But these bands are not invariably straight either; in the above example they followed the caprices of the vegetable body. They are to be found oblique in certain cases, but more often they surround the trunk in long spirals of varying width, showing that the lightning clasped the tree in the form of a serpent of fire.
Here is an example:—
During a violent storm on July 17, 1895, a poplar was blasted on the road through the forest of Moladier, 160 metres north-west of the castle of Valliere. The tree was 25 metres high, and in full leaf from base to summit; it was struck halfway up by the discharge, and a spiral furrow 10 centimetres wide twisted round the trunk to the ground.
I noted a similar case, August 25, 1901.
Lightning struck one of the highest trees in the park at Juvisy, a magnificent ash, stripping off and destroying the bark where the electric fluid curved round and round down the full length of the trunk, which was shattered by the meteor a few metres above the roots. Enormous fragments lay all round the trunk, some hurled to such a distance that it was obvious the explosive force of the phenomenon must have been of extraordinary violence.
I was able to trace the course of the lightning to the foot of the tree, along its roots to a great depth, by a black furrow.
The tree is not dead. The ivy which clung to it is dead.
The vast and splendid forest of Saint Germain often witnesses the presence of the lightning, and the magnificent trees which adorn and beautify this charming and celebrated place are, unfortunately, too often the victims of these inopportune visitations.
Lightning has no respect for old memories. It demolished with a single flash a superb giant whose long branches, laden with perfumed leaves, had given shade to many generations. The splendid tree, which had survived the severity of several centuries, fell beneath the arrow of the pernicious fluid. Such was the fate of an oak near l'Etoile du Grand-Veneur. Struck on the top, its upper branches were violently torn off.... A spiral furrow beginning at the top ended within a metre of the ground. But, wonderful to relate, the whole mass of the tree appeared to have been twisted mightily by a force which worked with so much power that the tree could never regain its original position. The fibre, instead of growing vertically, followed the furrow made by the lightning, and became twisted like a corkscrew. There exist certain singular trees, the fibre of which grows in spiral fashion, and is called twisted wood by carpenters and cabinet-makers. Pines and firs in mountainous countries are fairly often affected in this curious fashion. One can no more account for it than one can define the cause of the curved form of some flashes of lightning. One does not know exactly if they should be attributed to their following the direction taken by the fibre, or whether, on the contrary, the tree had been struck in its infancy by a spiral flash, and, submitting to that influence, continued to grow up corkscrew fashion.
It is most probable that the fall of the thunder-ball on the trees in this manner is governed by the laws of electricity. We may even note casually that traces of similar spirals have been remarked on objects as well as on the dead bodies of those struck by lightning, thus preserving the ceraunic likeness of the mortal blow.