s, can see those of
Mars by hiding the planet at or near the elongations, and that even
our own moonlight does not prevent the observations being made. It
chances for the benefit of observers, in the northern hemisphere
especially, that one of the sixteen year periods will culminate in
1893, when Mars will be most advantageously situated for close
examination. No doubt every one will avail himself of the opportunity,
and may we not reasonably hope that scores of amateur observers
throughout the United States and Canada will experience the delight of
seeing and studying the tiny moons of our ruddy neighbor?

And so I might proceed until I had wearied you with illustrations
showing what can be done with telescopes so small that they may fairly
be classed as "common," Webb says that such apertures, with somewhat
high powers, will reveal stars down to the eleventh magnitude. The
interesting celestial objects more conspicuous than stars of that
magnitude are sufficiently numerous to exhaust much more time than any
amateur can give to observing. Indeed, the lot of the amateur is a
happy one. With a good, though small, telescope, he may have for
subjects of investigation the sun with his spots, his faculae, his
prominences and spectra; the moon, a most superb object in nearly
every optical instrument, with her mountains, valleys, seas, craters,
cones, and ever-changing aspects renewed every month, her occupations
of stars, her eclipses, and all that; the planets, some with phases,
and other with markings, belts, rings, and moons with scores of
occupations, eclipses and transits due to their easily observed
rotation around their primaries; the nebulae, the double, triple and
multiple stars with sometimes beautifully contrasted colors, and a
thousand and one other means of amusing and instructing himself.
Nature has opened in the heavens as interesting a volume as she has
opened on the earth, and with but little trouble any one may learn to
read in it.

I trust it has been shown that expensive telescopes are not
necessarily required for practical work. My advice to an intending
purchaser would be to put into the objective for a refractor, or into
the mirror for a reflector, all the money he feels warranted in
spending, leaving the mounting to be done in the cheapest possible
manner consistent with accuracy of adjustment, because it is in the
objective or in the mirror that the _value_ of the telescope alone
resides. In the sh