Particulars refpeBing the new Vianet. 8l 



obftRiftion from the moon-light^ he obtained a diftin6l view 

 of it for a fhort lime. Through his ten feet refle&or, with 

 a magnifving power of fix hundred, and higher powers, he 

 perceived its difc, though very fmall, yet di(lin£lly round and 

 well dfcfinL-d; l)ut faw nothing further which denoted a ring or 

 a coma, or a fatellite. The favourable ftate of the air appear- 

 ing then very precarious, Dr. Herfchel did not atteniptto afcer- 

 tain the apparent diameter of the planet by means of his lamp- 

 micrometer, as fome preparations and adjuliments would 

 have been necelTary before he could have availed himfelf 

 of that curious apparatus. But in order to form fome efti- 

 mate as to a point of fo much importance, he adopted a happy 

 expedient, and very fuitable to the urgency of the moment. 

 The Georgian planet being fituated near at hand, in the 

 fame region of the heavens, he direfted his telefcope firft to 

 it, and tlien to the other, with his attention fixed upon 

 making a comparative ettimate of the apparent diameter of 

 each difc. In order to this, and to avoid as much as poflible 

 certain fallacies to which this method is more or lefs liable, he 

 was careful to form eftimates over and over again, according 

 as his telefcope was laft turned from the greater (life to the 

 fmallcr; and vice verfa. From fuch obfervations, frequently 

 repeated, he concludes that the apparent diameter of the 

 Ceres Ferdinavdea is about a fourth part only of the ap- 

 parent diameter of the Georgium Sidus. By applying there- 

 fore the proper calculation. Dr. Herfchel has inferred that the 

 real diameter of this newly found primary planet, called Ceres 

 Ferdinandea, is only a little more than half of the diameter 

 of our moon and lefs than 5-8ths of it. The fm.allnefs of 

 the planet, together with the great inclination of its orbit, 

 are peculiarities which may probably lead to other difcoveries 

 in the folar fyftcm. 



The following are fome places of the planet calculated 

 forward in foreign journals, but corre6ted by the lateft cb- 

 fervations, fliowing nearly where the planet may be expe6led 

 to appear : computed for 12 ' or ijj'' Greenwich time. 

 1802. R. A. Dec. N. 



Feb. 17. 188° 15' 14° 8' 



23. 187 39 14 49 



March 1. 186 50 ^5 Z^ 



The planet will be in oppofilion to the fun about the T3th 

 of March. 



'i'he following are the elements of the planet as calculated 

 by M. Gaufs, of Brunfwick, for an elliptic orbit. 

 Epoch i8ci, Jan. o, or Jan, i, which of the two is un- 

 certain - - - a' 17° 36' •^4' 



Vol.. Xlf. F Aphdiutn 



