E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
or Shower of gold. A bribe, money. The allusion is to the classic tale of Jupiter and Dana. Acrisios, King of Argos, being told that his daughters son would put him to death, resolved that Dana should never marry, and accordingly locked her up in a brazen tower. Jupiter, who was in love with the princess, foiled the king by changing himself into a shower of gold, under which guise he readily found access to the fair prisoner.