Deceased Fellows : — Dr. Olbers. 73 



general view of discovering new comets and planets, and of recording 

 any remarkable phaenomena that might occur. Their zeal in the 

 prosecution of these researches had been stimulated by the recent 

 discovery of Herscliel, as well as by the revival of a suggestion 

 made by Kepler of the probable existence of a planet between 

 Mars and Jupiter, in conformity with one of those mystical ana- 

 logies, which might have been treated as the visionary dreams 

 of an enthusiast, if they had not been so intimately connected with 

 the discovery of the great laws forming the true basis of all cor- 

 rect knowledge of the system of the universe. The absence like- 

 wise of a planet at the distance from the sun, re^iresented by 28, that 

 of the earth being 10, interfered with the completeness of an em- 

 pirical law which Bode of Berlin had suggested, and was not with- 

 out its influence in confirming their faith in these extraordinary an- 

 ticipations. The labours of this Association had been hardly organ- 

 ized, when the remarkable discovery of Ceres by Piazzi on the first 

 day of the present century, in almost the precise position which 

 Bode's singular law had assigned to it, seemed at once to convert 

 their dreams into realities. Dr. Olbers calculated a circular, and 

 Gauss an elliptic orbit for the same planet ; and so wonderful was 

 the accuracy of the first approximation to the elements which the 

 latter had made, that they enabled Olbers to re-discover it on the 

 1st of January 1802^ exactly one year after it had been first ob- 

 served. It was in consequence of having formed a configuration 

 of stars in the geocentric route of this planet, with a view to its 

 being more readily found, that he discovered Pallas on the 25th of 

 March of the same year*, at nearly the same distance from the sunf, 

 though moving in an orbit more than three times as much inclined 

 to the plane of the ecliptic. The discovery of two planets, in the po- 

 sition where one of them had been so anxiously sought for |, induced 

 Dr. Olbers to conjecture that they were fragments of a larger planet, 

 which had been scattered by some great catastrophe, and that 

 many others probably existed at nearly the same distance from the 

 sun, and possessing common nodes : he therefore earnestly recom- 

 mended astronomers to observe most carefully those spaces of the 

 heavens in which the nodes of these planets are placed ; a practice 

 which he himself observed for many years. His exemplary dili- 

 gence was rewarded by the discovery of Vesta on the 29th of March, 

 1807, nearly in the precise position in which he had conjectured that 

 it was most likely to be found §. This was the last of those remark- 

 able discoveries whose history illustrates in so striking a manner that 

 union of profound, yet somewhat visionary speculation, with uncon- 



* " Uebcreinenneuen von Dr. Olhers in Bremen endeckten hiJchst son- 

 derbaren comcten." Zach's Monatliche Correspondcnz for May, 1802. 



f If the distance of the earth from the sun bel, that of Ceres is 2'7674, 

 and that of Pallas 2'767G : the dift'ercnce is less therefore than 19,000 

 miles. 



I Their essays on this suljject were generally headed, " On the long-ex- 

 pected I'lanct between Jupiter and Mars." 



§ The longitude of the ascending node of I'allas is 172° 32' 35"; that 

 of Vesta is 171" 6' 37". 



