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LXIV. Notices respecting New Boohs. 



Popular Astronomy. By SoiON jNewcojsxb, LL.D., Professor U.S. 



Naval Observatory. London : Macinillan and Co., 1878. 

 ^T^HIS is by far the best-written work on Astronomy for the gen- 

 ■*■ eral reader we have seen for some time ; its style is so lucid, 

 and it is so full of sterling information, that a perusal of it cannot 

 fail to impart a knowledge of the salient features of a branch of 

 science which may well be considered the most ancient in the 

 world. Dividing his subject into four parts, the author develops 

 in each a leading astronomical idea, such as the earliest guesses ab 

 the construction of the external universe, the apparent and real 

 motions of the heavenly bodies, and the forces by which order 

 amongst them is maintained. Before treating of the groups of 

 Planets, Satellites, Comets, and Meteors as illustrative of this order, 

 he devotes the second part of his work to an exposition of the 

 methods and instruments employed for obtaining a knowledge of 

 the magnitudes, distances, and arrangements in space of the bodies 

 by which .we are surrounded. In the first chapter of this part, the 

 author enters largely into the construction of the two classes of 

 telescopes, Refracting and Reflecting, with an account of the prin- 

 cipal great reflecting telescopes of modern times ; in the second, 

 his subject is the application of the telescope to celestial measure- 

 ments ; in the third, the determination of distances in the heavens ; 

 in the fourth, the motion of light ; and in the fifth the construction 

 and use of the spectroscope. The third and fourth parts of the 

 work treat respectively of the Solar System and the Stellar 

 Universe. 



During the course of perusal we have noticed so many interesting 

 aspects in which Professor Newcomb has presented Astronomy to 

 his readers, that to particularize them would take up much more 

 space than we can give ; there are, however, a few that we cannot 

 pass over. The peculiar construction of the Professors mind fits 

 him especially for discriminating between truth and error so far as 

 a conception of the external world is concerned. He opens his work 

 with an account of the apparent diurnal motion of the celestial 

 sphere, and passes onto a description of the Ptolemaic system; and 

 here we notice his acumen in clearly distinguishing between those 

 views of Ptolemy which were correct and these in which he was in 

 error ; but perhaps the most interesting feature in connexion with 

 Ptolemy is our author's showing that his system was a necessary 

 step in the evolution of the true system of the universe subse- 

 quently developed by Copernicus, whose work was the greatest 

 step ever taken in astronomy. Prom Copernicus he passes on to 

 the work of Kepler and Newton, which culminated in the establish- 

 ment of the doctrine of universal gravitation. 



The portion of the universe most accurately known is "the Solar 

 System;" and it is in this part of the work that we see the astro- 

 nomical mind of the author strikingly developed: the subject-matter, 

 while condensed, is at the same time remarkably full; not one im- 



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