Suppose that the movements of the stars are absolutely regular; that there is no change from year to year, from century to century, from æon to æon; then, of course, the question as to whether or not these temples were pointed to a star, at rising or setting, would be easily and sufficiently settled by going to see; because if the stars did not change their apparent places in the heavens—accurately speaking, their declinations—and, therefore, the amplitudes at which they appear to rise and set, then, of course, a temple consecrated to Sirius ten thousand years ago would view the rising or setting of Sirius now as it did then.
But, as a matter of fact, astronomy tells us, as we have seen, that the apparent positions of the stars are liable to change. The change is much greater in the case of the stars than it is in the case of the sun, referred to in Chapters VI. and XI.; but still we have seen that the latter is one which has to be reckoned with the moment it becomes a question of inquiry into any time far removed from the present.
GROUND PLAN OF EDFÛ.
Hence, although in the case of the sun, there is, of course, no processional movement, and although a temple once oriented to the sun would remain so for a long time; still, after some thousands of years, the change in the obliquity of the ecliptic would produce a small change in the amplitude at which a solstice is observed.
But while, in the case of the sun, we have to deal with a change of something like 1° in seven thousand years; we have to face in the case of the stars a maximum change of something like 47° in a period of thirteen thousand years. The change of declination must be accompanied by a change of amplitude, and therefore by a change in the direction of the temples.
Hence, when we get a temple of known date, with an amplitude which has been accurately measured, we can determine from that amplitude the exact declination of the body the temple was intended to observe, supposing, of course, that the temple was oriented upon any astronomical considerations at all. If the declination of the body turns out to be 23° 30′ or less, the temple may have been, in all probability was, a solar one; if the declination is greater it cannot have had anything to do with the sun directly.
| GROUND PLAN OF THE TEMPLE OF HATHOR AT DENDERAH. | PLAN OF THE TEMPLE OF SETI AT ABYDOS. |
This being so, it will be understood why in an inquiry of this kind it is obviously desirable to begin with a region in which the number of temples is considerable. Such a condition we have in the region near Thebes; and the directions of the axes of the different temples—that is, the orientation of each of them, or, in other words, the amplitude of the direction in which each temple points—have all been tabulated. Chief among these we have the large temple of Karnak, showing that the amplitude of its orientation is 26° north of west, and the temple of Mut, showing that its orientation is 72½° north of east. There is a temple at right angles to the temple at Karnak, and again another with an amplitude of 63° south of west, and so on.