When we speak of the southern constellations, everyone thinks of the Southern Cross, and every traveller coming south for the first time is eager to see it. Some are disappointed because it is small and irregular, but it is very brilliant, and lies in an extremely rich region of the Milky Way. Very beautiful, too, is the way in which it is seen rising on its side and gradually becoming upright as it reaches its greatest height above the horizon, then sloping again as it glides westward.

The Cross seems to have been first so named by the Spanish explorer Amerigo Vespucci, at the beginning of the sixteenth century, and it was also described in letters by the Florentine Andrea Corsali, who says it is so beautiful that in his opinion no other constellation in the sky is worthy to be compared with it. Some think, however, that the stars had already been recognised as forming a Cross as early as the thirteenth century, because Dante in his Purgatory speaks of four stars which glorified the southern sky; but he does not say they were in the form of a cross, and he tells us that they had never been seen before by mortal man except by our first parents, whose original dwelling-place he sets in the southern hemisphere. This negatives the suggestion that some traveller had described them to him.

About the same time as the Cross, other groups were named by sailors and travellers in the part of the sky round about the south pole, for this region had been left a blank by the framers of the ancient constellations, doubtless because they lived too far north to see it. Some students of astronomy in the Middle Ages concluded that there really were no stars in this part, and Ristoro of Arezzo gravely argued that this proved the absence of any land further south than India and Ethiopia; for where there are no stars to pour down influences on the earth no animals can live, and therefore no vegetation is needed for their food, and no land for it to grow on.

The new constellations were mostly named after strange birds and fishes seen by explorers in their southern voyages, and they were admitted to scientific astronomy by Bayer, who made a map of the skies in 1604. He also introduced the plan of naming each star in a constellation by a Greek letter, the brightest of each constellation usually being called Alpha, the next brightest Beta, and so on. One of these constellations is Grus, the Crane (originally called the Flamingo), and it is convenient to be familiar with it, because from it we may easily identify several others. The chief stars of Grus form a striking curve with a bright star close beside it. This bright star is Alpha Gruis, and the brightest in the curve is Beta. A line through Alpha and Beta leads in one direction to the brightest star of the Phoenix, in the other direction to the brightest of the Indian; a line through Alpha and the little naked-eye double Delta takes one to Pavo, the Peacock; a line through Gamma (at one end of the curve) and Alpha goes to the brightest star in the Toucan. And these are all the modern groups containing bright stars except the Southern Triangle, near the Pointers to the Cross (see p. 6), and Columba, the Dove, not far from Sirius, each of which has one star brighter than third magnitude.[2] We may, however, also notice Alpha Hydri, the brightest star in the small Water-Snake, close to the bright star Achernar, and Alpha Doradūs, the brightest of the Sword-Fish, between Canopus and Achernar.

In the eighteenth century the French astronomer Lacaille, who did much excellent work in the southern hemisphere with a tiny telescope of only half an inch aperture, had the unhappy idea of filling up the spaces still left empty with scientific instruments. It is easy to make Birds of Paradise and Flying Fishes out of the stars, but such things as telescopes, easels, and sextants do not lend themselves to irregular groups, and they are very much out of place among the mythical beasts and heroes which we are accustomed to see on our star-maps. Fortunately the beginner need not learn to recognise these intruders, for there are no bright stars in them, although there are many interesting objects for telescopic study. We need only note that Octans, the Octant, occupies the region in which the south pole is situated, which is quite bare of bright stars. The pole itself may be found by drawing a line from head to foot of the Cross and carrying it on about four times as far again; or if the Cross is invisible, the pole may be found near the middle of a line from Canopus to Alpha Pavonis.