Historical studies

THE APPLICATION OF THE KALENDAR TO HISTORY
THE APPLICATION OF THE KALENDAR TO HISTORY.
i8. The extended recalculations of the elements
of the Ec:yptian kalcndar by Mr. E. B. Knobcl,
which he has favoured us with in this volume, call for
some general account of their sources and applications
which may be suited to archaeological readers.
The basis of all kalcndar changes in Egypt is the
broad main fact of ignoring leap year, and having
a year of 365 days, continuously reckoned onward
through long ages. That the year of 360 days had
disappeared very early is shewn by the five additional
days—or epagomenae—being named the birthdays
of Osiris, Horus, Set, Isis, and Nephthys, the Osiride
family. This shews that the year of 365 days is as
old as the introduction of the Osiride religion. Also
it is most probable that the festival of the Osirification
of the king, and installing a crown prince, took place
at intervals connected with the leap-year shift of the
kalcndar ; and as this festival appears at the beginning
of the 1st dynasty, and is obviously of older origin,
it shews that the quarter of a day was recognised,
and the extra five days already added, long before
that. For all historic periods we have only to consider
a continuous year of 365 days, down to Roman
times.
19. This reckoning came into relation to two
astronomical elements : (i) the position of the sun
in relation to the stars, always viewed by the Egyp-
tians as defined by the day in the year of the first
visibility of Sirius (Sothis) before the rising of the
sun, commonly called the heliacal rising of Sirius ;
(2) the seasons, which are best viewed as midsummer
and midwinter. That these two relations do not
keep step together is due to the wobbling round of
the earth's pole (like a spinning top wobbling) during
a period of about 25,800 years (slightly variable in
length), commonly called the precessional period.
Thus if we imagine the earth passing round a hori-
zontal orbit, with its pole tilted 23" from the upright,
each time that it comes to the same spot between
the sun and a star, the pole will have turned to a
point nearly 1' different ; or in a thousand years the
pole will point about 14° different, and midsummer
will be two weeks earlier in the orbit than before.
By W. M. FLINDERS PETRIE.
As the Egyptian kalendar ignored the fractional
day beyond 365, it follows that in relation to the
stars it retrograded "25636 of a day (or the fraction
over 365 in the sidereal year) in each year, so that it
agreed with the position of sun and stars after 1425
years, the first element named above. It retrograded
in relation to the seasons -24224 of a day (or the
fraction over 365 in the tropical year) in each year, so
that the kalendar agreed with the seasons after 1508
years, the second element named above.
20. So far we have dealt with the kalendar and
the earth alone. But we have in the Sothic period to
deal also with Sirius as well as the earth. This
involves two other considerations. The sun's appar-
ent path in winter is much nearer to Sirius than it is
in summer. The distance on the Egyptian horizon
{i.e. distance in azimuth) between the sun and Sirius
was
'