The Edwards perpetual calendar was proposed by Willard Eldridge Edwards in 1943[1]. Dr. Edwards claimed that he had worked his plan out as a student in 1918-1919. It resembles the World Calendar of Elisabeth Achelis in having 91-day quarters containing one 31-day month and two 30-day months, with one intercalary day (after the last day) in normal years and two (after the last day of June and the last day of the year) in leap years, not assigned a day of the week or a month and date, to make it perpetual. The differences are in details:
In the World Calendar, the 31-day month is the first month of each quarter, namely January, April, July, and October. In the Edwards perpetual calendar, the 31-day month is the third month of each quarter, namely March, June, September, and December.
Years in the World Calendar begin on Sunday; years in the Edwards perpetual calendar on Monday.
Edwards suggested the mnemonic "30-30-31; Monday-Wednesday-Friday" for the quarterly pattern. This gives the lengths and first days of the week of the three months in each quarter.
January, April, July, October
Mon
Tue
Wed
Thu
Fri
Sat
Sun
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
February, May, August, November
Mon
Tue
Wed
Thu
Fri
Sat
Sun
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
March, June, September, December
Mon
Tue
Wed
Thu
Fri
Sat
Sun
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
L
Advantages and disadvantages[]
Most of the advantages and disadvantages of the Edwards perpetual calendar are identical to those of the World Calendar, however, some people may prefer to have the years begin on Sunday, the first day of the week, and others on Monday, the first day of the business week; also, since Monday, Wednesday, and Friday are often grouped together, the Edwards mnemonic can make it easier to memorize the calendar.
References[]
↑W. E. Edwards, Edwards perpetual calendar, Printed by Honolulu star-bulletin, Ltd., 1943
See also[]
Aristean Calendar – a more recent variant proposal with 31:30:30 month length pattern
Fixed Quarters Calendar - another proposal with 31:30:30 month lengths and M/W/F month beginnings