Royal Astronomical Society. 551 



say nothing of their supposed periodicity, is [are] utterly irrecon- 

 cilable with the theory of a lunar origin. Benzenberg, however, 

 adopts this theory, and supposes the shooting stars to be small 

 masses of stone, from one to five feet in diameter, which are pro- 

 jected from lunar volcanoes, and circulate about the earth or about 

 the sun when their projectile velocity exceeds a certain limit. 



2. Dr. Olbers, and some other astronomers, have supposed the 

 shooting- stars to be the debris, or fragments of a large planet, burst 

 into pieces hj some internal explosion, of which Ceres, Pallas, Juno, 

 and Vesta, are the principal remaining portions. The smaller frag- 

 ments continue to circulate about the sun in orbits of great eccen- 

 tricity, and when they approach the region of space through which 

 the earth is moving, they enter the atmosphere with great velocity, - 

 and by reason of the resistance and friction are rendered incandes- 

 cent, and emit a vivid light so long as they remain within it. 



3. It has been suggested by Biot that the extraordinary displays 

 observed in November may be explained by supposing the meteors 

 to have their origin in the zodiacal light. The extent of this lens- 

 shaped nebulosity is not well ascertained ; but as the plane of its 

 principal section is not parallel to the ecliptic, if the earth passes 

 through it at one season, it must be remote from it at another. 

 But shooting- stars are observed at all times of the year ; and the 

 November meteors differ from those of other seasons in no respect 

 excepting in their greater multitude. 



4. The hypothesis first suggested by Chladni is that which ap- 

 pears to have met with most favour, having been adopted by Arago 

 and other eminent astronomers of the present day to explain the 

 November phenomena. It consists in supposing that, independently 

 of the great planets, there exist in the planetary regions myriads of 

 small bodies which circulate about the sun, generally in groups or 

 zones, and that one of these zones intersects the ecliptic about the 

 place through which the earth passes in November. The principal 

 difficulties attending this theory are the following : — First, that 

 bodies moving in groups in the circumstances supposed must neces- 

 sarily move in the same direction, and consequently, when they be- 

 come visible from the earth, would all appear to emanate from one 

 point and move towards the opposite. Now although the observa- 

 tions seem to show that the predominating direction is from north- 

 east to south-west, yet shooting- stars are observed on the same 

 nights to emanate from all points of the heavens, and to move in all 

 possible directions. Secondly, their average velocity (especially as 

 determined by Wartmann) greatly exceeds that which any body 

 circulating about the sun can have at the distance of the earth. 

 Thirdly, from their appearance, and the luminous train which they 

 generally leave behind them, and which often remains visible for 

 several seconds, sometimes for whole minutes, and also from their 

 being situated within the earth's shadow, and at heights far exceed- 

 ing those at which the atmosphere can be supposed capable of sup- 

 porting combustion, it is manifest that their light is not reflected 

 from the sun ; they must therefore be self-luminous, which is con- 



