Sometimes only the mosses and lichens are whisked off the sides of the trees, which escape with light scratches. Two great oaks which had been struck by fireballs, only bore traces of two punctures which might have been made by small shot.
Moreover, it is not uncommon to see the bark riddled with a multitude of little holes, like those made by worms.
Two men were struck by lightning near Casal Maggiore on August 15, 1791, beneath an elm tree. One of them had his elbow on the tree at the moment, and amongst other injuries were a number of little holes in the arm. There was a twist in the tree at the part where the elbow rested, and a hole penetrated the centre of it to the core of the wood. The surrounding bark looked as if it had been mite-eaten. Several scars started from this point and ascended almost perpendicularly towards the top of the trunk. There was no damage done to the branches.
Lightning cut through a chestnut tree, five metres high, on the roadside at Foulain (Haute-Marne), burning several leaves, then struck some water-pipes at a depth of a metre and a half, and finally passed into the dike through two holes a metre deep by a decimetre in diameter.
The bark is often reduced to thin splinters scattered on the soil, or hanging from the neighbouring trees, or even thrown to a considerable distance.
On June 25, a fireball fell near Jare (Landes) on a pine tree, which it shivered into a myriad slender strips, about 2 metres long, many of which were caught on the branches of pines within a distance of 15 metres. Only a stump, 2½ metres in height, remained standing. At the same time three other pines, which stood 18 and 25 metres away from the first, were destroyed. The bark had been stripped off each, but only as far as the incision made for extracting the resin.
Furrows, of varying width, and running in different directions, may at times be seen on trees, some short, others reaching to the top of the tree, and occasionally to the roots. These marks show the passing of the lightning.
Sir John Clark has seen a huge oak in Cumberland, at least 60 feet high and 4 feet in diameter, from which the lightning had stripped a piece of bark, about 10 centimetres wide and 5 centimetres thick, the whole length of the trunk in a straight line.
The furrow is not always single, it may be double, and either stretch in two parallel lines or diverge.
The Chevalier de Louville observed in the park of the castle at Nevers, a tree struck at the top of the trunk by lightning which, dividing in three shafts, hollowed three furrows that might have been made by three rifle shots fired towards the roots. These three furrows followed the irregularities of the trunk, always slipping, gliding between the wood and the bark, and curiously enough the former was not burnt.