A calendar is convenient for regulating civil life and religious observances and for historical and scientific purposes. The word is derived from the Latin calendarium, meaning “interest register” or “account book,” itself a derivation from calendae (or kalendae), the first day of the month in the Roman republican calendar, the day on which future market days, feasts, and other occasions were proclaimed.
The development of a calendar is vital for the study of chronology, since this is concerned with reckoning time by regular divisions, or periods, and using these to date events. It is essential, too, for any civilization that needs to measure periods for agricultural, business, domestic, or other reasons. The first practical calendar to evolve from these requirements was the Egyptian, and it was this that the Romans developed into the Julian calendar that served western Europe for more than 1,500 years. The Gregorian calendar was a further improvement and has been almost universally adopted because it satisfactorily draws into one system the dating of religious festivals based on the phases of the Moon and seasonal activities determined by the movement of the Sun. Such a calendar system is complex, since the periods of the Moon’s phases and the Sun’s motion are incompatible; but by adopting regular cycles of days and comparatively simple rules for their application, the calendar provides a year with an error of less than half a minute.
The basic unit of computation in a calendar is the day. Although days are now measured from midnight to midnight, this has not always been so. Astronomers, for instance, from about the 2nd century CE until 1925, counted days from noon to noon. In earlier civilizations and among primitive peoples, where there was less communication between different settlements or groups, different methods of reckoning the day presented no difficulties. Most primitive tribes used a dawn-to-dawn reckoning, calling a succession of days so many dawns, or suns. Later the Babylonians, Jews, and Greeks counted a day from sunset to sunset, whereas the day was said to begin at dawn for the Hindus and Egyptians and at midnight for the Romans. The Teutons counted nights, and from them the grouping of 14 days called a fortnight is derived. [Britannica]
Between 6-11th December the three calendars will be available in e-book format from Kindle for UK£0.99/US$0.95 as a special offer. Otherwise, they are available in paperback direct from the printer at a special discounted price …
Old Year, Old Calendar, Old Ways – Melusine Draco ISBN: 9781788762052 : Paperback : Pages 210 : £8.95. To order: https://www.feedaread.com/books/Old-Year-Old-Calendar-Old-Ways-9781788762052.aspx
The Roman Book of Days: The Calendar of Ancient Rome – Pauline Erina ISBN: 9781786971517 : Paperback : Pages 144 : £6.85 To order: https://www.feedaread.com/books/The-Roman-Book-of-Days-9781786971517.aspx
The Calendar of Ancient Egypt: Melusine Draco (revised and expanded edition) ISBN: 9781788765831 : Paperback :Pages 202 : £7.95 To order: https://www.feedaread.com/books/The-Calendar-of-Ancient-Egypt-9781788765831.aspx