On Sunday, August 19, 1900, several people were a.s.sembled in a room in the chateau of the Baron de France at Maintenay (Pas-de-Calais), when there was a violent storm raging over the country.

Suddenly there appeared in the midst of the eleven people who were there, a globe of blue fire about the size of an infant"s head, which quietly crossed the room, touching four people on its way. None of them were injured. An awful explosion was heard at the moment when the electric ball disappeared through an open door in front of the great staircase.

On August 3, 1809, a fireball struck the house of a Mr. David Sutton, not far from Newcastle-on-Tyne. Eight people were having tea in the drawing-room when a violent clap of thunder knocked down the chimney.

Immediately after they saw on the ground, at the door opposite the fireplace, the brilliant visitor which announced itself in the sonorous voice of Jupiter the thunderer. It remained discreetly at the entrance of the room, no doubt waiting for the sign to advance. No one making a move, it came into the middle of the room, and there burst with a crash, throwing out fiery grains like aeroliths.

The spectacle must have been magnificent--but, we must acknowledge, rather disquieting.

On September 27, 1772, at Besancon, a voluminous fireball crossed over a corn-shop and the ward of a hospital full of nurses and children.

This time again the lightning was merciful--it spared nurses and children, and went and drowned itself in the Doubs.

Nearly thirty years before, in July, 1744, it showed the same regard for an honest German peasant woman. She was occupied in the kitchen superintending the family meal, when, after a terrible clap of thunder, she saw a fireball the size of a fist come down the chimney, pa.s.s between her feet without hurting her, and continue on its course without burning or even upsetting the spinning-wheel and other objects on the floor.

Much frightened, the young woman tried to escape; she threw herself towards the door and opened it, when the fireball at once followed her, played about her feet, went into the next room, which opened out-of-doors, crossed it, and through the door into the yard.

It went round the yard, entered a barn by an open door, climbed the wall opposite, and reaching the edge of the roof, burst with such a terrific noise that the peasant woman fainted. The barn at once took fire and was reduced to cinders.

Towards the middle of the last century, March 3, 1835, the steeple of Crailsheim was set on fire by lightning. The guardian"s daughter, aged twenty years, was at this moment in her room and had her back turned to the window, when her young brother saw a fireball enter by the window-sill and descend on to his sister"s back, giving her a sudden shock all over her body. The young girl then saw at her feet a quant.i.ty of small flames, which went towards the kitchen, the door of which had been opened, and set fire to a pile of mossy wood. There was no further damage than this attempt at incendiarism, which was easily extinguished.

Occasionally a fireball seems to take a malignant pleasure in hurling itself like a fury against lightning conductors; but instead of quietly impaling itself like the linear lightning, and breathing its last sigh in a prolonged roar, it struggles, and comes forth victorious from this curious contest.

There are many cases of fireb.a.l.l.s playing about the lightning conductors without being caught.

In 1777, a fireball shot from the clouds on to the point of the lightning conductor on the Observatory of Padua. The conductor, which consisted of an iron chain, was broken at its junction with the stem.

However, it sent on the discharge.

Some years later, in 1792, a huge ball of lightning struck one of the two conductors on the house of M. Haller at Villiers la Garenne. This conductor was much injured by the audacious a.s.sailant, and so was the framework of the house; the keen fluid had damaged the metallic gutters.

At this point I must add that lightning conductors are of recent creation. Nor would it be surprising if there were defective ones which could not a.s.sure an efficient protection.

However, much later, on December 20, 1845, the same phenomenon was observed at the chateau of Bortyvon, near Vire. There, again, the fireball, ignoring the danger to which it was exposing itself, flung itself on a lightning conductor placed in the centre of the chateau.

It was spared, but the chateau suffered greatly. The electric ball descended from both sides of the metallic stem, causing a great deal of damage along its path. On touching the ground it expanded, and many persons affirm that they saw what was like a huge cask of fire rolling along the ground.

In truth, ball lightning seems in a certain measure to escape the influence of lightning conductors.

On September 4, 1903, towards ten o"clock in the evening, M. Laurence Rotch, director of the Observatory of Blue Hill (U.S.), happening to be in Paris, made the following curious observation from the Rond-point of the Champs Elysees.

Looking in the direction of the Eiffel Tower, he saw the summit of the edifice struck by white lightning coming from the zenith. At the same moment a fireball, less dazzling than the lightning, slowly descended from the summit to the second platform. It appeared to be about one yard in diameter, and to be situated in the middle of the tower, taking less than two seconds to cover a distance of about 100 yards.

Then it disappeared. The next day the observer ascertained, on visiting the tower, that it had actually been struck by lightning twice on the previous day.

It is to be noted that the meteor did not follow the conductor; but, after all, is not the whole tower itself the most powerful conductor imaginable? Would not the enormous ma.s.ses of iron used in its construction neutralize the attraction of the thin metallic rods, effectual for the protection of ordinary buildings, but incapable, one would think, of competing with the attractive force of this immense metallic framework?

Here are some cases where globular lightning has struck bells or telegraph wires, which it has followed with docility.

Several times it has been seen poised like a bird on a telegraph wire near a railway-station, and has then quietly disappeared.

[Ill.u.s.tration: THE EIFFEL TOWER AS A COLOSSAL LIGHTNING CONDUCTOR.

