It is made up of stanzas of four lines, each of eleven syllables, the last four of which only have to follow a pattern, this consisting of two iambuses or an iambus and a spondee.
"The Literature of Ecstasy"
Albert Mordell
The spondee is found in solemn hymns or in any verse expressing reverence and awe.
"Browning and the Dramatic Monologue"
S. S. Curry
Bacon therefore was amply justified in making use of F as a long syllable to form the second half of a spondee.
"Bacon is Shake-Speare"
Sir Edwin Durning-Lawrence