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 through space with extraordinary agility. It has not been possible to measure their speed with absolute accuracy, but their rapidity is such that their transit appears to be instantaneous. The latest researches seem to have proved that their speed is superior to that of light, which is 300,000 kilometres a second.

Lightning is not always of a dazzling whiteness, it is often yellow, red, blue, violet, or green. Its colour depends on the quantity of the electricity thrown on the atmosphere by the discharge; on the density of the air at the time of the passage of the ignited matter; on its hygrometrical state, and on the substances which it contains during suspension. It has been remarked in the study of physics that the electric spark is white in the open air, but that it gets a violet tinge in the vacuum of a pneumatic machine.

This proves that violet lightning comes from the far-off regions of the atmosphere. It traverses a bed of rarified air, and shows the great height of the storm-clouds from which it emanates.

The fulminating spark is so fugitive that it is difficult to form an idea of its length. One could easily take it to be a yard or so long, so illusory and deceptive are our impressions. As a matter of fact, it is proved that flashes of lightning cover a distance of several kilometres.

There are various methods to which one can have recourse in these scientific researches. The first, which gives the length of horizontal lightning, is based on a minute comparison between the trajectory described by the meteor and the known distance of the terrestrial points between which it travels. In order to gauge the extent of vertical lightning, you must estimate approximately the height of the clouds from which it comes, based on the irregularities of the earth of which the height is known.

But there is a still simpler method for approximate measurement within the reach of every one. It consists in multiplying 337 (the number of yards traversed by sound in a second) by the number of seconds during which the thunder lasts.

These methods all give the same result, and prove that lightning is often 1, 5, and 10 kilometres in length. The greatest length proved up to the present has been 18 kilometres. When one thinks of the instantaneousness of these flashes, one marvels at their incomparable agility, and we can only be lost in admiration of the magic force of the heavenly sling, which is capable of hurling these whole rivers of fire to roll in their sinuous course right through space, and in a space of time almost inappreciable to our senses.

Yet, in spite of the extreme rapidity of the lightning, it has been possible to determine that these meteors do not last the thousandth part of a second. To prove this, we take a circle of cardboard, divided from the middle into black and white sections. This circle can be turned like a wheel almost as quickly as one can wish. We know that luminous impressions remain on the retina the tenth part of a second; thus, if we imitate the childish game of turning a lighted coal—if the turn is made in the tenth of a second, each successive position of the coal remaining impressed on the retina for the same length of time—we have a continuous circle. In turning our cardboard wheel with the black and white spokes, if each spoke passes before our eyes in less than the tenth of a second, we can no longer distinguish between the sections, but can only see a grey circle. But we can make it rotate a hundred turns or more in a second; this being done, if we continue to observe the circle, we can no longer see the lines, they succeed each other more quickly in our eyes than the impression they produce. But if the circle turns before us in the darkness, and it is suddenly lighted up and as suddenly darkened, the impression produced on our eyes by each of the sections would last less than the tenth of a second, and the circle would appear to us as if it were stationary. In applying a calculated rotation to this contrivance, Charles Wheatstone has proved that some lightning does not last the thousandth part of a second. This measure is probably a minimum; in the majority of cases the duration of lightning is longer than this.

Often during the hot, transparent summer nights, we see a considerable number of flashes, which furrow the firmament with their gentle, bluish light. These fugitive gleams remind us in the sky of the will-o'-the-wisps, which come forth silently from marshy ground. The atmosphere is pure; there are no apparent traces of a storm, and yet the sky is glistening with thousands of small flames. The flashes succeed one another almost without interruption. These electric sparks are known as heat-lightning, but this is quite inaccurate, and has no meaning in the language of modern science.

In a great number of cases an astronomer would be able to discover certain characteristic signs indicating that a storm is taking place under the horizon at a very great distance from the point of observation. It is only at the moment when the sky is lighted up that one can see the ridge of clouds lying low on the horizon. At other times there is no sign of a storm, as far as the eye can see. The atmosphere is quite clear, and yet the sky is swept with a number of electric flashes. But afterwards you hear that a violent storm has devastated the region over which the gleams have appeared, and that it is to this that they are attributable. They are only reflected lights.

A sailor tells us that once when he was out at sea, more than 100 kilometres from Lima, he saw a number of bright flashes, without any thunder, to the east and north-east of the horizon. The weather was perfect, and the sky absolutely serene. Now we know that storms, and the electric phenomena which they produce, are unknown upon that coast; but this immunity does not extend for more than 100 kilometres to the interior of this country, so that this lightning which was observed at sea, 100 kilometres from the shore, must have taken place more than 200 kilometres away.

