THE SOLAR REGION. 57 



resentation of the orbits of the planets, such as is given in 

 our most epitomized manuals, there is scarcely any thing to 

 which we could compare the admiration and surprise of these 

 men the heroes of the early and limited knowledge of that 

 age excepting, perhaps, that which might have been expe- 

 rienced by Eratosthenes, Strabo, and Claudius Ptolemy, could 

 they have seen one of our maps of the world, on Mercator's 

 projection, not above a few inches in length and breadth. 



The return of comets in closed elliptical orbits, as a conse- 

 quence of the attractive force of the central body, indicates 

 the limits of the solar region. As, however, we are as yet 

 ignorant whether comets may not some day appear in which 

 the major axis may prove to be larger than any that have as 

 yet been observed and calculated, these bodies must be re- 

 garded as indicating, in their aphelia, merely the limits to 

 which the solar regions must at least extend. Hence we may 

 characterize the solar system by the visible and measurable 

 results of peculiar operating central forces, and by the cos- 

 mical bodies (planets and comets) which rotate round the Sun 

 in closed orbits, and are intimately connected with it. The 

 considerations which at present engage our attention do not 

 embrace a notice of the attraction which the Sun may exert 

 on other suns (or fixed stars) lying beyond the limits of these 

 reappearing cosmical bodies. 



According to the state of our knowledge at the close of 

 this half of the nineteenth century, the solar region includes 

 the following bodies, arranging the planets according to their 

 respective distances from the central body : 



22 PRINCIPAL PLANETS (MERCURY, VENUS, THE EARTH, 

 MARS ; Flora, Victoria, Vesta, Iris, Metis, Hebe, Parthen- 

 ope, Irene, Astrcea, Egeria, Juno, Ceres, Pallas, Hygiea ; 

 JUPITER, SATURN, URANUS, NEPTUNE) ; 



21 SATELLITES (1 belonging to the Earth, 4 to Jupiter, 

 8 to Saturn, 6 to Uranus, 2 to Neptune) ; 



197 COMETS, whose orbits have been calculated. Of 

 these, 6 are interior ; i.e., such as have their aphelia in- 

 closed within the outermost of the planetary orbits, viz., that 

 of Neptune : we may very probably add to these 



THE RING OF THE ZODIACAL LIGHT, which probably 

 lies between the orbits of Venus and Mars ; and likewise, 

 according to the opinion of numerous observers, 



THE SWARMS OF THE METEOR-ASTEROIDS which more 

 especially intersect the Earth's orbit at certain points. 

 C 2 



