WILLIAM GILBERT.
61
a pin. This apparatus, termed by him a versoium, constituted the
electroscope, by the aid of which he disproved the idea that the
alleged magical property was possessed only by amber or by jet. He
poured out the vials of his wrath upon the empty-headed and inert
philosophers who merely copy from one another and invent high-
sounding Greek words wherewith to cloak their ignorance. "For
not only do amber and jet, as they say, draw light bodies, but
diamond, sapphire, carbuncle, cat's-eye, opal, amethyst, vincentina
and bristolla (an English gem or spar), beryl and rock crystal do the
same." And he went on enumerating a host of other substances
possessing similar powers, following up the true gems with false gems
made from paste, glass of antimony, slags, belemnites, sulphur,
mastic, hard wax, sealing wax variously coloured, resin and arsenic,
and also, but less powerfully and only in dry weather, rock salt,
obsidian, and rock alum. All these substances, because they
resembled amber, he termed electrics; whilst he gave the name of
anelectrics to another class of substances which showed no such
power, and which included the following : Emerald, agate, cornelian,
pearls, jasper, alabaster, porphyry, coral, marble, flint, haematite,
emery, bone, ivory, ebony and other hard woods, cedar, gold, copper,
iron, and the other metals, and, lastly, the loadstone. The substance
which above all others possesses the magnetic property of attracting
iron shows no trace of electric action when rubbed in the hand.
From the terms assigned by Gilbert, the word electricitas—electricity—
came into use to denote the unseen agent operating in these actions.
Gilbert further showed that the power of attraction exercised by the
electric when rubbed was not limited to mere straws or chaff, but
that all metals and woods, and even stones and earths were attracted.
He even found that liquids, oil and water were drawn by the electric
force. He ascertained that moisture exercises a prejudicial effect on
electrical experiments. He observed that electrical effects can be
screened off, and in a way that magnetic effects cannot, by the inter-
position of a sheet of metal, or even by a piece of paper. He even
ascertained the screening effect of a ring of flames. His
observations stop short all too soon, leaving the infant science
truly in a state of infancy. Nevertheless he was the pioneer whose
first steps showed the path to be latter trodden by Robert
Boyle, by Francis Hauksbee, by Sir Isaac Newton, and by Benjamin
Franklin ; and therefore is beyond dispute the father of electric
science.