It is well remarked by Arago, that although we know nothing about lightning, beyond the well-ascertained fact that it is one of the manifestations of the equally vast and mysterious electric forces pervading the universe, we yet may ascertain a great deal about its mode of action by continued observation, made by many persons and at many places. As yet the wise recommendation of the French astronomer has, unfortunately, not been acted upon to any extent, or in any systematic manner; still, a good many facts and incidents have been gathered which serve to throw a strong light upon the apparently erratic, but in reality normal manner in which, as in obedience to some grand unfathomable cosmic law, the fire of the clouds flashes along its self-made path. That these observations are entirely modern, detracts nothing from their value. With all their famed civilisation, the classical nations of the ancient world never came to look upon lightning and thunderstorms as regular functions of nature, but regarded them with dread and horror. Even the greatest of their natural philosophers found in them means only for encouraging popular superstition. Thus Pliny the Elder, in his celebrated ‘Natural History,’ recommends, like Arago, notes being taken about thunderstorms, but for quite a different purpose. ‘Nothing is more important,’ says the celebrated author of the _Historia Naturalis_, than to observe from what region the lightnings proceed, and towards what region they return. Their return to the eastern quarter is a happy augury. When they come from the east, the prime quarter of the Heavens, and likewise return thither, it is the presage of supreme felicity.’ It is reported by travellers that this form of superstition--which has reference, of course, to the zigzag form of many strokes of lightning, apparently in turn advancing and retrograding--still exists in some districts of Southern Italy.