122 Scientific Intelligence. 



had sufficed to make this ellipse be abandoned and replaced by another 

 whose surface is nearly five times smaller than that of the former! 

 Will it be said that the star observed before 1835, is not that observed 

 since that time ? Moreover, the two ellipses are by the same illustrious 

 astronomer, Sir John Herschel. I do not know that he has been re- 

 proached in his own country for not having drawn from observations 

 more than they contained. And comets ! There is a comet whose mo- 

 tions during one part of its path may be represented indifferently by a 

 parabola or an ellipse, whose planes would be inclined at more than 

 60°. Every one is acquainted with the magnificent labors by which 

 Bessel has determined the distance of a star in Cygnus from the earth. 

 Bessel also determined the error which might be feared in the result he 

 obtained. Now translate this inaccuracy into post-leagues, and you 

 will throw ridicule (in your way of viewing it) on a work which is the 

 admiration of the world. The error is 1,000,000,000,000 — that is, one 

 billion of post-leagues. I shall conclude by considering the distance 

 of the Sun from the Earth, — which has cost astronomers so much labor, 

 so many journeys, dangers, and almost martyrdom. The measure- 

 ment of this fundamental element of our system has presented, in the 

 hands of the greatest astronomers, discordances greater than those ob- 

 jected to me. It may be obtained in two ways — by means of Mars, or 

 of the transits of Venus across the Sun. The first method is less pre- 

 cise than the second ; but in return it may be repeated as often as de- 

 sired, while the second can be employed only twice in about 120 years. 

 Mars was the first employed in 1750 by Lacaille and by other astrono- 

 mers of vast merit. They never found by this means more than 

 32,271,000 post-leagues for the distance of the Earth from the Sun. And 



the agreement of the results obtained by repeated measurements gave 

 perfect confidence in this number. Now when the transit of Venus 

 across the sun occurred in 1769, a distance of 38,410,000 post-leagues 

 was obtained by means of this transit. The difference of the two re- 

 sults, 6,145,000 leagues, is simply the fifth part of the former. I will 

 add that the difficulty is not completely resolved at present. I have 

 never had such a difference. Should it not be admitted then, for the 

 sake of consistency, that there are two Suns, as there are two Neptunes, 

 ■the Sun of Mars, and the Sun of Venus." * * * 



2. Eighth Satellite of Saturn. — The eighth satellite of Saturn, which 



was first noticed by Mr. Bond, of the Observatory at Cambridge, Mas- 

 sachusetts, Sept. 16, 1848, was detected two days later by Mr. Lassell, 

 of Liverpool, wilh the aid of his large reflector. Both discoverers 

 have agreed to call it Hyperion. A full account of the circumstances 

 of each discovery, is given in the Appendix of vol. iii, of the new se- 

 ries of the Memoirs of the American Academy. 



3. Elements of Petersen's Comet of Avg., 1848, (Institute No. 770.) 

 Prof. Schumacher has furnished the following elements of the comet 



discovered August 7, 1848, by Dr. Petersen, of Altona. 

 Perihelion passage, 1848, Sept. 8*0560 m. t. Gr. 

 Longitude of perihelion, 310° 34' 36'' \ App. Eqx. 



it 



41 ascending node, 211 34 36 j Aug. 19. 



84 28 22 

 9-504875. 



Inclination 

 Log. of pe 

 Motion, Retrograde. 







