Year of total confusion
NINETEEN ninety six a bissextile year. Contrary to what you might infer from such a term, this has nothing to do with the ancient custom which allows ladies as well as gentlemen to propose marriage on February 29th. It recall the way in which the Romans gave an extra day to February. And I am very much indebted to Dr J. V. Luce of Trinity College Dublin, who explained it all to me on the occasion of the last Leap Year Day in 1992.
Rather inconveniently, the year by the latest reckoning is about some thing like 365.24219879 days in length. Before Julius Caesar's time, however, the Romans standard year was 355 days long or very close to 12 full lunar cycles. This, of course, was much too short. So every second year they inserted an extra month of 27 or 28 days to bring alternate years up to either 377 or 388 days. The whole arrangement, eccentric though it was, came very close to being correct on average, providing a mean year of 3661/4 days.
But when Julius Caesar took up office, however, he discovered that a most terrible thing had happened. The Pontifical College in Rome, whether by neglect or for some private reasons of its own, had failed to announce the extra month on no less than three separate occasions. So the Roman calendar by then was in a mess the vernal equinox, which ought to come around the end of March, was falling on the Ides of May, about eight weeks in arrears.
Caesar, advised by the astronomer Sosigines of Alexandria, decided that thence forth there would be a new standard Roman year of 3651/4 days. To make up the odd quarter, he decreed that every fourth year should have what was called an "inter-calary" day, an extra day accommodated by counting February 23rd twice.
And here things become a little complex. We would think of February 23rd as the fifth day before the end of that month. But the Romans counted both the first and the last day in such an interval so to them February 23rd was the sixth day before February 28th. The "extra" February 23rd, as they saw it, was provided by double counting the sextile or sixth day before month's end. Thus the Leap Year was bis sextilis possessed of two late February sextiles.
But first, in order to correct the lapses of his predecessors, Caesar had to add no fewer than three extra months to 45 BC, making it probably the longest year in human history. Very aptly, it became known as ultimus annus confusionis the Year of Total and Complete Confusion.