Why does "cal 9 1752" produce incorrect results?

[Bob Strait]

khenry at umaxc.weeg.uiowa.edu (Ken Henry) writes:

>Does anybody know why "cal 9 1752" produce incorrect
>results?  It seems to be in the Unix systems I
>checked (BSD 4.3, AIX 3.1).  

Much depends on what you mean by "incorrect."  September, 1752,
was when the English-speaking world adopted the Gregorian
calendar, a couple of centuries after Pope Gregory and the
Roman Empire converted.  By that time the Julian calendar was
eleven days out of sync with the Gregorian calendar so they
simply dropped the 11 days.  Thus, the next day after
September 2, 1752, (Julian) became September 14, 1752, (Gregorian).
It looks funny, but it IS "correct."  By the way, that's
why we (used to) celebrate Washington's Birthday on February 22.
Washington was actually born on February 11, 1732 (Julian).
-- 
BUBBA	(aka Bob Strait)		...!mips!svcs1!rls
Silicon Valley Computer Society
Sunnyvale, CA
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