CURIOSITIES RESPECTING VARIOUS PHENOMENA OR APPEARANCES IN NATURE.

On the Ignis Fatuus.

The Ignis Fatuus is a luminous appearance, which is most frequently observed in boggy districts and near rivers, though sometimes also in dry places. By its appearance, benighted travellers are said to have been sometimes led into imminent danger, taking it for a candle at a distance; from which seemingly mischievous property it has been thought by the vulgar to be a spirit of a malignant nature, and been named accordingly, Will-with-a-Wisp, or Jack-with-a-Lantern; for the same reason that it had its Latin name Ignis Fatuus. This light is frequently seen about burying-places and dunghills. Some countries are also remarkable for it, as about Bologna in Italy, and some parts of Spain and Ethiopia. Its forms are so uncertain and variable, that they can scarcely be described, especially as philosophical observers seldom meet with it. Dr. Derham, however, one night perceived one of them, and got so near that he had a very advantageous view of it. This is very difficult to be obtained; for, among other singularities of the ignis fatuus, it avoids the approach of any person, and flies from place to place as if it were animated. That which Dr. Derham observed, was in some boggy ground betwixt two rocky hills; and the night was dark and calm, by which means he was enabled to advance within two or three yards of it. It appeared like a complete body of light without any division, so that he was sure it could not be occasioned by insects. It kept dancing about a dead thistle, till a very slight motion of the air, occasioned, as he supposed, by his near approach to it, made it jump to another place; after which it kept flying before him as he advanced.

Beccari obtained information, that two of these lights appeared in the plains about Bologna, the one north, the other south of that city, and were to be seen almost every dark night, especially that to the eastward, giving a light equal to an ordinary faggot. The latter appeared to a gentleman of his acquaintance, as he was travelling; moved constantly before him for about a mile, and gave a better light than a torch which was carried before him. Both these appearances gave a very strong light, and were constantly in motion. Sometimes they would rise, sometimes sink; but commonly they would hover about six feet from the ground; they would also frequently disappear on a sudden, and appear again in some other place. They differed also in size and figure, sometimes spreading pretty wide, and then contracting themselves; sometimes breaking into two, and then joining again. Sometimes they would appear like waves, at others they would seem to drop sparks of fire: they were but little affected by the wind; and in wet or rainy weather, were frequently observed to cast a stronger light than in dry weather: they were also observed more frequently when snow lay upon the ground, than in the hottest summer; but he was assured, that there was not a dark night throughout the whole year, in which they were not to be seen. The ground east of Bologna, where the largest of these was observed, is a hard chalky soil mixed with clay, which retains moisture long, but breaks and cracks in hot weather. On the mountains, where the soil is looser, the ignes fatui were less. From the best information, M. Beccari found that these lights were very frequent about rivers and brooks. He concludes his narrative with the following singular account.—

“An intelligent gentleman travelling in the evening, between eight and nine o’clock, in a hilly road about ten miles south of Bologna, perceived a light which shone very strongly upon some stones which lay on the banks of the Rio Verde. It seemed to be about two feet above the stones, and near the water. In size and figure it had the appearance of a parallelo-piped, above a foot in length, and half a foot high, the largest side being parallel to the horizon. Its light was so strong, that he could plainly see by it part of a neighbouring hedge and the water of the river; only in the east corner of it the light was rather faint, and the square figure less perfect, as if it were cut off or darkened by the segment of a circle. On examining it a little nearer, he was surprised to find that it changed gradually from a bright red to a yellowish, and then to a pale colour, in proportion as he drew nearer; and when he came to the place itself it quite vanished. Upon 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. When he examined the place of this luminous appearance, he could perceive no smell, nor any other mark of fire,” Another gentleman informed M. Beccari, that he had seen the same light five or six different times in spring and autumn; and that it always appeared of the same shape, and in the very same spot. One night in particular, he observed it come out of a neighbouring field to settle in the usual place.

A very remarkable account of an ignis fatuus is given by Dr. Shaw, in his Travels to the Holy Land. It appeared in the valleys of mount Ephraim, and attended him and his company for above an hour. Sometimes it appeared globular, or like the flame of a candle, at others it spread to such a degree as to involve the whole country in a pale inoffensive light, then contracted itself, and suddenly disappeared, but in less than a minute it would appear again; sometimes, running swiftly along, it would expand itself at certain intervals over more than two or three acres of the adjacent mountains. The atmosphere from the beginning of the evening had been remarkably thick and hazy; and the dew, as they felt it on the bridles of their horses, was very clammy and unctuous. Lights resembling the ignis fatuus are sometimes observed at sea, skipping about the masts and rigging of ships; and Dr. Shaw informs us, that he has seen these in such weather as that just mentioned, when he saw the ignis fatuus in Palestine. Similar appearances have been observed in various other situations; and we are told of one which appeared about the bed of a woman in Milan, surrounding it, as well as her body, entirely. This light fled from the hand which approached; but was at length entirely dispersed by the motion of the air.

