a.; also acronical, achronical, achronycal, acronichal. [f. prec. + -AL 1. Incorrectly spelt achronical, as if derived from χρόνος time; and with many intermediate forms.] Happening in the evening or at night-fall, vespertine, as the acronychal rising or setting of a star. (Sometimes used as if = Rising in the evening or at sunset and setting at sunrise; but this is not correct. When the rising is acronychal, the setting is cosmical, and vice versâ.)
1594. Blundeville, Exerc., IV. 35 (ed. 7), 492. Now to know the Acronical rising of any star at any time, bring the starre to the East part of the Horizon.
1622. Heylin, Cosmogr., III. (1682), 109. The rising and setting of the Stars, whether Heliacal, Acronical, Matutine, or Vespertine.
1642. More, Poems (1647), 173. At eventide when they rise Acronicall.
1697. Dryden, Virgil (1806), II. 159. The achronical rising … is when it appears at the close of day.
1751. Chambers, Cycl., s.v., The Achronychal is one of the three poetical risings, and settings of the stars; and stands distinguished from Cosmical and Heliacal.
1837. Whewell, Hist. Induct. Sci. (1857), I. 160. The acronycal and heliacal risings and settings of the stars.
1856. Burritt, Astron., 60 [Incorrect use.] When a star rose at sun-setting, or set at sun-rising, it was called the Achronical rising or setting.