Photograph taken June 3, 1902, at 9.20 p.m., by M. G. Loppe. Published in the _Bulletin de la Societe Astronomique de France_ (May, 1905)]

We see that it is not absolutely inimical to points, nor to metals, but it prefers its independence, and he must get up early who would catch it in a snare.

It is an anarchist--it acknowledges no rule.

But we must confess that if spheroidal lightning seems particularly capricious, it is because we are still ignorant of the laws which guide it. Our ignorance alone is the cause of the mystery.

We try to discover the enigma in the silence of the laboratories, where physicians question science without ceasing; we try to reproduce fireb.a.l.l.s artificially, but the problem is complicated, and its solution presents enormous difficulties.

Hypotheses are not wanting. Some years ago, M. Stephane Leduc recorded an interesting experiment, producing a moving globular spark.

When two very fine and highly polished metallic points, each in affinity with one of the poles of an electro-static machine, rest perpendicularly on the sensitive face of a gelatine bromide of silver photographic plate, which is placed on a metallic leaf, the two points being 5 to 10 centimetres the one from the other, an effluvium is produced round the positive point, while at the negative point a luminous globule is formed.

When this globule has reached a sufficient size, you can see it detach itself from the point, which ceases to be luminous, begin to move forward slowly on the plate, make a few curves, and then set off for the positive point; when it reaches this, the effluvium is extinguished, all luminous phenomenon ceases, and the machine acts as if its two poles were united by a conductor.

The speed with which the luminous globe moves is very slight. It takes from one to four minutes to cover a distance of 5 to 6 centimetres.

Sometimes, before reaching the positive point, the globe bursts into two or more luminous globules, which individually continue their journey towards the positive point.

On developing the plate, you will find traced on it the route followed by the globule, the point of explosion, the routes resulting from the division, the effluvium round the positive point. Also, if you stop the experiment before the arrival of the globule at the positive point, the photograph will only give the route to that point.

The globule makes its course the conductor. If during its journey you were to throw powder on the plate--sulphur, for example--the course it followed will be marked by a line of little aigrettes, looking like a luminous rosary.

Of all the known electric phenomena, this is the most a.n.a.logous with globular lightning.

[Ill.u.s.tration: PHOTOGRAPH OF THE POSITIVE POLE OF AN ELECTRIC SPARK.]

[Ill.u.s.tration: PHOTOGRAPH OF THE NEGATIVE POLE OF AN ELECTRIC SPARK.]

But the really complicated part of the question is when ball lightning loses part of its fluidity and becomes a semi-solid body, as in the following instance:--

On April 24, 1887, a storm burst over Mortree (Orne), and the lightning literally chopped the telegraph wire on the route to Argentan for a distance of 150 yards. The pieces were so calcinated that they might have been under the fire of a forge; some of the longer ones were bent and their sections welded together. The lightning entered by the door of a stable in the form of a fireball, and came near a person who was preparing to milk a cow; then it _pa.s.sed between the legs of the animal_, and disappeared without causing any damage. The terrified cow raised itself on its hind legs with frantic bellowing, and its master ran away, frightened out of his wits, but there was no harm done.

The inexplicable phenomenon was that at the precise moment when the lightning crossed the stable, a great quant.i.ty of incandescent stones fell before a neighbouring house. "Some of these fragments, of the size of nuts," wrote the Minister of Post and Telegraphs at the Academy, "are of a not very thick material, of a greyish-white, and easily broken by the fingers, giving forth a characteristic odour of sulphur. The others, which are smaller, are exactly like c.o.ke.

"It would perhaps be useful to say here, that during this storm the thunderclaps were not preceded by the ordinary muttering, they burst quickly like the discharge of musketry, and succeeded one another at short intervals. Hail fell in abundance, and the temperature was very low."

It is only by a semblance of disbelief that one can get the peasants to tell us the stories of what they pretend to have seen of the fall of aeroliths during storms. They have christened the uranoliths "thunder-stones."

These substances have evidently no relation to uranoliths, but they prove none the less that ponderable matter may accompany the fall of lightning.

Here are two more examples--

In the month of August, 1885, a storm burst over Sotteville (Seine-Inferieure); lightning furrowed the sky, the thunder muttered, and the rain fell in torrents. Suddenly, in the Rue Pierre Corneille, several small b.a.l.l.s, about the size of a common pea, were seen to fall; these burned on touching the ground, sending out a little violet flame. People counted more than twenty, and one of the spectators, on putting her foot on one of them, produced a fresh flame. They left no trace on the ground.

On August 25, 1880, in Paris, during a rather violent storm, in broad daylight, M. A. Trecul, of the Inst.i.tute, saw a very brilliant voluminous body, yellowish-white, and rather long in shape, being apparently 35 to 40 centimetres in length, by about 25 in width, with slightly conical ends.

This body was only visible for a few seconds; it seemed to disappear and re-enter a cloud, but in departing--and this is the chief point--it dropped a little substance, which fell vertically like a heavy body under the sole influence of gravity. It left a trail of light behind it, at the edges of which could be seen sparks, or rather red globules, because their light did not flash. Near the falling substance the luminous trail was almost vertical, while in the further part it was sinuous. The small substance divided in falling, and the light went out soon after, when it was on the point of reaching the tops of the houses. When it was disappearing, and at the moment of the division, no noise was heard, although the cloud was not far away.