Notices respecting New Books. 313 



give in the compass to which he has restricted himself a condensed 

 epitome of all the information within his reach alike useful for the 

 student and general reader. The chapters to which we especially 

 allude are those referring to libration, and the study and condition 

 of the moon's surface. From the remarkable sentence in the pre- 

 face, to the effect that nothing exists comparable to the author's 

 exposition of libration, we fully expected to find this subject ren- 

 dered in a much more lucid manner than it really is ; for it consists 

 merely of an extension of tracing on the apparent disk the path of 

 the middle point of the visible hemisphere in mean libration, the 

 essential principle of which, if we remember rightly, has been some 

 years before the public. As for the mathematical treatment of the 

 subject by such a master mind as that of Encke, and its importance 

 in the determination of the position of objects on the moon, it is not 

 even mentioned, so far as we could find ; and we searched carefully 

 for it. This is a subject that astronomers would certainly look for in 

 such a work. In the chapter on the study of the surface, while the 

 sketch of progress in mapping the moon gives a very fair idea of the 

 successive steps in the study from the time of Galileo to the 

 present, we miss the charm which we have always experienced 

 when consulting the selenographical portion of ' Webb's Celestial 

 Objects.' The description of lunar celestial phenomena is appa- 

 rently too picturesque ; for although we have no observational evi- 

 dence of an atmosphere, it is impossible for us in our terrestrial 

 abode to tell what effect would be produced when viewing the starry 

 heavens from a stand-point destitute of an atmospheric covering, 

 farther than the fact that the same constellations which we see and 

 which would be seen, were there eyes to see them, from all parts of 

 the solar system, are visible from the moon. It is not difficult to 

 ascertain the objects visible in every direction from the moon's sur- 

 face ; but for the greatly increased numbers of which Mr. Proctor 

 speaks we have, as it appears to us, no real evidence. In the con- 

 cluding chapter Mr. Proctor presents us with a most remarkable 

 theory — that of the craters having been produced by meteoric im- 

 pact. Many of the views set forth in connexion with the past and 

 present condition of the surface are highly speculative and calcu- 

 lated to induce much thought. The question, however, arises, 

 cannot thought be better expended on that which is real and tan- 

 gible than on that which is unreal and speculative? The work 

 itself, well conceived and in the main well executed, will afford 

 much food for thought ; and we commend it to the reader in the 

 hope that he will examine it with the utmost care, treasure up the 

 many truths it contains, and seek in contemporaneous and earlier 

 literature a knowledge of those subjects which are but slightly men- 

 tioned, and which are necessary to be known in order to obtain a 

 complete knowledge of the moon, her motions, aspects of her sur- 

 face, and physical condition. 



