me to
scrutinize the sharp cusps will be when the planet is nearly on the
line from the earth to the sun. The best hour of the day is near
sunset, the half-hour following sunset being the best of all. But if
Venus is near the sun, she will after sunset be too low down to be well
seen, and must be looked at late in the afternoon.

The planet Mars must always be an object of great interest, because of
all the heavenly bodies it is that which appears to bear the greatest
resemblance to the earth. It comes into opposition at intervals of a
little more than two years, and can be well seen only for a month or
two before and after each opposition. It is hopeless to look for the
satellites of Mars with any but the greatest telescopes of the world.
But the markings on the surface, from which the time of rotation has
been determined, and which indicate a resemblance to the surface of our
own planet, can be well seen with telescopes of six inches aperture and
upward. One or both of the bright polar spots, which are supposed to be
due to deposits of snow, can be seen with smaller telescopes when the
situation of the planet is favorable.

The case is different with the so-called canals discovered by
Schiaparelli in 1877, which have ever since excited so much interest,
and given rise to so much discussion as to their nature. The astronomer
who has had the best opportunities for studying them is Mr. Percival
Lowell, whose observatory at Flaggstaff, Arizona, is finely situated
for the purpose, while he also has one of the best if not the largest
of telescopes. There the canals are seen as fine dark lines; but, even
then, they must be fifty miles in breadth, so that the word "canal" may
be regarded as a misnomer.

Although the planet Jupiter does not present such striking features as
Saturn, it is of even more interest to the amateur astronomer, because
he can study it with less optical power, and see more of the changes
upon its surface. Every work on astronomy tells in a general way of the
belts of Jupiter, and many speculate upon their causes. The reader of
recent works knows that Jupiter is supposed to be not a solid mass like
the earth, but a great globe of molten and vaporous matter,
intermediate in constitution between the earth and the sun. The outer
surface which we see is probably a hot mass of vapor hundreds of miles
deep, thrown up from the heated interior. The belts are probably
cloudlike forms in this vaporous mass. Cer