Endlessly varied is the grouping of the stars. We find solitary stars, twin stars, large stars with small companions, bright stars with faint companions, stars alike in colour and type, stars in strongly contrasted colours, one young, the other aged, stars with invisible companions, couples close enough to touch one another, and couples so distant that the satellite takes more than a century to revolve round its primary. One or even both components of a bright pair may be themselves divisible into a closer pair, sometimes into a whole group of stars. More beautiful and wonderful still are the clusters of stars of various tints and magnitudes, where scores, even hundreds, are gathered together in what to the eye is a tiny patch, though it may in fact take light many years to cross from one side of it to the other. The finest example in the heavens of this kind of cluster is Kappa Crucis, near β in the Southern Cross.[8] It is just visible to the naked eye as a small star, and in a binocular the main star is seen to be surrounded by a number of others; in a telescope it is a glorious sight. Orange and red stars are easily distinguished in the brilliant throng, even if we have not Herschel’s eye for colour and fail to discriminate the “greenish-white, green, red, blue-green, and ruddy” which made up what he likened to “a superb piece of fancy jewellery.” He charted over a hundred stars of all magnitudes from 7 to 17. Herschel’s observations at the Cape were made between 1834 and 1838. When Mr. Russell charted the stars of Kappa Crucis at the Sydney Observatory in 1872, he found 25 that had not been recorded by Herschel, although the great reflector was much larger than the Sydney instrument; many of Herschel’s stars had drifted, and five could not be found at all. If changes so striking as this take place in less than forty years, “it is evident,” as Russell observed, “that more attention should be bestowed on clusters.” [8] It is easy to remember the names of the stars in the Southern Cross. Begin at the foot, which is obviously the brightest, and count round the Cross in clockwise direction α, β, γ, δ. κ is beyond β in a line with γ, β. Quite a dozen star-clusters of this kind are visible to the naked eye in the southern hemisphere, the most striking being in Scorpio, where it shines as a conspicuous silvery spot just beyond the Scorpion’s tail, midway between κ Scorpii and γ Sagittarii. It is named M 7, which means the seventh in Messier’s list of clusters and nebulae. In a binocular it is seen to be a group of very many stars, some close together, others scattered. Lacaille, with his little half-inch telescope, counted from 15 to 20 stars, and Herschel, with his large reflector, estimated the number at 60. At Cordoba Observatory no less than 139 were catalogued.