The wood of trees is not so good a conductor of electricity as the human body. For this reason, a person leaning against a tree receives the full discharge; at times the tree is splintered, because it did not serve as a perfect conductor. Yet the conductive power of certain species is so remarkable, that the neighbourhood of particular trees may be regarded as a protection against lightning (this, however, without coming in contact with them!). The tips of the branches pointing towards the clouds, and the moisture they receive, undoubtedly influence the electricity of the atmosphere; and, moreover, by means of these graceful branches, an inaudible but continual exchange is effected between the electricity of the earth and sky, thus holding the balance between two opposite charges. Colladon asserts that poplars planted near houses may, in favourable conditions, act as lightning conductors, on account of their height and powers of conducting. He adds that it is necessary to take other circumstances regarding the situation of the dwelling into account, which are not always easy to define. Their protection of the neighbourhood is not constantly the same. For it to be effectual, the foliage should be very low, and they should be at least two metres distant from the roof and walls. Their roots, too, should be in a damp soil, and metal should not enter largely into the construction of the neighbouring houses. In these conditions, poplars may fulfil the useful functions of lightning conductors. At times, during a storm, several trees are struck by the same flash. For instance, on May 23, 1886, in Belgium, three poplars were blasted by a single thunderbolt. On the other hand, trees planted in lines are sometimes struck alternately. A case occurred where the lightning seemed to have taken aim and touched all the odd numbers in a row without striking the others. Certain plantations act on the fluid with an extraordinary intensity. At Lovenjoul, in Belgium, a wood of undergrowth and big trees, planted in marshy ground, seems to possess this singular privilege, and the agriculturists of the country declare that no storm ever passes their way without lightning falling there. In the middle of this wood one can count seven oaks, near to one another, struck by it. Not far off, a huge ash, and a little farther away two poplars, likewise blasted. All the trees have not been struck in the same way; some are scorched or stripped of their leaves; the others have their trunks perforated, or split in different parts. Usually trees are cleft from top to bottom; in some cases the furrow is horizontal or perpendicular in the direction of the branches. Pieces of bark or of wood are sometimes torn off lengthwise, and only adhere to the trunk in strips here and there. But that does not prove conclusively that the lightning struck upwards from the ground; it may have rebounded (?) after striking from above.