From the PREFACE:
 
"The object which the Author and Publisher of this little work have proposed to themselves, has been the production, at a moderate price, of a useful and reliable guide to the amateur telescopist.

Among the celestial phenomena described or figured in this treatise, by far the larger number may be profitably examined with small telescopes, and there are none which are beyond the range of a good 3-inch achromatic. The work also treats of the construction of telescopes, the nature and use of star-maps, and other subjects connected with the requirements of amateur observers."

                       --R.A.P.