One of our correspondents, M. Soleyre of Constantine, sent us word, in 1899, of an interesting case of lightning without thunder.

"In August," he says, "I noticed it in the valley of the Arve above Salambes; when I came back to Algiers I saw it again on September 16, and on October 19.

"It was not sheet lightning, but ordinary lightning concentrated in very thin lines. This lasted long, and was very near. Another thing, there was no hail. This is not very rare in Algiers."

On September 1, 1901, I happened to be in Geneva at about 6 p.m. The weather was heavy but very fine. I noticed a good deal of lightning on the south-west of the horizon. It went on almost without interruption above the Savoy Alps. Each flash illuminated at the same time the ridge of the mountains and the fringed edge of the great sombre clouds lying low on the horizon. This lightning was silent; the noise of the thunder did not reach Geneva. The next day I learnt that a terrible storm had devastated the neighbourhood of ChambÉry and Aix-les-Bains.

Moreover, apart from storms, there have been other records of this lighting up of the sky being observed at great distances.

Thus, in 1803, a service of luminous communications was established on Mount Brocken in the Hartz Mountains in order to determine the differences of longitude. The combustion of 180 to 200 grammes of powder, burnt in the open air, for each of the signals, produced a light which was observed by astronomers stationed on Mount Kenlenberg, although they were 240 kilometres from Brocken, which is itself invisible from Kenlenberg.

On certain fÊte-days, July 14, for example, when the principal monuments in Paris are illuminated, at a distance of 20 and 30 kilometres we can see a sort of luminous vapour which floats above the town and reflects the lights of the boulevards, although the lights themselves are invisible from the point of observation.

Here is another example which any Parisian can verify: the captive balloon of the AËrodrome at Porte-Maillot, which soars some hundreds of yards above Paris during the spring and summer, as seen from the dark paths of the Bois de Boulogne, appears against the azure of the sky like a magnificent globe bathed in light, resembling an enormous moon. Well, this gentle, pale light is only the reflection of the lights of Paris which are invisible from the Bois de Boulogne.

The earth and all the planets which are dark in themselves, shine in space lighted up by the sun.

The silent lightning which flashes in the sky is only the reflection of a distant storm. Whether on account of the spherical shape of the earth or on account of the irregularities of the land, the clouds are invisible, but the effluvium which escapes from them can be seen at a great distance.

These poetic and ephemeral flames which glide through the sky, appeal to the imagination of the dreamer, and yet they are quite as terrible as the flashes which are accompanied by thunder. If the noise which accompanies these is not perceptible, it is because the sound of the thunder does not carry far, and has been lost in space before reaching us.

It is the same with the silent lightning which gleams in a stormy sky. This phenomenon is particularly frequent in the Antilles. Either the storm breaks too far from the observer, or the discharge has taken place between two beds of clouds, the lower of which intercepts the waves of sound without preventing the escape of the electric spark, and the thunder is not heard.

As a rule we imagine that lightning always descends, that it comes to us from the higher celestial regions to be lost in the common reservoir. But this is quite inaccurate. Lightning sometimes ascends. Sometimes it descends and reascends. That is to say, after it reaches the ground, either there is no attraction there, or a stronger force draws it back to the aerial regions, and it flies back to the clouds whence it came.

As a rule we only fear the direct lightning. This is a great mistake. There are many cases of lightning striking from a distance.

For example, at the end of May, 1866, an English coastguard was making his rounds on the coast of one of the Shetland Isles, when a flash of lightning passed near him, striking a great rock. The unfortunate man was completely blinded, and plunged into darkness thus suddenly, he would inevitably have fallen down an abyss, if his companions, attracted by his cries, had not come to the rescue and taken him home.

Here is another case:—

On September 24, 1826, a terrible storm burst over Versailles, accompanied by a great deal of thunder and lightning. At the moment when the lightning struck Galli's farm, an old man who was in a street in Versailles, at a distance of two kilometres from the farm, suddenly felt a violent shock, accompanied by a feeling of oppression and giddiness and a semi-paralysis of the tongue and the whole of his left side. Next morning this had passed away, but in the evening at the same time as the shock had occurred, he felt similar sensations of fainting, and it was the same to the end of the week. It would be well to remark here that at the moment of the accident, M. B—— happened to be near the wall of a house, not far from the metallic tube which conducted the rain-water into the level of the pavement.

