Let us take, now, another star, called the _Dog Star_—its real name is _Sirius_ (pronounced Sir´-i-us)—which is not far from a line with and overhead of the Earth’s equator; suppose we are some place on the earth where we can see both the North Star and the Dog Star at the same time, and keeping in mind that the Earth is turning round on its axis; it must be plain, then, that though both of these stars are fixed in the sky and never change their positions we on the Earth will turn away from the Dog Star until the Earth has turned half way round, but we will not turn away from the North Star. The eye, however, is easily deceived; for example, if we are on a moving train nearby objects, such as houses, trees, etc., will seem to be moving in the opposite direction to which we are going while we seem to be standing perfectly still. The illusion is much more complete when we are seeing the stars, for the motion of the Earth as it spins on its axis and shoots round the Sun in its orbit is so steady that we cannot notice it; for this reason it seems as if it is the stars which are moving and that we are standing still. It is easy to understand now why the Big Dipper, and all the other stars, seem to move in great circles round the North Star as well as why the Big Dipper marked with cardboard stars on your chart may not have the same relative position to the horizon as the Big Dipper of real stars in the northern sky, when you view them together as in Fig. 4. Not only does the revolution of the Earth on its own axis once in every 24 hours cause the Big Dipper to seem to turn round the North Star, but the yearly journey of the Earth round the Sun makes a change in the position of the Big Dipper as we see it at different seasons of the year. And what has been said about the Big Dipper is just as true of all the other constellations. For these reasons we would need an almanac to help us keep track of the exact hour when the Big Dipper would be in a given position for every night in the year. But you can always find the Big Dipper any evening in autumn about nine o’clock, by remembering that it is turned right side up as shown in Figs. 3 and 4. Again, if you look for the Big Dipper in winter at about nine o’clock in the evening you will find it standing on its handle a little to the east as in Fig. 9. In spring about 9 o’clock, it will have moved on round the North Star until it is upside down, as in Fig. 10, while in summer, at 9, it is hung up by its handle high in the sky, as shown in Fig. 11. The four positions of the Big Dipper during the same hours of the different seasons are shown in Fig. 12, which also shows the four positions of the Big Dipper during each 24 hours. [Illustration: FIG. 9.—THE NORTH STAR AND BIG DIPPER IN WINTER.] By turning the chart round on the board _counter-clockwise_ you will soon come to a point where the Big Dipper of paper stars and the Big Dipper of real stars are in exactly the same position.