START OF THE PROJECT GUTENBERG EBOOK THUNDER AND LIGHTNING*** E-text prepared by Greg Bergquist, JoAnn Greenwood, and the Online Distributed Proofreading Team (http://www.pgdp.net) from page images generously made available by Internet Archive (https://archive.org) Note: Project Gutenberg also has an HTML version of this file which includes the original illustrations. See 42245-h.htm or 42245-h.zip: (http://www.gutenberg.org/files/42245/42245-h/42245-h.htm) or (http://www.gutenberg.org/files/42245/42245-h.zip) Images of the original pages are available through Internet Archive. See https://archive.org/details/thunderlightning00flamuoft THUNDER AND LIGHTNING * * * * * Medium 8vo, cloth extra, 10_s._ 6_d._ FLAMMARION'S POPULAR ASTRONOMY Translated from the French by J. ELLARD GORE, F.R.A.S. With 3 Plates and 288 Illustrations. "The six books into which the book is divided give a very lucid and accurate description of the knowledge which has been acquired of the moving bodies of space, both as respects their motions and physical constitutions. Of the translation we can only speak in terms of praise. Not only does it well represent the original, but Mr. Gore has added useful notes for the purpose of bringing the information up to date, and has also increased the number--already very considerable--of the excellent illustrations, so that the work is likely to become as popular in England as it has been in France."--ATHENÆUM. "The work which Mr. J. E. Gore has translated into English has made for itself a name and reputation in France ... and has gone into general circulation to the number of a hundred thousand copies. This last fact is proof how well within the bounds of possibility it is to make the latest discoveries of science comprehensible and fascinating to the common mind. M. Flammarion has attained this triumph through the grasp of his knowledge, the lucidity of his style, and his power of bringing home the most stupendous and complicated of the things revealed to us in the depths of space. M. Flammarion's pages should find almost as great acceptance in this country as in his own. Simplicity of arrangement and of statement are part of his charm and of his success."--SCOTSMAN. "M. Flammarion's latest volume, if it does not displace its English rivals, may well take a high place in the rank to which they belong. It is full, lucid, and, thanks to Mr. Gore's careful revision, well up to date.... Mr. Gore's edition is so carefully brought abreast of the latest discoveries that the English student may now congratulate himself on being in an even better position than the countrymen of M. Flammarion."--DAILY CHRONICLE. "Young students of astronomy who wish to obtain a general idea of the most wonderful and fascinating of all sciences will find precisely what they seek in M. Flammarion's eloquent and poetic chapters.... There are many illustrations in this able and attractive treatise."--SPEAKER. "It is a fascinating work, extending to nearly seven hundred pages, and dealing in popular language with some of the most interesting of the discoveries and speculations of astronomers."--DAILY NEWS. "M. Flammarion is a sound practical astronomer; he has rendered good and laborious service to the science, and he possesses a valuable faculty of popular exposition.... The volume is profusely and well illustrated, some of the best plates making here their first appearance."--SATURDAY REVIEW. "A high place must be accorded to Flammarion's 'Popular Astronomy.' Never before has the science of the heavens been treated with such fulness and interest as in this fascinating book; for Flammarion is a man of letters as well as a man of science--a man of letters, too, endowed with the wondrous gifts of lucidity and charm which distinguish the best French writers.... Flammarion's book is much more absorbing than most novels, more romantic than most romances, more poetic than most poems, yet strictly and scientifically accurate."--LUDGATE MONTHLY. "It must be confessed that M. Flammarion not only arrests the attention, but assists the reader to grasp astronomical theories--a task in which less popular writers often fail when they make the attempt."--LITERARY WORLD. "The book is a most fascinating one, and holds the reader from start to finish.... As a manual for those who wish to obtain a good general knowledge of astronomy this work will be found unsurpassed."--SCIENCE GOSSIP. LONDON: CHATTO & WINDUS, 111 ST. MARTIN'S LANE, W.C. * * * * * THUNDER AND LIGHTNING by CAMILLE FLAMMARION Translated by Walter Mostyn [Illustration] WITH ILLUSTRATIONS London Chatto & Windus 1905 Printed by William Clowes and Sons, Limited, London and Beccles. CONTENTS CHAPTER PAGE I. THE VICTIMS OF LIGHTNING 1 II. ATMOSPHERIC ELECTRICITY AND STORM-CLOUDS 17 III. THE FLASH AND THE SOUND 31 IV. FIREBALLS 57 V. THE EFFECTS OF LIGHTNING ON MANKIND 89 VI. THE EFFECTS OF LIGHTNING ON ANIMALS 128 VII. THE EFFECTS OF LIGHTNING ON TREES AND PLANTS 155 VIII. THE EFFECTS OF LIGHTNING ON METALS, OBJECTS, HOUSES, ETC. 188 IX. LIGHTNING CONDUCTORS 240 X. PICTURES MADE BY LIGHTNING 249 THUNDER AND LIGHTNING CHAPTER I THE VICTIMS OF LIGHTNING It would be an interesting thing to make a careful study once a year, towards the end of the summer, of the habits and customs of thunder and lightning. Perhaps in this way we should succeed one day in determining the still mysterious nature of these elusive forces. I, for my part, have been engaged upon the task for many years past. It has produced a big accumulation of records, and in this volume I can find room but for a _résumé_ of them, as varied as possible. In my first chapter I shall present a few characteristic examples, just to give my readers some hint of this variety. Not to go too far back, let us begin with a harmless--I might almost say playful--fireball performance, of which M. Schnaufer, Professor at Marseilles, has given me the particulars. In October, 1898, the fireball in question made its appearance in a room and advanced