114 COSMOS. 



enables the eye to penetrate furtlier into distance. Sir Alex- 

 ander Burnes likewise extols as a consequence of the purity of 

 the atmosphere in Bokhara the enchanting and constantly-re- 

 curring spectacle of variously-colored shooting stars. 



The connection of meteoric stones with the grander phe- 

 nomenon of fire-halls — the former being known to be project- 

 ed from the latter with such force as to penetrate from ten 

 to fifteen feet into the earth — has been proved, among many 

 other instances, in the falls of aerolites at Barbotan, in the 

 Department des Landes (24th July, 1790), at Siena (16th 

 June, 1794), at Weston, in Connecticut, U. S. (14th Decem- 

 ber, 1807), and at Jnvenas, in the Department of Ardeche 

 (15th June, 1821). Meteoric stones are in some instances 

 thrown from dark clouds suddenly formed in a clear sky, and 

 fall with a noise resembling thunder. Whole districts have 

 thus occasionally been covered with thousands of fragmentary 

 masses, of uniform character but unequal magnitudes, that 



each other, Geneva and Aux Plancliettes, the number of the meteors 

 counted wei'e as 1 to 7. (Wartmann, Mem. sur les Eloiles Jilanies, p. 

 17.) The tail of a shooting star (or its train), on the subject of which 

 Brandes has made so many exact and delicate observations, is in no 

 way to be ascribed to the continuance of the impression produced by 

 light on the retina. It sometimes continues visible a w^hole minute, 

 and in some rare instances longer than the light of the nucleus of the 

 shooting star; in which case the luminous track remains motionless. 

 (Gilb., Ann., bd. xiv., s. 251.) This circumstance further indicates the 

 analogy between large shooting stars and fire-balls. Admiral Krusen- 

 stern saw, in his voyage round the world, the train of a fire-ball shine 

 for an hour after the luminous body itself had disappeared, and scarce- 

 ly move throughout the whole time. {Reise, th. i., s. 58.) Sir Alex- 

 ander Bumes gives a charming description of the transparency of the 

 clear atmosphere of Bokhara, which was once so favorable to the pur- 

 suit of astronomical observations. Bokhara is situated in 39° 43' north 

 latitude, and at an elevation of 1280 feet above the level of the sea. 

 " There is a constant serenity in its atmosphere, and an admirable clear- 

 ness in the sky. At night, the stars have uncommon luster, 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, as- 

 suming every color — fiery red, blue, pale, and faint. It is a noble 

 country for astronomical science, and great must have been the ad- 

 vantage enjoyed by the famed observatory of Samarkand." (Burnes, 

 Travels into Bokhara, vol. ii. (1834), p. 158.) A mere traveler must 

 not be reproached for calling ten or twelve shooting stars in an hour 

 *' many," since it is only recently that we have learned, from careful 

 observations on this subject in Europe, that eight is the mean number 

 which may be seen in an hour in the field of vision of one individual 

 (Quetelet, Corresp. Mathim., Novem., 1837, p. 447); this number is, 

 however, limited to five or six by that diligent observer, Olbers. 

 (Schum., Jahrh., 1838, s. 325.) 



