NOTES. XX 



l&nger visible. This influence of ths condition of the atirxrephere sometimes 

 shews itself even in the temperate zoae, and in a difference between places at 

 very small distances apart ; "Wartrnann mentions that on one occasion of the 

 periodical November phenomenon, the number of shooting stars observed at 

 Geneva and aux Planchettes (places very near to each other), were as 1 : J. 

 (Wartmanu, Mem. sur les etoiles filantes, p. 17). The tail or train of a 

 shooting star, which Brandes has made the subject of so many exact and deli- 

 cate observations, is by no means to be ascribed to the prolongation of im- 

 pressions on the retina. Its visibility sometimes lasts an entire minute, in 

 rare cases even longer than the light of the head or nucleus of the shooting 

 star. The luminous path in such cases remains motionless (Gilb. Ann. 

 Bd. xiv. S. 251). This circumstance, too, shews the analogy between large 

 shooting stars and fire balls. Admiral Krusenstern, in a voyage round the 

 world, saw the train of a fire-ball which had long disappeared continue to shine 

 for the space of an hour, during which time it changed its place exceedingly 

 little. (Reise, Th. i. S. 58.) Sir Alexander Burnes gives a charming descrip- 

 tion of the transparency of the atmosphere in Bokhara as favourable to a love 

 for astronomy ; the latitude is 3943' and the elevation above the level of the 

 sea about 1200 (1280 English) feet. "There is a constant serenity in the 

 atmosphere, and an admirable clearness in the sky. At night the stars have 

 an uncommon lustre, and the milky way shines gloriously in the firmament. 

 There is also a never-ceasing display of the most brilliant meteors, which dart 

 like rockets in the sky : ten or twelve of them are sometimes seen in an hour, 

 assuming every colour, fiery, red, blue, pale and faint. It is a noble country 

 for astronomical science, and great must have been the advantage enjoyed by 

 the famed observatory of Samarkand." (Burnes, Travels in Bokhara, vol. ii. 

 1834, p. 158). A solitary traveller must not be reproached for calling ten or 

 twelve shooting stars in an hour many ; it has only been by very careful ob- 

 servations in Europe directed to this particular subject, that it has been found 

 that, for the range of vision of a single individual, eight is the mean number of 

 meteors that may be seen per hour (Quetelet, Corresp. Mathem. Nov. 1837, 

 p. 447), while so diligent an observer as Olbers limited the number to five 

 or six. (Schum. Jahrb. 1838, S. 325.) 



( 6I ) p. 109. On meteoric dust, see Arago, Annuaire, 1832, p. 254. I 

 have very recently endeavoured to show in another work, (Asie Centraie, t. i. 

 p. 408), the probability that the Scythian tradition of the sacred gold which 

 fell glowing from Heaven, and remained in the possession of the Para- 

 latse, (Herodot. iv. 5 7), arose from the obscure recollection of a fall of 



