with any telescopes hitherto constructed." The following stars are instances of this kind : No. I is a triple star, A 31, B 81, and C 11, dist. 11.5′′ and 49′′, the whole involved in a large nebulosity 3' in diameter. No. 2 is a 2-mag. star, "involved in an immense nebulous atmosphere." No. 3 is an 8th-mag. star, "exactly in the centre of a round bright atmosphere." No. 4 is a 4-mag. star, "involved in a considerable nebula 3′ in diameter, exactly round." Nebulous stars can only be usefully scrutinised in large telescopes. Besides the clusters and nebulæ belonging to the foregoing classes, there are others for the most part of irregular form and large dimensions, which it is convenient to class by themselves. Under this head may be included the following: The remarks which follow in inverted commas are nearly all by Sir John Herschel, though an actual reference to that effect is not in every case given. 1. This is described by Sir J. Herschel as "a superb globular cluster, immediately preceding the nubecula minor; it is very visible to the naked eye, and one of the finest objects in the heavens. It consists of a very condensed spherical mass of stars, of a pale rose colour, concentrically enclosed in a much less condensed globe of white ones 15′ or 20' in diameter." In his account of this cluster Sir John remarks that he cannot remember a single elliptical nebula which is resolvable, all the resolvable clusters being more or less circular in their outlines. "Between these 2 characters then (ellipticity of form and difficulty of resolution) there undoubtedly exists some physical connexion. It deserves also to be noticed that in very elliptic nebula which have a spherical centre (as in M 65), a resolvable or mottled character often distinguishes the central portion, while the branches exhibit nothing of the kind." [Fig. 143, Plate XXIV.] 2. Frequently called the "Crab nebula in Taurus." It has an elliptic outline in most instruments, but in Lord Rosse's reflector "it is transformed into a closely-crowded cluster, with branches, streaming off from the oval boundary, like claws, so as to give it an appearance that in a measure justifies the name by which it is distinguished." 3 is the "great nebula in the sword-handle of Orion,” surrounding the multiple star in that constellation. It was discovered by Huyghens about the year 1656. "In its more prominent details may be traced some slight resemblance to the wing of a bird. In the brightest portion are 4 conspicuous stars forming a trapezium. The nebulosity in the immediate vicinity of these stars is flocculent, and of a greenish white tinge; about half a degree northward of the trapezium are 2 stars involved in a bright branching nebula of singular form, and southward is the star Orionis, also situated in a nebula. Careful examination with powerful telescopes has traced out a continuity of nebulous light between the great nebula and both these objects, and there L * Res. of Ast. Obs., p. 19. An exception to this rule is 1 M Tauri. can be but little doubt that the nebulous region extends northwards as far as in the belt of Orion, which is involved in a strong nebulosity, as well as several smaller stars in the immediate neighbourhood." Secchi, in fact, says that the nebulous mass in Orion has, speaking roughly, a triangular outline with a M m |