Re: Why not 13 months? (Was La Systeme Metrique)

Whittet (
25 Jul 1995 16:08:43 GMT

In article <>, says...
>In article <>,
> (Isolde) wrote:
>> I'm no astrologer or astronomer, but I like the 13 month calendar made of
>> 28-day months--moon-ly months, mind you, not political ones! The
>> arbitrary and political basis for our monthly system has no business in
>> the reckoning the natural year!!!
>"No business in reckoning the natural year"?
>One cannot choose but wonder how the human race is going to cope once it
>starts living on worlds where the "natural year" happens to be something
>other than 365 days!
>Human calendars are for human convenience. They have been devised because
>it is the *natural* year which is arbitrary. Human calendars only seem
>arbitrary because the "natural year", however you define it, is not only
>not a whole number but not even a convenient whole number.
>A year made up of thirteen 28-day months (=364 days) does indeed *almost*
>fit the natural year.
>The chief problem is that 13 happens to be a prime number. This makes it
>mathematically impossible to subdivide a year in any satisfactory fashion.
>You cannot even divide such a year into the customary four seasons and
>hope to come out with the same number of whole months in each season.
>By contrast, a 12-month year can be easily divided into halves
>(six-monthly periods), quarters (3-monthly), thirds (4-monthly), and
>sixths (bimonthly) of more or less equal size.

try four seasons of 91 days = 364 days
13 x 7 = 91

thus the year of 13 months can be divided into 4 seasons of 13 weeks !
>Stephen Souter