Ten days that set the world to right


If you have difficulty coping with the new millennium and the change of date involved, spare a thought for those who had an even bigger change to cope with on New Year's Day in 1583. On that day, the Gregorian calendar was introduced in several parts of Europe.

In 1572, Ugo Buoncompagne ascended St Peter's throne as Gregory XIII. It was a challenging time for the Roman church, which was faced with the loss, not just of individuals, but of whole nations following the rise of European Protestantism. Gregory did his best to stem this tide, but his real place in history was assured by the major reform of the western calendar undertaken during his reign.

Julius Caesar had carried out the last big correction some 1,600 years earlier. But the length of the Julian year was not exactly right; at 365.25 days, it was longer than the solar year by 11 minutes and 14 seconds, with the result that the vernal equinox that Caesar had carefully manoeuvred to March 21st had now, by Gregory's time, slipped back again to March 11th.

The vernal equinox was of great importance to the church authorities, because it was a linchpin for the date of Easter.

In 1545, the Council of Trent ordered action to correct the error and, by the time Gregory was elected, he found at his disposal a number of constructive suggestions from the astronomer Aloysius Lilius which he agreed to promulgate by papal bull.

The bull itself took another decade to prepare, and was finally issued in February 1582. It decreed, among other things, that the day following the feast of St Francis that year, October 5th, 1582, was to become October 15th, eliminating the 10 days which had become superfluous.

The new calendar was adopted in Catholic countries throughout Europe, if not on the appointed day, at least within a decent interval, and on New Year's Day, 1583, the change was implemented in many parts of Germany and Switzerland.

In Protestant countries, however, and in those of the Orthodox persuasions, it became almost a matter of principle to resist the proposal, no matter how sensible the changes it implied might seem. It was therefore not until nearly 200 years later, in 1752, that the new-style calendar was adopted in England, by which time it was necessary to lose 11 days to bring the seasons into line.

Russia changed only after the Bolshevik revolution in 1917, and Greece, the last European country to conform, did so as recently as 1923, when a 13-day adjustment was required.