The Wichita daily eagle. [volume] (Wichita, Kan.) 1890-1906, 1892-06-16
THE GREGORlAN CALENDAR.
Why We Have Leap Years and How .
Great Change Was Brought About.


Great Change Was Brought About.
When a clock has for time been going
too fast or too slow, two things have to be
done; it has to be altered, first, so that it
may go at the proper speed, and secondly,
so that it may show the correct time; it
has to be regulated and it has to be set
right. With regard to what might be
called the clock of the year, or rather of
the calendar or the almanac, the first of
these corrections is by far the more impor
tant; but both were attended to in the Six
tenth century. This supposed clock of
the year had been going too slow, but it
was made go faster by the year which it
measured off being made very little
shorter, and the clock was at the same time
Set forward.
All this was done by Pope Gregory XIII,
or under his direction, and the result is the
calendar now in almost universal use.
named from him the Gregorian calendar.
The shortening of the year, so that the
equinoxes, ETC., might no longer fall back,
was brought about in a very ingenious
way. The number of years having SCI
days had to be reduced somehow, for the
dates had been going back at the rate of
about one day in Us years. 1t was OBJ
served that this made a very little more
than three days in 400 years; and thenit was
further seen that these three days could be
got by grouping the century years in tours
ike the years in general and making only
one in every four of them leap year. In
ordinary course these years were all leap
years, but by decree which Pope Gregory
issued in 15S3, it was ordered that after the
year 1900 there should be three of the CEN
fury years with 365 days and the fourth
with 3G6.
The well known rule for finding what
years are leap years applies to the century
years only after their two ciphers are cut
off. 1t may be stated thus: Divide the
date number of the year by 4; if there is
no remainder it is leap year. Should the
date number end with two ciphers, these
are TO be struck off before dividing. As
the groups of four years ending with leap
year always start afresh after each century
year the division of the last two figures By
4 will be sufficient (as 92 instead Of 1922,
and the rule may be given thus: Divide by
4 the last two figures of the date number,
but the first two when the last two are
ciphers; if there is no remainder the year is
a leap year. 1t Will be seen that, as IS and
~ are not uINISIDie DI "liHDub EtDldlH-
der, 1900 and 1900 are not leap years, but.
as 90 is so divisible, 200 is one.
Our leap years have thus been accounted
for. The change that was thus introduced
does not secure absolute exactness, but il
approaches this SO nearly that the clock Of
the year viii not need 10 he regulated
again for something like thirty centuries
Astronomers tell US land their eomputa-
tons are wonderfully precise that the
length OF the year Is about 80 days, )
hours. IS minutes and - seconds. To add
an extra day every four years, which Is the
leap year method, il 70 make ,
the year go days aad 6 hours long. but
this is II minutes and IL seconds too much
The correction by emitting three leap year I
days in four centuries, as has just been /
explained. reduced this by the four hun /
dredth part OF three days-that Is. by 70 |
minutes and IS seconds The year is thas /
stin left too long by " seconds; but thai /
surplus will barely amount 10 a day Of - |
hours. or 81, 30 seconds, in 3.;sS3 years; 80
the need for any further ra0islling with /
our leap years Ia very long way ia the |
George Macarthur n 81 /