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.

PLEASURES OF THE TELESCOPE

CHAPTER I

THE SELECTION AND TESTING OF A GLASS

"O telescope, instrument of much knowledge, more precious than any
scepter! Is not he who holds thee in his hand made king and lord of
the works of God?"--JOHN KEPLER.

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 nebulae, 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, p