AEROLlTESf. 1215 



gmall planetary masses in space is simpler, and, at the same 

 lime, more analogous with those entertained concerning the 

 formation of other portions of the solar system. 



It is very probable that a large number of these cosmical 

 bodies traverse space undestroyed by the vicinity of our at- 

 mosphere, and revolve round the Sun without experiencing 

 any alteration but a slight increase in the eccentricity of their 

 orbits, occasioned by the attraction of the Earth's mass. We 

 may, consequently, suppose the possibility of these bodies re- 

 maining invisible to us during many years and frequent revo- 

 lutions. The supposed phenomenon of ascending shooting 

 stars and fire-balls, which Chladni has unsuccessfully endeav- 

 ored to explain on the hypothesis of the rejiection of strongly 

 compressed air, appears at first sight as the consequence of 

 some unknoM'n tangential force propelling bodies from the 

 earth ; but Bessel has shown by theoretical deductions, con 

 firmed by Feldt's carefully-conducted calculations, that, owing 

 to the absenco of any proofs of the simultaneous occurrence 

 of the observed disappearances, the assumption of an ascent 

 of shooting stars was rendered wholly improbable, and inad- 

 missible as a result of observation. =^ The opinion advanced 

 by Olbers that the explosion of shooting stars and ignited fire- 

 balls not moving in straight lines may impel meteors upward 

 in the manner of rockets, and influence the direction of their 

 orbits, must be made the subject of future researches. 



Shooting stars fall either separately and in inconsiderable) 

 numbers, that is, sporadically, or in swarms of many thou- 



orlgln in the regions of space, as heavenly bodies which had long rt;- 

 maiued invisible. Respecting this last opinion, which is that oi" Diog- 

 enes of Apollonia, and entirely accoi'ds with that of the present day, 

 see pages 124 and 125. It is worthy of remark, that in Syria, as I have 

 been assured by a learned Orientalist, now resident at Smyrna, Andrea 

 de Nericat, who instructed me in Persian, there is a popular belief that 

 agrolites chiefly fall on clear moonlight nights. The ancients, on the 

 contrary, especially looked for their fall during lunar eclipses. (See 

 Pliuy, xxxvii., 10, p. 164. Solinus, c. 37. Salm., Exerc, p. 531; and 

 the passages collected by Ukert, in his Geogr. der Griechen u-nd Rdmer, 

 th. ii., 1, s. J31, note 14.) On the improbability that meteonc masses 

 are fonned from metal-dissolving gases, which, according to Fusiuieri, 

 may exist in the highest strata of our atmosphere, and, previously dif- 

 fused through an almost boundless space, may suddenly assume a sohd 

 condition, and on the penetration and misceability of gases, see my 

 Relat. Hist., t. i., p. 525. 



* Bessel, in Schum., Astr. Nachr., 1839,' No 380 und 381, s. 222 und 

 346. At the conclusion of the Memoir there is a comparison of ',he 

 Sun's longitudes with the epochs of the November phenoraenou, fiom 

 the period of th<^ first ob.servations in Cumaua in 17'JG . 



