In the constellation of the Sword-fish, on the edge of the Great Cloud of Magellan, is another nebula, 30 Doradūs, the Great Looped Nebula, which is even more marvellous in complexity of structure than the Keyhole Nebula in Argo. No photograph can reproduce, and no words can describe, the filmy appearance of these nebulae as seen in a telescope. The Looped Nebula seems to consist entirely of strangely curved and twisted streamers on a background of dark sky, with a few sparkling stars of various brightness scattered over it. At the complicated centre one of the loops forms a nearly perfect figure-of-eight, and another takes the outline of an eye. Brightest of all the large gaseous nebulae is the well-known Orion Nebula, in the sword of the giant. A 3-inch telescope shows the main features well, the dark bay running into its brightest region, the row of three brilliant stars and the “trapezium” of four tiny ones very close together, and the long outlying branches which have such fantastic curves. Because of its comparative brightness, its entrancing beauty, and its position where it can be seen from all latitudes, this nebula has been studied more than any other. The first drawing of it was made in 1656, the first photograph in 1880. It remains a baffling mystery still, but a few facts have emerged. Its distance is immeasurable: it has been guessed at a thousand light-years. It must, therefore, be inconceivably vast in extent, but it is probably excessively tenuous, like a comet’s tail, of which a million miles contain a negligible amount of matter. It is almost stationary in space, and a careful study of its form since 1758 proves that there has been no visible change, except perhaps in the relative brightness of some of its parts. Yet a recent spectroscopic investigation shows that movements are taking place in different directions within the nebula, and a slow rotation of the whole mass, or of its brightest portion, is suggested. It is composed of faintly luminous gas, though whether it glows from heat or from some other cause we do not know. Photographs of nebulae are very misleading with regard to brightness: one must remember that they have often been exposed for many hours. Helium, hydrogen, and an unknown gas which we call nebulium are mingled together, but not in equal quantities. In some of the fainter regions of the nebula, especially on the south and west borders, hydrogen produces a great deal of the light; in the brightest parts, near the trapezium, the glow of nebulium is much more prominent. It is scarcely doubtful that many of the stars which appear to be involved in the nebula are physically connected with it, especially since they are of a type frequently found near nebulae, viz. very blue Orion-type stars with some of their hydrogen lines not dark but bright, as in the nebula.