If the observer be on the equator, the movements of the stars will appear to be as indicated in this diagram (Fig. 3)--that is, all the stars will rise and set, and each star will be, in turn, twelve hours above the horizon, and the same time below it. But if we consider the position of an observer in a middle latitude, say at Stonehenge, we find that some stars will always be above the horizon, some always below--that is, they will neither rise nor set. All other stars will both rise and set, but some of them will be above the horizon for a long time and below for a short time, whereas others will be a very short time above the horizon and a long time below it, each star completing a circle in a day (Fig. 4). Wherever we are upon the earth we always imagine that we are on the top of it. The idea held by all the early peoples was that the surface of the earth near them was an extended plain: they imagined that the land that they knew and just the surrounding lands were really in the centre of the extended plain. Plato, for instance, was content to think the Mediterranean and Greece upon the top of a cube, and Anaximander placed the same region at the top of a cylinder. By the use of a terrestrial globe we can best study the conditions of observation at the poles of the earth, the equator and some place in middle latitude. The wooden horizon of the globe is parallel to the horizon of a place at the top of the globe, which horizon we can represent by a wafer. By inclining the axis of the globe and watching the movement of the wafer as the globe is turned round, we can get a very concrete idea of the different relations of the observer’s horizon to the apparent paths of the stars in different latitudes. We have next to deal with the astronomical relations of the horizon of any place, in connection with the observation of the sun and stars at the times of rising or setting, when of course they are on or near the horizon; and in order to bring this matter nearer to the ancient monuments, we will study this question for both Thebes and Stonehenge. We may take the latitude of Thebes as 25°, Stonehenge as 51°, and we will begin with Thebes. To consider an observer on the Nile at Thebes and to adjust things properly we must rectify a celestial globe to the latitude of 25° N., or, in other words, incline the axis of the globe at that angle to the wooden horizon.