The day that never come

September 2, 1752, was a great day in the history
of sleep. That Wednesday evening, millions of
British subjects in England and the colonies went
peacefully to sleep and did not wake up until
twelve days later. Behind this feat of narcoleptic
prowess was not some revolutionary hypnotic
technique or miraculous pharmaceutical
discovered in the West Indies. It was, rather, the
British Calendar Act of 1751, which declared the
day after Wednesday the second to be Thursday
the fourteenth. Prior to that cataleptic
September evening, the official British calendar
differed from that of continental Europe by
eleven days—that is, September 2 in London was
September 13 in Paris, Lisbon, and Berlin. The
discrepancy had sprung from Britain's continued
use of the Julian calendar, which had been the
official calendar of Europe since its invention by
Julius Caesar (after whom it was named) in 45 B.C.
Caesar's calendar, which consisted of eleven
months of 30 or 31 days and a 28-day February
(extended to 29 days every fourth year), was
actually quite accurate: it erred from the real
solar calendar by only 11½ minutes a year. After
centuries, though, even a small inaccuracy like
this adds up. By the sixteenth century, it had put
the Julian calendar behind the solar one by 10
days. In 1582, Pope Gregory XIII ordered the
advancement of the calendar by 10 days and
introduced a new corrective device to curb
further error: century years such as 1700 or 1800
would no longer be counted as leap years, unless
they were (like 1600 or 2000) divisible by 400. If
somewhat inelegant, this system is undeniably
effective, and is still in official use in the
United States. The Gregorian calendar year
differs from the solar year by only 26 seconds—
accurate enough for most mortals, since this only
adds up to one day's difference every 3,323 years.
Despite the prudence of Pope Gregory's correction,
many Protestant countries, including England,
ignored the papal bull. Germany and the
Netherlands agreed to adopt the Gregorian
calendar in 1698; Russia only accepted it after
the revolution of 1918, and Greece waited until
1923 to follow suit. And currently many Orthodox
churches still follow the Julian calendar, which
now lags 13 days behind the Gregorian. Since their
invention, calendars have been used to reckon time
in advance, and to fix the occurrence of events
like harvests or religious festivals. Why So
Difficult? Since their invention, calendars have
been used to reckon time in advance, and to fix the
occurrence of events like harvests or religious
festivals. Ancient peoples tied their calendars to
whatever recurring natural phenomena they could
most easily observe. In areas with pronounced
seasons, annual weather changes usually fixed
the calendar; in warm erclimates such as
Southern Europe, Africa, and the Middle East, the
moon was used to mark time. Unfortunately, the
cycles of the sun and moon do not synchronize
well. A lunar year (consisting of 12 lunar cycles,
or lunations, each 29½ days long) is only 354 days,
8 hours long; a solar year lasts about 365¼ days.
After three years, a strict lunar calendar would
have diverged from the solar calendar by 33 days,
or more than one lunation. The Muslim calendar is
hence the only purely lunar calendar in
widespread use today. Its months have no
permanent connection to the seasons— Muslim
religious celebrations, such as Ramadan, may thus
occur at any date of the Gregorian calendar. The
phases of the moon have nonetheless remained a
popular way to divide the solar year, if only
because a 365¼-day year doesn't exactly lend
itself to equal subdivision (the 71¼-day month
has yet to find favor among menologists). To
compensate for the difference in the solar and
lunar year, calendar makers introduced the
practice of intercalation—the addition of extra
days or months to the calendar to make it more
accurate. The semi lunar Hebrew calendar,
consisting of twelve 29- and 30-day months, adds
an intercalary month seven times every 19 years
(which explains the sometimes confusing drift of
Passover—and consequently Easter— through
April and March). Despite its widespread use, the
Gregorian calendar has a number of weaknesses. It
cannot be divided into equal halves or quarters;
the number of days per month is haphazard; and
months or even years may begin on any day of the
week. Best of All Possible Calendars? Despite its
widespread use, the Gregorian calendar has a
number of weaknesses. Holidays pegged to specific
dates may also fall on any day of the week, and
vanishingly few Americans can predict when
Thanksgiving will occur next year.