cxlvi 



NOTES. 



a different period of revolution, viz. 175 years, which would trace it back to 

 the years 1668, 1493, and 1318. (Compare Outlines of Astronomy, p. 370 

 to p. 372, with Galle, in Olbers Cometenbahnen, S. 208, and Kosmos, Bd. i. 

 S. 144, Engl. ed. p. 93.) Other combinations of Peirce and Clausen even 

 give periods of revolution of 21| or 7, years, sufficient proof of how 

 hazardous it is to trace back the comet of 1843 to the time of the Archon 

 Asteus. The mention in the Meteorol. lib. i. cap. 7, 10, of a comet under the 

 Archon Nicomachus, has the advantage of informing us that Aristotle was at 

 least 44 years old when that work was written. It has always surprised me 

 that this great man, who must have been already 14 years old at the time of the 

 earthquake of Achaia, and of the appearance of the great comet in Orion with a 

 tail of 60 in length, should have spoken with so little animation of so bril- 

 liant an object, contenting himself with merely enumerating it as one of the 

 comets " that had been seen in his time." The surprise is increased on finding 

 it said in the same chapter that he had seen with his own eyes something 

 nebulous, or even a faint appearance of a mane (K<fyirj), round a fixed star in 

 the " thighbone of the Dog" (perhaps Procyon in Cam's minor), Meteorol. 

 i. 6, 9. Aristotle also speaks (i. 6, 11) of his observation of the occultation 

 of a star in Gemini by the disk of Jupiter. What is said of a nebulous mane 

 or vaporous envelope of Procyon (?), reminds me of a phsenomenon repeatedly 

 spoken of in the ancient Mexican imperial annals, according to the Codex 

 Tellerianus. " This year" (it is said) " Citlalcholoa" (the planet Venus, also 

 called in Aztec Tlazoteotl, see my Vues des Cordilleres, T. ii. p. 303) " was 

 again seen to smoke." The appearances seen respectively in the Greek and 

 Mexican sky were probably small halos round the star and the planet, the 

 phsenomenou being one of atmospheric refraction. 



(^T) p. 400. Edouard Biot, in the Comptes rendus, t. xvi. 1843, p. 751. 



(658) p- 401. Galle, in the appendix to " Olbers Cometenbahnen," S. 221, 

 No. 130. (On the probable passage of the two-tailed comet of 1823, see 

 Edinb. Rev. 1848, No. 175, p. 193.) The memoir referred to in the text, 

 containing the true elements of the comet of 1680, does away with Halley's 

 fanciful idea, according to which that comet, having a supposed period of 

 revolution of 575 years, would have appeared at certain great epochs in the 

 history of mankind : at the time of the Flood according to the Hebrews, at 

 the time of Oxyges according to the Greeks, the Trojan War, the destruction 

 of Nineveh, the death of Julius Csesar, &c. Encke's calculation gives the 

 pomet's period 8814 years. Its least distance from the surface of the Suu, 

 on the 17th Dec. 1680, was only 32000 German, or 128000 English, geogra- 



