1911 Encyclopædia Britannica/Alcyone

ALCYONE, or Halcyone, in Greek mythology, daughter of Aeolus and wife of Ceyx. For their presumption in calling themselves Zeus and Hera they were changed into birds—Alcyone into a diver, Ceyx into a kingfisher. According to another story, Ceyx was drowned and his body cast on the shore. His wife found the body, and the gods, out of compassion, changed both her and her husband into kingfishers. By command of Zeus (or Aeolus) the winds ceased to blow during their brooding-time, for seven days before and after the shortest day, that their eggs might not be carried away by the sea. Hence the expression “halcyon days,” used in ancient and modern times to denote a period of calm and tranquillity.

Apollonius Rhodius i. 1087; Ovid, Metam. xi. 410 et seq.; Hyginus, Fabulae, 65.