o
solve it were successful. Then in a series of experiments that have
scarcely ever been equaled in brilliancy and originality, he gave to
the world the principle on which is based the wonderful development of
modern electrical science.

The principle is briefly stated. The space, around a wire carrying an
electric current, or in the neighborhood of a magnet, has a directive
effect upon a magnetic needle, and is hence called a magnetic field.
Now if a conductor, or coil of wire, be placed in the field across the
direction of a magnetic needle, and the field be varied either by
varying the current or moving the magnet, a current will be developed
in the conductor. It is impossible at this distance to appreciate the
interest excited by the announcement of this principle, not only among
scientists, but also among inventors and those who saw practical
possibilities for the future; and probably no one more fully
appreciated its value than Faraday himself. Yet he made no effort to
develop it further, or even to protect his interest by a patent, as is
common in these days. He was eminently a scientist, and this was his
free gift to the world. He said: "I have rather been desirous of
discovering new facts and relations than of exalting those already
obtained, being assured the latter would find their full development
hereafter."

Among the first to attempt successfully to exalt the new discovery was
Pixii, an instrument maker of Paris, in 1832. He wound two coils of
very fine insulated wire upon the ends of a piece of soft iron, bent
in a horseshoe form. A permanent horseshoe magnet was then placed with
poles very close to the ends of the iron in the coils. The field so
produced was then rapidly varied by revolving the magnet on an axis
parallel to its length. The soft iron cores of the coils became
strongly magnetized as the poles of the revolving magnet came opposite
to them; and their polarity was reversed at each half-revolution of
the magnet. By this plan currents of considerable intensity and
alternating in direction at each revolution were induced in the coil.

The ends of the coil were next connected to the external circuit
through a "commutator." This is a device which is arranged to convert
the alternating current of the coils into a current of one direction
in the external circuit, and which in some form is found on all
direct-current dynamos. Joseph Saxton, an American, improved upon
Pixii's machine by rotating