closes with the first observations of radiant electricity; and the
fourth brings us to our own day. We shall here concern ourselves with a
few outstanding features of each phase, enough to characterize the
strange path along which man has been led by the discovery of
electricity.

Until the beginning of modern times, nothing more was known about
electricity, or of its sister force, magnetism, than what we find in
Pliny's writings. There, without recognizing a qualitative distinction
between them, he refers to the faculty of rubbed amber and of certain
pieces of iron to attract other small pieces of matter. It required the
awakening of that overruling interest in material nature,
characteristic of our own age, for the essential difference between
electric and magnetic attraction to be recognized. The first to give a
proper description of this was Queen Elizabeth's doctor, Gilbert. His
discovery was soon followed by the construction of the first electrical
machine by the German Guericke (also known through his invention of the
air pump) which opened the way for the discovery that electricity could
be transmitted from one place to another.

It was not, however, until the beginning of the eighteenth century that
the crop of electrical discoveries began to increase considerably:
among these was the recognition of the dual nature of electricity, by
the Frenchman, Dufais, and the chance invention of the Leyden jar (made
simultaneously by the German, von Kleist, and two Dutchmen,
Musschenbroek and Cunaeus). The Leyden jar brought electrical effects
of quite unexpected intensity within reach. Stimulated by what could be
done with electricity in this form, more and more people now busied
themselves in experimenting with so fascinating a force of nature,
until in the second third of the century a whole army of observers was