The following phenomenon, to which we have already alluded, is no less curious:—

On July 22, 1868, at about 7 o'clock in the evening, at Gien-sur-Cure (NiÈvre), the thunder had been growling violently for some time, when all of a sudden the lightning struck a thatched house, which it set on fire. At the same time a woman who was in a house ten yards away, felt a shock, and saw the tiled floor rise beneath her. Her two sabots were broken on her feet, and a bottle of Holy Water with which she was blessing the house was broken in her hand, only the neck remained in her fingers. She herself suffered nothing but the shock. Nineteen of the tiles were flung in all directions.

Here is another very remarkable case of ascending lightning, published in the Comptes Rendus of the Academie des Sciences:—

At Porto-Alegre, on June 9, 1870, at 2 a.m., during a violent storm, on the property of M. Laranja e Oliveira, at Brazil, a servant was entering the house; he was about ten yards away, when a flash of lightning illuminated it; at the same moment he felt a great tingling in the flesh of his feet, then in his legs, then all over his body, and finally in his head, on which the hair stood on end to such an extent that he was obliged to hold his hat on in order to prevent its falling off. At the same time, a white flame burst from the ground about two yards in front of him, accompanied by a shower of sparks. Terrified by such a phenomenon, which he attributed to souls from another world, he thought he was petrified to the spot; finally, he ran away. Anything metallic which he had about him at the time of this occurrence became magnetized. A key which was in his pocket remained magnetic for two days.

Thus, as well as the ordinary fulguration, in which the lightning (which we imagine descends from the clouds) acts directly on the body, and the lightning which strikes indirectly, there are other electric shocks which can be experienced by men and animals. Notable among these is the striking from the earth, commonly known as choc de retour, and which is in reality only an instance of the ascending current, or of lightning striking from a distance. We must also describe the striking by a man who has been struck.

The AbbÉ Richard, in his Histoire de l'Air, tells the following story:—

In the neighbourhood of the village of Rumigny, in Picardy, on August 20, 1769, at six o'clock in the morning, there was a sudden irruption of fulminating matter from the bosom of the earth in such quantities as to produce the most violent results. The sky was cloudy, and looked like a storm. A young farmer and his wife were following, at some distance, a vehicle drawn by four horses. Suddenly the driver of this, without seeing the lightning or hearing the thunder, was thrown to the earth. His four horses were stretched dead on the ground near the carriage. There was a smoking hole in the ground, from which the effluvium came forth and killed the young man and his wife at ten paces off and separated from each other by twenty paces. The current also knocked down, at a hundred paces, the father of the young man in the same fashion as it had done the driver, but without injuring one or the other.

The bodies showed no signs of a wound, only a considerable swelling and a great deformity of the features. The woman, who was young and pretty, became hideous; the whole of her body as well as that of her husband was absolutely yellow. The four horses had their intestines drawn from their bodies. They were all thrown on the same side. The man's hat was pierced and his hair burnt, but he had no bruise on his head.

This account, in which we must not be surprised to find the ideas and language of the time (let us observe in passing that the man who was struck did not hear the thunder, and had not even time to see the lightning of which he was the victim)—this account, I say, gives us an instance of ascending lightning. Here is another.

The traveller Brydone gives the following example, which he himself observed:—

On July 19, 1785, a storm burst near Coldstream between 12 and 1 a.m. A woman who was cutting hay on the banks of the Tweed fell backwards. She at once called to her companions, and said she had just received a violent blow on her foot for which she could in no way account. At the time there was no thunder or lightning in the sky. The shepherd of a farm at Lennel Hill saw a sheep fall near him, which a few minutes before appeared to be in perfect health; he found it stone dead. The storm then appeared very far off. Two carts laden with coal, and each driven by a young driver seated on a small seat in front, crossed over the Tweed. They had just climbed a small hill near the banks of this river when they heard a great detonation round about, similar to that which would be produced by the discharge of several guns. At the same instant the driver of the second cart saw the first, with his companion and the two horses, fall to the ground. The driver and horses were stone dead. The ground was pierced with three circular holes at the very spot where the wheels had touched it when the accident happened. Half an hour after this event the holes emitted an odour which Brydone compared to that of ether. The two circular iron bands which covered the felloes of the wheels showed evident signs of fusion in the two spots which rested on the ground at the moment of the detonation, and in no other place. The skin of the horses had been burnt, particularly about the legs and under the stomach. The body of the driver had marks of burning here and there. His clothes, his shirt, and, above all, his hat, were reduced to shreds, and gave out a strong smell.

Orioli gives an example of two men who were surprised by a violent storm near the village of Benvenide. They lay down on the ground to let the meteor pass. Some moments later one of them got up feeling very tired, but the other was dead. The bones of the latter were so soft that it was easy to bend them; his whole body was of the consistency of paste. The tongue had been torn from the roots, and no one knew what had become of it.

