infection, if infection it
may be called. There are in New York, Philadelphia, St. Louis, and
other centers of population on this continent leading newspapers
which, every week or so, publish columns of original matter
contributed by writers evidently able to place before their readers in
an attractive form articles dealing accurately, and yet in a popular
vein, with the many-sided subject of astronomy. In scientific matters
generally, there is abroad in this and other countries a spirit of
inquiry, never more apparent than at the present time.

Readers and thinkers may, no doubt, be numbered by thousands. So far,
however, as astronomy is concerned, the majority of readers and
thinkers is composed of non-observers, most of whom believe they must
be content with studying the theoretical side of the subject only.
They labor under the false impression that unless they have telescopes
of large aperture and other costly apparatus, the pleasures attaching
to practical work are denied them. The great observatories, to which
every intelligent eye is directed, are, in a measure, though
innocently enough, responsible for this. Anticipation is ever on
tiptoe. People are naturally awaiting the latest news from the giant
refracting and reflecting telescopes of the day. Under these
circumstances, it may be that the services rendered, and capable of
being rendered, to science by smaller apertures may be overlooked,
and, therefore, I ask to be permitted to put in a modest plea for the
common telescope. What little I shall have to say will be addressed to
you more for the purpose of arousing interest in the subject than for
communicating to you any information of a novel or special character.

When making use of the term "common telescope," I would like to be
understood as referring to good refractors with object glasses not
exceeding three or three and one-half inches in diameter. In some
works on the subject telescopes as large as five inches or even five
and one-half inches are included in the description "common," but
instruments of such apertures are not so frequently met with in this
country as to justify the classing of them with smaller ones, and,
perhaps, for my purpose, it is well that such is the fact, for the
expense connected with the purchase of first rate telescopes increases
very rapidly in proportion to the size of the object glass, and soon
becomes a serious matter. Should ever the larger apertures become
numerous on