A confusion of metre and rhythm, which is, I believe, at the bottom of our false iambic system of prosody, is so common that it seems desirable to make some remarks on the subject before proceeding further. For this purpose, since I do not find myself able to put the matter more clearly in other language, I venture to borrow a little from what is said on the matter in my manual on English prosody, where it is more fully discussed.

Rhythm and Metre, though they have elements in common, are as entities quite distinct. Metre has reference to the metrical units or feet into which a line of verse can be divided, all of which must be (theoretically at least) of equivalent time-value. If they were not, it would be impossible to compare two lines with one another in respect of their length, saying that the one has three feet and the other five; there would be no common factor of measurement. It is because they can be divided into units and so measured, that verses are called ‘measures.’ Rhythm in its widest sense denotes movement in regular succession, or a succession of regular movements; thus the pendulum of a clock and a dancer's feet move in rhythm.