E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Castor and Pollux.
What we call comazants. Electric flames sometimes seen in stormy weather playing about the masts of ships. If only one flame showed itself, the Romans called it Helen, and said that it portended that the worst of the storm was yet to come; but two or more luminous flames they called Castor and Pollux, and said that they boded the termination of the storm.