affects only the magnetic parts of a substance.
That the electrical current is not confined to the conducting wire,
but is comparatively widely diffused in the surrounding space, is
sufficiently demonstrated from the foregoing observations."(2)

The effect of Oersted's demonstration is almost incomprehensible. By it
was shown the close relationship between magnetism and electricity. It
showed the way to the establishment of the science of electrodynamics;
although it was by the French savant Andre Marie Ampere (1775-1836) that
the science was actually created, and this within the space of one week
after hearing of Oersted's experiment in deflecting the needle. Ampere
first received the news of Oersted's experiment on September 11, 1820,
and on the 18th of the same month he announced to the Academy the
fundamental principles of the science of electro-dynamics--seven days of
rapid progress perhaps unequalled in the history of science.

Ampere's distinguished countryman, Arago, a few months later, gave
the finishing touches to Oersted's and Ampere's discoveries, by
demonstrating conclusively that electricity not only influenced a
magnet, but actually produced magnetism under proper circumstances--a
complemental fact most essential in practical mechanics.

Some four years after Arago's discovery, Sturgeon made the first
"electro-magnet" by winding a soft iron core with wire through which
a current of electricity was passed. This study of electro-magnets was
taken up by Professor Joseph Henry, of Albany, New York, who succeeded
in making magnets of enormous lifting power by winding the iron core
with several coils of wire. One of these magnets, excited by a single
galvanic cell of less than half a square foot of surface, and containing
only half a pint of dilute acids, sustained a weight of six hundred and
fifty pounds.

Thus by Oersted's great discovery of the intimate relationship of
magnetism and electricity, with further elaborations and discoveries by
Ampere, Volta, and Henry, and with the invention of Daniell's cell, the
way was laid for putting electricity to practical use. Soon followed the
invention and perfection of the electro-magnetic telegraph and a host of
other but little less important devices.

FARADAY AND ELECTRO-MAGNETIC INDUCTION

With these great discoveries and inventions at hand, electricity became
no longer a toy or a "plaything for philosophers," but of enormous
and growing importance comm