Historical studies

proper motion of Sirius, or its gradual shift in relation
to the stars as a whole. By the observations of
its motion this would roughly amount to 3° in 9000
years.
21. Now that we have dealt with the astronomical
facts we turn to see how they appeared to the
Egyptians.
The seasons are the cardinal fact of astronomy to
early man ; and their rotation is readily fixed—and
the length of the apparent year estabHshed— by
observing the number of days between the sun
appearing on the same point of the horizon at rising
or setting. This doubtless formed the first basis
of observations, and other questions would be
ulterior.
The Egyptian adopting a year of 365 days, divided
into 12 months of 30 days, and 5 days over, would
find that in a few years his months of the kalendar
were slipping back in the seasons and falling earlier,
as fixed by sunrise direction. When he had extended
his observations further, and included the rising of
Sirius, he would find that his kalendar months agreed
with the rising of Sirius after 1425 years, and that
they agreed with the seasons after 1508 years. The
Sirius period is affected by another element, the
proper motion of Sirius, and the change of the earth's
pole in regard to it. Hence the period of 1425 years
was lengthened in appearance as follows :
—
Dates. Intervals.
From — 7171 to —5705 1466
-5705 to -4235 1470
-423s to -277s 1460
-277Sto-i3i7 1458
-1317 to + 139 1456
+ 139 to +1591 1452
+ 1591 to +3039 1448
So that during the times of Egyptian history the
allowance of 1460 years comes very near the truth.
But its coincidence with exactly a day in 4-years
shift is only a coincidence, and it must be perceptibly
different in other ages.
22. The question now is, of the two adjustments
of the names of the kalendar months, and of their
numbers,—that to Sirius, or that to the seasons,
which did the Egj^ptians adopt as a standard ? The
result is indicated by Mesore being reckoned the
first month of the year in the xiith-xixth dynasties,
and Thoth being reckoned as the first month in
Roman times. This shews that the kalendar was
being adjusted to the two incongruous reckonings, of
—
THE SOTHIS PERIOD AND THE MONTHS
Sirius and of the seasons. If the kalendar names
were kept to the Sothis period, as they seem to have
been fixed in Roman times, and as the uniform 365day
year would bring them ; and if the numbering of
the months was adjusted to agree with the seasons
at each epoch ; then the first month seasonally would
move on to 1508 years while the Sothis period and
kalendar names were renewed at 1452 to 1470 years ;
that is to say the month numbers by the seasons
would at each Sothis period advance along the
kalendar names by 38 years in early times or 56
years in mediaeval times, that is by 10 to 14 days.
As the 1st of Thoth is said to coincide with Sirius
rising in +139 A.D., and as the epagomenal days
were doubtless kept to the end of the xiith month in
all ages, the kalendar dates of the first month fixed
seasonally would be
+ 139