REMARKS ON THE SMALL PLANETS. 201 



sickness. As early as the 24th of January he had sent intelligence 

 of his discovery to Bode and Oriani; but his letters were two months 

 in reaching them, at which time the new star was lost in the rays of 

 the sun. Bode, therefore, could not distinguish it, but he remained 

 convinced that this was the unknown planet, an opinion to which 

 Piazzi subscribed and gave the name of Ceres to the object of his 

 discovery. 



A problem in astronomy, altogether new, now presented itself to 

 geometers to determine, namely, the orbit of a planet after six 

 weeks of observation. Many trials were made, but with results little 

 accordant. The illustrious Gauss, then scarcely known, arrived at a 

 solution by methods peculiar to himself, and it was by taking this 

 calculation for the basis of his researches that Olbers found the planet 

 anew, 1st January, 1802, a year, to a day, after its first discovery. 

 From that time Ceres took a definite place in our system, very nearly 

 at the distance from the sun indicated by the law of Bode, thus, filling 

 the gap which Kepler had signalized. 



While constructing special charts to facilitate for the future the 

 finding of Ceres on the celestial sphere, Olbers perceived, 28th of 

 March, 1802, a star not in the catalogue : he followed it for several 

 days and recognized, from its proper movement, a second planet 

 situated at the same distance from the sun as the former, but describing 

 a wholly different orbit. This was more than astronomers had asked for, 

 and Pallas was received with a greater degree of reserve than Ceres. 

 Some astronomers went so far as to deny its planetary character, an 

 opinion to which the great eccentricity and extraordinary inclination 

 of its orbit gave countenance by assimilating it to the comets, its re- 

 semblance to which was still more enhanced by the vaporous appear- 

 ance which it assumed through the imperfect telescopes of Schrceter. 



As to Olbers, he regarded the two bodies as fragments of a more 

 considerable planet which some unknown force had shattered. On 

 this hypothesis, it resulted from the laws of mechanics that all the 

 projected asteroids, while describing orbits of very diJOTerent eccen- 

 tricity and inclinations, must continue to maintain the same mean 

 distance from the sun, and repass, moreover, in each of their revolu- 

 tions, the point in space where the catastrophe had occurred. That 

 point was necessarily one of the nodes of the orbits of Ceres and Pal- 

 las, situated, the first in the constellation of Yirgo, the second in 

 the Whale. It was in these two regions of the heavens, according to 

 the theory of Olbers, that the trajectories of fragments still unper- 

 ceived must meet, and here, above all, that an attentive examination 

 of telescopic stars might be expected to yield new discoveries; a con- 

 jecture which did not long remain unverified. The 2d of September, 

 1804, Harding perceived in the Whale a third planet, which he named 

 Juno; and Vesta, the fourth and long the last, was discovered by 

 Olbers himself, the 29th March, 1807, in the northern wing of Virgo. 

 Vesta is much less remote from the Sun than the three other aste- 

 roids. The difference amounts to a fourth of its mean distance, that 

 is, to twenty millions of leagues, a fact not calculated very strongly 



