112 



NOTES TO PRECEDING SECTION. 



Pliny, too, evidently plays upon Apollonius' words, when 

 he says, " Sunt qui et htec sidpra pcrpetua esse credant 

 suoque ambitu ire, sed non nisi relicta a sole cerni." 



it» (p. 35.)— Olbers, in the Astr. Nachr. 1828, S. 157, 184. 

 Arago, de la constitution physique des cometes im Annuaire 

 de 1832, p. 203 — 208. The ancients had already seen it as 

 remarkable that we can see through comets as through a 

 flame. Tlie oldest testimony to stars having been seen 

 through comets, is that of Democritus (Aristot. Meteorol. 

 i. 6, 11). This statement leads Aristotle to the not unim- 

 portant observation, that he himself had seen the occulta- 

 tion of one of the stars of Gemini by Jupiter. Seneca very 

 certainly refers to the translucency of the tail only (Nat. 

 Quicst. vii. 18) : " Non in ea parte qua sidus ipsum est 

 spissi et solidi ignis, sed qua rarus splendor occurrit et in 

 crines dispergitur. Per intervalla ignium, non per ipsos" 

 (vii. 26). The last portion of the remark is superfluous, as 

 we do positively See through a flame if it be not too thick, 

 as remarked by Galileo (Lettera a Mons. Cesarini, 1619). 



20 (p. 35.)— Bessel in den Astr. Nachr. 1836, Nr. 301, S. 

 204—200. Struve im Recueil des Mem. de I'Acad. de St. 

 Pet. 1836, p. 140-143, and Astr. Nachr. 1836, Nr. 303. 

 " For Dorpat, the star during the conjunction, was only 

 2"-2 from the brightest point of the comet. The star re- 

 mained steadily visible, and was not sensibly weakened ; 

 whilst the nucleus of the comet appeared to be extinguished 

 beside the brilliancy of the minute star (9th to the 10th 

 magnitude)." 



21 (p. 35.) — The first attempts of Arago to apply polariza- 

 tion to Comets were made on the 3d July, 1819, the evening 

 of the sudden appearance of the great comet. I was present 

 in the observatory, and along with M. Mathieu and the late 

 M. Bouvard, was satisfied of the inequality of the strength 

 of light in the polariscope when it received the light of the 

 comet. With Capella, which was near the comet, and 

 about the same altitude, the images were of like intensity. 

 When Halley's comet appeared in 1835, the apparatus was 

 so altered that it gave two images of complementary col- 

 ours — green and red, according to the discovery by Arago 

 of chromatic polarization. Annales de Chimie", t. xiii. p. 

 108. Annuaire, 1832, p. 216. " On doit conclure," says 

 Arago, "de I'ensemble de ces observations que la lumiere 

 de la comete n'etait pas en totalite compos6e de rayons 

 doues des proprieies de la lumiere directe, propre ou assim- 

 ilee : il s'y trouvait de la lumiere refl6chie sp6culairement 

 ou polarisee, c'est-:i-dire venant du soleil. On ne peut as- 

 surer d'une maniere absolue que les cometes brillent seule- 

 ment d'un eclat d'emprunt. En eflfet en devenant lumineux, 

 par eux-ni^mes, les corps ne perdent pas pour cela la faculte 

 de r6flechir des lumieres etrangeres." 



2i (p. 36.)— Arago, in Ann. 1832, p. 217—220. Sir John 

 Herschel, Astnm. ^ 488. 



23 (p. 36.)— Encke, in the Ast. Nachr. 1843, Nr. 489, S. 

 130—132. 



24 (p. 36.) — Laplace, Exp. du Syst. du Monde, p. 216 and 

 237. 



25 (p. 36.)— Littrow, Beschreibende Astr. 1835, S. 274. 

 On the inner comet lately discovered by M. Faya, of the 

 Parisian Observatory, whose excentricity is 551, perihe- 

 liac distance 1 690, and apheliac distance 5-832, Schuni. 

