645 



ASTEROIDS. 



ASTEROIDS. 



646 



which had not been verified by any subsequent astronomer, although 

 the result was supported by Bouvard, who obtained nearly the same 

 value by an application of Laplace's formula; for the perturbations of 

 Saturn by Jupiter. On the other hand, the researches of Encke on 

 Vista, and those of Gauss on Pallas, seemed to indicate that some such 

 alteration as that suggested by Nicolai was necessary. The doubt was 

 cleared up by Mr. Airy, who, upon remeasuring the elongations of 

 Jupiter's satellites, found that the observations of Pound were con- 



siderably erroneous. The value of Jupiter's mass thus corrected (^fra) 

 has been found to satisfy the results of observation in so far as the 

 perturbations of the asteroids are concerned, although the theory of 

 Saturn would appear still to leave some room for doubt. 



The asteroids must be bodies of very inconsiderable magnitude, for 

 notwithstanding their comparative proximity to the earth, they only 

 in a few instances exceed in brightness stars of the eighth magnitude, 

 even when observed at the times of opposition ; while, generally 



expressed the brightness of the various OB 

 sition in the year 1859. The numbers in 1 

 to the time of opposition aa given in the second column. 



Time of 



t Asteroid. Opposition. 



Victoria . . January 5 

 Hestia . . . 7 



Pales . 17 



Daphne ? . . February 

 Harmonia . . 9 