towards a young girl who was seated at the table, her feet hanging down without touching the floor. The luminous globe moved along the floor in the girl's direction, began to rise quite near her and then round and round her, spiral fashion, darted off towards a hole in the chimney--a hole made for the stove-pipe, and closed up with glued paper--made its way up the chimney, and, on emerging into the open air, gave out upon the roof an appalling crash which shook the entire house. It was a case of coming in like a lamb and going out like a lion! A similar occurrence is recorded as having been observed in Paris, on July 5, 1852, in a tailor's room, including the same curious detail of the departure through the hole in the chimney, closed up with paper. It was in the Rue Saint Jacques, near the Val de Grâce. The fireball burst into the room from the chimney, knocking over the paper guard in front of the fireplace. In appearance it suggested a young cat, gathered up into a ball, as it were, and moving along without using its paws. It approached the tailor's legs as though to play with them. The tailor moved them away to avoid the contact, of which he naturally was in terror. After some seconds, the globe of fire rose vertically to the height of the man's face as he sat, and he, to save himself, leaned quickly back and fell over. The fireball continued to rise, and made its way towards a hole which had been made at the top of the chimney for the insertion of a stove-pipe in the winter, but which, as the tailor put it afterwards, "the fireball couldn't see," because it was closed up with paper. The ball stripped off the paper neatly, entered the chimney quite quietly, and having risen to the summit, produced a tremendous explosion, which sent the chimney-top flying, and scattered it in bits all over the neighbouring courtyard and surrounding roofs. There we have a unique occurrence, recorded for us by Babinet and Arago, and of which I have given here the exact particulars. In both these cases we have to note the attraction of the hole in the chimney and the explosion of the thunderbolt on getting to the top. But it is not easy to detect the law underlying these phenomena. In one of the latest volumes of the Association Française a somewhat similar case is dealt with. "A violent storm," says the writer, M. Wander, "had descended upon the commune of Beugnon (Deux-Sèvres). I happened to be passing through a farm, in which were two children of about twelve and thirteen. These children were taking refuge from the rain under the door of a stable, in which were twenty-five oxen. In front of them extended a courtyard, sloping downwards towards a large pond, twenty or thirty yards away, beside which grew a poplar-tree. Suddenly there appeared a globe of fire, of the size of an apple, near the top of the poplar. We saw it descend, branch by branch, and then down the trunk. It moved along the courtyard _very slowly_, seeming almost to pick its way between the pools of water, and came up to the door where stood the children. One of them was bold enough to touch it with his foot. Immediately a terrible crash shook the entire farm to its foundations, the two children were thrown to the ground uninjured, but eleven of the animals in the stable were killed!" Who is to explain these anomalies? The child who touched the fireball escapes with a fright, and a few feet behind him eleven animals out of twenty-five perish on the spot! During the storm which broke out at the town of Gray, on July 7, 1886, my friend M. Vannesson, President of the Tribunal, saw a fireball of from thirty to forty centimetres in diameter, which exploded on the corner of a roof, cutting clean off the end portion of the central beam to the length of about half a yard (like a bundle of matches, but without setting it on fire), scattering the splinters over the upper story and loosening the plaster upon the walls below. It then _rebounded_ on the roofing of a little outside staircase, made a hole in it, smashing and sending flying the slates, came down upon the road, and rolling right in the midst of some passers-by--who, like the child in the farm, escaped with a fright--disappeared. My learned fellow-member of the Astronomical Society of France, Dr. Bougon, has discovered an account of one of the most remarkable fireballs ever recorded in _La Gloire des Confesseurs_, a work written by Gregory of Tours, the twentieth bishop of that town. On the dedication day of an oratory which he had constructed in one of the outer buildings of the episcopal palace, all the participants in the procession from the cathedral, while approaching the oratory with the sacred relics and singing the litanies, saw a globe of fire, so intensely brilliant that their eyes were dazzled, and they could scarcely keep them open. Seized with terror, priests, deacons, sub-deacons, choristers, together with the distinguished citizens of the town, who were carrying the relics upon their shoulders, all with one accord threw themselves on the ground, face downward. Then Gregory, remembering that on the occasion of the death of St. Martin, some of whose bones were among the relics being carried from the cathedral, a globe of fire was said to have been observed to leave the saint's head and ascend heavenwards, believed himself to be in the presence of a miracle, vouchsafed as evidence at once of St. Martin's sanctity and the genuineness of his relics. This globe of fire did no damage and burnt nothing. _Discurrebat autem per totam cellulam_, TANQUAM FULGUR, _globus igneus_. There is to be seen at the Louvre a picture by Eustache Lesueur, entitled "La Messe de Saint Martin," which seemed to me at first to illustrate this narrative, but the spectators are shown in silent wonder instead of being prostrated as in the story. Moreover, Gregory of Tours tells us in his life of St. Martin, that one day during Mass a globe of fire was seen to appear above the head of the bishop, and then to rise heavenwards, to the