74 



OOS3IOS. 



ve regard the Sun and the Earth, or the Earth and the Moon. 

 as double stars, and the whole of our planetary solar system 

 as a multiple cluster of stars, the analogy thus suggested 

 must be limited to the universality of the laws of attraction 

 in different systems, being alike applicable to the independent 

 processes of light and to the method of illumination. 



P'or the generalization of cosmical views, corresponding 

 with the plan we have proposed to follow in giving a delinea- 

 tion of nature or of the universe, the solar system to which 

 the Earth belongs may be considered in a twofold relation : 

 firstly, with respect to the different classes of individually 

 agglomerated matter, and the relative size, conformation, 

 density, and distance of the heavenly bodies of this system ; 

 And secondly, with reference to other portions of our starry 

 cluster, and of the changes of position of its central body, the 

 Sun. 



The solar system, that is to say, the variously formed matter 

 circling round the Sun, consists according to the present state 

 of our knowledge of eleven primary planets* eighteen satellites, 



[Since the publication of Baron Humboldt's work, in 1845, several 

 other planets have been discovered, making the number of those be- 

 longing to our planetary system sixteen instead of eleven. Of these, 

 Astrea, Hebe, Flora, and Iris are members of the remarkable group of 

 asteroids between Mars and Jupiter. Astrea and Hebe were discovered 

 by Hencke at Driesen, the one in 1846 and the other in 1847; Flora 

 and Iris were both discovered in 1847 by Mr. Hind, at the South Villa 

 Observatory, Regent's Park. It would appear from the latest determi- 

 nations of their elements, that the small planets have the following 

 order with respect to mean distance from the Sun : Flora, Iris, Vesta, 

 Hebe, Astrea, Juno, Ceres, Pallas. Of these, Flora has the shortest period 

 (about 3| ye vrs). The planet Neptune, which after having been predicted 

 by several astronomers was actually observed on the 25th of September, 

 1846, is situated on the confines of our planetary system beyond Uranus. 

 The discovery of this pi met is not only highly interesting from the im- 

 portance attached to it as a question of science, but also from the evidence 

 it affords of the care and unremitting labour evinced by modern astro- 

 nomers in the investigation and comparison of the older calculations, 

 and the ingenious application of the results thus obtained to the obser- 

 vation of new facts. The merit of having paved the way for the dis- 

 covery of the planet Neptune is due to M. Bouvard, who in his perse- 

 vering and assiduous efforts to deduce the entire orbit of Uranus from 

 observations made during the forty years that succeeded the discovery 

 of that planet in 1781, found the results yielded by theory to be at vari- 

 ance wi*.h fact, in a degree that had no parallel in the history of astro- 



