"The water-spouts, says Mr. Shaw, which I had an opportunity of seeing, appeared as so many cylinders of water, which fell from the clouds, although by the reflection of the columns which descend, or by the drops which detach themselves from the water they contain, it sometimes seems, especially when we are at some distance, that the water is drawn up from the sea. To render a reason for this phenomena we may suppose that the clouds being collected in one part by opposite winds, they force them by pressing them with violence to condense and descend in this manner."
There still remain many facts to be acquired before we can give a complete explanation of these phenomena; it appears to me, that if there are under the waters of the sea, at particular places, soils mixed with sulphur, bitumen, and minerals, these matters may be inflamed and produce a great quantity of air, which being newly generated and prodigiously rarefied, ascends with rapidity, and may raise these water-spouts from the sea to the sky; so likewise if, by inflammation, the sulphurous matters which a cloud contains, a current of air is formed, which descends perpendicularly from the clouds towards the sea, all its water may follow the current of air, and form a water-spout which will fall from the sky upon the sea; but it must be allowed that the explanation of this kind of water-spout, no more than that we have given of those produced by contrary winds, is not satisfactory; and it might be asked why these kinds of water-spouts, which fall perpendicularly from the clouds, are not as often seen on the land as on the sea?
The History of the Academy, anno 1727, mentions a land water-spout which appeared at Capestan, near Beziers; it descended from a cloud like a black pillar, which diminished by degrees, and at length terminated in a point upon the surface of the earth. It obeyed the wind which blew from west to south-west. It was accompanied with a very thick smoke, and made a similar noise to that of a troubled sea. It tore up and carried away trees to the distance of forty or fifty feet, marking its way by a large track, on which three carriages might have passed each other. There appeared another pillar of the same kind, but which soon joined the first; and after the whole had disappeared, a great quantity of hail fell on the earth.
This kind of water-spout appears to be still different from the other two: it is not mentioned to have contained water; and it seems, by what I have related, and by the explanation given thereof by M. Andoque, to the academy, that this water-spout was only a whirlwind, rendered visible by the dust and condensed vapours which it contained.
In the same history, anno 1741, a water-spout is spoken of, seen on the lake of Geneva; the upper part was inclined to a very black cloud, and the lower, which was narrower, terminated a little above the water. This phenomenon remained only a few minutes, and, at the moment it was dissipated, a thick vapour was perceived at the part where it first appeared; the waters of the lake boiled and seemed to make an effort to rise up. The air was very calm during the whole time; and when it disappeared neither wind nor rain ensued. "After all we are acquainted with," says the historian of the academy, "concerning water-spouts, is not this another proof that they are not formed by the conflict of the winds, but almost always produced by volcanos or subterraneous vapours, from which we know the bottom of the sea is not exempt? Whirlwinds and hurricanes, which we commonly thought to be the cause of these appearances, may possibly be only the effect, or an accidental event thereof."
OF VOLCANOS AND EARTHQUAKES.
The burning mountains, called volcanos, contain in their bowels, sulphur, bitumen, and other matters of an inflammable nature, the effects of which are more violent than that of gunpowder, or even thunder, and have from the earliest ages terrified mankind, and desolated the country. A volcano is an immense cannon, whose orifice is often more than half a league: from this wide mouth are vomited forth torrents of smoke and flames, rivers of bitumen, sulphur, and melted metals, clouds of cinders and stones, and sometimes it ejects enormous rocks to many leagues distance, which human powers united could not move; the conflagration is so terrible, and the quantity of burnt, melted, calcined, and vitrified matters which the mountain throws out, is so great, that they destroy cities and forests, cover fields an hundred and two hundred feet in thickness, and sometimes form hills and mountains, which are only heaps of these matters piled up together. The action of this fire, and the force of its explosion, is so violent, that it produces by its re-action, succussions which shake the earth, agitate the sea, overthrow mountains, and destroy the most solid towers and edifices, even to very considerable distances.