Although the metrical system in English poetry is predominantly qualitative, quantitative meter, too, has been attempted in English language, but not with much success because of the nature of English language. Quantitative metrical system is used mainly in Classic Greek, Classical Latin and Italian poetry.
Quantitative meter is when the rhythm of a verse is determined based on the length of the time it takes to articulate the syllables and/or consonants in a verse, and not by the number of stressed or unstressed syllables there are in a verse.
An example of quantitative meter in English language is Edmund Spenser's poem Iambicum Trimetrum.