Note 40 — Chapter IV · THE MAN IN THE IRON MASK.
George Maidment translation
The Gregorian calendar was abolished by the National Convention in 1793, who decreed that September 22, 1792, should be regarded as the first day of a new era. The year was divided into twelve months, with names derived from natural phenomena. Nivose (snowy) was the fourth of these months. Thus, the period mentioned in the text includes from December 21, 1800, to January 19, 1801.—T.