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. CHAPTER IV THE VARIOUS NEW-YEAR DAYS With regard to the astronomical year it may be stated that each solstice and equinox has in turn in some country or another, and even in the same country at different times, been taken as the beginning of the year. We have, then, to begin with, the following which may be called _astronomical_ years:-- Solstitial { June December June. year. { December June December. Equinoctial { March September March. year. { September March September. Next, if we treat the intermediate points we have found in the same way, we have the following _vegetation_ years:-- Flower { May November May. year. { November May November. Harvest { August February August. year. { February August February. It will have been gathered from Fig. 7 that the temples or cromlechs erected to watch the first sunrise of the May-November-May year could also perform the same office for the August-February-August year; and in a stone circle the priests, by looking along the axis almost in an opposite direction, could note the sunsets marking the completion of the half of the sun’s yearly round in November and February.