Thunder and Lightning Part 17

In June, 1823, at Moisselles, lightning fell upon a great elm, and striking against an enormous k.n.o.b, rebounded on to a neighbouring elm half its own height, pierced it through and through, shivering it to tatters; the trunk was burst open to the roots, it looked as if it had been bored through from one end to the other by a red-hot bullet that blackened and charred it.

Does it not seem as if the lightning plays with the lives of the trees as with man? It threatens, changes, apparently spares, returns to the charge and finally annihilates. And this sport is accompanied, at times, by inconceivable effects.

But records are still more eloquent than reflections: Nature, in her own mute speech, tells us of a thousand marvels.

Is not the following phenomenon enough to make lightning more mysterious in its fantastic and varied mode of action?

On the 19th of April, lightning struck an oak in the forest of Vibraye (Sarthe), cut this tree, measuring a metre and a half in circ.u.mference, at two-thirds of its height, pulverized the lower parts, strewed the shreds over a circuit of fifty metres, and planted the upper part exactly on the spot from which the trunk had been s.n.a.t.c.hed, with all the rapidity of a flash.

Moreover, the annual concentric circles were separated by the sudden drying up of the sap so effectually, that, the strips only remained welded together where the knots made too great an obstacle to their separation.

How was the lightning able to plant in the earth, with such inconceivable rapidity, the top of the tree where the roots had been?

This is something which no one can explain. It alone is capable of creating such situations.

But it has done better still! Two years later, in 1868, it took the opportunity of playing a good trick on two trees of different species, an English oak and a forest pine, which, without race jealousy, fraternized in the forest of Pont-de-Bussiere (Haute-Vienne). These two trees were about ten yards apart, and were simultaneously hit by the explosive matter, and in the twinkling of an eye, their leaves were changed. The pine needles found themselves on the oak, and the leaves of the oak went to brighten the austerity of the pine with their delicate verdure. There was nothing commonplace about the metamorphosis. Accordingly all the inhabitants went in crowds to the scene of this miracle to contemplate the unusual spectacle of a pine-oak and an oak-pine.

And the unexpected happened: both trees appeared to thrive very well in these new conditions: the pine continued to be agreeably adorned with its festival foliage, whilst the oak agreed perfectly with the sombre needles of the pine.

After such marvels, my readers will not be surprised to learn that lightning sometimes shatters the living wood, or decayed wood, into a thousand morsels without setting it on fire.

For instance, a bundle of f.a.ggots lying on the hearth has been reduced to atoms by lightning, without any trace of combustion being visible.

A fireball fell on a sheaf of barley in the open field without setting it on fire, and buried itself in the ground without doing other further damage.

In certain cases the electric fluid chars wood at varying depths: the blackened layer is often very slight; sometimes, on the contrary, combustion is complete.

As for the leaves, they are unhurt as a rule. When they are attacked they shrivel up; an autumnal shade takes the place of their charming green tints; they turn brown and dry up quickly.

One of the trees in the Champs-elysees having been struck, it was proved that all round it the ground was full of little holes. In two or three places the bark was raised from beneath; the leaves were yellow and shrivelled up as parchment would be by the fire; the upper part remained green. Everything seemed to prove that the lightning came out of the ground.

At other times the same effect may be observed on the leaves, when the trunk and roots are apparently uninjured. It is not unusual to see the tree instantly stripped of its leaves as if by some mysterious power.

The lightning acts also on the roots, as we have seen in the preceding examples. They have been seen uncovered where the ground was much disturbed, torn in strips, or cleft in more or less regular pieces.

We see that lightning does not make more ado about exhaling its baleful breath on the life of plants, than on animals and men. And moreover, that it often strikes these latter with sudden death without leaving a trace of its pa.s.sing, just as sometimes it strikes the trees without leaving any exterior injury. Now and then life is not completely extinguished, and little by little the tree recovers its health. Often the vitality is not changed, one sees the tree which was struck bear fruit as before the catastrophe.

Has it not been a.s.serted that lightning may exert a benign influence on vegetation?

This was the opinion of the ancients.

_A propos_ of this, Pliny said, "That thunder is rarely heard in winter, and that the great fertility of the soil is due to the frequency of thunder and rain in spring; for the countries where it rains often and in good earnest during the spring, as in the island of Sicily, produce many and excellent fruits."

It has been proved in our times that the ancients were right in extolling rainwater as nourishment for the products of the earth, and science has discovered the cause to be the presence of great quant.i.ties of nitrogen and ammonia in the thunder-rain and in hail.

Perhaps electricity has a similar effect.

In the neighbourhood of Castres, on April 13, 1781, an old poplar was stripped of its bark in several places. Now, shortly afterwards it burst into leaf, although the neighbouring poplars were much later than it.

The ravages caused in the fields by the electric meteor to forage and vegetables are sometimes considerable. This is especially so with gra.s.s when cut, to hayc.o.c.ks, ricks of straw, barley, etc. We have a collection of records of men or animals who, when leaning against haystacks, were struck.

As a rule the haystack is burnt; sometimes, however, the gra.s.s is simply scattered and thrown to a distance.

In 1888, a very curious occurrence was observed at Vayres (Haute-Vienne).

The lightning struck a field of potatoes at the village of Puytreuillard; some of the stalks were burnt to cinders; but most remarkable of all, _the potatoes were done to a turn_, just as if they had been cooked beneath hot ashes.

