552 COSMOS. 



produced for some time. On the 24th of March, the smaller 

 comet was scarcely perceptible, on account of the decreasing 

 luminous intensity. The larger one only was seen up to the 

 16th or 20th of April, when this also disappeared. I have 

 described the wonderful phenomenon in detail, 27 so far as it 

 could be observed. Unfortunately, the actual separation and 

 the immediately previous condition of the older comet escaped 

 observation. Did the separated comet become invisible only 

 on account of distance and feeble luminosity, or did it resolve 

 itself? Will it be again detected as an attendant, and will 

 the Comet of Biela present similar anomalies at other re- 

 appearances ? 



The formation of a new planetary body by separation natu- 

 rally excites the question, whether, in the innumerable comets 

 revolving round the Sun, several have not originated by a 

 similar process, or do not daily originate so ? whether they 

 may not acquire different orbits by retardation, i. e. unequal 

 velocity of revolution, and the unequal influence of pertur- 

 bations ? In a treatise already alluded to, Stephen Alexander 

 has attempted to explain the genesis of all the interior comets 

 by the assumption of such an hypothesis, certainly but inade- 

 quately founded. In antiquity also similar occurrences appear 

 to have been observed, but not sufficiently described. Seneca 

 states, upon the authority, as he himself says, of an unreliable 

 witness, that the comet which was considered to have caused 

 the destruction of the two towns of Helice and Bura sepa- 

 rated into two parts. He adds ironically, why has no one 

 seen two comets unite to form one? 88 The Chinese astro- 



27 Compare Outlines, 580-583 ; Galle, in Gibers' Cometen- 

 lalmen, p. 232. 



28 " Ephorus non religiosissimse fidei, ssepe decipitur, saepe 

 decipit. Sicut hie Cometem, qui omnium mortalium oculis 

 custoditus est, quia ingentis rei traxit eventus, cum Helicen 