Of the same kind also, most probably, are those small luminous appearances which sometimes appear in houses, or near them, called, in Scotland, Elf-candles, and which are supposed to portend the death of some person about the house. In general these lights are harmless, though not always; for some of them have encompassed stacks of hay and corn, and set them on fire; so that they became objects of great terror to the country people. Of these, it was observed, that they would avoid a drawn sword, or sharp-pointed iron instrument; and that they would be driven away by a great noise.

Several philosophers have endeavoured to account for these appearances, but hitherto with no great success; nor indeed does there seem to be sufficient data for solving all their phenomena. Sir Isaac Newton calls it a vapour shining without heat; and supposes that there is the same difference between a vapour of the ignis fatuus and flame, that there is between the shining of rotten wood and burning coals. But though this seems generally to be the case, there are exceptions, as has been instanced in the vapours which set fire to the stacks of corn. Dr. Priestley supposes that the light is of the same nature with that produced by putrescent substances; others, that the electrical fluid is principally concerned; but none have attempted to give any particular solution of the phenomena.

From the frequent appearance of the ignis fatuus in marshes, moist ground, burying-places, and dunghills, putrefaction seems to be concerned in the production of it. This process is attended with the emission of an aqueous steam, together with a quantity of fixed inflammable and alkaline air, blended together in one common vapour. It is likewise attended with some degree of heat, and there are some vapours, that of sulphur particularly, which becomes luminous with a degree of heat much less than that sufficient to set fire to combustibles. The putrid vapour, therefore, may be capable of shining with a still smaller degree of heat than that of sulphur, and consequently may become luminous by that which putrefaction alone affords. This would account for the ignis fatuus, were it only a steady luminous vapour arising from places where putrid matters are contained; but its extreme mobility, and flying from one place to another on the approach of any person, cannot be accounted for on this principle. If one quantity of the putrid vapour becomes luminous by means of heat, all the rest ought to do so likewise; so that though we may allow heat and putrefaction to be concerned, yet of necessity we must have recourse to some other agent, which can be no other than electricity. Without this, it is impossible to conceive how any body of moveable vapour should not be carried away by the wind; but so far is this from being the case, that the ignes fatui described by M. Beccari, were but little affected by the wind. It is, besides, proved by undoubted experiment, that electricity is always attended with some degree of heat; and this, however small, may be sufficient to give a luminous property to any vapour on which it acts strongly: not to add, that the electric fluid itself is no other than light, and may therefore by its action easily produce a luminous appearance independent of any vapour. We have a strong proof that electricity is concerned, or indeed the principal agent, in producing the ignis fatuus, from an experiment related by Dr. Priestley, of a flame of this kind being artificially produced.

A gentleman, who had been making many electrical experiments for a whole afternoon in a small room, on going out of it, observed a flame following him at some little distance. This was doubtless a true ignis fatuus, and the circumstances necessary to produce it were then present, viz. an atmosphere impregnated with animal vapour, and likewise strongly electrified, for the quantity of perspiration emitted by a human body is by no means inconsiderable; and it, as well as the electricity, would be collected by reason of the smallness of the room. In this case, however, there seems to have been a considerable difference between the artificial ignis fatuus, and those commonly met with; for this flame followed the gentleman as he went out of the room, but the natural ones commonly fly from those who approach them. This may be accounted for, from a difference between the electricity of the atmosphere in the one room and the other; in which case the flame would naturally be attracted towards that place where the electricity was either different in quality or in quantity; but in the natural way, where all bodies may be supposed equally electrified for a great way round, a repulsion will as naturally take place. Still, however, this does not seem to be always the case. In those instances where travellers have been attended by an ignis fatuus, we cannot suppose it to have been influenced by any other power than what we call attraction, and which electricity is very capable of producing. Its keeping at some distance, is likewise easily accounted for; as we know that bodies possessed of different quantities of electricity may be made to attract one another for a certain space, and then repel without having ever come into contact. On this principle we may account for the light which surrounded the woman at Milan, but fled from the hand of any other person. On the same principle may we account for those mischievous vapours which set fire to the hay and corn stacks, but were driven away by presenting to them a pointed iron instrument, or by making a noise. Both these are known to have a great effect upon the electric matter; and by means of either, lightning may occasionally be made to fall upon, or to avoid, particular places, according to the circumstances by which the general mass happens to be effected. On the whole, therefore, it seems most probable, that the ignis fatuus is a collection of vapours of the putrescent kind, very much affected by electricity; according to the degree of which, it will either give a weak or strong light, or even set fire to certain substances. This opinion seems to be confirmed from some luminous appearances observed in privies, where the putrid vapours have been collected into balls, and exploded violently on the approach of a candle. This last effect, however, we cannot so well ascribe to the electricity, as to the ascension of the inflammable air which abounds in such places.

