The measure of the song is anapestic (that is, with the accent on every third syllable), with modifications.
A poetic foot of three syllables which bears the accent on the third syllable is called an anapestic foot.
Technically the poem is anapestic tetrameter much varied by the introduction of iambic feet.
Anapestic feet are used freely to improve the music; in fact, they are nearly as numerous as the iambic feet.
Again we find, especially in dactyllic and anapestic lines, a trochee or spondee thrown in to vary the movement.
Here we have a hexameter which is neither iambic nor anapestic, but a combination of the two rhythms.
Often it seems to an English reader to have an anapestic effect, and to be best described as anapestic tetrameter.
Virgilius Mars wrote in hexameters; Horatius Flaccus in alcaic, sapphic, and anapestic verse.
There is evident a tendency toward the rising verse and the anapestic foot.
In like manner we have anapestic lines of all lengths from monometer to hexameter.