The names of the constellations will be found on the charts, and also the individual names of the most celebrated stars, but the constellation boundaries are not shown, because, in nine cases out of ten, the precise limits of a constellation are not important for the beginner to know, and to search for them would simply lead to confusion. As he progresses in his knowledge of the sky any uncertainty about the constellation to which particular stars belong can be settled by consulting the six charts, drawn to a larger scale, at the end of the book. On _these_ charts more of the small stars are shown, and in addition there will be found the Greek letters which astronomers attach to the principal stars of each constellation for the sake of ready identification. On these charts, too, the constellation boundaries will be seen, indicated by dotted lines. The tracing of these lines is more or less a matter of arbitrary choice. There are no international boundary disputes among the heavenly powers, and the frontier lines may run anywhere, provided only that they do not include in one constellation any stars which by common usage, or prescription, belong to another. The constellations have been reshaped many times in the past. The “geography of the heavens” has known as many changes as that of the earth, the ambition of the old astronomers being sometimes as insatiable as that of founders of terrestrial kingdoms and empires. About three centuries ago the starry sky was “Christianized,” St. Matthew, St. Peter, St. John, St. Joseph, St. Michael, St. Stephen, St. Gabriel, St. Mary Magdalen, St. Katharine, together with Noah, Aaron, Job, and Eve, taking the places of the heathen gods, goddesses, and heroes in the sky, while Saturn became Adam, Jupiter Moses, Mars Joshua, Mercury Elias, Venus St. John Baptist (!), the Moon the Virgin Mary, and the Sun Christ (see Appendix). It is not an unheard-of thing in uranography (“description of the heavens”; analogue to geography) for a star, or a group of stars, to change allegiance, or even to belong to two constellations at the same time. The bright star Alpheratz is still an example of this double nationality, for, although it shines on the head of Andromeda and is her jewel _par excellence_, yet her neighbor Pegasus also lays claim to the star, and uranographers so far admit the justice of his claim that they call Alpheratz, according to circumstances, either Alpha (α) Andromedæ or Delta (δ) Pegasi.