A belief which was very general in ancient times and derived without doubt from a recollection of the circ.u.mstances which were said to accompany the birth of Bacchus, gave the vine the privilege of protecting the neighbourhood from the fatal effects of lightning. But this again is only a legend. The following observation proves it:--

On July 10, 1884, at Chanvres (Yonne), fifty vine-stocks were frizzled up by lightning.

It used to be supposed, too, that the electric fluid held the lily in particular respect. But here is a note which shows us that the white flower is visited by the burning flashes. During a violent thunderstorm on June 25, 1881, at Montmorin (Haute-Garonne)----But let M. Larroque, who witnessed the curious phenomenon, describe it: "In a clump of lilies in my garden," says he, "I see the highest of them surrounded by a violet glimmer, which formed an aureola round the corolla. This glimmer lasted for eight or ten seconds. As soon as it disappeared, I went close to the lily, which, to my great surprise, I found had been deprived of its pollen, while the surrounding flowers were laden with it. So the electric fluid must have scattered or carried off the pollen."

When Jupiter thunders, he still seems to dominate our world, as in the days when the graceful legends of mythology flourished.

And not only does he work above ground, but, contrary to the belief of the ancients, his influence extends beneath the soil.

A great number of men were working in the mines at Himmelsfurth on July 5, 1755. They were, as often happens, working at various points along the vein of metal, and never dreaming of the events which might take place on the surface of the ground. All at once they were conscious of several very violent shocks, given in the oddest and most extravagant fashion. Some felt the shock in their backs, while their neighbours received them on their arms or legs. They might have been shaken by a mysterious invisible hand, stretching now up from below, now from above, now from the sides of the galleries. One of the miners found himself hurled against the wall, two others, whose backs were turned, almost came to blows, each believing that his mate had thumped him.

The real culprit was the thunder, of whom they might well demand an explanation of these strange proceedings.

Here is another example which bears out the foregoing:--

On the 25th of May, the watchman on guard at the pit mouth of one of the princ.i.p.al mines at Freyberg, perceived an electric glimmer run along the wire rope going to the bottom of the mines, and used by the miners to exchange signals with the men employed in working the lifts.

Suddenly all the pits were brilliantly lit up. At the same moment the watchman saw a clear vivid flame shoot out at the other end of the chain. On this occasion the lightning behaved with due discretion, and shone through the mine without giving any one the slightest shock.

In vain the monster Tiberius, and the infamous Caligula, sought a subterranean refuge from lightning. Their impure consciences, laden with crimes, dreaded the chastis.e.m.e.nt of heaven. By fleeing from the lightning flash, they believed themselves saved from death. Lightning dogs our footsteps, and works even when the criminals believe themselves in safety. It is conceivable that the ancients should have dreaded it as an instrument of celestial justice.

Usually lightning strikes the ground with a vertical stroke, but at times obliquely, when it traces long, horizontal lines. Often the ground may be seen turned up at the foot of trees which have been struck, the sod is torn, and stones thrown to a great distance.

Sometimes, too, an excavation may be seen in the ground near the object struck, of varying breadth and height. This opening may be like a funnel or hemispherical.

In a case observed on June 6, 1883, at Cote (Haute-Saone), a circular hole, having a depth of 120 metres, has been seen in a d.y.k.e on the declivity of the road, below a coach which was not struck.

Occasionally the hole is but the beginning of a ca.n.a.l, hollowed rather deeply and perpendicularly in the ground, the sides of which serve as a sheath to the fulgurite. But before treating of fulgurite tubes, which const.i.tute the most curious phenomena in the world connected with lightning, we shall discuss certain remarkable effects observed on the surface of the ground.

Falling on solid rocks, the electric spark can break them, cut them, or pierce them in one or more places. Often instead of spoiling or cutting off pieces of the stone, it covers the surface instantaneously with a vitreous coat, having blisters of various colours. This vitrification is often to be seen on mountains.

De Saussure found rocks of schistous amphiboles covered with vitreous bubbles, like those seen on tiles where struck by lightning. Humboldt made similar observations on porphyritic rocks at Nevada de Toluca, in Mexico, and Ramond, at the Sanadoire rock in Puy-de-Dome.

In these cases, the spark, on reaching the surface, melts it more or less completely over a varying extent, and this fusion, worked upon by an extraordinary heat, produces a coat having a peculiar appearance, but in which microscopical a.n.a.lysis finds the elements of the body it covers.

Thus the vitreous layer deposited over chalk is of chalky origin; that covering granite is of the nature of granite, etc.

This does not apply to certain deposits found on rocks, and even on trees, which have been struck by lightning, and which are of very different origin.

Whilst the former is only the stone in a fused or vitrified condition, the latter is caused by the presence of foreign bodies, some fragments of which have been detached by the ray and travel with it. This transport of solid substances by lightning has often been observed.

Here are two examples of this strange phenomenon:--

On July 28, 1885, at Luchon, on the Bigorre road a pa.s.ser-by saw lightning fall twenty yards away from him. Recovered from the shock, he went out of curiosity to look at the result, and saw the wall at the edge of the road, the schistous and chalky rocks, even the trees themselves, coated over with layers of brown. It was certainly a case of the lightning having effected a deposit. This latter was very curious. Lines could be traced on it with the finger-nail, it fell to powder under slight pressure, became soft with gentle rubbing, caught fire from a candle, and then gave off a resinous odour with much smoke. What is this resinous matter? That is what no one yet can say.

In the month of July, 1885, on the day following a violent thunderstorm which had struck the telegraph-office in the station of Savigny-sur-Orge, I myself picked up a little black powder off the telegraph poles, which had been left by the lightning, and which had a sulphurous smell.