170 
Jamshid. In Egypt, the commencement of the year was 
fixed at the time when the inundation of the Nile had 
sufficiently abated to allow the operations of agriculture to 
commence; and it was observed in the first instance rudely, 
by a nilometer, but afterwards with greater accuracy by a 
gnomon: the first day of the year being the first day in 
which the meridian shadow of an object had attained to a 
standard length; which standard length appears from cal- 
culation to have corresponded with a south declination of 
about 121°. The solar year, intervening between the suc- 
cessive occurrences of this phenomenon, was greater than 
the mean tropical year, on account of the changes in the 
equation of the sun’s centre, and in the obliquity of the 
ecliptic; and is shewn to have been about 1767 B.C., 
neglecting the perturbations caused by the moon and planets, 
365,243246, differing little from 365,2433 ... which would be 
its length, if the phenomenon gained a fifth part of a year, 
in 300 years of 365 days. The Egyptians, observing this 
equality, and being dissatisfied with the year that they for- 
merly used, on account of the 366th day, which, occurring 
in every fourth or fifth year, disordered their calendar, 
resolved that with the next cycle they would limit the year 
to 365 days, allowing no more intercalations. This change 
they accordingly made, on the 8th Nov. 1767, from which date 
they commenced not only a new lunisolar cycle of 600 solar 
years, that is 6002 years of 365 days, but also a cycle of the 
seasons, consisting of 1500 solar years, or 1501 years of 365 
days. The recurrence of either of these cycles was celebrated 
as the return of a phoenix; and those mentioned by Tacitus, 
as having occurred under Sesostris, Amasis, Ptolemy Philadel- 
phus, and Tiberius, are fixed in the autumns of the proleptic 
Julian years, 1167, 567 and 267 B. C., and A. D. 34. The 
date thus assigned for the reign of Sesostris agrees with that 
which Mr. Cullimore has deduced from the astronomical 
sculptures on the memnonium. The great period of 3000 
