[281] “errantium modo;” this may mean, that they move in orbits like those of the planets and exhibit the same phænomena, or simply that they change their situation with respect to the fixed stars. [282] Seneca remarks on this point, “Placet igitur nostris (Stoicis) cometas ... denso aëri creari. Ideo circa Septemtrionem frequentissime apparent, quia illic plurimi est aëris frigor.” Quæst. Nat. i. 7. Aristotle, on the contrary, remarks that comets are less frequently produced in the northern part of the heavens; Meteor. lib. i. cap. 6. p. 535. [283] _Ubi supra._ [284] See Aristotle, _ut supra_, p. 537. [285] “Videtur is non cometes fuisse, sed meteorus quidam ignis;” Alexandre in Lemaire, i. 296. [286] Virgil, Geor. i. 488 _et seq._, Manilius, i. 904 _et seq._, and Lucan, i. 526 _et seq._, all speak of the comets and meteors that were observed previous to the civil wars between Pompey and Cæsar. In reference to the existence of a comet about the time of Julius Cæsar, Playfair remarks, that Halley supposed the great comet of 1680 to have been the same that appeared in the year 44 A.C., and again in Justinian’s time, 521 P.C., and also in 1106; Elem. Nat. Phil. ii. 197, 198. See Ptolemy’s Cent. Dict. no. 100, for the opinion, that comets presented an omen especially unfavourable to kings. To this opinion the following passage in the Paradise Lost obviously refers; “And with fear of change perplexes monarchs.” [287] Seneca refers to the four comets that were seen, after the death of Cæsar, in the time of Augustus, of Claudius, and of Nero; Quæst. Nat. i. 7. Suetonius mentions the comet which appeared previous to the death of Claudius, cap. 46, and Tacitus that before the death of Nero, Ann. xiv. 22. [288] “A Julio Cæsare. Is enim paulo ante obitum collegium his ludis faciendis instituerat, confecto Veneris templo;” Hardouin in Lemaire, i. 299. Jul. Obsequens refers to a “stella crinita,” which appeared during the celebration of these games, cap. 128. [289] “Hoc est, hora fere integra ante solis occasum;” Hardouin in Lemaire, i. 299. [290] All these circumstances are detailed by Suetonius, in Julio, § 88. p. 178. [291] “terris.” [292] Seneca remarks, “... quidam nullos esse cometas existimant, sed species illorum per repercussionem vicinorum siderum,... Quidam aiunt esse quidem, sed habere cursus suos et post certa lustra in conspectum mortalium exire.” He concludes by observing, “Veniet tempus, quo ista quæ nunc latent, in lucem dies extrahat, et longioris diei diligentia;” Nat. Quæst. lib. 7. § 19. p. 807. [293] For some account of Hipparchus, see note [189], p. 37. [294] Nothing is known respecting the nature of these instruments, nor have we any means of forming even a conjecture upon the subject.