CHAPTER I.

THE ELECTRICITY OF FRICTION.


A schoolboy who rubs a stick of sealing-wax on the sleeve of his
jacket, then holds it over dusty shreds or bits of straw to see
them fly up and cling to the wax, repeats without knowing it the
fundamental experiment of electricity. In rubbing the wax on his
coat he has electrified it, and the dry dust or bits of wool are
attracted to it by reason of a mysterious process which is called
"induction."

Electricity, like fire, was probably discovered by some primeval
savage. According to Humboldt, the Indians of the Orinoco
sometimes amuse themselves by rubbing certain beans to make them
attract wisps of the wild cotton, and the custom is doubtless very
old. Certainly the ancient Greeks knew that a piece of amber had
when rubbed the property of attracting light bodies. Thales of
Miletus, wisest of the Seven Sages, and father of Greek
philosophy, explained this curious effect by the presence of a
"soul" in the amber, whatever he meant by that. Thales flourished
600 years before the Christian era, while Croesus reigned in
Lydia, and Cyrus the Great, in Persia, when the renowned Solon
gave his laws to Athens, and Necos, King of Egypt, made war on
Josiah, King of Judah, and after defeating him at Megiddo,
dedicated the corslet he had worn during the battle to Apollo
Didymaeus in the temple of Branchidas, near Miletus.