great edification of the devout. It was this "miracle," evidently, that Lesueur intended to represent. Here is another case of a remarkably harmless fireball which is often cited. The Abbé Spallanzani it is who tells the story. On August 29, 1791, a young peasant woman was in a field during a storm, when suddenly there appeared at her feet a globe of fire of about the size of a billiard ball. Slipping along the ground, this little fireball reached her feet, caressed them, as it were, made its way up under her clothes, and issued again from the middle of her bodice, and, still keeping its globular form, darted off into the air and exploded noisily. When it got under her petticoats, they blew out like an umbrella, and she fell back. Two witnesses of the scene ran to her assistance, but she was unhurt. A medical examination revealed only a slight erosion of the skin, extending from the right knee to the middle of her breast; her chemise had been torn in two along the same line, and there was a hole through her bodice where the thunderbolt had got out. In the "Memoirs of Du Bellay" the following very curious narrative is to be found. In all probability it is a fireball that is in question:-- "On March 3, 1557, Diane of France, illegitimate daughter of Henri II., then the Dauphin, married François de Montmorency. On the night of their wedding, an oscillating flame came into their bedroom through the window, went from corner to corner, and finally to the nuptial bed, where it burnt Diane's hair and night attire. It did them no other harm, but their terror can be imagined." Perhaps it may be as well to take with a pinch of salt the statement that the lady's attire was burnt in this way without harm to her person, yet there are other authentic stories of a similar kind almost as curious. In 1897, at Linguy (Eure-et-Loire), a man and his wife were sleeping quietly, when suddenly a terrible crash made them jump out of bed. They thought their last hour had come. The chimney, broken to pieces, had fallen in and its wreckage filled the room, the gable-end was put out and the roof threatened to come down. The effects of the thunderbolt in the room itself were less alarming than its effects outside, but were very curious. For instance, bricks from one wall had been dashed horizontally against the wall opposite, with such extraordinary force that they were to be seen imbedded in it up above a dresser upon which pots and pans, etc., were ranged, and within a few inches of the ceiling, while the windows of the room had been smashed into bits, and a looking-glass, detached from the wall, stood on end whole and entire upon the floor, delicately balanced. A chair near the bed, upon which articles of clothing had been placed, had been spirited away to a spot near the door. A small lamp and a box of matches were to be found undamaged upon the floor. An old gun, suspended from a beam, was violently shaken and had lost its ramrod. The thunderbolt actually frolicked over the bed, leaving its occupants more dead than alive from terror but quite unhurt. It passed within a few inches of their heads and passed through a fissure in a partition into an adjoining dairy, where it carried a whole row of milk-cans, full of milk, from one side of the room to another, breaking the lids but not upsetting a single can. It broke four plates out of a pile of a dozen, leaving the remaining eight intact. It carried away the tap from a small barrel of wine, which emptied itself in consequence. It ended by passing out through the window without further breakage, leaving the husband and wife unscathed but panic-stricken. One of the strangest tricks to which lightning is addicted is that of undressing its victims. It displays much more skill and cleverness in such diversions than is to be found in animals or even in many human beings. Here is one of the most curious instances of this on record, as narrated by Morand:-- "A woman in man's costume. A storm suddenly comes on. A flash of lightning strikes her, carries off and destroys her clothes and boots. She is left stark naked, and she has to be wrapped up in a cloth and taken thus to the neighbouring village." In 1898, at Courcelles-les-Sens, Mlles. Philomène Escalbert, aged 19, Adèle Delauffre, aged 22, and Madame Léonie Legère, aged 44, were standing round a reaping-machine, when a flash of lightning struck Madame Legère and killed her on the spot. The two young girls were stripped to the skin, even their boots being torn from their feet. Otherwise they were left safe and sound--and astonished. On October 1, 1868, seven persons took refuge during a storm under a huge ash-tree near the village of Bonello, in the Commune of Perret (Côtes-du-Nord), when suddenly the tree was struck by lightning, and one of them--a woman--was killed. The six others were knocked to the ground without being seriously damaged. The clothes of the woman who had been killed were torn into shreds, many of which were found clinging to the branches of the tree. On May 11, 1869, a farmer at Ardillats was tilling the ground with his two oxen, not far from his dwelling-place, about four in the afternoon. The air was close and heavy, and the sky covered with black clouds. Suddenly there was a great thunderclap, and a flash of lightning struck both man and beasts dead on the spot. The man was found stripped to the skin, and his boots had been carried thirty yards away. In July, 1896, at Epervans (Saône-et-Loire), a young man named Petiot, who was mowing in a meadow, was struck dead by lightning while lighting a cigarette, and left in a state of complete nakedness. On August 11, 1855, a man was struck by lightning near Vallerois (Haute-Saône), and stripped naked. All that could be found afterwards of his clothes was a shirt-sleeve, a few other shreds, and some pieces of his hobnailed boots. Ten minutes after he was struck he regained consciousness, opened his eyes, complained of the cold, and inquired how he happened to be naked. There is no