The tail of a comet is the lightest part of its atmosphere; it is a transparent mist, a subtile vapour, which the heat of the sun exhales from the body of the comet: this vapour composed of extremely rarefied aqueous and aerial particles, follows the comet when it descends to its perihelion, and precedes when it re-ascends, so that it is always situate opposite to the sun, as if it sought to be in the shade, and avoid the too great heat of that luminary. The column which this vapour forms is often of an immense length, and the more a comet approaches the sun, the longer and more extended is its tail, and as many comets descend below the annual orb of the earth, it is not surprising that the earth is sometimes found surrounded with the vapour of this tail; this is precisely what happened at the time of the deluge. In two hours the tail of a comet will evacuate a quantity of water equal to what is contained in the whole ocean. In short, this tail was what Moses calls the cataracts of Heaven, "and the cataracts of Heaven were opened." The terrestrial globe meeting with the tail of a comet, must, in going its course through this vapour, appropriate to itself a part of the matter which it contains; all which, coming within the sphere of the earth's attraction, must fall on it, and fall in the form of rain, since this tail is partly composed of aqueous vapours. Thus rain may come down in such abundance as to produce an universal deluge the waters of which might easily surmount the tops of the highest mountains. Nevertheless, our author, cautious of not going directly against the letter of holy writ, does not say that this rain was the sole cause of the universal deluge, but takes the water from every place he can find it. The great abyss as we see contains a considerable quantity. The earth, at the approach of the comet, would prove the force of its attraction; and the waters contained in the great abyss would be agitated by so violent a kind of flux and reflux, that the superficial crust would not resist, but split in several places, and the internal waters be dispersed over the surface, "And the fountains of the abyss were opened."