400 PERIODIC COMETS. 



at Paris annually, the produce of six weeks, far from covering the highest 

 mountains, would scarcely have formed a depth of eighty feet. It is therefore 

 necessary to refer to other sources than the cataracts of heaven. Whiston has 

 found them in the nebulosity and tail of the comet. 



According to him, the nebulosity reached the earth near the Gordian 

 (Ararat) mountains Those mountains intercepted the entire tail. The ter- 

 restrial atmosphere, thus charged with an immense quantity of aqueous parti- 

 cles, was sufficient to produce forty days' rain of such violence as the ordinary 

 state of the globe can give us no idea. 



Notwithstanding all its strangeness, I have exposed the theory of Whiston 

 in detail, both on account of the celebrity which it has so long enjoyed, as well 

 as because it appeared improper to treat with contempt the productions of 

 the man whom Newton himself designed as his successor in the university of 

 Cambridge ; yet the following are objections which it seems his theory cannot 

 resist. 



Whiston having required an immense tide to explain the mystery of the bib- 

 lical phenomena of the great deep, was not content to pass his comet extremely 

 near the earth at the moment of the deluge : he has, moreover, given it a very 

 great magnitude, in supposing it six times greater than the moon. 



Such a supposition is completely gratuitous, and this is also its least fault ; 

 for it. is not sufficient to account for the phenomena. If the moon really pro- 

 duces a tide on the waters of the ocean, it is because its angular diurnal 

 motion is not very considerable ; that in the space of some hours its distance 

 from the earth scarcely varies ; during a considerable time it remains vertically 

 over almost the same points of the globe ; the fluid which it attracts has there- 

 fore always time to yield to its action before it moves to a region where the 

 force which emanates from it will be otherwise directed. But it was not the 

 same with the comet of 1680. Near to the earth, its apparent angular motion 

 must have been extremely rapid ; in a few minutes it corresponded with a nu- 

 merous series of points situated on terrestrial meridians very distant from each 

 other. As to its rectilinear distance from the earth, it might, without doubt, 

 have been very small, but only during a few instants. The union of these cir- 

 cumstances, it must be observed, was but little favorable to the production of 

 a great tide. 



I am very well aware that, to diminish these difficulties, it is sufficient to in- 

 crease the comet to make its mass not only six times the size of the moon, 

 but thirty or forty times larger ; but I reply that the comet of 1680 does not 

 afford that latitude. On the 1st of November in that year it passed very near 

 to the earth. (See figure 3, in which the orbit of this comet is represented.) 

 It is shown that at the period of the deluge its distance was not less ; then, as 

 in 1680, it produced neither celestial. cataracts, nor terrestrial tides, nor ruptures 

 of the great deep ; as, moreover, its train nor its hair did not inundate us, we 

 may in all confidence say that Whiston's theory is a mere romance, unless, in 

 abandoning the comet of 16<80, we venture to attribute the same effect to 

 another much more considerable star of the same description. 



Whiston, as we have just seen, proposed to attribute to physical causes not 

 only some deluge, but that of Moses, with all the circumstance related in the 

 book of Genesis. His celebrated countryman, Halley, had viewed the prob- 

 lem in a less special manner. 



There exists, says he, far from the sea, marine productions, even upon the 

 highest mountains, which regions have been formerly under the sea. From 

 what impulse has the ocean abandoned the limits in which, in our days, it with 

 very slight oscillations remains constantly bounded ? It is here that Halley 

 calls to his aid, not like Whiston, a comet passing in our vicinity and causing 



