METEORS. 143 



opposite region of the sky. Pogson did observe 

 a comet, but certainly not Biela's, although prob- 

 ably another fragment of the missing body. 



The theory of the actual disintegration of 

 comets was enunciated by Schiaparelli in 1873, 

 and developed in his work ' Le Stelle Cadenti/ 

 He was led to regard comets as cosmical clouds 

 formed in space by " the local concentration of 

 celestial matter." He then remarks that a cos- 

 mical cloud seldom penetrates to the interior of 

 the Solar System, " unless it has been trans- 

 formed into a parabolic current," which may 

 occupy years, or centuries, in passing its 

 perihelion, " forming in space a river, whose 

 transverse dimensions are very small with respect 

 to its length : of such currents, those which are 

 encountered by the earth in its annual motion 

 are rendered visible to us under the form of 

 showers of meteors diverging from a certain 

 radiant." 



Schiaparelli next pointed out that when the 

 current of meteors encounters a planet, the re- 

 sulting perturbations cause some of the meteoric 

 bodies to move in separate orbits, forming the 

 bolides and aerolites which fall from the sky at 

 intervals. " The term falling stars" he says, 

 " expresses simply and precisely the truth 

 respecting them. These bodies have the same 



