How often one has remarked great tree trunks in the forests, decayed and desolate, standing sadly, like poor headless bodies? Very often lightning has been the executioner of these trees.
In the month of May, 1867, in the forest of Fontainebleau, a magnificent oak, about two metres in circumference, was completely decapitated by lightning; its branches fell on the ground. The part of the trunk left standing was barked to the roots and splintered into fragments of varying sizes. They were scattered on the ground or hung from the branches of the surrounding trees. Several pieces of considerable size were hurled more than thirty metres away, much to the injury of the bark of the trees which they struck.
In numerous cases, the tree struck by lightning is broken in several places, and fragments of it thrown far and wide.
On July 2, 1871, at the farm of Etiefs, near Rouvres, canton of Auberive (Haute-Marne), lightning struck an Italian poplar, sixty years old, thirty metres high, and three metres round at a height of one metre from the ground, splintering off enough wood to make a heap sixty-five centimetres round, and fifty centimetres high.
An ash was struck by lightning on July 17, 1895, on the road to Clermont. This tree, ten metres high, was broken at a point 3⅕ metres from the ground, and the crown, still hanging by a shred from the trunk, lay on the embankment. The violence of the explosion threw pieces thirty centimetres wide and 3½ metres in length, into a field from twenty-five to thirty metres off.
On July 4, 1884, in Belgium, a willow was reduced to a heap of atoms on the ground. In March, 1818, at Plymouth, a fir more than a hundred feet high and forty feet in circumference, the admiration of the countryside, disappeared, literally shattered into bits. Some fragments were thrown two hundred and fifty metres away.
One of the most curious effects of lightning is to divide the interior of the tree into concentric layers, fitting them perfectly one into the other, but at the same time separating them with extraordinary precision.
Arbres roulés (thus are the trees called which are victims of this odd phenomenon), as a rule, do not show any injury on the outside. But the body, dissected by the electric fluid, soon succumbs.
An oak, twenty-five metres high, having been struck on August 25, 1818, was opened to be examined carefully, and it was stated that the concentric layers were as detached from one another as the tubes of an opera-glass.
The fireball sometimes hollows a canal through the centre of the trees from the top to the bottom, the sides of which are burnt black. The following is a curious example:—