IGNES FATUI, OR MOCK FIRES.
These meteors, denominated by the vulgar, Will-with-a-wisp, and Jack-with-a-lantern, and at sea or on the coast, mariner’s lights, or St. Helmo’s[Helmo’s] fires, are now considered as real exhalations from the earth, produced by gas, vapor, or some other attenuated substance, emanating from vegetable, animal or mineral materials, and combined with the matter of light or heat, or both. Instead of being dense or solid, they are uniformly rare and subtile; and, instead of originating in the loftiest regions of the atmosphere, or beyond its range, are generated for the greater part in low, marshy plains or valleys. To the fearful and superstitious, they are a source of as much terror as the nobler and sublimer meteors which have just been contemplated; and it is probable that they have occasionally been the source of real and extensive damage, when in a state of actual combustion, and that they have still more frequently seduced a timid and benighted traveler into dangerous bogs and quagmires.
In Italy, in the Bolognese territory, they are so frequent, in the morassy grounds, that they are to be seen every night, some of them affording as much light as a kindled torch, and others not being larger than the flame of a candle, but all of them so luminous as to shed a luster on the surrounding objects. They are constantly in motion, but this motion is various and uncertain. They sometimes rise and at other times sink, sometimes suddenly disappearing, and appearing again in an instant in some other place. They usually hover about six feet from the ground, differing both in figure and size, and spreading out and contracting themselves alternately. Sometimes they break to appearance into two parts, soon after uniting again in one body, and at intervals float like waves, letting fall portions of ignited matter, like sparks from a fire. They are more frequently observed in winter than in summer, and cast the strongest light in rainy and moist weather. They are most friendly to the banks of brooks and rivers, and to morasses; but they are likewise seen on elevated grounds, where they are, however, of a comparatively diminutive size.
In the month of March, 1728, a traveler being in a mountainous road, about ten miles south of Bononia, perceived, as he approached the river Riovedere, between eight and nine in the evening, a light shining very brightly on some stones which lay on the banks. It was elevated about two feet above them; its figure describing a parallelopiped, more than a foot in length, and about six inches high, its longest side lying parallel to the horizon. Its light was so strong that he could distinguish by it very plainly a part of a neighboring hedge, and the water in the river. On a near approach, it changed from a bright red to a yellowish color, and on drawing still nearer, became pale; but when the observer reached the spot it vanished. On his stepping back, he not only saw it again, but found that the further he receded, the stronger and more luminous it became. This light was afterward seen several times, both in spring and autumn, precisely at the same spot, and preserving the same shape.
On the twelfth of December, 1776, several very remarkable ignes fatui were observed on the road to Bromsgrove, five miles from Birmingham, in England, a little before daylight. A great many of these lights were playing in an adjacent field, in different directions; from some of which there suddenly sprang up bright branches of light, somewhat resembling the explosion of a rocket, filled with many brilliant stars, if, in the case of the latter, the discharge be supposed to be upward, or vertical, instead of taking the usual direction. The hedge, and the trees on each side, were strongly illuminated. This appearance continued a few seconds only, when the ignes fatui played as before. The spectator was not sufficiently near to observe whether the apparent explosions were attended with any report.
In the month of December, 1693, between the twenty-fourth and thirtieth, a fiery exhalation, without doubt generated in the same way with the meteors described above, set fire to sixteen ricks of hay, and two barns filled with corn and hay, at the village of Hartech, in Pembrokeshire. It had frequently been seen before, proceeding from the sea, and in these instances lasted for a fortnight or three weeks. It not only fired the hay, but poisoned the grass, for the extent of a mile, so as to induce a distemper among the cattle. It was a weak blue flame, easily extinguished, and did not in the least burn any of the men who interposed their endeavors to save the hay, although they ventured, not only close to it, but sometimes into it. All the damage sustained happened constantly in the night.
Belonging to this class of meteors is the draco volans, a fiery exhalation, frequent in marshy and cold countries. It is most common in summer; and, although principally seen playing near the banks of rivers, or in boggy places, still it sometimes mounts up to a considerable hight in the air, to the no small terror of the amazed beholders. Its appearance is that of an oblong (sometimes roundish) fiery body, with a long tail. It is entirely harmless, frequently sticking to the hands and clothes of the spectators, without doing them the least injury.