In this system of night observation we have the germ of the use in later times of an instrument called the “night-dial,” specimens of which, dating from the fourteenth century, can be seen in our museums. The introduction of graduated circles permitted the employment of circumpolar stars, and the “guards” of the Little Bear or the “pointers” of the Great Bear were thus used. There was a disc with a central aperture through which the pole star could be observed; the disc could be adjusted for every night in the year; an arm was then moved round so that the direction of the pointers (or the guards) with regard to the vertical could be measured; on a second concentric circle the time of night could be read off. [Illustration: FIG. 62.--A “night-dial.”] [119] _Dawn of Astronomy_, 1894, p. 343. [120] Jensen, _Kosmologie der Babylonier_, p. 147. [121] _Dawn of Astronomy_, p. 215. [122] _Ibid._, p. 214. CHAPTER XXIX A SHORT HISTORY OF SUN TEMPLES _The Original Cult_ I have given detailed evidence showing that the first circle builders in Britain worshipped the May-year sun, whether they brought it with them or not. This year was used in Babylon, Egypt, and afterwards in Greece. In the two former countries May was the harvest month, and thus became the chief month in the year. The dates were apt to vary with the local harvest time. The earliest extant temple aligned to the sun at this festival seems to have been that of Ptah at Memphis, 5200 B.C. I have already referred to this temple in relation to the clock-star observations carried on in it. This approximate date of the building of the temple is obtained by the evidence afforded (1) by the associated clock-star (see p. 298), and (2) by the fact that the god Ptah represented the star Capella, since there is a Ptah temple at Thebes aligned on Capella at a later time, when by the processional movement it had been carried outside the solar limit. There was also a similar temple at Annu (Heliopolis, lat. N. 30° 10′), but it has disappeared. The light of the sun fell along the axis when the sun had the declination N. 11°, the Gregorian dates being April 18 and August 24. Another May-year temple was that of Menu at Thebes, Az. N. 72° 30′ W. (lat. N. 25°; sun’s declination N. 15°; Gregorian date, May 1). [Illustration: FIG. 63.--Layard’s plan of the Palace of Sennacherib discovered in the mound of Kouyunjik. The temple axis, XXXVI., XXXIV., XXIX., XIX. (XXII. is on a lower level), faces the rising of the May sun.] As we have seen (p. 299), Spica had this declination in 3200 B.C., and the coincidence may have been the reason for the erection, or, more probably, the restoration, of the temple,[123] especially as γ Draconis came into play as a new clock-star at the same date. [Illustration: FIG. 64.--Layard’s plan of the Mound at Nimrood showing its equinoctial orientation.]