With regard to the dates shown I have already pointed out that farming operations would not occur at the same time in different lands; that ploughing and seed time and harvest would vary with crops and latitudes; and I must now add that when we wish to determine the exact days of the month we have to struggle with all the difficulties introduced by the various systems adopted by different ancient nations to bring together the reckoning of months by the moon and of years by the sun.
Fig. 7.—The astronomical and vegetation divisions of the year.
In more recent times there is an additional difficulty owing to the incomplete reconstruction of the calendar by Julius Cæsar, who gave us the Julian year. Thus, while the spring equinox occurred on March 21 at the time of the Council of Nice, in 325 A.D., by the year 1751 the dating of the year on which it took place had slipped back to the 10th. Hence the Act 24 George II. c. 23, by which September 2, 1752, was followed by September 14 instead of by the 3rd, thus regaining the eleven days lost. This change from the so-called “old style” to the “new style” is responsible for a great deal of confusion.
Another cause of trouble was the forsaking by the Jews of the solar year, with which they commenced, in favour of the Babylonian lunar year, which has been continued for the purposes of worship by Christians, giving us “movable feasts” to such an extent that Easter Day, which once invariably marked the spring equinox, may vary from March 22 to April 25, and Whit Sunday from May 10 to June 13. It is at once obvious that no fixed operations of Nature can be indicated by such variable dates as these.
Hence in what follows I shall only deal with the months involved; these amply suffice for a general statement, but a discussion as to exact dates may come later.
To sum up, then, the astronomer-priests had (1) to watch the time at night by observing a star rising near the north point of the horizon. This star would act as a warner of sunrise at some time of the year.
(2) To watch for the rising or setting of other stars in various azimuths warning sunrise at the other critical times of the May or Solstitial years.
(3) To watch the sunrise and sunset.
(4) To mark all rising or setting places of the warning stars and sun by sight-lines from the circle.