162 cosmos. 



the third part of all the 43 known planetary bodies, i. e., of 

 all principal and secondary planets. 



Although the attention of astronomers was long directed 

 in the solar regions to increasing the number of the members 

 of partial systems — the Moons which revolve round principal 

 planets — and to the planets to be discovered in the furthest 

 regions beyond Saturn and Uranus, now, since the accidental 

 discovery of Ceres by Piazzi, and especially since the foreseen 

 discovery of Astrea by Encke, as well as the great improve- 

 ments in the star-charts* (those of the Berlin Academy con- 

 tain all stars as far as the 9th, and partly to the 10th mag- 

 nitudes), a nearer space presents to us the richest, and per- 

 haps inexhaustible field for astronomical industry. It is an 

 especial merit of the Astronomischen Jahrbuch, which is 

 published in my native town by Encke, the Director of the 

 Berlin Observatory, with the assistance of Dr. Wolfers, that 

 the ephemerides of the increasing host of small planets are 

 treated of with particular completeness. Up to the present 

 time, the region nearest to the orbit of Mars appears to be 

 the most filled ; but the breadth of this measured zone is in 

 itself more considerable than the distance of Mars from the 

 Sun,f " when the difference of the radii-vectores in the near- 

 est perihelion (Victoria) and the most distant aphelion (Hy- 

 giea) is taken into consideration." 



The eccentricities of the orbits, of which those of Ceres, 

 Egeria, and Vesta are the smallest, and Juno, Pallas, and 

 Iris the greatest, have already been alluded to| above, as 

 well as their degrees of inclination toward the ecliptic, which 

 decreases from Pallas (34° 37') and Egeria (16° 33') to Hy- 

 giea (3° 47'). A tabular view of the elements of the small 

 planets follows here, for which I am indebted to my friend 

 Dr. Galle. 



* With regard to the influence of improved star-charts upon the dis- 

 covery of the small planets, see Cosmos, vol. hi., p. 116. 



t D'Arrest, Ueber das System der Kleinen Planeten zwiscken Mars una 

 Jupiter, 1851, p. 8. t Cosmos, vol. iv., p. 102 and 172. 