telling what lightning will not do. Sometimes it will snatch things out of your hand and carry them right away. There is a case of a mug being thus spirited away from a man, who had just been drinking out of it, and deposited undamaged in a courtyard near--the man himself suffering no injury. A youth of eighteen, holding up a missal from which he is singing, has it torn out of his hands and destroyed. A whip is whisked out of a rider's hand. Two ladies, quietly knitting, have their knitting-needles stolen. A girl was sitting at her sewing-machine, a pair of scissors in her hand; a flash of lightning, and her scissors are gone and she is sitting _on_ the sewing-machine. A farmer's labourer is carrying a pitchfork on his shoulder; the lightning seizes it, carries it off fifty yards or so, and twists its two prongs into corkscrews. On July 22, 1878, at Gien (Nievre), a woman while sprinkling her house with holy water during a storm, saw her holy-water bottle smashed actually in her fingers by the lightning, which at the same time smashed up the tiled pavement of the room. In a church at Dancé (Loire) during vespers, one day in June, 1866, a flash of lightning killed the priest and all the congregation, knocked over the monstrance on the altar, and buried the Host in a heap of _débris_. On June 28, 1885, the cupola of the Javisy Observatory, which was not then provided with a lightning conductor, was struck by lightning. An enormous piece of oak from _un angle de construction_ was torn to shreds, and one splinter was lodged in the hinge of a window behind the _pivot_, in the part between the _pivot_ and the frame, hardly a twenty-fifth of an inch apart, and this without breaking the glass. In other cases lightning has been known to split men in two, almost as with a huge axe. On January 20, 1868, this happened to a miller's assistant in a windmill at Groix. The lightning struck him, and split him from his head downwards in two. In the course of July, 1844, four inhabitants of Heiltz-le-Maurupt, near Vitry-le-Françoise, took refuge under trees during a storm, three of them under a poplar, and the fourth under a willow, against which doubtless he leaned. In a few minutes this one was struck by lightning. A bright flame was observed to be issuing from his clothes, but he remained standing, and seemed unconscious of what had happened. "You're on fire! You're on fire!" exclaimed his friends. Getting no reply, they went up to where he was, and found to their horror that he was a corpse. A clergyman named Butler was a witness of the following incident, which took place at Everdon. Ten harvest-men took refuge under a lodge on the approach of a storm. There was a thunderclap, and in a moment four of them were killed by lightning. One of them was found dead, still holding between finger and thumb a pinch of snuff he had been in the act of taking. A second had one hand upon the head of a small dog, also killed, and still sitting upon his knees, and in the other hand a piece of bread; a third was sitting, his eyes open, facing in the direction from which the storm came. At Castellane, in August, 1898, during a violent storm, a flock of sheep was struck by lightning while crossing the mountain of Peyresy. Seventy-five of them were killed. The shepherd escaped. The sheep probably were all wet from the rain, and clinging together in one great mass. In the same month a pond at Vauxdîmes (Côte-d'Or) was demolished, and all the fish in it killed. Quite recently, a young man at Franxault (Côte-d'Or) was killed by lightning on his way home from work. All the nails were found to have been torn out of his shoes, and the links of his silver watch-chain were all moulded together. To fuse silver in this way a heat of 957 degrees is needed! On July 5, 1883, at Buffon (Côte-d'Or), a woman had one of her earrings melted in the same way, but she was not killed. On the same day at Void (Meuse) two workmen, who had taken shelter under a willow, were thrown a distance of four yards without being killed. On August 10, of the same year, at Chanvres (Yonne), a vine-dresser was struck by lightning and killed, but his heart continued to beat for thirty hours. Dr. Gaultier de Claubry was struck by lightning, with the extraordinary result that his beard was taken off him, roots and all, so that it never grew again. At Fresneaux (Oise), a young girl of twenty, Mlle. Laure Leloup, had her head shorn by lightning. A wide furrow was to be traced on the crown of her head, caused by the electric fluid. Her hair was removed right down to the skin as though by a razor. On September 4, 1898, a flash of lightning lit up all the electric lamps in the Prefecture of Lyon. Really it is extraordinary the queer things lightning will do! Death in one case, an innocent practical joke in another! I have hundreds of quaint records before me. Impossible to deduce any kind of law from them all. You are tempted to believe that the electric current has a brain. A young woman was picking cherries off a rather tall cherry-tree. A young man stood underneath. The young woman was struck by lightning, and fell dead. This was in July, 1885. In September, 1898, at Remaines, near Ramerupt (Aube), a certain M. Finot, an innkeeper, was standing on his doorstep looking out at a storm, when a flash of lightning followed by a thunderclap sent him flying back into the hall. He remained unconscious for a time, and his sight was affected for ten hours. The extraordinary thing, however, in his case was that he had been a victim of rheumatism until then, and walked with difficulty and only with a stick, and that ever since this occurrence he has been able to do without the stick, and to pursue his avocations quite comfortably. He feels that he has no reason to regret his experience, though he is not anxious to go through anything of the kind again. This kind of electrical phenomenon might be catalogued under the title "Medicinal Lightning." Now for a case of "Judicial Lightning." On July 20, 