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a round mottled nebulosity. In Scorpio (R. A. 16 h. 48 m. S. D. 29° 40') is a nebula like a comet, with a brilliant centre, surrounded with a faint light. West of a Cancri is a mass of stars with nebulosity; it is a cluster much compressed, in which two hundred stars have been observed. Below the left arm of Sagittarius near Sagittarii is a faint nebula like the nucleus of a

small comet. About a degree and a half north of Orionis is a mass of stars, with two bright nuclei, surrounded with nebulosity. Near 406 Leporis is a fine nebula, bright in the centre and a little diffused; it is resolvable into a mottled nebulosity. Near 24 Ursæ Majoris is an oval nebula, bright in the centre, and exhibiting a mottled nebulosity: close to it is another nebula, faint and elongated, with a telescopic star at its extremity. Between the knee and left leg of Hercules (R. A. 17 h. 10 m. N. D. 43° 22′) is a beautiful nebula, bright in the centre, and surrounded with great nebulosity which is resolvable into stars.

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Many of this kind, exactly round figure, globular space filled

Near 3 Ursa Majoris is a faint nebula, and another near γ Ursa Majoris. Between and 8 Cassiopeia is a mass of stars. Between n and Herculis is a beautiful object (See Plate I. Fig. 1.) says Sir John Herschel, are of an and convey the complete idea of a full of stars, insulated in the heavens. and constituting in itself a family or society apart from the rest, and subject only to its own internal laws. It would be a vain task to attempt to count the stars in one of these globular clusters. They are not to be reckoned by hundreds; and on a rough calculation, grounded on the apparent intervals between them at the border, (where they are

not seen projected on each other,) and the angular diameter of the whole group, it would appear that many clusters of this description must contain, at least, ten or twenty thousand stars, compacted and wedged together in a round space, whose angular diameter does not extend 8' or 10'; that is to say, in an area not more than a tenth part of that covered by the moon.

Annular nebulæ are among the rarest objects in the heavens. The most conspicuous of this class is to be found exactly half-way between the stars ẞ and y Lyræ, and may be seen with a telescope of moderate power. It is small and particularly well defined, so as in fact to have much more the appearance of a flat oval ring than of a nebula. The axes of the ellipse are to each other in the proportion of four to five, and the opening occupies about half its diameter, its light is not quite uniform, but has something of a curdled appearance, particularly at the exterior edge; the central opening is not entirely dark, but is filled up with a faint hazy light, uniformly spread over it, like a fine gauze spread over a hoop.*

Planetary nebulæ are very extraordinary objects. (See Plate I, Fig. 2.) They have, as their name imports, exactly the appearance of planets: round or slightly oval discs, in some instances quite sharply terminated, in others a little hazy at the borders, and of a light exactly equable, or only a very little mottled, which, in some of them approaches in vividness to that of actual planets. Whatever be their nature they must be of enormous magnitude. One of them is found in the parallel of v Aquarii

* See Plate II. for drawings of various nebulæ, each of which may be considered as a specimen of its class.

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