lunar disc is Aristarchus, the peaks
of which shine often like stars, when the mountain is within the
unillumined portion of the moon. The darkest regions are Grimaldi and
Endymion and the great plain called Plato by modern astronomers--but, by
Hevelius, the Greater Black Lake.

The Sun.--Observation of the sun is perhaps on the whole the most
interesting work to which the possessor of a moderately good telescope
can apply his instrument. Those wonderful varieties in the appearance of
the solar surface which have so long perplexed astronomers, not only
supply in themselves interesting subjects of observation and
examination, but gain an enhanced meaning from the consideration that
they speak meaningly to us of the structure of an orb which is the
source of light and heat enjoyed by a series of dependent worlds whereof
our earth is--in size at least--a comparatively insignificant member.
Swayed by the attraction of this giant globe, Jupiter and Saturn, Uranus
and Neptune, as well as the four minor planets, and the host of
asteroids, sweep continuously in their appointed orbits, in ever new but
ever safe and orderly relations amongst each other. If the sun's light
and heat were lost, all life and work among the denizens of these orbs
would at once cease; if his attractive energy were destroyed, these orbs
would cease to form a _system_.

The sun may be observed conveniently in many ways, some more suited to
the general observer who has not time or opportunity for systematic
observation; others more instructive, though involving more of
preparation and arrangement.

The simplest method of observing the sun is to use the telescope in the
ordinary manner, protecting the eye by means of dark-green or
neutral-tinted glasses. Some of the most interesting views I have ever
obtained of the sun, have resulted from the use of the ordinary
terrestrial or erecting eye-piece, capped with a dark glass. The
magnifying power of such an eye-piece is, in general, much lower than
that available with astronomical eye-pieces. But vision is very pleasant
and distinct when the sun is thus observed, and a patient scrutiny
reveals almost every feature which the highest astronomical power
applicable could exhibit. Then, owing to the greater number of
intervening lenses, there is not the same necessity for great darkness
or thickness in the coloured glass, so that the colours of the solar
features are seen much more satisfactorily than when astr