child. Genius is not an acquired gift. It is born in the individual.
Apart from the marvellous achievements of the man, a mere glance at the
magnificent head, with its high intellectual forehead, the firm lips,
the intelligent inquiring eyes, and the bright face, as seen in existing
pictures, assures us that they portray an unusual individuality,
incompatible with even a suspicion of belonging to an ordinary man.
Doubtless the growing child did give early promise of his future
greatness. Doubtless he was a formidable member of that terrible class
of inquiring youngsters who demand the why and the wherefore of all
around them, and refuse to accept the unsatisfactory belief of their
fathers that things "are because they are." In its self-complacency, the
busy world is too apt to fail to notice unusual abilities in
children,--abilities that perhaps too often remain undeveloped from lack
of opportunities. But whether young Faraday did or did not, at an early
age, display any unusual promise of his life-work, all his biographers
appear to agree that he could not be regarded as a precocious child.
Faraday disclaimed the idea that his childhood was distinguished by any
precocity. "Do not suppose that I was a very deep thinker, or was marked
as a precocious person," says Faraday, when alluding to his early life.
"I was a very lively, imaginative person, and could believe in the
'Arabian Nights' as easily as the 'Encyclopaedia,' but facts were
important to me, and saved me. I could trust a fact and always
cross-examined an assertion. So when I questioned Mrs. Marcet's book [he
is alluding to her 'Conversations on Chemistry'], by such little
experiments as I could find means to perform, and found it true to the
facts as I could understand them, I felt that I had got hold of an
anchor in chemical knowledge, and clung fast to it."
But while there may be a question as to the existence of precocity in
the young lad, there does not appear to be any reason for believing that
his unusual abilities were the result of direct heredity. His father, an
ordinary journeyman blacksmith, never exhibited any special intellectual
ability, though possibly poverty and poor health may have been
responsible for this failure. His mother, too, it appears, was of but
ordinary mentality.
The environment of those early years--that is, from 1804 to 1813, while
in the book-binding business--was far from calculated to develop any
marked abilities inherent in our young philosopher. What would seem less
calculated to inspire a wish to obtain a deeper insight into the
mysteries of the physical world than the trade of book-binding,
especially in the case of a boy whose scholastic education ceased at
fourteen years and was limited to the mere rudiments of learning? But,
fortunately for the world, the inquiring spirit of the lad led him to
examine the inside of the books he bound, and thus, by familiarizing
himself with their contents, he received the inspiration that good
writing is always ready to bestow on those who properly read it. Two
books, he afterwards informs us, proved of especial benefit; namely,
"Marcet's Conversations on Chemistry," already referred to, and the
"Encyclopaedia Britannica." To the former he attributes his grounding in
chemistry, and to the latter his first ideas in electricity, in both of
which studies he excelled in after years. As we have seen, even at this
early age he followed the true plan for the physical investigator,
cross-questioned all statements, only admitting those to the dignity of
facts whose truth he had established by careful experimentation.
But our future experimental philosopher has not as yet fairly started on
the beginnings of his life-work. The possibilities of the book-binding
trade were too limited to permit much real progress. A circumstance
occurred in the spring of 1812 that shaped his entire after-life. This
was the opportunity then afforded him to attend four of the last
lectures delivered at the Royal Institution, by the great Sir Humphry
Davy. Faraday took copious notes of these lectures, carefully wrote them
out, and bound them in a small quarto volume. It was this volume, which
he afterwards sent to Davy, that resulted in his receiving, on March 1,
1813, the appointment of laboratory assistant in the Royal Institution.
His pay for this work was twenty-five shillings a week, with a lodging
on the top floor of the Institute, a very fair compensation for
the times.
Very congenial were the duties of the young assistant. They were to keep
clean the beloved apparatus of the lecturers, and to assist them in
their demonstrations. The new world thus opened was full of bright
promise. He keenly felt the deficiencies of his early education, and
did his best to extend his learning, so that he might be able to make
the most of his opportunities. But what he perhaps appreciated the most
was the inspiration he received from the great teacher Davy, who was
then Professor of Chemistry and Director of the Laboratory of the Royal
Institution; for Faraday assisted at Davy's lectures, and in an humble
way even aided his investigations, sharing the dangers arising from the
explosion of the unstable substance, chloride of nitrogen, that Davy was
then investigating. Faraday has repeatedly acknowledged the debt owed to
the inspiration of this teacher. Davy also, in later life generously
recognized, in his former assistant, a philosopher greater than himself.
As the renowned astronomer, Tycho Brahe, discovered in one of his
pupils, John Kepler, an astronomer greater than the master, and as
Bergman, the Swedish chemist, in a similar manner, discovered the
greater chemist Scheele, so when Davy, in after years, was asked what he
regarded as his greatest discovery, he briefly replied,
"Michael Faraday."
