Eta Argūs continued to fade, and for many years it has not been visible to the naked eye. When the present writer looked for it in April 1908 it was beyond the power of the binocular, although seventh-magnitude stars in the neighbourhood were clearly distinguished and identified. In a telescope it in no way stands out from the crowd of small stars scattered over the nebula whose light it once almost blotted out by its brilliance. Reports now and then arise that Eta is brightening again, but it always turns out that some neighbour in the throng, a little brighter than the faded star, has been mistaken for it. A few other cases are known in which a bright star has appeared where none had been seen before. It is said that it was the appearance of such a “new star” in Scorpio in the year 136 B.C. which led Hipparchus of Rhodes to draw up his famous star-catalogue. In A.D. 1572 “Tycho’s star” blazed out in Cassiopeia, and in 1604 “Kepler’s star” in Ophiuchus astonished everyone. The old chronicle says: “It was exactly like one of the stars, except that in the vividness of its lustre and the quickness of its sparkling it exceeded anything Kepler had ever seen before. It was every moment changing into some of the colours of the rainbow, as yellow, orange, purple, and red, though it was generally white when it was at some distance from the vapours of the horizon.” This “new star” must have been even brighter than Eta Argūs,[7] for it outshone Jupiter, and was only surpassed by Venus. It remained visible for about a year and then vanished. [7] Now often called Eta Carinae, since Argo has been subdivided (see p. 7). Since the skies have been more carefully watched by astronomers all over the world, and especially since they have been frequently photographed, quite a considerable number of new stars have been recorded, and about half a dozen have become visible to the naked eye. In the twenty-seven years between 1885 and 1912, twenty were recorded, and half of these were discovered by Mrs. Fleming of Harvard Observatory from the examination of photographs. Astronomers are still asking, like Herschel, what is the origin of these mysterious objects? Are they literally new stars, or is it the last flare-up of a dying system, or are we witnessing some catastrophe which only overtakes a few suns among the universe of stars? A collision between two dark stars, or between a star and a nebula, is a supposition which naturally suggests itself, and some probability is lent to this supposition by the fact that nearly every new star has appeared in or near the Milky Way, where stars throng most thickly; but there are difficulties in the way of accepting this hypothesis. There is a strong likeness between all that have been examined spectroscopically, and in the declining stage they become so distinctly nebular in type that we seem justified in saying that new stars change into small gaseous nebulae.