Sprung rhythm is a poetic rhythm designed to imitate the rhythm of natural speech. It is constructed from feet in which the first syllable is stressed and may be followed by a variable number of unstressed syllables. The British poet Gerard Manley Hopkins said he discovered this previously unnamed poetic rhythm in the natural patterns of English in folk songs, spoken poetry, Shakespeare, Milton, et al. He used diacritical marks on syllables to indicate which should be stressed in cases "where the reader might be in doubt which syllable should have the stress" (acute, e.g. shéer) and which syllables should be pronounced but not stressed (grave, e.g., gleanèd).
Some critics believe he merely coined a name for poems with mixed, irregular feet, like free verse. However, while sprung rhythm allows for an indeterminate number of syllables to a foot, Hopkins was very careful to keep the number of feet per line consistent across each individual work, a trait that free verse does not share. Sprung rhythm may be classed as a form of accentual verse, as it is stress-timed, rather than syllable-timed, and while sprung rhythm did not become a popular literary form, Hopkins's advocacy did assist in a revival of accentual verse more generally.
The Windhover
To Christ our Lord
I caught this morning morning's minion, king-
dom of daylight's dauphin, dapple-dawn-drawn Falcon, in his riding
Of the rolling level underneath him steady air, and striding
High there, how he rung upon the rein of a wimpling wing
In his ecstasy! then off, off forth on swing,
As a skate's heel sweeps smooth on a bow-bend: the hurl and gliding
Rebuffed the big wind. My heart in hiding
Stirred for a bird, – the achieve of, the mastery of the thing!
Brute beauty and valour and act, oh, air, pride, plume, here
Buckle! AND the fire that breaks from thee then, a billion
Times told lovelier, more dangerous, O my chevalier!
No wonder of it: shéer plód makes plough down sillion
Shine, and blue-bleak embers, ah my dear,
Fall, gall themselves, and gash gold-vermilion.