In the Appendix to Dr. Priestley’s third volume of Experiments and Observations on Air, Mr. Warltire gives an account of some very remarkable ignes fatui, which he observed on the road to Bromsgrove, about five miles from Birmingham. The time of observation was the 12th of December, 1776, before daylight. Many of these lights were playing in an adjacent field, in different directions; from some of which suddenly sprang up bright branches of light, somewhat resembling the explosion of a rocket that contained many brilliant stars, if the discharge was upwards, instead of the usual direction; and the hedge, and trees on each side of the hedge, were illuminated. This appearance continued but a few seconds, and then the jack-with-a-lantern played as before. Mr. Warltire was not near enough to observe if the apparent explosion was attended with any report.

Cronstedt gives it as his opinion, that ignes fatui, as well as falling stars, are owing to collections of inflammable air raised to a great height in the atmosphere. But, with regard to the latter, the vast height at which they move, evidently shews that they cannot be the effect of any gravitating vapour whatever; for the lightest inflammable air is one-twelfth of that of the common atmosphere: and we have no reason to believe, that at the distance of forty or fifty miles from the earth, the latter has near one-twelfth of its weight at the surface. From the account given by Mr. Warltire, we should be apt to conclude, that there is a strong affinity betwixt the ignes fatui and fireballs, insomuch that the one might be very easily converted into the other. Electricity can assume both these appearances, as is evident in the case of points; or even when the atmosphere is violently electrified, as around the string of an electrified kite, which always will appear to be surrounded with a blue flame in the night, if the electricity be very strong. On the whole, it appears that electricity, acting upon a small quantity of atmospherical air with a certain degree of vigour, will produce an appearance resembling an ignis fatuus; with a superior force it will produce a fire-ball; and a sudden increase of electrical power might produce those sparks and apparent explosions observed by Mr. Warltire. This appearance has produced many superstitious fears in the ignorant and uneducated.

To those who have, unfortunately, been badly educated in this respect, a friendly act would be, to endeavour with sound reasoning to convince them of their error, and dissuade them from giving heed, in future, to idle, superstitious, or inconsistent stories of any kind; advising them to furnish themselves with such knowledge, as may have a tendency to produce true pleasure and happiness through life, and which, when dying, they can reflect upon without uneasiness. “The natural offspring of prevailing superstition is infidelity. Of the truth of this, the present times afford us a lamentable example. Where ignorance and fear once ruled supreme, there has rash philosophy but too successfully planted presumption and atheism. ’Tis the diffusion of pure and solid knowledge, which alone can preserve us from the dominion of these opposite tyrants. How should this consideration increase our zeal and stimulate our endeavours! The immediate sphere of our action may be circumscribed, but our exertions will not on that account be entirely lost. In that circumscribed sphere let us labour to root out every superstitious lying vanity, and plant pure religion and unsophisticated truth in its stead.

“How charming, how enlivening to the soul, to gaze upon the dawning beams of opening light, to behold them irradiate that dismal gloom of intellectual darkness, which long overwhelmed the millions of mankind: how supremely pleasing, to view them wider and wider spreading their invigorating influence: how rapturously transporting, to contemplate the resplendent prospect of pure and perfect day!

“——————Power supreme!
O everlasting King! to thee we kneel,
To thee we lift our voice!”—

“O spread thy benign, thy vivifying light over the dwellings of the sons of men; dispel the yet impending mists of ignorance and superstition: and, O preserve us from the dismal gulf of infidelity and atheism; let thy truth run and prevail gloriously; let pure celestial wisdom overspread the earth as the waters cover the sea!—Then shall millions kneel before thee with grateful and enraptured hearts; then shall they rejoice to sing the praises of thee, their Benefactor, their Father, and their God: then shall this vale of tears be filled with the mansions of joy and gladness, and become a blissful foretaste of those regions, where thy saints, crowned with unfading glory and felicity, surround thy throne with never-ceasing hallelujahs!”

See Naylor on Vulgar Superstitions.