COMETS. 103 



t character regarding the most wonderful class of the cosmic- 

 al bodies belonging to our solar system, ought not,, to be en- 

 tirely passed over in this sketch of a general picture t>f nature. 

 Although, as a rule, the tails of comets increase in magni- 

 tude and brilliancy in the vicinity of the sun, and are directed 

 away from that central body, yet the comet of 1823 offered 

 the remarkable example of two tails, one of which was turned 

 toward the sun, and the other away from it, forming with 

 each other an angle of 160. Modifications of polarity and 

 the unequal manner of its distribution, and of the direction in 

 which it is conducted, may in this rare instance have occa- 

 sioned a double, unchecked, continuous emanation of nebulous 

 matter.* 



Aristotle, in his Natural Philosophy, makes these emana- 

 tions the means of bringing the phenomena of comets into a 

 singular connection with the existence of the Milky Way. 

 According to his views, the innumerable quantity of stars 

 which compose this starry zone give out a self-luminous, in- 

 candescent matter. The nebulous belt which separates the 

 different portions of the vault of heaven was thereibre regard- 

 ed by the Stagirite as a large comet, the substance of which 

 was incessantly being renewed.! 



197, 200, 202, und 230. Also in Schumacher, Jahrb., 1837, s. 149, 168. 

 William Herschel, in his observations on the beautiful comet of 1811, 

 believed that he had discovered evidences of the rotation of the nucleus 

 and tail (Phil. Trans, for 1812, Part i., p. 140). Dunlop, at Paramat- 

 ta, thought the same with reference to the third comet of 1825. 



* Bessel, in Astr. Nachr., 1836, No. 302,8.231. Schum., Jahrb., 1837. 

 s. 175. See, also, Lehmami, Ueber Comeienschiceife (On the Tails of 

 Jomets), in Bode, Astron. Jahrb. fur 1826, s. 1G8. 



t Aristot., Meteor., i., 8, 11-14, und 19-21 (ed. Ideler, t. i., p. 32-34). 

 Biese, Phil, des Aristoteles, bd. ii., s. 86. Since Aristotle exercised so 

 great an influence throughout the whole of the Middle Ages, it is very 

 much to be regretted that he was so averse to those grander views of 

 the elder Pythagoreans, which inculcated ideas so nearly approxima 

 ting to truth respecting the structure of the universe. He asserts that 

 comets are transitory meteors belonging to our atmosphere in the very 

 book in which he cites the opinion of the Pythagorean school, accord- 

 ing to which these cosmical bodies are supposed to he planets having 

 long periods of revolution. (Aristot., i., 6, 2.) This Pythagorean doc 

 trine, which, according to the testimony of Apollonius Myudius, was 

 still more ancient, having originated with the Chaldeans, passed over 

 to the Romans, who in this instance, as was their usual practice, were 

 merely the copiers of others. The Myndian philosopher describes the 

 path of comets as directed toward the upper and remote regions of 

 heaven. Hence Seneca says, in his Nat. Quasi., vii., 17: ' Comele* 

 POH est species falsa, sed proprium sidus sicut solis et luncc : altiora mnn- 

 di secat et tune demum apparet quum in irmtrn cur sum sui venil ;" and 

 again (at vi'.,27), " Comete aiernos ese ct sortis ejusdem, cnjus c^tcia 