1872, a negro named Norris was hanged in the State of Kentucky for having killed a mulatto, a fellow-workman of his. At the moment of his setting foot upon the scaffold, there was a terrible clap of thunder, and the condemned man was struck dead by lightning. The sheriff was so much moved by the occurrence that he resigned his office. Let us wind up this little collection of strange cases with another occurrence reported from the United States. An immense grange had been built by a man named Abner Millikan, an ardent republican, who adorned the front walls of his farm with portraits of MacKinley and Hobart. During a violent storm that broke out, the building was struck by lightning several times, and it looked as though it were enveloped in great sheets of flame. Millikan, who had been at some distance from the spot, rushed thither much alarmed, and found to his relief that no damage had been done. The portraits alone had been destroyed, and--here is the strange detail--the lightning had traced the politicians' features upon the wall. Certainly lightning plays queer pranks. And I have said nothing yet of the photographs lightning sometimes takes. _Pranks_ they seem to us, but we may be sure there is some method in their mischievousness. It is the same with women. Women in their caprices are but obeying some law of nature. They are not so capricious as they seem. These strange facts teach us, anyway, not for the first time, that our knowledge of the universe is still very incomplete, and that its study is worth following up in all its chapters. We may be certain that electricity exercises a much more important influence in nature than is generally supposed, and that it plays a _rôle_ in our own lives which is still practically unrecognized. In the oppression we feel before the coming of a storm, and the sense of relief we experience when it has passed, we have an instance of the way in which physical and moral influences are apt to blend or overlap. CHAPTER II ATMOSPHERIC ELECTRICITY AND STORM-CLOUDS With such strange facts before us--facts the strangeness and diversity of which baffle all hypotheses and forbid all definite conclusions--we can but keep adding to our observations and accumulating other facts which may tend to elucidate the mystery. The terrible ravages caused every year by lightning make it necessary for us to find some means of preventing the recurrence of certain memorable catastrophes. It is only in the actual investigation of the phenomenon, in the study of all its smallest manifestations, that we can hope to discover the methods of the mysterious power. From the earliest times mankind has devoted much thought to the subject. If we glance back towards past centuries we find that thunder and lightning have ever been regarded as a terrible agent of the will of the powers above. The strongest and subtlest brains of antiquity, Anaxagoras, Aristotle, Seneca, were unable to form any kind of reasonable view regarding the fantastic phenomena resulting from the force of nature and held so mysterious to us moderns. Thunder and lightning were generally believed by them to be due to emanations from the earth or to vapours contained in the air. The Etruscans, who flourished fifteen hundred years before Christ, and who were much given to the study of nature, are said to have observed the tendency of lightning to make for points, but no theory upon the subject has come down to us from them. Electricity for the ancients was an unplumbed ocean, whose slightest fluctuations affected them in ways they could not understand. In vain they appealed to their gods to help them to explain the enigma. Olympus turned a deaf ear to their prayers. Their imagination exhausted itself in researches into the nature of such things as amber, in which they recognized the curious attribute of attraction and repulsion for objects of slight weight. The poets attributed it to the tears of Phaëton's sisters, lamenting over the dreams of Eridan. Certain naturalists regarded it as a kind of gum issuing from trees during the dry days. No one gave any thought to electricity, by whose subtle fluid the earth and everything upon it is penetrated and enveloped. The superstitions connected with lightning would furnish forth material in themselves for a very curious volume of stories--half comic, half tragic. With the Romans the fall of a thunderbolt was always taken as an omen. In the reign of Domitian, thunder was to be heard once so constantly during a period of eight months that the tyrant, frightened by the bombardment from on high, at last cried out in his terror: "Let the blow come, then, where it will!" The stroke fell upon the capitol, and upon the temple of the Flavian family, as well as upon the emperor's palace and the very room in which he slept. The inscription beneath the triumphal statue was even torn away by the tempest and thrown into a neighbouring garden. Otto de Guérike, burgomaster of Magdeburg and inventor of the air-pump, was the first person to discover the means of producing the electric spark, about 1650. About the same time, Dr. Wall, while watching electricity being released from a roll of amber, noticed a spark and a sudden sharp report, suggestive of a minute flash of lightning, followed by a minute peal of thunder. The analogy was striking. This discovery opened out a new horizon to physicists, and almost immediately the feeble electric light produced by the hand of man came to be associated with the monstrous sheaves of fire let loose in space by unknown forces. L'Abbé Nollet, considered in the France of his time as an oracle in regard to natural philosophy, expressed himself as follows upon this subject:--"If some one, after comparing the phenomena, were to undertake to prove that thunder is in the hands of nature what electricity is in ours, that those electrical wonders with which we are now able to make so much play are petty imitations of those great lightning effects which frighten us; that both result from the