E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Every year divisible by four. Such years occur every fourth year. In ordinary years the day of the month which falls on Monday this year, will fall on Tuesday next year, and Wednesday the year after; but the fourth year will leap over Thursday to Friday. This is because a day is added to February, which, of course, affects every subsequent day of the year. (See BISSEXTILE.)
The ladies propose, and, if not accepted, claim a silk gown. St. Patrick, having driven the frogs out of the bogs, was walking along the shores of Lough Neagh, when he was accosted by St. Bridget in tears, and was told that a mutiny had broken out in the nunnery over which she presided, the ladies claiming the right of popping the question. St. Patrick said he would concede them the right every seventh year, when St. Bridget threw her arms round his neck, and exclaimed, Arrah, Pathrick, jewel, I daurnt go back to the girls wid such a proposal. Make it one year in four. St. Patrick replied, Bridget, acushla, squeeze me that way agin, an Ill give ye leap-year, the longest of the lot. St. Bridget, upon this, popped the question to St. Patrick himself, who of course, could not marry; so he patched up the difficulty as best he could with a kiss and a silk gown.
The story told above is of no historic value, for an Act of the Scottish Parliament, passed in the year 1228, has been unearthed which runs thus:
Ordonit that during ye reign of her maist blessed maiestie, Margaret, ilka maiden ladee of baith high and lowe estait, shall hae libertie to speak ye man she likes. Gif he refuses to tak hir to bee his wyf, he shale be mulct in the sum of ane hundridty pundes, or less, as his estait may bee, except and alwais gif he can make it appeare that he is betrothit to anither woman, then he schal be free.