NOCTURN, or Nocturne (Lat. nocturnus, of or belonging to the night, nox), in the Roman Church, one of the three divisions of the office of matins, corresponding with the vigils, beginning at 9 P.M. midnight and 3 A.M. respectively. The service consists of psalms, lessons and antiphons (see Breviary). The term “nocturne” is applied to a musical composition, answering to the earlier “serenade,” of a quiet, dreamy and romantic character. The name and style are said to have originated with John Field (1782–1837). The best-known compositions of this kind are the pianoforte pieces of Chopin. J. McNeill Whistler also introduced the term into painting by using the name for some of his night-pieces. A “nocturnal” is an instrument for finding the hour of the night by observation of the relative positions of the pole-star and other stars, generally the pointers of Ursa Major. The British Museum contains a fine nocturnal made about 1560 by Humfray Cole (see Navigation).