Notices respecting New Books. 381 



rounded by a nebulous photosphere of greater or less extent, accord- 

 ing to its brightness. He also notices, as a peculiarity of the climate 

 which gave occasion to frequent remark, the great opacity of cloud 

 as compared with that which prevails in this countrj'. 



The climate was found to have a much more prejudicial effect on 

 the metallic specula than had been anticipated. He had provided him- 

 self with three mirrors (each of 1 8^ inches in clear diameter of polished 

 surface), but fortunately he had taken the precaution also to carry 

 out with him the polisRing apparatus, and he soon found that the 

 operation was very much more frequently required than in England. 

 At first some slight imperfections of surface, induced by exposure, 

 were tolerated from an apprehension that in a climate so much w'armer 

 difficulties would arise in hitting the proper temperature of the po- 

 lishing material ; but confidence in this respect being once restored, 

 and practice constantly improving, he soon became fastidious, "and 

 on detection of the slightest dimness on any part of the surface the 

 metal was at once remanded to the polisher." It is scarcely necessary 

 to add that the polisher was Sir John himself. To no other hands 

 than his own could that delicate operation have been entrusted. 



The " Introduction," from which the preceding details are taken, 

 concludes with the following statement : — 



" It remains to say something as to the mode of introducing this 

 work into the world. To the munificent destination of His Grace, the 

 late Duke of Northumberland, of a large sum in aid of its publica- 

 tion, it owes its appearance as a single and separate work, instead 

 of a series of unconnected memoirs scattered over the volumes of 

 academical bodies. The lamented decease of that illustrious noble- 

 man prevented his witnessing its final comi^lelion. His liberal in- 

 tentions how-ever have been fully carried out by the worthy successor 

 to his titles and his spirit ; whose kind and gracious interest in it, I 

 should be wanting in all proper feeling, were I to omit this opportu- 

 nity of acknowledging." 



The contents of the volume are arranged under seven chapters, 

 which are headed as follows : — 



I. Of the Nebulae of the Southern Hemisphere. 



II. Of the Double Stars in the Southern Hemisphere. 



III. Of Astrometry, or the Numerical Expression of the Apparent 

 Magnitude of the Stars. 



IV. Of the Distribution of Stars, and of the Constitution of the 

 Galaxy in the Southern Hemisphere. 



V. Observations of Halley's Comet, with Remarks on its Physical 

 Condition, and that of Comets in general. 



VI. Observations of the Satellites of Saturn. 



VII. Observations of the Solar Spots. 



There are besides four short appendices, and the work is illustrated 

 by seventeen beautiful plates, giving representations of the more re- 

 markable ol)jects from drawings made by the author himself, who 

 thus aj)pears to include among his other accomplishments the skill 

 of a first-rate artist. These delineations, it may be proper to observe, 

 have an object beyond the ordinary purposes of illustration. They 



