A Short Guide to Calendars
with particular attention to Western Europe
In England the Julian calendar was in use until 1752, since then the Gregorian calendar has been used. These two calendars are very similar but the Julian year is slightly longer, by three days in 400 years. Although the difference is quite small it is not insignificant - over the centuries these days would accumulate until a change became necessary.
The Julian calendar, named after Julius Caesar, was introduced to the Roman empire on 1st January 45 BC. This calendar was to continue in use for many centuries until it was replaced by the more accurate Gregorian calendar from the late 1500s. The exact date of this change varied from country to country.
The length of the perfect calendar year would be exactly the same as the length of the natural year, and therefore the seasons would remain fixed. For example the first day of spring, the spring equinox, when day and night are of equal length would occur on the same day year after year. If the calendar year were longer or shorter than the natural year the spring equinox would fall consistently earlier or later each year until a noticeable error was produced. This is exactly what happened with the Julian calendar, by the sixteenth century the equinoxes were falling ten days earlier than they had been at the time of its introduction. If nothing was done the difference would continue to grow.
At that time the Church held sway in most matters in the western world. It had become concerned about the spring or vernal equinox, the date of which was used to calculate the date of Easter. The formula for fixing Easter was decided in 325, at that time the vernal equinox was on 20/21 March. By 1582 this event had moved to 10/11 March and in that year Pope Gregory XIII corrected the problem by omitting 10 days from the calendar, Thursday 4th October was to be followed by Friday 15th October.
As might have been expected, protestant countries asserted their independence by ignoring the papal ruling. Britain managed to resist changing until 1752. So for almost two centuries journeys across Europe often involved a change of date as a border was crossed. The Orthodox countries, Greece and Russia, resisted change until the twentieth century.
The new calendar was called Gregorian after the pope, it had fewer leap years and this reduced length would ensure that further errors did not accumulate.
This confusing entry is found in Samuel Pepys's diary on 1st January 1666. Although the legal year 1666 was not to start until 25th March, the first day of January was still called 'New Yeares Day'. To save confusion (or perhaps to add to it) people often identified the year between these two days in this or similar fashion.
When introducing the Gregorian calendar in 1752 England also changed the first day of the official year; In Scotland this has already happened in 1600.