The task of the scientific historian, who endeavors honestly to record
the progress of research, and to trace the influence of the work of some
individual on the times in which he lived, is by no means an easy one;
for, in scientific work one discovery frequently passes so insensibly
into another that it is often difficult to know just where one stops
and the other begins, and much difficulty constantly arises as to whom
the credit should be given, when, as is too often the case, these
discoveries are made by different individuals. It is only when some
great discovery stands alone, like a giant mountain peak against the
clear sky, that it is comparatively easy to determine the extent and
character of its influence on other discoveries, and justly to give the
credit to whom the credit is due. Such discoveries form ready points of
reference in the intellectual horizon, and mark distinct eras in the
world's progress. This is true of all work in the domain of physical
science, but it is especially true in that of electricity and magnetism,
in which Faraday was pre-eminent. The scope of each of these sciences is
so extended, the number of workers so great, and the applications to the
practical arts so nearly innumerable, that it is often by no means an
easy task correctly to trace their proper growth and development.
Faraday's investigations covered vast fields in the domain of chemistry,
electricity, and magnetism. It is to the last two only that reference
will here be made. Faraday's life-work in electricity and magnetism
began practically in 1831, when he made his immortal discovery of the
direct production of electricity from magnetism. His best work in
electricity and magnetism was accomplished between 1831 and 1856,
extending, therefore, over a period of some twenty-five years, although
it is not denied that good work was done since 1856. Consequently, it
was at so comparatively recent a date that most of Faraday's work was
done that some of the world's distinguished electricians yet live who
began their studies during the latter years of Faraday's life. The
difficulties of tracing, at least to some extent, the influence that
Faraday's masterly investigations have had on the present condition of
the electrical arts and sciences will, therefore, be considerably
lessened.
The extent of Faraday's researches and discoveries in magnetism and
electricity was so great that it will be impossible, in the necessarily
limited space of a brief biographical sketch, to notice any but the more
prominent. Nor will any attempt be made, except where the nature of the
research or discovery appears to render it advisable, to follow any
strict chronological order; for, our inquiry here is not so much
directed to a mere matter of history as to the influence which the
investigation or discovery exerted on the life and civilization of the
age in which we live.
There is a single discovery of Faraday that stands out sharply amidst
all his other discoveries, great as they were, and is so important in
its far-reaching results that it alone would have stamped him as a
philosophical investigator of the highest merits, had he never done
anything else. This was his discovery of the means for developing
electricity directly from magnetism. It was made on the 29th of August,
1831, and should be regarded as inspired by the great discovery made by
Oersted in 1820, of the relations existing between the voltaic pile and
electro-magnetism. It was in the same year that Ampere had conducted
that memorable investigation as to the mutual attractions and repulsions
between circuits through which electric currents are flowing, which
resulted in a theory of electro-magnetism, and finally led to the
production of the electro-magnet itself. Ampere had shown that a coil of
wire, or helix, through which an electric current is passing, acted
practically as a magnet, and Arago had magnetized an iron bar by placing
it within such a helix.
In common with the other scientific men of his time, Faraday believed
that since the flow of an electric current invariably produced
magnetism, so magnetism should, in its turn, be capable of producing
electricity. Many investigators before Faraday's time had endeavored to
solve this problem, but it was reserved to Faraday alone to be
successful. Since success in this investigation resulted from some
experiments he made while endeavoring to obtain inductive action on a
quiescent circuit from a neighboring circuit through which an electric
current was flowing, we will first briefly examine this experiment. All
his experiments in this direction were at first unsuccessful. He passed
an electric current through a circuit, which was located close to
another circuit containing a galvanometer,--a device for showing the
presence of an electric current and measuring its strength,--but failed
to obtain any result. He looked for such results only when the current
had been fully established in the active circuit. Undismayed by failure,
he reasoned that probably effects were present, but that they were too
small to be observed owing to the feeble inducing current employed. He
therefore increased the strength of the current in the active wire; but
still with no results.
Again and again he interrogates nature, but unsuccessfully. At last he
notices that there is a slight movement of the galvanometer needle at
the moment of making and breaking the circuit. Carefully repeating his
experiments in the light of this observation, he discovers the important
fact that it is only at the moment a current is increasing or decreasing
in strength--at the moment of making or breaking a circuit--that the
active circuit is capable of producing a current in a neighboring
inactive circuit by induction. This was an important discovery, and in
the light of his after-knowledge was correctly regarded as a solution of
the production of electricity from magnetism.
Observing that the galvanometer needle momentarily swings in one
direction on making the circuit, and in the opposite direction on
breaking it, he establishes the fact that the current induced on making
flows in the opposite direction to the inducing current, and that
induced on breaking flows in the same direction as the inducing current.