Now, just as the earth can strike, so can the human body become fulminating and act like lightning. After having been struck, it can effectively acquire the power to strike in its turn.

For instance, on June 30, 1854, a man named Barri was killed by lightning near the Jardin des Plantes, in Paris, and his body lay for some time exposed to a beating rain. After the storm had passed, two soldiers from the neighbouring guard-house tried to remove the body, and each received a violent blow when they touched it. They got off with a shock, perhaps because the body had been drenched with rain, which acted as a conductor to the electricity, and thus it had had time to lose a part of the fluid.

What a mysterious world is that of atmospheric electricity! It is truly the New World for the scientific mind—a mine, fruitful in unknown and even unsuspected marvels, which is perpetually disclosing its riches for our admiration.

One of our most valued collaborators in our researches on the nature of lightning is photography. Faithfully and unhesitatingly it registers an indestructible document of the fugitive lightning, which imprints itself on the sensitized plate, and the astronomer can afterwards examine the smallest details of the sudden apparition comfortably and at his leisure. We have already a considerable number of plates of the outline of the lightning in flight. An examination of these electric pictures is very interesting.

Who knows whether, later on, when phonography is brought to perfection, it will not also register the noisy accompaniment to the electric flash? Then, with the help of the cinematograph, we could have dramatic representations of sensational storms. While the photograph unrolls all the phases of the lightning, from its emerging from the cloud to its fall to earth, before the gaze of the spectators, the phonograph will repeat the sonorous accents of the terrorizing voice of thunder.

Thunder, as all the world knows, is the noise which accompanies lightning. It is produced when a change of electricity—a neutralization—takes place between two points more or less distant. The causes which provoke it are still somewhat of a mystery.

The luminous rocket which flings itself precipitately from a cloud saturated with electricity, spreads itself like a trail of flames in the atmosphere where an infinity of invisible molecules are floating; these it repels. The passage of this whirlwind of fire in a centre which is greatly compressed produces a momentary void into which the surrounding air at once rushes, and it is the same all the way along the route followed by lightning.

In all probability the equilibrium of the atmosphere, which is momentarily disturbed by the intrusion of the ignited matter, hastily re-establishes itself by a rush of the air which the lightning has ejected, and which is swallowed up with a crash in the opening which has been made. It is, on a large scale, a similar phenomenon to that which is produced by opening a case which has been hermetically sealed. The air rushing in makes a dull noise.

Pouillet objects to this very natural explanation on the ground that the flight of a cannon-ball ought to produce a similar noise. But this objection errs in its basis, because, as regards velocity, a cannon-ball is as a tortoise as compared with the arrow of lightning, and as regards size, who can compare a few grammes of powder to the torrents of fire launched into space by the prodigious force of electricity?

The lightning discharge produces a violent concussion in the cloud, and very often a shower of rain immediately follows it. The electric conditions of the different clouds which make a storm being separately liable the one to the other, the discharge of one must lead to that of several others more or less distant. In all cases the noise is caused by the expansion of the air where a more or less partial void has been made. It is the same with firearms, crÈve-vessie, etc.

One of the chief characteristics of thunder is the rolling, which is often prolonged, and reverberates on the sides of steep mountains. This voice, with its lugubrious tone, becomes grave and sometimes sinister in the revolution of space—this voice, celestial and infernal, seems to momentarily dominate the world, while the clouds are enveloped with a thousand diabolical flames. Sometimes it rings in the air with fierce calls, at others it spreads itself in dull, languorous complaints.

Nevertheless, the intenseness of thunder undergoes a thousand fluctuations, and presents astonishing variations. Generally it strikes and frightens, but the curious thing is that, for the ear, in reality it is less strong than the crinkling noise of a piece of paper torn close to it.

Often, too, it may be compared to the discharge of firearms, a pistol or a cannon.

Thus, when the lightning penetrated Volney's apartments at Naples, the people present, among whom was Saussure, had the impression of a pistol-shot in the next room.

There is a case given of M. and Mme. Boddington, who were seated on the back seat of their coach in order to enjoy the view of the country, and had given the inside seats to two servants. Suddenly there was a flash of lightning, which struck M. and Mme. Boddington and flung the postillion to a great distance. The servants were untouched, and escaped with a fright. When they got over their terror, one of them said that a very brilliant flash of lightning had been immediately followed by a noise similar to that of a heavily charged musket. He thought some one had shot the horses. His fright had stunned him so that he hardly knew what had happened.

At other times thunder is accompanied by a whistling noise, but as a rule it is the rolling which predominates.