 Astr. Nachr. 1844, Nr. 495. 



2(5 (p. 37 ) — Laugier, dans les Comptes, rendus des Stan- 

 ces de I'Acad. 1843, t. xvi. p. 1006. 



27 (p. 37.) — Fries, Vorlesungen iiber die Sternkunde 1833, 

 8.262—267. A not very fortunate argument for the benefi- 

 cent nature of comets occurs in Seneca, who speaks (Nat. 

 Quicst. vii. 17 and 21) of the comet, "Quern nos Neronis 

 principatu laetissimo vidimus et qui cometis detraxit infami- 

 am." 



28 (p. 38.) — One of my friends, accustomed to trigonomet- 

 rical surveys, saw his chamber illuminated by a fire-ball at 

 mid-day, and while the sun was shining, in the town of Po- 

 payan (N. lat. 2° 26' ; 5520 feet above the sea level). He 

 was standing with his back to the window, and when he 

 turned round a great portion of the course traversed by the 

 ball was still most brilliantly lighted. The titles for falling- 

 stars are often extremely "vulgar : the Germans speak of 

 them as star-snvffs : according to the vulgar idea the lights 

 of heaven want snuffing. In the woody country of the Ori- 

 noco, and on the solitary banks of the Cassiquiare, the shoot- 

 ing stars were designated by the natives star-urine, and the 

 dew which lay on the beautiful leaves of the Heliconias like 

 pearls, was star-spittle. The Lithuanian Mythus gives a 

 more noble and imaginative interpretation of the nature and 

 significance of falling stars : " The spinstress Werpeja be- 

 gins to spin the thread of the destiny of the new-born child, 

 and each of these threads ends in a star. And then when 

 death approaches the man, the thread breaks and the star 

 falls, quenching its light, to the earth."— Jacob Grimm, 

 deutsche Mythologie, 1843, S. 685. 



29 (p. 38.)— From the account of Denison Olmsted, Profes- 

 sor of Yale College, New Haven, Connecticut, U. S., vide 

 Poggendorff' s Anualeu der Physik, Bd. xxx. S. 194. Kep- 

 ler, who banishes falling stars ffom astronomy, they being. 



according to him, mere meteors, engendered by emanation* 

 from the earth, still expresses himself very cautiously ui 

 regard to them. " Stella; cadentes," says he, " sunt materia 

 viscida inflammata. Earum aliquas inter cadendum absu- 

 muntur, aliquaj vere in terram cadunt, pondere suo tractce. 

 Nee est dissimile vero, quasdam conglobatas esse ex mate- 

 ria fojculentA, in ipsam auram aetheream immixta; exque 

 aetheris regione, tractu rectilineo, per aerem trajicere, ceu 

 minutos cometas, occuM causa motua utrorumque." — Kep- 

 ler, Epit. Astnm. Copernicanae, t. i. p. 80. 



30 (p. 38.)— Relation historique, t. i. p. 80, 213, and 527. 

 If we distinguish a head or nucleus and a tail in falling stais 

 as in comets, we are made aware of the greater transparency 

 of the atmosphere in tropical regions by the greater length 

 and brilliancy of their trains. The phenomenon need not 

 therefore be more frequent because it is more readily seen, 

 and remains longer visible. The influence of the state ot 

 the atmosphere also shows itself occasionally in connection 

 with falling stars even in our temperate zone, and at very 

 short distances. Wartmann informs us, that on occasion 

 of one of the November phenomena, the difference between 

 the number of meteors seen at Geneva, and at Planchettes, 

 two places very near to one another, was 1 : 7 (M6m. sur les 

 Etoiles filantes, p. 17). The train of the falling star, upon 

 which Brandes has made so many accurate and delicate ob- 

 servations, is by no means to be ascribed to the continuance 

 of the impression of light upon the retina. It sometimes 

 continues visible for a whole minute ; in rare cases even 

 longer than the light of the head of the falling star. The 

 luminous track then usually remains motionless (Gilb. Ann. 

