COMETS. 



the last appearance, in 1835, was less brilliant 

 than its former ones had led astronomers to 

 expect it would prove), by Olbers's comet of 

 March G, 1815, and by Pons's comet of 1812, 

 the elements of which were calculated by 

 Encke. Both of the latter were invisible to 

 the naked eye. The great comet of Halley has 

 already greeted us for the ninth known time ; 

 Laugier's computations('*) having recently de- 

 monstrated that it is identical with the comet 

 of 1378, recorded in Ed. Biot's Chinese Cata- 

 logue of Comets. From 1378 to 1835 its period 

 lias varied between 7491 and 77-58 years, the 

 mean having been seventy-six years. 



Contrasted with the celestial bodies above 

 mentioned, we behold another series of bodies 

 requiring millenniums for their barely determi- 

 nable periods. Thus, Argelander says that the 

 splendid comet of 1811 requires 3065 years for 

 its revolution, whilst Encke fixes 8800 years for 

 the awfully grand one of 1680. These bodies, 

 therefore, recede respectively 21 and 44 times 

 farther from the Sun than Uranus ; that is, 

 8400 and 17,600 millions of miles. The Sun's 

 attractive force extends therefore even to this 

 enormous distance ; but then, whilst the comet 

 of 1680, at its perihelion, travels at the rate of 

 53 miles (above 1,300,000 English feet) per sec- 

 ond, or 13 times faster than the Earth, its ve- 

 locity hardly attains 10 8 E. feet per second at 

 its aphelion. The last-mentioned rate is only 

 thrice greater than the velocity of water in our 

 most sluggish European rivers, and but half 

 the velocity which I observed in the Cassi- 

 quiare, a branch of the Orinoko. Amongst the 

 immense number of uncomputed or undiscov- 

 ered comets, there are most probably many 

 which have a major orbital axis far exceeding 

 that of the comet of 1680. In order to give 

 some idea, if not of the extent of the sphere of 

 attraction, at least of the spacial distance of a 

 fixed star, or other sun, from the aphelion of 

 the comet of 1680 (the most distant traveller 

 of all the celestial bodies of our system, ac- 

 cording to our present knowledge), I need only 

 remind the reader that the most recent esti- 

 mates of parallax still make the nearest fixed 

 star 250 times farther from the sun than the 

 aphelion of this comet, which is only 44 times 

 as remote as Uranus, whilst the star a Cen- 

 tauri is 11,000, and the star 61 Cygni (after 

 Bessel's very accurate observations) is 31,000 

 times more distant than the planet. 



After this consideration of the greatest elon- 

 gations of comets from the central body of the 

 solar system, let us glance at those which have 

 approached it most nearly. The instance of 

 the greatest known proximity of a comet to the 

 earth occurred with that of Lexell and Burk- 

 hardt, celebrated for the perturbations it suffer- 

 ed from Jupiter ; this comet was only six 

 times the distance of the moon from us on June 

 28Lh, 1770. In 1767 and 1779, the same comet 

 twice traversed the system of Jupiter's satel- 

 lites, without causing the slightest perceptible 

 derangement in their orbits ; orbits which have 

 been so thoroughly investigated by physical 

 astronomers. But the great comet of 1680, 

 when at its perihelion, was from eight to nine 

 times nearer to the surface of the sun than 

 Lexell's was to the earth. On December 17th, 

 the sun and the comet of 1680 were only one- 



sixth of the diameter of the former body apart ; 

 in other words, seven-tenths of the moon's dis- > 

 tance from us. Owing to the feebleness of the 

 light of distant comets, perihelia beyond the 

 orbit of Mars are rarely observable by man ; 

 the comet of 1729 is, in fact, the only one of 

 those hitherto computed which has its perihe- 

 lion between the orbits of Pallas and Jupitor, 

 and which has been observed beyond the path 

 of the latter planet. 



Since scientific acquirements, some solid, by 

 the side of much superficial learning, have pen- 

 etrated in wider circles into social hfe, the 

 fears of the possible evils wherewith comets 

 threaten us have increased in weight, and their 

 direction has become more definite. The cer- 

 tainty of there being several periodical comets 

 within the known planetary orbits, visiting us 

 at short intervals ; the considerable perturba- 

 tions which Jupiter and Saturn cause in their 

 paths, whereby apparently harmless wanderers 

 of the sky may be converted into peril-fraught 

 bodies ; the orbit of Biela's comet passing 

 through that of the earth ; the existence of a 

 cosmical ether, that resisting and retarding 

 fluid which tends to contract the orbits of all 

 the planetary bodies ; the individual differences 

 in the bodies of comets which permit us to 

 suspect considerable gradations in the quantity 

 of the mass of the nucleus ; all these circum- 

 stances amply replace, in multiplicity of grounds, 

 the dread which, in former centuries, was en- 

 tertained of flaming swords, and an universal 

 conflagration to be lighted up by fiery stars. 



As the grounds for confidence derivable from 

 the doctrine of probabilities only operate on the 

 understanding, are only of avail among the re- 

 flecting, and produce no effect on gloomy ap- 

 prehension and imagination, modern science 

 has been charged, not altogether without rea- 

 son, with seeking to allay the fears which it 

 has itself created. It is a principle laid deeply 

 in the desponding nature of man, in his inhe- 

 rent disposition to view things on the dark 

 rather than on the bright side, that the unex- 

 pected, the extraordinary, excites fear, not 

 hope or joy(^0. The strange aspect of a 

 mighty comet, its pale nebulous gleam, its sud- 

 den appearance in the heavens, have in all 

 countries, and almost at all times, been held as 

 portentous indications of change or dissolution 

 of the old-established order of things. And 

 then, as the apparition is never more than 

 short lived, arises the belief that its significance 

 must be reflected in contemporaneous or im- 

 mediately succeeding events. And such is the 

 enchainment of events, that some particular 

 incident scarcely fails to turn up which can be 

 fixed upon as the calamity prognosticated. It 

 is only in these times that a spirit of greater 

 hopefulness, in connection with the appearance 

 of comets, has shewn itself among the people. 

 In the beautiful valleys of the Rhine and the 

 Moselle, ever since the appearance of the brill- 

 iant comet of 1811, comets have been regarded 

 as exerting a favourable influence on the ripen- 

 ing of the grape ; nor have various years of in- 

 different vintage, along with the appearance of 

 other comets, instances of which have not 

 been wanting, been able to shake the faith ^f 

 the wine-growers of the north of Germany in 

 their beneficial influences. 



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