mark the intervals; and all is one unremitted roar of elementary confusion. It should seem, however, that the lightning of those countries is not so fatal, or so dangerous, in a proportion to its energy, as that with us; since, in this case, the torrid zone would be uninhabitable. When these terrors have ceased, with which, however, the na. tives are familiar, meteors of another kind begin to make their ap. pearance. The intense beams of the sun, darting upon stagnant waters, that generally cover the surface of the country, raise va. pours of various kinds. Floating bodies of fire, which assume different names, rather from their accidental forms, than from any real difference between them, are seen without surprise. The draco volans, or flying dragon; will-o'-the-wisp; the ignis fatuus, or wan dering fires of St. Helmo, or the mariner's light, are every where frequent; and of these we have numberless descriptions. [EDITOR. SECTION II. Of the Ignis Fatuus, as observed in England. By Sir Thomas Dereham, Bart. F.R.S. the Rev. William Derham, F.R.S. and others. It being the opinion of divers skilful naturalists, particularly Mr. Fr. Willoughby and Mr. Ray, that ignes fatui are only the shining of a great number of the male glow-worms in England, or of the pyrausta in Italy, flying together, Mr. D. consulted his friend, Sir Thomas Dereham, about the phenomenon, being in. formed that those ignes fatui are common in all the Italian parts. But of the pyraustæ, or fire-flies, he says, he never observed any such effects, though there is an immense number of them in June and July. He also says, that these pyraustæ are called Lucciole, i. e. small lights, and that they are not the farfalls, as Mr. Ray thought, which are butterflies. But Mr. D. has reason to think, that insects are not concerned in the ignes fatui, from the following observations; the first made by himself, and the others received from Italy, by the favour of Sir Thomas Dereham. His own observation he made at a place in a valley between rocky bills, which he suspected might contain minerals, in some boggy ground near the bottom of those hills. Where, seeing one in a calm, dark night, with gentle approaches, he got up within two or three yards of it, and viewed it with all possible care. lle found it frisking about a dead thistle growing in the field, till a small motion of the air made it skip to another place, and thence to another, and another. It is about fifty-five years since he saw this phenomenon, but he had as fresh and perfect an idea of it, as if it was but a few days. And as he took it then, so he is of the same opinion now, that it was a fired vapour. The male glow-worms Mr. D. knows emit their shining light, as they fly; by which means they discover and woo the females; but he never observed them to fly together in so great numbers, as to make a light equal to an ignis fatuus. And he was so near, that had it been the shining of glow-worms, he must have seen it in little distinct spots of light; but it was one continuous body of light. As to the comunication from Italy, it is observed that these lights are pretty common in all the territory of Bologna. In the plains they are very frequently observed; the country people call them cularsi, perhaps from some fancied similitude to those birds; and because they consider them as birds, the belly and other parts of which are resplendent like our shining flies. They are most frequent in watery and morassy ground, and there are some such places, where one may be almost sure of seeing them every night, if it be dark; some of them giving as much light as a lighted torch, and some no larger than the flame of a common candle. All of them have the same property in resembling, both in colour and light, a flame strong enough to reflect a lustre on neighbouring ob jects all around. They are continually in motion, but this motion is various and uncertain. Sometimes they rise up, at others they sink. Sometimes they disappear of a sudden, and appear again in an instant in some other place. Commonly they keep hovering about six feet from the ground. As they differ in size, so also in figure, spreading sometimes pretty wide, and then again contracting themselves. Sometimes breaking to all appearance into two, soon after meeting again into one body; sometimes floating like waves, and letting drop some parts like sparks out of a fire. And in the very middle of the winter, when the weather is very cold, and the ground covered with snow, they are observed more fre. quently than in the hottest summer. Nor does either rain or snow n anywise prevent or hinder their appearance; on the contrary, they are more frequently observed, and cast a stronger light, in rainy and wet weather. But since they do not receive any damage from wet weather; and since, on the other hand, it has never been observed, that any thing was set on fire by them, though they must needs in their moving to and fro, meet with a good many combustible substances, it may from thence be inferred, that they have some resemblance to that sort of phosphorus that shines in the dark, without burning any thing. As to the appearance of this phenomenon in mountainous parts, they differ in nothing else but in size; these latter being never observed any larger than the flame of an ordinary candle. In general, these lights are great friends to brooks and rivers, being frequently observed along their banks; perhaps because the air carries them thither