It is difficult to estimate the influence in modifying and shaping the
nineteenth century civilization that has resulted from the discovery
of the dynamo and the production of heavy currents of electricity.
That it has had great influence is evident without question. The arc
light for out-of-doors lighting and the incandescent lamp for inside
has modified all our previous ideas of illumination. Effects in light
are now produced daily that were beyond imagination twenty years
since. The trolley and the electromoter have largely solved the
problem of rapid transit through our crowded cities. Thus larger
business facilities, suburban homes and cheaper living, cleanliness
and better sanitary conditions are electrical results.
The transmission of energy by the electric current from a central
plant makes possible many small industries that could not exist
without it, and gives employment and happiness to hundreds. The art of
Electro-metallurgy seems but the development of months: yet it already
employs millions of capital and is adding thousands daily to the
world's wealth. Steam and wind and tide contribute to the work. Even
Niagara is being touched by the spirit of the time and sends her
wasting energy thrilling through the electric wires to turn the wheels
of many busy factories. It is perhaps not the least remarkable fact in
connection with this work that it is largely the product of the last
thirty years, and that it had its very beginning less than seventy
years since. Edison and Thompson and Brush are honorable household
names; yet they are still living to produce even greater electric
marvels. In fact, so rapid and brilliant has been the development that
in the brilliancy some of the pioneers in the work have been almost
forgotten, except by the specialist and the student, and it is no
small part of this sketch to do them honor. The tiny spark of Faraday
may be lost in the brilliancy of the million-candle-power
search-light, yet the brilliancy of the search-light but enhances the
wonder of the discovery of the spark.
The discovery of electro-magnetic induction marked the beginning of a
new era; for in it lay all the possibilities of the future of
electrical science. Michael Faraday, the third son of a poor English
blacksmith, was born at Newington, Surrey, England, September 3, 1791.
His father's health was never the best, and due to the resulting
straitened circumstances his early education consisted of the merest
rudiments of reading, writing and arithmetic. His early life was, no
doubt, largely spent in the street; but at thirteen he became errand
boy to a book-seller of London. About a year later he was apprenticed
to a book binder, with whom he served seven years, learning the trade.
It was while an apprentice that Faraday began reading scientific
articles on chemistry and physics in the books he was set to bind. He
also tried to repeat the experiments of which he read. And more, he
pondered over them long and earnestly, until he saw clearly the
principles involved in them. It was in these early days of
experimenting and self-education that the desire to become a
philosopher was implanted in his mind. He embraced every chance for
scientific study and caught every opportunity for intellectual
self-improvement. In the last year of his apprenticeship he was
enabled through the kindness of a customer at his master's shop, to
attend a course of four lectures on chemistry, given by Sir Humphry
Davy at the Royal Institution. This marked the turning point in his
life. He made careful notes of the lecture, and afterward transcribed
them neatly into a book and illustrated them with drawings of the
apparatus used.
After completing his apprenticeship, Faraday began life as a
journeyman bookbinder. He had, however, as he says, "no taste for
trade." His love of science became a consuming desire that he sought
in every way to gratify. Inspired by his longing for scientific
pursuits, he sent his lecture notes to Sir Humphry Davy, with the
request that if opportunity offered he would give him employment at
the Royal Institution. Davy was favorably impressed with the lecture
report, and sent a kindly reply to the young philosopher. Shortly
after this a vacancy did happen to occur at the Institution, and upon
the recommendation of Davy, Faraday was elected to the place. Thus, in
1813, in the humble capacity of an assistant charged with the simple
duty of dusting and caring for the apparatus, Michael Faraday began
the life that was destined to make him the first scientist of the
world and to bring honor to the Institution which had given him his
opportunity.
There is inspiration and encouragement to be found in reading the
story of Faraday's success. He has been called a genius; but his
genius seems to have largely consisted in persistent industry and the
habit acquired in those early days of thinking over his experiments
and reading until he had a clear perception of all there was in them.
He lived in his work, and loved it. In the fifty busy years that
followed his installment at the Royal Institution he digged deep into
nature's secrets, and gave the world many brilliant gems as evidence
of his industry. But of all his discoveries, _electro-magnetic
induction_ is the crowning masterpiece and that for which the world
stands most his debtor.
The principle of conservation of energy, now so well known and
universally accepted, was then but a vague guess in the minds of the
more advanced in science. Faraday was among the first to accept the
new doctrine, and many of his brilliant discoveries were made in his
effort to prove the truth of these important generalizations. He was
acquainted with Sturgeon's method of making magnets by sending a
current of electricity through a wire wound around a bar of iron; and
he reasoned, if electricity will make a magnet, a magnet ought to make
electricity. As early as 1821 his note book contains this suggestion:
"Convert magnetism into electricity." Again and again he attacked the
problem; but it was not until the autumn of 1831 that his efforts to
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 the coils, or armature as it is called,
and making the heavier magnet stationary. The essential points of
construction being worked out, improvements followed rapidly. Dr.
Werner Siemans, of Berlin, introduced an important modification by
making the revolving armature of a cylinder of soft iron, having a
groove cut throughout its length on opposite sides. In these grooves a
wire was wound and the armature was rotated on its axis between the
poles of several magnets.
In all the earlier machines permanent magnets of steel were used. The
next important step was to use electro-magnets of soft iron, excited
by a current flowing through many turns of wire wound around the legs
of the magnet. These could be made much more strongly magnetic than
the permanent magnets. The exciting current was at first obtained from
a small permanent magneto machine; but it was afterward found that the
machine could be made self-exciting. Soft-iron electro-magnets, after
being once magnetized, remain slightly magnetic. This will produce a
weak current in the revolving armature which is turned into the magnet
coils. The magnets are thus further magnetized, and again react upon
the armature with greater intensity. In this way a _strong_ current is
rapidly built up, and after wholly or in part passing around the
magnet coils to sustain its magnetism, can be carried out into the
circuit to serve the great variety of purposes to which it is now put.
The essential points in the evolution of the dynamo can here be
sketched only in broadest outline. Even to catalogue in detail, the
improvements of Edison and Brush, Gramme and Wheatstone, and a host of
others who have contributed to the work, would require a volume. One
fact, however, should ever be kept in mind: Whatever may be the extent
of the superstructure of electrical science, it is all built upon the
foundation of electro-magnetic induction laid by Michael Faraday. The
little "magnetic spark" he first produced, and the trembling of his
galvanometer-needle, were but signals of the birth of the giant of the
century.
These are the days of electricity and steel, and a fitting part of the
intense age in which they exist. That we have as yet seen but a
partial development of the possibilities of the electrical discovery,
no one can doubt. The rush of the trolley car, and the blinding flash
of the electric light, are but challenges thrown out to the future for
even greater achievements. That they will come no one will question;
but where is the daring prophet who will hazard a guess as to what
they will be?