The clerk or precentor read aloud the words of each line in a hymn (with the accompaniment of a melodic variation) before the congregation sang it (with simple instrumental accompaniment). It allowed members of the congregation who could not read to take part in the singing.

Lining out - title page

Lining out (mp3)

Psalm 119, in Daniel Purcell, The Psalms Set full for the Organ or Harpsicord as they are Plaid in Churches and Chappels in the mañer given out; as also with their Interludes of great Variety (London: I. Walsh, n.d. [1718]),
St. Mary’s College chapel choir, Durham university (UK)
Directed by Alice Stevenson
Private recording in St. Mary’s College chapel, 2 December 2015.
 

Lining out - score part 1

Lining out - score part 2