[The following memorial lines are by no means modern. They occur, with slight variations, in an old play, called 'The Returne from Parnassus,' 4to, Lond. 1606; and another version may be seen in Winter's 'Cambridge Almanac' for 1635. See the 'Rara Mathematica,' p. 119.]

Thirty days hath September,
April, June, and November;
February has twenty-eight alone,
All the rest have thirty-one,
Excepting leap-year, that's the time
When February's days are twenty-nine.