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 this continent, let us hope it shall be found to have been
as one of the results of societies like this, striving to make more
popular the study of astronomy.
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