nd regarded it as the germ or foundation upon which other
discoveries were to be made. The prediction proved entirely correct,
Volta himself being the chief discoverer.

Working along lines suggested by Galvani's discovery, Volta constructed
an apparatus made up of a number of disks of two different kinds of
metal, such as tin and silver, arranged alternately, a piece of some
moist, porous substance, like paper or felt, being interposed between
each pair of disks. With this "pile," as it was called, electricity
was generated, and by linking together several such piles an electric
battery could be formed.

This invention took the world by storm. Nothing like the enthusiasm it
created in the philosophic world had been known since the invention
of the Leyden jar, more than half a century before. Within a few weeks
after Volta's announcement, batteries made according to his plan were
being experimented with in every important laboratory in Europe.

As the century closed, half the philosophic world was speculating as to
whether "galvanic influence" were a new imponderable, or only a form of
electricity; and the other half was eagerly seeking to discover what new
marvels the battery might reveal. The least imaginative man could see
that here was an invention that would be epoch-making, but the most
visionary dreamer could not even vaguely adumbrate the real measure of
its importance.

It was evident at once that almost any form of galvanic battery,
despite imperfections, was a more satisfactory instrument for generating
electricity than the frictional machine hitherto in use, the advantage
lying in the fact that the current from the galvanic battery could
be controlled practically at will, and that the apparatus itself
was inexpensive and required comparatively little attention. These
advantages were soon made apparent by the practical application of the
electric current in several fields.

It will be recalled that despite the energetic endeavors of such
philosophers as Watson, Franklin, Galvani, and many others, the field
of practical application of electricity was very limited at the close of
the eighteenth century. The lightning-rod had come into general use, to
be sure, and its value as an invention can hardly be overestimated. But
while it was the result of extensive electrical discoveries, and is
a most practical instrument, it can hardly be called one that puts
electricity to practical use, but simply acts as a me