tain it is that they are
continually changing, so that the planet seldom looks exactly the same
on two successive evenings. The rotation of the planet can be very well
seen by an hour's watching. In two hours an object at the centre of the
disk will move off to near the margin.

The satellites of this planet, in their ever-varying phases, are
objects of perennial interest. Their eclipses may be observed with a
very small telescope, if one knows when to look for them. To do this
successfully, and without waste of time, it is necessary to have an
astronomical ephemeris for the year. All the observable phenomena are
there predicted for the convenience of observers. Perhaps the most
curious observation to be made is that of the shadow of the satellite
crossing the disk of Jupiter. The writer has seen this perfectly with a
six-inch telescope, and a much smaller one would probably show it well.
With a telescope of this size, or a little larger, the satellites can
be seen between us and Jupiter. Sometimes they appear a little brighter
than the planet, and sometimes a little fainter.

Of the remaining large planets, Mercury, the inner one, and Uranus and
Neptune, the two outer ones, are of less interest than the others to an
amateur with a small telescope, because they are more difficult to see.
Mercury can, indeed, be observed with the smallest instrument, but no
physical configurations or changes have ever been made out upon his
surface. The question whether any such can be observed is still an open
one, which can be settled only by long and careful scrutiny. A small
telescope is almost as good for this purpose as a large one, because
the atmospheric difficulties in the way of getting a good view of the
planet cannot be lessened by an increase of telescopic power.

Uranus and Neptune are so distant that telescopes of considerable size
and high magnifying power are necessary to show their disks. In small
telescopes they have the appearance of stars, and the observer has no
way of distinguishing them from the surrounding stars unless he can
command the best astronomical appliances, such as star maps, circles on
his instrument, etc. It is, however, to be remarked, as a fact not
generally known, that Uranus can be well seen with the naked eye if one
knows where to look for it. To recognize it, it is necessary to have an
astronomical ephemeris showing its right ascension and declination, and
star maps showing where the parallels