Again, the truer the orientation of the temple to the star, and the greater the darkness the priest was kept in, the sooner would he catch the star quivering in the light of either early or late dawn.
In the first place, the diaphragms would indicate the true line that he had to watch; he would not have to search for the star which he expected; and obviously the more he was kept in the dark the sooner could he see the star.
Is there any additional line of evidence beyond the structural conditions of the temples that the Egyptians used these temples to observe the stars? Here a very interesting question comes in: a temple built at one period to observe a star could not go on for ever serving its purpose, for the reason that the declination of the star must change, as we have seen, by precession. Therefore a temple built with a particular amplitude to observe a particular star at one period would be useless later on.
We have here possibly a means of testing whether or not any of these temples were used to observe the stars. In those very early days, 3000 or 4000 years B.C., we must assume that the people who observed the stars had not the slightest idea of these possible precessional changes; they imagined that they were just as safe in directing a temple to a star as they were in directing a temple to the sun. But with a star changing its declination in an average way, the same temple could not be used to observe the same star for more than 200 or 300 years; so that at the end of that time, if they still wished to observe that particular star, they must either change the axis of the old temple, or build a new one. I have mentioned an average time as the change of the star's declination is involved.
Now this change of direction is one of the most striking things which have been observed for years past in Egyptian temples.
As a matter of fact, we find that the axes of the temples have been changed, and have been freely changed; that there has been a great deal of work done on many of the temples which are not oriented to the sun, in order to give them a twist.
Once a solar temple, a solar temple for thousands of years; once a star temple, only that star temple for something like 300 years, so that the conditions were entirely changed.
We get cases in which the axis of a temple has had its direction changed, and others in which, where it has been difficult or impossible to make the change in a temple, the change of amplitude has been met by putting up a new temple altogether. We are justified in considering such temples as a series in which, instead of changing the orientation of a pre-existing temple, a new temple has been built to meet the new condition of things. That, I think, is a suggestion which we are justified in making to Egyptologists on astronomical grounds.
PLAN OF TWO TEMPLES AT MEDÎNET-HABÛ.