Invariable Calendar

In April 1900, Professor L. A. Grosclaude of Geneva proposed the Invariable Calendar, New Era Calendar, or Normal Calendar with 12 months and four 91-day quarters of exactly 13 weeks. An additional day, termed New Year's Day, that was not any day of the week and not part of any month, would occur between December 31st and January 1st. Another such day is inserted between June 31st and July 1st on leap years.

In this model, each date of the month (and quarter) would always occur on the same day of the week. Grosclaude lists many business advantages to this. The 15th and 30th always occur on weekdays

Proposed Calendar

Criticism

• Easter would break the religious tradition of following full moons.
• Difficulties of defining the dates of New Year's and Leap Days when they don't belong to any month or week.

Other Calendars and Proposals

• List of calendars: Reform calendars
• Calendar reform: Specific proposals

Sources

• A Proposed Plan For An Invariable Calendar, Sunday Magazine, David Friedman, June 25th, 2010 at 9:02 am, PDF
• A PROPOSED PLAN FOR AN INVARIABLE CALENDAR, June 26, 1910, The New York Times, Hedley P. Somner, PDF
• The Reform of the Calendar, Popular Astronomy, vol. 20, pp.232-236, 04/1912, Ralph E. Wilson, PDF
  • The Reform of the Calendar, Publications of the Astronomical Society of the Pacific, Vol. 24, No. 141, p.113, PDF
• Wanted—A Brand-New Calendar, Popular Science, Jan 1927, pp. 33-34, 134-135, Frank Parker Stockbridge
• THE REFORM OF THE CALENDAR, ALEXANDER PHILIP, 1914, Diagram, PDF