Such a superficial examination of stars as we have made scarcely touches the subject. It is as the study of the baptismal register, where the names were anciently recorded, without any knowledge of individuals. The heavens signify much more to us than to the Greeks. We revolve under a dome that investigation has infinitely enlarged from their estimate. Their little lights were turned by clumsy machinery, held together by material connections. Our vast worlds are connected by a force so fine that it seems to pass out of the realm of the material into that of the spiritual. Animal ferocity or a human Hercules could image their idea of power. Ours finds no symbol, but rises to the Almighty. Their heavens were full of fighting Orions, wild bulls, chained Andromedas, and devouring monsters. Our heavens are significant of harmony and unity; all worlds carried by one force, and all harmonized into perfect music. All their voices blend their various significations into a personal speaking, which says, "Hast thou not heard that the everlasting God, the Lord, the creator of the ends of the earth, fainteth not, neither is weary?" There is no searching of his understanding. Lift up your eyes on high, and behold who hath created all these things, that brought out their host by number, that calleth them all by their names in the greatness of his power; for that he is strong in power not one faileth.
Number.
We find about five thousand stars visible to the naked eye in the whole heavens, both north and south. Of these twenty are of the first magnitude, sixty-five of the second, two hundred of the third, four hundred of the fourth, eleven hundred of the fifth, and three thousand two hundred of the sixth. We think we can easily number the stars; but train a six-inch telescope on a little section of the Twins, where six faint stars are visible, and over three thousand luminous points appear. The seventh magnitude has 13,000 stars; the eighth, 40,000; the ninth, 142,000. There are 18,000,000 stars in the zone called the Milky Way. When our eyes are not sensitive enough to be affected by the light of far-off stars the tastimetre feels their heat, and tells us the word of their Maker is true—"they are innumerable."[*]
[Footnote *: Telescopic Work.—Look at the Hyades and Pleiades in Taurus. Notice the different colors of stars in them both. Find the cluster Præsepe in Fig. 70, just a trifle above a point midway between Procyon and Regulus. It is equally distant from Procyon and a point a little below Pollux. Sweep along the Milky Way almost anywhere, and observe the distribution of stars; in some places perfect crowds, in others more sparsely scattered. Find with the naked eye the rich cluster in Perseus. Draw a line from Algol to α of Perseus (Fig. 67); turn at right angles to the right, at a distance of once and four-tenths the first line a brightness will be seen. The telescope reveals a gorgeous cluster.]
Double and Multiple Stars.
If we look up during the summer months nearly overhead at the star ε Lyra, east of Vega (Fig. 72), we shall see with the naked eye that the star appears a little elongated. Turn your opera-glass upon it, and two stars appear. Turn a larger telescope on this double star, and each of the components separate into two. It is a double double star. We know that if two stars are near in reality, and not simply apparently so by being in the same line of sight, they must revolve around a common centre of gravity, or rush to a common ruin. Eagerly we watch to see if they revolve. A few years suffice to show them in actual revolution. Nay, the movement of revolution has been decided before the companion star was discovered. Sirius has long been known to have a proper motion, such as it would have if another sun were revolving about it. Even the direction of the unseen body could always be indicated. In February, 1862, Alvan Clark, artist, poet, and maker of telescopes (which requires even greater genius than to be both poet and artist), discovered the companion of Sirius just in its predicted place. As a matter of fact, one of Mr. Clark's sons saw it first; but their fame is one. The time of revolution of this pair is fifty years. But one companion does not meet the conditions of the movements. Here must also be one or more planets too small or dark to be seen. The double star ξ in the Great Bear (see Fig. 70) makes a revolution in fifty-eight years.
Procyon moves in an orbit which requires the presence of a companion star, but it has as yet eluded our search. Castor is a double star; but a third star or planet, as yet undiscovered, is required to account for its perturbations. Men who discovered Neptune by the perturbations of Uranus are capable of judging the cause of the perturbations of suns. We have spoken of the whole orbit of the earth being invisible from the stars. The nearest star in our northern hemisphere, 61 Cygni, is a telescopic double star; the constituent parts of it are forty-five times as far from each other as the earth is from the sun, yet it takes a large telescope to show any distance between the stars.[*]
[Footnote *: Telescopic Work.—Only such work will be laid out here as can be done by small telescopes of from two to four inch object-glasses. The numbers in Fig. 75 correspond to those of the table.
| No. | Name. | Fig. | Dist. of Parts. | Magnitudes. | Remarks. |
|---|---|---|---|---|---|
| 1. | ε Lyræ | 72 | 1' 56" | Quadruple. | |
| 2. | ζ Lyræ | 72 | 44 | 5 & 6 | Topaz and green. |
| 3. | β Cygni | 73 | 34-1/2 | 3 & 6 | Yellow and blue. |
| 4. | 61 Cygni | 73 | 20 | 5 & 6 | Nearest star but one. |
| 5. | Mizar | 67 | 14 | 3 & 4 | Both white. |
| 6. | Polaris | 67 | 18-1/2 | 2 & 9 | Test object of eye and glass. |
| 7. | ρ Orionis | Frontispiece. | 7 | 5 & 8 | Yellow and blue. |
| 8. | β Orionis | " | 9 | 1 & 8 | Rigel. |
| 9. | δ " | " | 10 | 2 & 8 | Red and white. |
| 10. | θ " | " | Septuple. | ||
| 11. | λ " | " | 5 | White and violet. | |
| 12. | σ " | " A, B. | 11 | 4 & 10 | Octuple. |
| 13. | Castor | 69 | 5-1/2 | 2 & 3 | White. |
| 14. | Pollux | 69 | Triple. | Orange, gray, lilac. | |
| 15. | γ Virginis | 70 | 5 | 3 & 3 | Both yellow. |
When γ Virginis was observed in 1718 by Bradley, the component parts were 7" asunder. He incidentally remarked in his note-book that the line of their connection was parallel to the line of the two stars Spica, or α and δ Virginis. By 1840 they were not more than 1" apart, and the line of their connection greatly changed. The appearance of the star is given in Fig. 75 (15), commencing at the left, for the years 1837 '38 '39 '40 '45 '50 '60 and '79. also a conjectural orbit, placed obliquely, and the position of the stars at the times mentioned, commencing at the top. The time of its complete revolution is one hundred and fifty years.