same mechanism; and if he could make it evident that a cloud produced by the action of the winds, by heat, and by the mingling of exhalations, bears the same relation to a terrestrial object as an electrified body bears to an unelectrified body in its close proximity, I admit that the idea, if well worked out, would captivate me greatly; and, to work it out, how many plausible arguments there are at the disposal of a man who is properly versed in electricity!" The invention of the Leyden jar in 1746, and Franklin's brilliant investigations, make these conjectures the more probable. Since then electricity has gone ahead and become one of the most important branches of modern natural philosophy. When Franklin demonstrated that the air is in a permanent condition of electrification even when the sky is clear, people began to study not thunder alone but the general electrical state of the atmosphere. And ever since meteorological observatories have made it a practice to register every day the degree and nature of atmospheric electricity by the use of very ingenious instruments. But the records obtained up till now leave us in doubt upon many points. The subject is still full of new surprises. Whence come those masses of electricity which move about in the clouds, sometimes escaping from them in thunderclaps and causing such tremendous ravages upon this earth of ours? The evaporation of the sea is one of their principal causes. The atmosphere is continually impregnated with electric effluvia which flow silently through the soil through the medium of all bodies, organized or not, attached to the earth's surface. Plants afford an especially welcome pathway to this fluid. The green leaves you see rustling in the wind are often being traversed by electrical currents, luckily harmless, of precisely the same nature as those of the deadly lightning. On the other hand, the earth itself emits a certain quantity of electricity, and it is from the attraction exerted by these two fluids upon each other that thunder comes into existence. To put it in another way, thunder is a sudden striking of a balance between two different masses of electricity. Minute researches have established the fact that in ordinary conditions the terrestrial globe is charged with resinous, or negative electricity, while the atmosphere holds in suspension _vitrée_, or positive electricity. In two words, our planet and its aerial envelope are two great reservoirs of electricity, between which take place continual exchanges which play a _rôle_ in the life of plants and animals complementary to that which is played by warmth and moisture. The aurora borealis, which sometimes illumines, with a brilliancy as of fairyland, the darkness of night in the Arctic and all the regions of the North, finds its explanation in the same phenomenon. It also is a striking of a balance, silent but visible, between two opposing tensions of the atmosphere and the earth; thus the apparition of the aurora borealis in Sweden or Norway is accompanied by electric currents moving through the earth to a distance sufficiently great to cause the magnetic needle to record the occurrence in the Paris Observatory. Indeed, the electricity which pervades the earth, silently and invisibly, is identical with that which moves in the heights of the enveloping atmosphere, and, whether it be positive or negative, its essential unity remains the same, these qualities serving only to indicate a point, more or less in common, between the different charges. The heights of the atmosphere are more powerfully electrified than the surface of the globe, and the degree of electricity increases in the atmosphere with the distance from the earth. Atmospheric electricity undergoes, like warmth, and like atmospheric pressure, a double fluctuation, yearly and daily, as well as accidental fluctuations more considerable than the regular ones. The maximum comes between six and seven in the morning in summer, and between ten and twelve in winter; the minimum comes between five and six in the afternoon in summer, and about three in the afternoon in winter. There is a second maximum at sunset, followed by a diminution during the night until sunrise. This fluctuation is connected with that of the hygrometric condition of the air. In the annual fluctuation the maximum comes in January, and the minimum in July; it is due to the great atmospherical circulation; the winter is the time when the equatorial currents are most active in our hemisphere, and when the aurora borealis is to be seen most often. On the other hand, the water of oceans and rivers is continually evaporating under the influence of solar heat, and rises into the atmosphere, where it remains in the form of an invisible gaseous vapour. Soon it becomes cold again, and, in the process of condensation, transparent gaseous molecules become transformed into minute drops, which accumulate into a cloud. Generally speaking, clouds are, like the atmosphere, charged with positive electricity. Sometimes, however, there are negative clouds. You may frequently see, on the summits of mountains, clouds which seem to cling to the peaks for a while, as though drawn to them by some force of attraction, and then move away to follow the general direction of the winds. It often happens that in this case the clouds have lost their positive electricity in thus coming in contact with the mountains, and have derived from them in its place the negative electricity which, instead of holding them, has a tendency to drive them off. A mass of clouds lying between the negative earth and a mass of positive clouds above is almost neutral; the positive electricity accumulates towards its lower surface, and the first drops of rain will make it disappear. This mass will, from that moment, become like the surface of the soil--that is to say, it will become negative under the influence of the mass above it, endowed with a strong positive tendency. The cloud remains suspended in space until the