more easily than any where else. In all other particulars, as in their motion, the manner of their appearance, their disappearing sometimes very suddenly, their light, the height they rise to, and their not being affected either by rainy or cold weather, they are the very same with the cularsi above described, or the large Will with a Wisp, as observed in the plains. A young gentleman, a very accurate and skilful observer of natural appearances, travelling sometime in March last, between eight and nine in the evening, in a mountainous road, about ten miles south of Bologna, as he approached a certain river, called Rioverde, he perceived a light, which shone very strongly on some stones that lay on the banks. It seemed to be about two feet above the stones, and not far from the water of the river: in figure and size it had the appearance of a parallelopiped, somewhat above a Bolognese foot in length, and about half a foot high, its longest side lying parallel to the horizon: its light was very strong, insomuch that he could very plainly distinguish by it part of a neighbouring hedge, and the water in the river. The gentleman's curiosity tempted him to examine it a little nearer; in order to which, he advanced gently towards the place, but was surprised to find, that insensibly it changed from a bright red to a yellowish, and then to a pale colour, in proportion as he drew nearer; and that when he came to the place itself, it was quite vanished. On this he stepped back, and not only saw it again, but found that the farther he went from it, the stronger and brighter it grew; nor could he, on narrowly viewing the place where this fiery appearance was, perceive the least blackness, or smell, or any mark of an actual fire. The same observation was confirmed by another gentleman, who frequently travels that way, and who asserted, that he had seen the very same light five or six different times, in Spring and Autumn, and that he had always observed it in the very same shape and the same place; which seems very difficult to be accounted for. He said further, that once he took particular notice of its coming out of a neighbouring place, and then settling itself into the figure above described. [Phil. Trans. Abr. 1729. SECTION III. Luminous and Inflammable Exhalation on the Snows of the Appennines. We have ventured in the first section of this chapter to ascribe the greater number of luminous exhalations that float over the surface of the earth to the extrication and inflammation of hydrogen. gas, similar to that which is so frequently elicited in coal mines, under the name of fire-damp. In the midst of the snows on the summit of the Apennines, was traced in the middle of last century, a luminous and burning exhalation which evidently proceeded from this cause. It is clearly and accurately described by Robert More, Esq. in a letter published in the Philosophical Transactions, vol. xlvii.; in which, among other facts of natural history, he observes that the fire among the snows on the summit of the Apen. nines is of the same sort with that about a little well at Brosely in Shropshire; of which the Society has had an account; the same as of the foul air sent them from Sir James Lowther's coal pits; and the like made by a gentleman with filings of iron and oil of vitriol. The flame, when he saw it, was extremely bright, covered a surface of about three yards by two, and rose about four feet See Philos. Trans. No. 482.-Orig. † No. 482, No. 442.—Orig. high. After great rains and snows, they said, the whole bare patch, of about nine yards diameter, flames. The gravel, out of which it rises, at a very little depth, is quite cold. There are three of these fires in that neighbourhood; and there was one they call extinct. He went to the place to light it up again, and left it flaming. The middle of the last place is a little hollowed, and had in it a puddle of water: there were strong ebullitions of air through the water; but that the air would not take fire; yet what rose through the wet and cold gravel flamed brightly. Near either of these flames, removing the surface of the gravel, that below would take fire from lighted matches. [Phil. Trans. 1750. SECTION IV. 1. Fiery Exhalations or Damp, that set on Fire various HayRicks in Pembrokeshire. In a Letter from Mr. Edward Floyd, to Dr. Leister, F.R.S. dated I am wholly intent at present on giving you the best account I can of a most dismal and prodigious accident at Hartech in this county (Pembrokeshire), from the 24th to the 30th of December, 1693. It is of the unaccountable firing of sixteen ricks of hay, and two barns, one full of corn, the other of hay. I call it un. accountable, because it is evident they were not burnt by common fire, but by a kindled exhalation, which was often seen to come from the sea, and lasted at least a fortnight or three weeks; and annoyed the country, both by poisoning the grass and firing the hay, for the space of a mile. It was a weak blue flame, easily extinguished, and did not in the least burn any of the men who interposed their endeavours to save the hay, though they ventured not only closeto it, but sometimes into it. All the damage sustained happened constantly in the night. There are three small tenements in the same neighbourhood, where the grass is so infected, that it absolutely kills all manner of cattle that feed on it. The grass has been infectious these three years, but not thoroughly fatal till this last. |
