_The Magellanic Clouds_[60].—These are marked as Nubecula Major and Nubecula Minor on celestial globes and charts. They form two extensive aggregations of nebulæ and star-clusters, and are readily visible to the naked eye in or near Hydrus, and not far from the south pole of the heavens. They may be likened to detached patches of the Milky Way. Sir J. Herschel says the Nubecula Major is situated between the meridians of 4^h 40^m and 6^h and the parallels of 66° and 72° of S. declination, and extends over a space of some 42 square degrees. The Nubecula Minor lies between 0^h 28^m and 1^h 15^m and 72° and 75° of S. declination, and spreads over about 10 square degrees. The composition of these objects is very complex and diversified, and affords very rich ground for exploration with a large telescope. Nebulæ exist in profusion and in every variety, and are intermingled with star-clusters varying in condensation from the compact globular form to groups more loosely scattered, and such as we often find in the Milky Way. Nearly three hundred nebulæ and clusters are included in the major “cloud,” while more than fifty others closely outlie its borders. In the minor about forty such objects have been discovered. It is very strange to find them collected together in this manner; for in other regions of the firmament they are usually found separated, and certain classes appear to have their own special zones or localities of distribution. Sir J. Herschel pointed out that “globular clusters (except in one region of small extent) and nebulæ of regular elliptic forms are comparatively rare in the Milky Way, and are found congregated in the greatest abundance in a part of the heavens most remote possible from that circle, whereas in the Nubeculæ they are indiscriminately mixed with the general starry ground and with irregular though small nebulæ.” _Double Nebulæ._—Instances are not wanting of conspicuous double nebulæ. M. 51 and 76, near ζ Ursæ and θ Andromedæ, may be classed in this category. There is a very interesting, though a smaller object just W. of α and β Geminorum, or in R.A. 7^h 18^m·6, Dec. +29° 43′. Two bright, round nebulæ are separated by an interval of 28″. These double nebulæ are usually round, and are sometimes resolvable into stars. Whether they are physical or mere optical pairs has yet to be ascertained. So many examples exist that it seems highly probable they have a real connection, though no motion has yet been certainly detected to prove they are binary systems. Such motion may, however, be very slow, and require observations extending over a much longer interval before it is revealed.