href="@public@vhost@g@gutenberg@html@files@28752@[email protected]#CHAPTER_IV" class="pginternal" tag="{http://www.w3.org/1999/xhtml}a">57

Crater and Corvus, Hydra, Virgo, the "Field of the Nebulæ," Libra, Boötes, and the great Arcturus, Canes Venatici, and Corona Borealis.   CHAPTER V In Summer Star-lands 75 Scorpio and its red-green gem, Ophiuchus, Sagittarius, Scutum Sobieskii, Capricornus, Serpens, Hercules, Draco, Aquila, and Delphinus.   CHAPTER VI From Lyra To Eridanus 97 Lyra and its brilliant Vega, Cygnus, Vulpecula, Aquarius, Equuleus, Pegasus, Cetus, and Eridanus.   CHAPTER VII Pisces, Aries, Taurus, and the Northern Mars 117 The first double star ever discovered, the Pleiades and their photographic wonders, the Royal Family of the Sky, Andromeda, Cassiopeia, Perseus and Cepheus, Ursa Major, Camelopardalus, Ursa Minor, and the Pole Star.   CHAPTER VIII Scenes on the Planets 139 Jupiter, its belts and its moons—Saturn, the ringed planet—Saturn's moons and Roche's limit—Mars and its white polar caps and so-called seas and continents—Venus and her atmosphere—The peculiar rotations of Venus and Mercury.   CHAPTER IX The Mountains and Plains of the Moon and the Spectacles of the Sun 156 Peculiarities of the lunar landscapes—The so-called seas, the craters, the ring mountains, the inclosed plains, the mountain ranges, Tycho's mysterious streaks, and other lunar features described—How to view the sun and its spots.   CHAPTER X Are There Planets Among the Stars? 183 Significance of Dr. See's observations—Why our telescopes do not show planets circling around distant suns—Reasons for thinking that such planets may exist—The bearing of stellar evolution on the question.   INDEX 193

---

CHAPTER I

THE SELECTION AND TESTING OF A GLASS

If the pure and elevated pleasure to be derived from the possession and use of a good telescope of three, four, five, or six inches aperture were generally known, I am certain that no instrument of science would be more commonly found in the homes of intelligent people. The writer, when a boy, discovered unexpected powers in a pocket telescope not more than fourteen inches long when extended, and magnifying ten or twelve times. It became his dream, which was afterward realized, to possess a more powerful telescope, a real astronomical glass, with which he could see the beauties of the double stars, the craters of the moon, the spots on the sun, the belts and satellites of Jupiter, the rings of Saturn, the extraordinary shapes of the nebulæ, the crowds of stars in the Milky Way, and the great stellar clusters. And now he would do what he can to persuade others, who perhaps are not aware how near at hand it lies, to look for themselves into the wonder-world of the astronomers.

There is only one way in which you can be sure of getting a good telescope. First, decide how large a glass you are to have, then go to a maker of established reputation, fix upon the price you are willing to pay—remembering that good work is never cheap—and finally see that the instrument furnished to you answers the proper tests for a telescope of its size. There are telescopes and telescopes. Occasionally a rare combination of perfect homogeneity in the material, complete harmony between the two kinds of glass of which the objective is composed, and lens surfaces whose curves are absolutely right, produces a telescope whose owner would part with his last dollar sooner than with it. Such treasures of the lens-maker's art can not, perhaps, be commanded at will, yet,