moment when, under the influence of the ambient medium, it dissolves in rain. The causes of the instability of clouds are very numerous. My readers are aware that the atmosphere is being constantly agitated by vast currents which pass from the equator to the poles, and from which the different winds result. The clouds take part in this universal whirl of atmospheric waves. Transported from one point to another--often far beyond the region where they came into existence--subjected to every vicissitude of atmosphere, and blown about by contrary currents, they follow the gigantic movements which take the form sometimes of cyclones and tempests. Under the influence of warmth, and probably also by its transformation, these movements engender great masses of electricity, and presently, when the clouds have become saturated with it, the electricity breaks out, and there is a thunderstorm. The electric fluid, escaped from the cloud in which it has been imprisoned, flies to unite itself, either with the negative electricity stored in the surface of the earth, or else with the electricity in other neighbouring clouds. Almost always the cloud torn open by the electric discharge dissolves in rain or hail. Thus a storm is the outcome of violent movements produced by the force of electricity when this has reached its maximum of intensity. Thunderstorms are generally heralded by certain premonitory signs. The barometer goes down steadily. The air, calm and heavy, is pervaded by a bitter sulphurous odour. The heat is stifling. An abnormal silence reigns over the land. All this has a remarkable effect upon certain organisms, and produces nervous complaints, a buzzing in the ears, a sense of painful oppression, a sort of good-for-nothingness that we combat in vain. In most cases storms come to us in France ready made, so to speak, from the sea, borne in by the currents from the south-west; they are the off-shoots of the cyclones, and are born in the tropics, moving in lines from the south-west to the north-east. Ordinarily they lose part of their strength _en route_ and come to an end suddenly with us. There are, of course, home-made storms also, so to speak, especially in France during our hot summers, when the sun is shining all the day, and thus promoting the rapid evaporation of our seas and rivers. The air is charged with a heavy mist which veils the horizon; the barometer is going down, the thermometer going up. The sun looks leaden though there are no clouds. When it approaches the meridian and its rays are most scorching, columns of vapour ascend and become condensed into the light clouds termed _cirri_. At the end of some hours these clouds become attracted to each other, descend a little, and become grouped together into what look like great masses of cotton-wool. These are termed _cumuli_. Presently a small grey cloud joins the others. It looks innocent and harmless, but very often this is the beginning of the battle. First there ensues, perhaps, a discharge or two of lightning without casualties, but soon the bombardment becomes general, and long blinding fusillades flash through space. The heavens, darkened over, seem to have sunk quite low, and to have become a great black mass, from which the lightning escapes in sudden jets. Rain and hail pelt down upon the earth to an accompaniment of the rumbling of thunder. Confusion has fallen upon the entire universe. Then, finally, the fight comes to a close. The clouds disperse and allow us to see once again a wide expanse of sunlit blue. The birds, their hearts freed again from terror, begin to sing again. Flowers and foliage and soil, refreshed by the rain, give out sweet perfumes. An immense joy takes the place of the sense of melancholy and oppression. It is good to see the sun again! Alas, though, there are grim realities to be faced presently. The hailstones have destroyed the crops and begotten famine--the lightning has sown death and plunged whole families into mourning. It is with these misfortunes before us that we make up our minds to do what in us lies to diminish the destructiveness of this terrible force. How are storm-clouds to be detected? Generally speaking, their shape is very clearly defined, and they have a look of solidity about them. Their lower surface is often unbroken, presenting a level plain from which there rise huge ragged protuberances like great plumes. Sometimes, on the other hand, they have great projections underneath, trailing quite near the ground. Storm-clouds move generally in large numbers, and are generally composed of two separate masses, differently electrified--the lower one giving out negative electricity, the higher positive electricity. The flashes of lightning occur generally between these two masses, though also, less frequently, between the lower mass and the earth. It may be said that, generally speaking, storms are the result of the meeting of two masses of clouds differently electrified. For long, physicists refused to admit the validity of any other theory, and combated in particular the idea that lightning could issue from a single isolated cloud. This has, however, been established now as a fact, and in such cases the flashes have always, of course, taken place between the cloud and the earth. Marcorelle, of Toulouse, reports that on September 12, 1747, the sky being then pure and cloudless but for one round speck, there was suddenly a thunderclap and a flash which killed a woman on the spot, burning her breast but doing no damage to her clothes. Here is another interesting case. Two priests of the Cathedral of Lombey, who were standing in the area of their chapter-house, busy winnowing, saw a small cloud approaching them little by little. When it was immediately above them a flash of lightning broke out and struck a tree just beside them, splitting it from top to bottom. They heard no thunderclap. The weather was quite fine. There was no wind, and this was the only cloud in the sky. Storms are far more prevalent in