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 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.

It is not by any means proposed to inflict upon you a history of the telescope, but your indulgence is asked for a few moments while reference is made to one or two matters connected with its invention, or, rather, its accidental discovery and subsequent improvement.

The opening years of the seventeenth century found the world without a telescope, or, at least, such an instrument as was adapted for astronomical work.  It is true that long years before, Arabian and some other eastern astronomers, for the purpose, possibly, of enabling them to concentrate their gaze upon celestial objects and follow their motions, had been accustomed to use a kind of tube consisting of a long cylinder without glasses of any kind and open at both ends.  For magnifying purposes, this tube was of no value.  Still, it must have been of some kind of service, or else the first telescopes, as constructed by the spectacle makers, who had stumbled upon the principle involved, were exceedingly sorry affairs, for, soon after their introduction, the illustrious Kepler, in his work on “Optics,” recommended the employment of plain apertures, without lenses, because they were superior to the telescope on account of their freedom from refraction.