“BY their clever researches, Franklin, de Romas, and many others have revealed to us the nature of lightning; they have taught us, in particular, that when its quantity is small, it leaps to meet one’s finger in bright, crackling sparks, without danger to the experimenter, and that all bodies containing it attract neighboring light substances, just as the kite-string attracted the straws in the experiment made by de Romas, and just as sealing-wax and rubbed paper attract the down of feathers. In short, they taught us that electricity is the cause of thunder.

“Now there are two distinct kinds of electricity, which are present in equal quantities in all bodies. As long as they are united, nothing betrays their presence; it is as if they did not exist. But, once separated, they seek each other across all obstacles, attract each other, and rush toward each other with an explosion and a flash of light. Then all is in complete repose until these two electric principles are again separated. The two electricities, therefore, supplement and neutralize each other; that is to say, they form something invisible, inoffensive, inert, that is found everywhere and is called neutral electricity. To electrify a body is to decompose its neutral electricity, to disunite the two principles which, when mixed, remain inert, but, separated from each other, manifest their wonderful properties and their violent tendency to recombination. Rubbing is one way of effecting the separation of the two electric principles, but it is far from being the only one. Every radical change in the inmost nature of a body also causes a manifestation of the two electricities. So clouds, which are water changed into vapor by the sun’s heat, are often found to be electrified.

“When two differently electrified clouds come near together, immediately their contrary electricities run toward each other to recombine, and with a loud report there is a burst of flame that throws a bright and sudden light. This light is lightning; this burst of flame is a thunderbolt; the noise of the explosion is thunder. Finally, the electric spark can dart from a cloud electrified in one way to a spot on the ground electrified in the other.

“Generally you know a thunderbolt only by the sudden illumination it produces and the crash of its explosion. To see the thunderbolt itself you must overcome an unwarranted fear and look attentively at the clouds, the center of the storm. From moment to moment you can see a dazzling streak of light, simple or ramified, and of very irregular sinuous shape. A glowing furnace, metals at white heat, have not its brilliancy; the sun alone furnishes a comparison worthy the sovereign splendor of the thunderbolt.”

“I saw the thunderbolt,” put in Jules, “when it struck the big pine the day of the storm. For a moment I was blinded by its brightness, as if I had looked the sun full in the face.”

“The next storm,” said Emile, “I will watch the sky to see the ribbon of fire, but on condition that uncle is there. I should not dare to alone; it is so terrible.”

“I, too,” added Claire, “will do my best to overcome my fear, if Uncle is only there.”

“I will be there, my children,” their uncle promised them, “if my presence reassures you, for it is a most imposing sight, that of a stormy sky set on fire by lightning and full of the rumbling of the thunder. And yet, when from the bosom of the clouds there comes the dazzling flash of the thunderbolt and the whole region echoes with the crash of the explosion, a foolish fear dominates you; admiration has no further place in your mind, and your terrified eyes close at the magnificence of the electrical phenomena of the atmosphere, proclaiming with so much eloquence the majesty of the works of God. From your heart, congealed with fear, there comes no outburst of gratitude, for you do not know that at this moment, in the flashes of lightning, the uproar of the shower, of the thunder, and of the unchained winds, a great providential act is being accomplished. Thunder, in fact, is far more the cause of life than of death. In spite of the terrible but rare accidents that it causes, obeying in that the inscrutable decrees of God, it is one of the most powerful means that Providence employs to render the atmosphere wholesome, to clear the air we breathe of the deadly exhalations engendered by decay. We burn straw and paper torches in our rooms to purify the air; with its immense sheets of flame the thunderbolt produces an analogous effect in the surrounding atmosphere. Each of those lightning flashes that make you start with fear is a pledge of general salubrity; each of those claps of thunder that freeze you with fear is a sign of the great work of purification that is operating in favor of life. And who does not know with what delight, after a storm, the breast fills itself with pure air, when the atmosphere, purified by the fires of the thunderbolt, ............