Intercalation and Sothic synchronism: the Ebers calendarAs we have seen in previous chapters, lunar calendars need to be intercalated
in order to remain in line with the seasons.Without intercalation, the drift of
the lunar calendar from the seasons, at a rate of about eleven days a year,
would have been far more severe than that of the civil calendar.
There is no explicit evidence that Egyptian lunar calendars were interca-
lated; however, the Ebers calendar has been used as evidence that the lunar
calendar was regulated by the rising of Sothis, which may imply a practice of
intercalation. In the previous section, I have discussed (and criticized)
the theory that the Ebers document presents afixed Sothic calendar alongside
the drifting civil calendar. I shall now consider the more likely theory that the
Ebers document presents a lunar calendar (in thefirst column) in relation to
the civil calendar (in the second; see text citation above, near n. 32). Prima
facie this interpretation is more likely, because unlike thefixed Sothic calen-
dar, the lunar calendar is well attested in other Egyptian sources.
As we have seen above, thefirst two lines of the Ebers document give the
date of the rising of Sothis as III Shemu, day 9, in year 9 of Amenhotep (late
sixteenth centuryBCE). According to the‘lunar’interpretation of this text, the
termth
%
yin thefirst column on the next line (l. 3) designates thefirst lunar
month of the year, which must always follow the heliacal rising of Sothis. The
termwp-rnpton the previous line (l. 2) represents therefore the last (lunar)
month of the year, a meaning that is actually attested in other sources (see
above, n. 32). The last month of the year is listed at the beginning of the
document, on the same line as the mention of the rising of Sothis, because it is
the lunar month within which the rising of Sothis occurs.^63 The purpose of the
rest of the document, as recently explained by Depuydt (1996b), would be to
provide a rule for establishing, on the basis of the civil date, the name of the
current lunar month. Thus ifwp-rnptis the lunar month during which the
heliacal rising of Sothis occurs, which in this year (year 9 of Amenhotep I) is
III Shemu day 9, a similar relation can be projected onto the subsequent
months of that year: the next month,th
%
y, is the lunar month during which
day 9 of the next civil month (IV Shemu) occurs, etc. This rule is not entirely
accurate, because lunar months are shorter on average than civil calendar
months, but it is very simple and easy to use, and accurate enough to be
effective.^64
(^63) Parker (1950) and in summary (1974). For a rebuttal of Parker’s interpretation, see Clagett
(1989–99) ii. 8–23 and 31; but whilst Parker clearly overstated his evidence, Clagett’s rebuttal
ultimately rests on his own interpretation of the Ebers calendar as referring to an (ad hoc) Sothic
year, which in my view remains less likely.
(^64) Depuydt (1996b) argues also that the reason why day 9 of every civil month is implicitly
called‘rising of Sothis’in the Ebers document is that this civil date functions, for every lunar
month, in the same way as the date of the actual rising of Sothis functions for the month of
The Egyptian Calendar 147