some countries than in others. According to Pliny, thunder was unknown in Egypt, and, according to Plutarch, in Abyssinia. This could not be said now, however, perhaps because these lands have grown unworthy of their exemption. It might be said, however, of Peru, whose pure and limpid skies are never troubled by tempest. _Jupiter tonans_ must be a myth indeed to a people who know nothing of thunderclaps or wet days. Storms diminish in number in high latitudes, but there are local conditions which affect their distribution. Then they are particularly frequent in countries that are thickly wooded and in mountainous districts. Arago came to the conclusion, after a considerable number of observations, that, out in the open sea or among islands, there is no thunder in the north beyond the 75th degree of latitude. This is not absolutely so, but it is a fact that storms are very much rarer in the polar regions. They become more and more frequent towards the equator, and are very numerous in the tropics. On either side of the equator storms come year after year with remarkable regularity in the wet season, and at the time of the monsoons. At Guadeloupe and Martinique there is never any thunder in December, January, February, or March. In temperate climates there are scarcely any storms in winter; they begin in the spring, and attain their maximum of intensity in the heat of summer. In Italy there are thunderstorms at almost all times of the year. In Greece they come chiefly in spring and autumn. It is noticeable that in all latitudes they come most often in the afternoon. CHAPTER III THE FLASH AND THE SOUND The Romans attributed a mysterious influence to each manifestation of electricity. They divided lightning into individual and family lightning, lightning of advice, monitory, explanatory, expostulatory, confirmatory, auxiliary, disagreeable, perfidious, pestiferous, menacing, murderous, etc., etc. They adapted it to every taste and circumstance, but modern science has come to put order into this Capharnaum. When a cloud is superabundantly charged with electricity, this electricity, which is compressed in the cloudy envelope, tries to escape in order to join the electricity accumulated either in another cloud or on the ground. An electric deflagration ensues, and a long ignited dart precipitates itself into space, showing us on a large scale what our experience of physics has taught us in a small way in our laboratories. This luminous and often dazzling trail constitutes lightning. Lightning is not always the same, and in order to classify the different forms it takes more easily, it can be divided into three groups--diffused lightning, linear lightning, and fireballs. This last is the most curious of the three. The variety and eccentricity of fireballs are celebrated in the history of lightning, and I propose to devote the following chapter to their vagaries. Diffused lightning is the commonest of all. You can count hundreds of flashes on a stormy night. Occasionally they succeed one another with such rapidity that the sky is momentarily entirely illumined with a fantastic brightness. At these times great sombre clouds can be seen surging from the darkness of the night, to shine suddenly with an ephemeral brightness of a diffused red, blue, or violet tinge. Their irregular shapes, with their jagged edges of light, are visible against the dark background of the heavens, and the thunder growls monotonously. Whether the exchange of electricity is produced on a vast stretch between two rows of clouds, or whether it is manifested by a long thin spark launched like an arrow and veiled by the curtain of clouds, all that can be seen is a strange light, vague, diaphanous, instantaneous, which sometimes spreads itself like a sheet of fire all over the horizon. It is diffused lightning which gives us the finest storm effects on those heavy summer evenings when the air is breathless and saturated with electricity. Suddenly the clouds are illumined, nebulous veils of light on which can be seen, in sombre fantastic, fugitive vision, the outlines of the trees, houses, and other landmarks. Then, all at once, heaven and earth fall back into a darkness deeper than before, owing to the contrast. Linear lightning is more terrible. It is regarded by astronomers as the most perfect form of destructive lightning. It is a strong flash--a thin trail of light--very clear, and extraordinarily rapid, which shoots from an electric cloud to the earth, or from one cloud to another. Like a supple and undulating serpent of fire, it twists itself luminously into space, spreading itself menacingly in the heavens with its long spirals of light. Sometimes--in a hurry, no doubt, to reach its prey--it effects its passage in a straight line, but as a rule it follows a sinuous track, and forms itself into a zigzag at an obtuse angle. The different forms which this lightning takes are no doubt attributable to various causes. One of the chief of these seems to be the unequal distribution of humidity in the air, which renders it a more or less good conductor. In fact, fulminic matter is strongly attracted towards damp regions, and goes quickly from one point to another, guided in its chosen way by the hygrometrical conditions of the atmosphere; and it is these constant changes of direction which determine the meanderings of its course. Thus the lightning would trace a sort of plan of the hygrometrical state of the air for a certain portion of the atmosphere. For it, the short road is hardly ever the straight line. On the other hand, the variability of the overloading of electricity has something to say to the form it takes. Sometimes lightning forms itself into two or three branches, and becomes forked lightning. Or it even divides itself into a number of points from a principal branch, out of which a great many sparks burst forth. These incandescent sheaves move
{'title': 'Thunder and Lightning by Camille Flammarion', 'source': 'Project Gutenberg', 'lang': 'en'}