The object of the present work is to provide a popular guide to the study of the sky by furnishing a summary of our present knowledge of the Solar system, a guide to the positions of the planets for the first half of the present century, a series of star maps, some examples of the finest achievements in the art of drawing and photographing celestial objects, and a list of interesting objects which may be observed with small telescopes. In the text will be found a descriptive account of the plates, and of the methods of using the maps and tables. It is, however, desirable to draw attention in this place to certain characteristics of the work, and to make my acknowledgment to the friends who have kindly assisted me.