THE EIFFEL TOWER AS A COLOSSAL LIGHTNING CONDUCTOR.
Photograph taken June 3, 1902, at 9.20 p.m., by M. G. Loppé. Published in the Bulletin de la Société Astronomique de France (May, 1905)
We see that it is not absolutely inimical to points, nor to metals, but it prefers its independence, and he must get up early who would catch it in a snare.
It is an anarchist—it acknowledges no rule.
But we must confess that if spheroidal lightning seems particularly capricious, it is because we are still ignorant of the laws which guide it. Our ignorance alone is the cause of the mystery.
We try to discover the enigma in the silence of the laboratories, where physicians question science without ceasing; we try to reproduce fireballs artificially, but the problem is complicated, and its solution presents enormous difficulties.
Hypotheses are not wanting. Some years ago, M. Stéphane Leduc recorded an interesting experiment, producing a moving globular spark.
When two very fine and highly polished metallic points, each in affinity with one of the poles of an electro-static machine, rest perpendicularly on the sensitive face of a gelatine bromide of silver photographic plate, which is placed on a metallic leaf, the two points being 5 to 10 centimetres the one from the other, an effluvium is produced round the positive point, while at the negative point a luminous globule is formed.
When this globule has reached a sufficient size, you can see it detach itself from the point, which ceases to be luminous, begin to move forward slowly on the plate, make a few curves, and then set off for the positive point; when it reaches this, the effluvium is extinguished, all luminous phenomenon ceases, and the machine acts as if its two poles were united by a conductor.