Project:Old Style and New Style Dates
During Tchaikovsky's lifetime the calendar used throughout the Russian Empire was twelve days behind that used in the West. So, for example, the composer's birthdate was recorded in the Votkinsk registry of births as having occurred on Thursday 25 April 1840, which was exactly the same day as Thursday 7 May 1840 in western Europe and North America.
These differences were due to the adoption of the Gregorian calendar in most countries, while others (including the Russian and Ottoman empires) retained the earlier Julian calendar. In 1900 the two systems became further out-of-step, when Wednesday 28 February was followed by Thursday 29 February in countries using the Julian calendar, but by Thursday 1 March in those following the Gregorian. This 13-day difference lasted until the Gregorian calendar was introduced in most of Russia on 14 February 1918. Turkey did not fully adopt the new calendar until 1926.
While travelling outside Russia, Tchaikovsky often used both dating systems in his correspondence, e.g. "25 December 1879/6 January 1880". Unfortunately he did not always do this consistently (or accurately), but to avoid confusion the dual dating system is always used on our pages when referring to his letters (irrespective of his location at the time of writing his letters).
Many post–1918 publications from the Soviet Union and the Russian Federation still give the "Old Style" dates for events before February 1918, referring (for example) to Tchaikovsky's death on 25 October 1893, even though its anniversary is usually commemorated on the "New Style" date of 6 November. To prevent confusion in such cases, and if dual dating is either not possible or impractical, we have added the following abbreviations when referring to dates before February 1918:
- [O.S.] for "old style" dates following the Julian calendar, mainly used in Russia and the Ottoman Empire
- [N.S.] for "new style" dates following the Gregorian calendar, used in other countries
For example: "25 October/6 November 1893" = "25 October 1893 [O.S.]" = "6 November 1893 [N.S.]".