THE SMALL PLANETS. 509 



The mutual relation of the orbits of the asteroids and the 

 enumeration of the individual pairs of orbits, has been made 

 the subject of acute investigation, first by Gould 63 in 1848, 

 and more recently by D' Arrest. The latter says, "The 

 strongest evidence of the intimate connection of the whole 

 group of small planets appears to be, that if the orbits are 

 supposed to be represented materially as hoops, they all hang 

 together in such a manner that the whole group may be 

 suspended by any given one. If it so happened that Iris, 

 which Hind discovered in August, 1847, was still unknown, 

 as many other bodies in this region certainly are, the group 

 would consist of two separate parts, a result which must 

 appear so much the more unexpected as the zone which these 

 orbits occupy in the solar system is wide." ** 



We cannot take leave of this wonderful group of planets 

 without mentioning, in this fragmentary enumeration of the 

 individual members of the solar system, the bold view of a 

 gifted and deeply investigating astronomer, as to the origin 

 of the asteroids and their intersecting orbits. A result 

 deduced from the calculations of Gauss, that Ceres approaches 

 extremely near to Pallas in her ascending passage through 

 the plane of that planet's orbit, led Olbers to form the con- 

 jecture that " both planets, Ceres and Palls s, may be frag- 

 ments of a single large principal planet . hich has been 

 destroyed by some natural force, and formerly occupied the 

 gap between Mars and Jupiter, and that the discovery of 

 an additional number of similar fragments which describe 

 elliptical orbits round the Sun, in the same region, may be 

 expected." 65 



63 Benjamin Althorpe Gould (now at Cambridge, Massa- 

 chusetts, U.S.) Untersuchungen uber die gegenseitige Lage der 

 Bahnen zwischen Mars und Jupiter ', 1848, pp. 9-12. 



64 D' Arrest, op. cit. p. 30. 



65 Zach, MonatL Corresp. Bd. vi. p. 88. 



