398 PERIODIC COMETS. 



lyrical solution of this problem : the actual elliptic orbit of a comet being known 

 what was its previous orbit ? What will it be hereafter, taking into accoun 

 in both cases the perturbating effects caused by the planets of our system ? 



Well, then, by putting these formularies into numbers by substituting, fo 

 its component indeterminate letters, the particular elements of the comet ol 

 1770 it will first be found that in 1767, previous to the approach of that body 

 to Jupiter, the elliptic orbit which it described corresponds, not to five but to 

 fifty years of revolution round the sun ; afterward, that in 1779, on its depar 

 turc out of the attraction of the same planet, the orbit of the comet could not be 

 completed in less than twenty years. From the same researches it results that 

 before 1767, during the whole progress of its revolutions, the shortest distance 

 of the comet from the sun was one hundred and ninety-nine millions of leagues 

 (five hundred and ninety-seven millions of miles), and that after 1779 the mini- 

 mum of distance became one hundred and thirty-one millions of leagues (three 

 hundred and ninety-three millions of miles). This was still too far removed 

 for the comet to be perceptible from the earth. 



However singular it may appear, we are, then, fully authorized to say of the 

 comet of 1770, that the action of Jupiter brought it to us in 1767, and that 

 the same action, producing an inverse effect, removed it from us in the year 

 1779. 



WHISTON'S COMET. 



A remarkable comet appeared in the year 1680, which has been rendered 

 $ memorable by the attempt of Whiston to prove that it was periodic, and that 

 } on one of its former visits it was the proximate cause of the Mosaic deluge. < 

 $ Arago, in his essay on comets, has discussed fully the question raised by $ 

 I Whiston. 



Whiston, says he, proposed to show not only in what manner a comet might 

 ) have occasioned the deluge of Noah, but was desirous, moreover, that his ex- 

 ^ planation should agree minutely with all the circumstances of that great catas- 

 <J trophe as related in Genesis. Let us see how he has succeeded in his object. 

 The biblical deluge happened in the year 2349 before the Christian era, ac- 

 cording to the modern Hebrew text ; or the year 2926, after the Samaritan 

 text, the Septuagint, and Josephus. Is there, then, reason to suppose that at 

 either of those periods a great comet had appeared ? 



Among the comets observed by modern astronomers, that of 1680 may, from 

 its brilliancy, without hesitation be placed in the first rank. 

 $ A great many historians, both native and foreign, mention a very large comet, 

 j in similitude to the blaze of the sun, having an immense train, which appeared in 

 ) the year 1106. In ascending still higher, we find a very large and terrific 

 comet designated by the Byzantine writers by the name of Lampadias, because 

 it resembled a burning lamp, the appearance of which may be fixed in the year 

 531. All the world knows, in fine, that a comet appeared in the month of 

 September, in the year of the death of Caesar, during the games given by the 

 emperor Augustus to the Roman people. That comet was very brilliant, as it 

 became visible from the eleventh hour of the day, that is, about five o'clock ir 

 the evening, or brfore sunset. Its date is in the year 43 before our era. 



Since we have not any exact observation of the comets of 43, or 531, or 

 of 1106 ; since we cannot calculate their parabolic orbits ; since we want th? 

 only criterion which would enable us to decide with perfect certainty eith.-r 

 the identity or dissemblance of two comets, let us at least remember that those 

 of 1680, of 1106, of 531, and of 43, were very brilliant, and let us compare ? 

 with each other the dates of these apparitions : 



