Suppose that the sun is rising, let a rod throw a shadow; mark the position of the shadow; at sunset we again note where the shadow falls. If the sun rises exactly in the east and sets exactly in the west, those two shadows will be continuous, and we shall have made an observation at the absolute equinox. But suppose the sun not at the equinox, a line joining the ends of the shadows equally long before and after noon will be an east and west line. It is true that there may be a slight error unless we are very careful about the time of the year at which we make the observations, because when the sun is exactly east or west at the time of rising or setting it changes its declination most quickly. So it is better to make the above observations of the sun nearer the solstices than the equinoxes, for the reason stated.[7] We have now got so far. If the Egyptians worshipped the sun and built temples to it, they would be more likely to choose the times of the solstices and the equinoxes than any other after its annual movement had been made out. Is it possible to bring any tests to bear to see whether they did this or not? Certainly: examine the temples which still remain, and where they have disappeared examine the _temenos_ walls which still exist as mounds in many cases. Suppose we take, to begin with, as before, that region of the earth's surface in the Nile valley with a latitude of about 26° N. The temples will have an amplitude of about 26° N. or S. if they have anything to do with the sun at the solstices. Any structures built to observe the sun will have an east and west aspect true if they have anything to do with the sun at the equinoxes. Dealing with a solstitial temple, the first thing to observe is the amplitude of the temple, which must depend upon the latitude in which it was wished to note the rising or setting of the sun at either of the solstices. If we take the latitude 26° N., which is very nearly the latitude of Thebes, the amplitude has to be 26° as stated above; so that a temple at Thebes having an amplitude of 26° would be very likely to have been oriented to the sun at the moment that it was as far from the equator as it could be--_i.e._, at the time of the longest day of the year--in which case we should be dealing with the summer or northern solstice; or of the shortest day of the year, if dealing with the winter or southern solstice. As we deal with higher latitudes, we gradually increase the amplitude, until, if we go as far as the latitude of the North Cape, the sun at the summer solstice, as everybody knows, has no amplitude either at rising or setting, because it passes clear above the horizon altogether, and is seen at midnight. These are the conditions which will define for us a solstitial solar temple. We see the amplitude of the temple must vary with the latitude of the place where it is erected.