266 On the alleged Periodical Meteors and on Shooting Stars, 



more than 1 2 hours, and beginning 6 hours sooner than in 

 the United States. 



Now as in the month of November the earth advances in 

 its orbit 445,500 leagues in 18 hours, a change of place during 

 which the appearances are incessantly succeeding one another, 

 it would be necessary that these meteors, if they really consti- 

 tute asteroids, should exist by millions in the zone where they 

 appear. But then these heavenly bodies, which should ap- 

 proach so very near to the earth, must frequently fall down 

 upon it, from the attractive power which the mass of our globe 

 would inevitably exercise on them ; and this is what has not 

 yet been observed. 



When astronomers at the beginning of this century had suc- 

 cessively discovered Ceres, Pallas, Juno and Vesta, which re- 

 volve around the sun between Mars and Jupiter in orbits 

 which have not a very great eccentricity, the idea of making 

 asteroids originate from the fragments of a planet which might 

 have been destroyed by means of an internal explosion was 

 already put forth ; but M. Biot remarked that, with regard to 

 these four telescopic stars, this hypothesis is inadmissible, be- 

 cause, according to the theory of attraction, such an explosion 

 would have necessarily given to these fragments unequal ve- 

 locities of projection in starting from the same point, whence 

 great unequal axes would have resulted, which is contrary to 

 observation*. 



It is known that Professor Brandes proved long ago, by 

 corresponding observations made in different places and often 

 repeated, that there are shooting stars which circulate with a 

 velocity of 1 3 leagues, of 25 to a degree, in a second, at a 

 height of 180 leagues above the surface of the earth f. It is 

 also manifest, from the observations made in the United States 

 compared by Professor Olmsted, that the centre from whence 

 the meteoric shower of the 13th of November of 1833 set out, 

 was elevated at a mean height of more than 800 leagues, and 

 consequently that it was in a region which affords no aliment 

 for combustion. The vivid lustre then which these meteors 

 exhibit, and which they could not borrow from the sun, is 

 their own inherent property. But as in our planetary system 

 we know of no celestial circulating body which shines with its 

 own light, this essential fact, which must necessarily be kept 



* Traite Elementaire d* Astronomie Physique, 2nd edit., vol. iii. p. 42. 



t These quantities, on the exactness of which we can rely, are the re- 

 sults of comparative observations begun in 1798 by MM. Benzenberg and 

 Brandos, and continued on a greater scale, in 1823, by M. Brandes and his 

 pupils, at Breslaw, Dresden, Leipe, Brieg, Gleiwitz, &c. — Bibl. Univ., vol. 

 li. p. 203; Annuaire du Bureau des Longitudes de Paris for 1836, p. 292. 



