Calendar Wiki

Alternate month names for use with the Hanke-Henry Permanent Calendar and for use with the World Calendar with Leap Weeks[]

Dr. Dick Henry of John Hopkins University  has developed a leap week calendar called the Hanke Henry Calendar.  The Hanke Henry Calendar uses months with the lengths of 30:30:31 (i.e. 30-30-31–30-30-31–30-30-31–30-30-31, +7 in leap year).  But, as in Dr. Bromberg’s Symmetry Calendars, he uses the names of the current months of the Gregorian Calendar for the names of the months in the Hanke Henry Calendars.  This can cause some confusion when trying to determine to which calendar the given date refers.

Also, there is a proposal to use the format of the World Calendar with Leap Weeks. The World Calendar uses months with lengths of 31:30:30 (i.e. 31-30-30-31-30-30-31-30-30-31-30-30).

To help alleviate this confusion, and to facilitate the use of either calendar simultaneously with the current Gregorian Calendar, Walter Ziobro likewise proposed the use of unique alternate month names for use with the Hanke Henry Calendar, and with the World Calendar with Leap Weeks. The base of each name is derived from the corresponding Gregorian month name.

Dr. Henry has proposed a leap year rule in which the leap week is added to any year that begins or ends on Thursday in the Gregorian Calendar.  This is virtually the same as the rule for the 53rd, or leap week, in the ISO 8601 week dating system, The only difference is that Dr. Henry starts each year on a Sunday, instead of a Monday.  

The proposal for the World Calendar with Leap Weeks uses a 62-year leap week cycle.  Ziobro would replace that rule  with the ISO 8601 leap week rule to make it compatible with other proposals using the same rule. Like the Hanke Henry calendar, the World Calendar with Leap Weeks begins on a Sunday.  Also, Ziobro adds the leap week to the end of the last month.    

Unique 3-letter abbreviations are in parentheses; 
Hanke-Henry   Length ISO weekday start World Leap Week Length ISO weekday start
Janus (Jas) 30 days W52-7* Janus (Jas) 31 days W52-7* 
Februs  (Fbs)  30 days W05-2 Febum (Fbm) 30 days W05-3 
Marcus (Mrs) 31 days W09-4 Marchum (Mrm) 30 days W09-5
Aprilus (Aps) 30 days W13-7 Aprilus (Aps) 31 days W13-7 
Mayus (Mys) 30 days W18-2 Mayum (Mym) 30 days W18-3 
Junus (Jns) 31 days W22-4 Junum (Jnm) 30 days W22-5
Julus (Jls) 30 days W26-7 Julus (Jls) 31 days W26-7 
Augustus (Aus) 30 days W31-2 Augustum (Aum) 30 days W31-3 
Septus (Sps) 31 days W35-4 Septum (Spm) 30 days W35-5
Octus (Ocs) 30 days  W39-7 Octus (Ocs) 31 days W39-7 
Novus (Nvs) 30 days  W44-2 Novum (Nvm) 30 days W44-3 
Decus (Dcs) 31/38 days W48-4 Decum (Dcm) 30/37 days W48-5 

*W53-7 in year after leap week.

Note: Recently the Hanke-Henry website has been displaying a modified version of their calendar, which retains the 30-30-31 month-day quarter format, but which begins each quarter on a Monday. This revision can be used with the following alternate names:

Janum (Jam) 30 days W01-1
Februm (Fbm) 30 days W05-3
Marchum (Mrm) 31 days W09-5
Aprilum (Apm) 30 days W14-1
Mayum (Mym) 30 days W18-3
Junum (Jnm) 31 days W22-5
Julum (Jim) 30 days W27-1
Augustum (Aum) 30 days W31-3
Septum (Spm) 31 days W35-5
Octum (Ocm) 30 days W40-1
Novum (Nvm) 30 days W44-3
Decum (Dcm) 31/38 days W48-5