Castor and Pollux
2 of the 7 encyclopedias on this shelf carry an entry for Castor and Pollux. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
in Greek and Roman mythology, twin sons of Leda, wife of Tyndareus, and Zeus, who was said to have wooed Leda in the form of a swan. In Homer they are represented as sons of Leda and Tyndareus and brothers of Clytemnestra and the beautiful Helen of Troy. Castor was famous for his skill in taming and managing horses; Pollux for knowledge of boxing and wrestling. The brothers were devotedly attached to each other and were inseparable companions in many adventures. They were among the heroes of the Argonautic expedition. On the voyage a terrible storm arose. While all were calling on the gods for assistance, two stars suddenly appeared above the heads of Castor and Pollux. The storm immediately subsided and thereafter the twin brothers were regarded as the special guardians of seamen. On their return from this expedition the brothers found that their sister Helen had been carried off by Theseus. They went to her rescue and were successful in bringing her home again. According to another account Pollux only was the son of Zeus. He was therefore immortal; but Castor, the son of Tyndareus, was mortal. The brothers became involved in a quarrel with Idas and Lynceus. Castor was slain, and Pollux, inconsolable, besought Jupiter to allow him to die too, unless Castor might share his immortality. Zeus consented that the two might divide their time between the lower world and the abodes of the gods. Still another story is that Zeus rewarded their fraternal affection by giving them a place among the stars. The two bright stars in the constellation Gemini, or "The Twins," are known as Castor and Pollux. The brothers received divine honors, especially among the Dorians. They were called Dioscuri, Sons of Jove. It was believed that in time of battle or great peril they occasionally appeared to mortals mounted on magnificent white steeds, clad in shining garments, and with stars above their heads. It is thus they are represented in ancient art. The electric flames sometimes seen to play about the masts of vessels during storms are often called Castor and Pollux. If only one flame appeared, the Romans called it Helen, and prophesied a continuation of the storm. If two flames were seen they were called Castor and Pollux, and boded a cessation of the storm. These lights are also called St. Elmo's fire. See St. Elmo'S Fire The names Castor and Pollux are of frequent occurrence in literature. In Acts xxviii: 11, we find St. Paul embarking in a ship named Castor and Pollux. But when the sons of Leda shed Their star-lamps on our vessel's head, The storm-winds cease, the troubled spray Falls from the rocks, clouds flee away, And on the bosom of the deep In peace the angry billows sleep.--Horace. So like they were, no mortal Might one from other know; White as snow their armor was, Their steeds were white as snow. Never on earthly anvil Did such rare armor gleam, And never did such gallant steeds Drink of an earthly stream. . . . . . . . . . . Back comes the chief in triumph Who in the hour of fight Hath seen the great Twin Brethren In harness on his right. Safe comes the ship to haven Through billows and through gales, If once the great Twin Brethren Sit shining on the sails.--Macaulay.
Collier's New Encyclopedia (1921)
two demigods known by the ancients under the joint name of Dioscuri, that is, sons of Zeus or Jupiter. Castor was celebrated as a horse tamer; Pollux for his prowess as a boxer. Homer describes them as sons of Leda and Tyndareus, King of Lacedemon, and, therefore, brothers of Helen. Hence, too, their patronymic of Tyndaridæ (sons of Tyndareus). Another fable ascribes their birth to an amour of Jupiter with Leda; while a third account makes Pollux and Helen only the fruit of this intercourse, and Castor the lawful son of Tyndareus, whence it was supposed that the latter was mortal, and Pollux immortal. The brothers are described as having first distinguished themselves by the rescue of their sister Helen, who had been carried off by Theseus. They were engaged in the celebrated hunt of the Calydonian boar; were sharers in the renowned expedition of the Argonauts; and, finally, in a war against Messene, undertaken for the purpose of chastising Idas and Lynceus, sons of the king of that country. Castor was slain by Idas, who was immediately struck dead by a thunderbolt from Jove, and Lynceus fell by the hand of Pollux. The latter, devotedly attached to his brother, besought Jupiter either to restore Castor to life or to deprive him himself of his immortality. On this, according to one story, Jupiter granted them alternate life, so that each lived or died daily-a term extended by some writers to six months of alternate life and death of each. Another version makes Jupiter reward their affection by translating the two brothers into constellations, under the name of Geministars which never appear together, but when one rises the other sets, and so on alternately. These demi-gods were chiefly worshipped as protectors of seamen, though they were supposed to be helpers of the brave generally. They are usually represented on medals, basreliefs, and gems, as youthful horsemen, with egg-shaped helmets crowned with stars, and spear in hand. The ancients very commonly swore "by Castor" (Æcastor) and "by Pollux" (Ædepol), as the English did by St. George, and the French by St. Denis.