 Bd. xiv. S. 251). This circumstance also proclaims the 

 analogy between large shooting stars and fire-balls. Admi- 

 ral Krusenstern, in his voyage round the world, saw the 

 tail of a fire-ball that had long vanished, remain visible for 

 an hour, with very little apparent motion (Reise, Th. i. S, 

 58). Sir Alexander Burnes gives a charming account of the 

 transparency of the dry atmosphere of Bokhara (N. lat. 39^ 

 43', 1200 feet above the sea-level), so favourable formerly 

 to the study of astronomy : " There is a constant serenity 

 in its atmosphere, and an admirable clearness in the sky. 

 At night, the stars have uncommon lusire, and the inilky- 

 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 astro- 

 nomical science, and great must have been the advantage 

 enjoyed by the famed observatory of Samarkand." Burnes' 

 Travels into Bokhara, vol. ii. (1834) p. 158. We must not 

 charge ic upon the solitary traveller that he speaks of ten 

 or twelve falling stars in an hour as many ; it has but lately 

 been discovered, from careful observation, that eight meteors 

 per hour are the mean number that fall within the circle of 

 vision of an individual (vide Quetelet, Correspond. Malhem. 

 Nov. 1837, p. 447.) Olbers, the acute observer, reduces 

 this number to from five to six. (Schum. Jahrb. 1838, S. 

 325.) 



31 (p. 38.) — On meteoric dust, vide Arago, in Annuaire 

 pour 1832, p. 254. 1 have very lately in another place ( Asie 

 centrale, t. i. p. 408) endeavoured to show how the Scythian 

 myth of the sacred gold that fell glowing from heaven, and 

 remained the property of the golden hordes of Paralatae 

 (Herod, iv. 5 — 7), may have been the obscure recollection 

 of the fall of an Aerolite. The ancients also had their fa- 

 bles (Dio Cassius, Ixxv. 12.^9) strangely enough of silver that 

 fell from heaven, and with which attempts were made to 

 plate the copper money under the Emperor Severus. Me- 

 tallic iron was nevertheless recognized in meteoric stones 

 by Pliny (ii. 56). The frequently recurring phrase lapidi- 

 bus pluit, must not be always viewed as referring to aero- 

 lites. In Livy (xxv. 7) it is used in connection with the re- 

 jected masses — pumice, rapilli, of the not quite extinct vol- 

 canic Mons Albanus, Monte Cavo : vide Heyne, Opusc. 

 Acad. t. iii. p. 261, and my own Relation historique, t. i. p. 

 394. To another circle of ideas belongs the conflict of Her- 

 cules against the Ligyes, on the way from Caucasus to the 

 Hesperides. It is an attempt mythically to explain the ori- 

 gin of the rounded quartz blocks in the Ligyan stone field 

 at the mouth of the Rhone, which Aristotle ascribes to aa 

 earthquake, Posidonius to the action of the waves of an in- 

 land sea. But in the fragments of the Prometheus Unbound 

 of jEschylus, all goes forward as in a fall of Aerolites : Ju- 

 piter draws together a cloud, and " covers the land with a 

 shower of rounded stones for rain." Posidoni us allows him- 

 self to jest at the geological myth of the fragments and 

 blocks. The Ligyan stone field for the rest is faithfully de- 

 scribed by the ancients. The country is now called La 

 Crau. — Guerin, Mesures barometriques dans les Alpes et 

 M6t6orologie d'Avignon, 1829, ch. xii. p. 115. 



32 (p. 39.) — The specific gravity of Aerolites varies be- 

 tween 1-9 (Alais) and 4-3 (Tabor). The more common den- 

 sity is about 3, water being assumed as 1. What is stated 

 in the text in regard to the actual diameter of fire-balls, is 

 based on the few satisfactory measurements we possess. 



