8 measure), the measure represents, practically, either the duple or triple species, Simple or Compound.

Thus, a measure of four beats, sometimes called (needlessly) quadruple rhythm, is merely twice two beats; the species is actually _duple_; the alternation of heavy and light pulses is regular; and therefore the third beat is again an accent, as well as the first, though _less heavy_.

A measure of 6-8 is triple species, with accents at beats one and four, precisely as if an additional vertical bar were inserted after the third beat.

In a word, then, the size of the adopted measure is of no consequence, as long as it is retained uniformly through the section to which it belongs; and there is no _real_ difference between 2-4 and 4-4 measure, excepting in the number of bars used.
A curious and rare exception to this rule of the compound measure occurs when five or seven beats are grouped together.

This involves a mingling of the duple and triple species, and, consequently, an irregular disposition of the accents; for instance, 5-4 measure is either 3+2 or 2+3 beats, with corresponding accentuation: [Illustration: Beat accentuation] RHYTHM .-- This word signifies arrangement,--a principle applied, in music, to the distribution or arrangement of the tones according to their various _time-values_.