ar globe. Nobody who has not seen
the moon with a telescope--it need not be a large one--can form a
correct and definite idea of what the moon is like.

The satisfaction of viewing with one's own eyes some of the things the
astronomers write and talk about is very great, and the illumination
that comes from such viewing is equally great. Just as in foreign travel
the actual seeing of a famous city, a great gallery filled with
masterpieces, or a battlefield where decisive issues have been fought
out illuminates, for the traveler's mind, the events of history, the
criticisms of artists, and the occurrences of contemporary life in
foreign lands, so an acquaintance with the sights of the heavens gives a
grasp on astronomical problems that can not be acquired in any other
way. The person who has been in Rome, though he may be no archaeologist,
gets a far more vivid conception of a new discovery in the Forum than
does the reader who has never seen the city of the Seven Hills; and the
amateur who has looked at Jupiter with a telescope, though he may be no
astronomer, finds that the announcement of some change among the
wonderful belts of that cloudy planet has for him a meaning and an
interest in which the ordinary reader can not share.

[Illustration: JUPITER SEEN WITH A FIVE-INCH TELESCOPE.

Shadow of a satellite visible.]

Jupiter is perhaps the easiest of all the planets for the amateur
observer. A three-inch telescope gives beautiful views of the great
planet, although a four-inch or a five-inch is of course better. But
there is no necessity for going beyond six inches' aperture in any case.
For myself, I should care for nothing better than my Byrne five-inch of
fifty-two inches' focal distance. With such a glass more details are
visible in the dark belts and along the bright equatorial girdle than
can be correctly represented in a sketch before the rotation of the
planet has altered their aspect, while the shadows of the satellites
thrown upon the broad disk, and the satellites themselves when in
transit, can be seen sometimes with exquisite clearness. The contrasting
colors of various parts of the disk are also easily studied with a glass
of four or five inches' aperture.

There is a charm about the great planet when he rides high in a clear
evening sky, lording it over the fixed stars with his serene,
unflickering luminousness, which no possessor of a telescope can resist.
You turn the glass upon him and he floats