We ask ourselves to what it is due that this rolling lasts so long. There are several causes. The first is due to the length of lightning and the difference in speed between sound and light. Let us suppose, for example, a flash of lightning, AE, 11,000 metres long. The observer stationed at O, underneath extremity E of the lightning (which is one kilometre high), will see the lightning in its full length in one indivisible instant. The sound will form itself also at the same instant all along the line of lightning, but the sound-waves will only reach the ear of the observer at different times. That which starts at point E, the nearest, will arrive in 3 seconds, sound travelling about 337 metres a second. That which is formed at the same moment at point D, 2000 yards from point O, will take double the time to arrive. That which comes from point C will not arrive for 12 seconds. The sound formed at B will not arrive until the time necessary to cover 8 kilometres—that is to say, not for 23 seconds—and the sound formed at A will only reach after 32 seconds. Thus the rolling will have lasted more than half a minute from start to finish.

And if, which is very often the case, the astronomer is not exactly under one of the extremities of the lightning, but at some other point in its course, he first hears a clap, then an increased noise, then a diminution. In fact, in this case, the sound which leaves point D just overhead, which is 1000 metres off, arrives alone in 3 seconds, but the sounds formed from D to E on one side, and from C to D on the other, arrive at the same time, having joined each other, taking 9 seconds, which is the necessary time to come from 1000 to 3000 metres. The sounds beyond C arrive and depart according to distance, as in the preceding example, and the thunder has lasted 23 seconds instead of 32 seconds.

I must add that lightning is never straight, but always crooked.

The length of time the thunder rolls has nothing to do with the distance of the cloud where the phenomenon begins. It is proportionate to the length of the lightning with which it is associated. The rolling is often still more prolonged by a succession of small discharges, which follow each other very rapidly between the stormy clouds; by the zigzags and ramifications of the lightning caused by the hygrometrical diversity of the different beds of air; by the echoes repeated by the mountains, the earth, the water, and the clouds themselves—to all which must be added also the interferences caused by the encounter of the different systems of sound-waves.

Its duration is extremely variable, however; it rarely exceeds 30 seconds, though the noise may sometimes seem to last much longer, so that an observation of this kind may have any value—one must take into consideration the echo, and isolate a single clap from the series of discharges which take place in the bosom of the storm. The longest verified duration of a single discharge is 45 seconds. That is tremendous if we think of the instantaneousness of the lightning, and reflect that the flash and the sound are produced in reality at the same moment, that they are dependent the one on the other, and that in their various manifestations there is only the difference of motion.

Sound moves like a tortoise behind the swift lightning, whose vibrations spread in the air with inconceivable rapidity.

Hence these 45 seconds correspond to a flash of lightning more than 15 kilometres in length, but we know that there are even longer ones.

I have already said that we can calculate the distance of the celestial cannon from which the fulminating discharge comes by counting the number of seconds which separate the apparition of the lightning from the first growls of the thunder. Thus the longest interval that has been proved between the appearance of the lightning and the noise it produces is 24 kilometres. This, however, is a maximum.

Numerous observations have proved that thunder is never heard beyond 20 or perhaps 25 kilometres. Lightning pierces the cloudy veil, but the voice of thunder does not carry so far. In this the great Jupiter shows himself inferior to the ingenuity of human pigmies, whose destructive and barbarous art has been able to invent infernal machines the noise of which can be heard much further.

Cannon can easily be heard at a distance of 40 kilometres. Sometimes, in sieges and big battles the cannonades can be heard muttering lugubriously more than 100 kilometres away.

During the siege of Paris, Krupp's cannon—that most expeditious of all vehicles of civilization in the eyes of the statesmen of this planet!—could be heard as far as Dieppe, 140 kilometres away, during the nights when they were bombarding. The cannonade of March 30, 1814, which crowned the First Empire, as it crowned the Second, was heard between Lisieux and Caen, a distance of 175 kilometres. Arago even alleges that the cannon at Waterloo could be heard as far as Creil, which is 200 kilometres away. Thus man's thunder can be heard at a greater distance than that of nature. It is true that it is incomparably more vicious, and that it has a great many more victims.

In its natural state, if we might explain it thus—left to itself—it comes directly to us from the high regions of the atmosphere, and is the most terrible of aerial messengers—a subtle messenger, malicious and violent, it is the terror of the human race. But ruled by the genius of man, it becomes a powerful agent towards modern civilization, and we cannot sufficiently admire its many advantages.

If we could tame lightning and guide it safely, its services would probably become innumerable. Lightning as man's right hand! Why not? Was it not the auxiliary of the gods in the dark ages? To-day, is it not regarded by astronomers as one of the most important forces of nature? Why should it not be the collaborator of man's intelligence to-morrow?