Having thus established the fact of current induction, he makes the step
of substituting magnets for active circuits; a simple step in the light
of our present knowledge, but a giant stride at that time. Remembering
that current induction, or, as he called it, voltaic current induction,
takes place only while some effect produced by the current is either
increasing or decreasing, he moves coils of insulated wire towards or
from magnet poles, or magnet poles towards or from coils of wire, and
shows that electric currents are generated in the coils while either the
coils or the magnets are in motion, but cease to be produced as soon as
the motion ceases. Moreover, these magnetically induced currents differ
in no respects from other currents,--for example, those produced by the
voltaic pile,--since, like the latter, they produce sparks, magnetize
bars of steel, or deflect the needle of a galvanometer. In this manner
Faraday solved the great problem. He had produced electricity directly
from magnetism!
With, perhaps, the single exception of the discovery by Oersted, in
1820, of the invariable relation existing between an electric current
and magnetism, this discovery of Faraday may be justly regarded as the
greatest in this domain of physical science. These two master minds in
scientific research wonderfully complemented each other. Oersted showed
that an electric current is invariably attended by magnetic effects;
Faraday showed that magnetic changes are invariably attended by electric
currents. Before these discoveries, electricity and magnetism were
necessarily regarded as separate branches of physical science, and were
studied apart as separate phenomena. Now, however, they must be regarded
as co-existing phenomena. The ignorance of the scientific world had
unwittingly divorced what nature had joined together.
In view of the great importance of Faraday's discovery, we shall be
justified in inquiring, though somewhat briefly, into some of the
apparatus employed in this historic research. Note its extreme
simplicity. In one of his first successful experiments he wraps a coil
of insulated wire around the soft iron bar that forms the armature or
keeper of a permanent magnet of the horse-shoe type, and connects the
ends of this coil to a galvanometer. He discovers that whenever the
armature is placed against the magnet poles, and is therefore being
rendered magnetic by contact therewith, the deflection of the needle of
the galvanometer shows that the coiled wire on the armature is traversed
by a current of electricity; that whenever the armature is removed from
the magnet poles, and is therefore losing its magnetism, the needle of
the galvanometer is again deflected, but now in the opposite direction,
showing that an electric current is again flowing through the coiled
wire on the armature, but reversed in direction. He notices, too, that
these effects take place only while changes are going on in the strength
of the magnetism in the armature, or when magnetic flux is passing
through the coils; for, the galvanometer needle comes to rest, and
remains at rest as long as the contact between the armature and the
poles remains unbroken.
In another experiment he employs a simple hollow coil, or helix, of
insulated wire whose ends are connected with a galvanometer. On suddenly
thrusting one end of a straight cylindrical magnet into the axis of the
helix, the deflection of the galvanometer needle showed the presence of
an electric current in the helix. The magnet being left in the helix,
the galvanometer needle came to rest, thus showing the absence of
current. When the bar magnet was suddenly withdrawn from the helix, the
galvanometer needle was again deflected, but now in the opposite
direction, showing that the direction of the current in the helix had
been reversed.
The preceding are but some of the results that Faraday obtained by
means of his experimental researches in the direct production of
electricity from magnetism. Let us now briefly examine just what he was
doing, and the means whereby he obtained electric currents from
magnetism. We will consider this question from the views of the present
time, rather than from those of Faraday, although the difference between
the two are in most respects immaterial.
Faraday knew that the space or region around a magnet is permeated or
traversed by what he called magnetic curves, or lines of magnetic force.
These lines are still called "lines of magnetic force," or by some
"magnetic streamings" "magnetic flux," or simply "magnetism." They are
invisible, though their presence is readily manifested by means of iron
filings. They are present in every magnet, and although we do not know
in what direction they move, yet in order to speak definitely about
them, it is agreed to assume that they pass out of every magnet at its
north-seeking pole (or the pole which would point to the magnetic north,
were the magnet free to move as a needle), and, after having traversed
the space surrounding the magnet, reenter at its south-seeking pole,
thus completing what is called the magnetic circuit. Any space traversed
by lines of magnetic force is called a magnetic field.
But it is not only a magnet that is thus surrounded by lines of
magnetic force, or by ether streamings. The same is true of any
conductor through which an electric current is flowing, and their
presence may be shown by means of iron filings. If an active
conductor--a conductor conveying an electric current, as, for example, a
copper wire--be passed vertically through a piece of card-board, or a
glass plate, iron filings dusted on the card or plate will arrange
themselves in concentric circles around the axis of the wire. It
requires an expenditure of energy both to set up and to maintain these
lines of force. It is the interaction of their lines of force that
causes the attractions and repulsions in active movable conductors.
These lines of magnetic force act on magnetic needles like other lines
of magnetic force and tend to set movable magnetic needles at right
angles to the conducting wire.
The setting up of an electric current in a conducting wire is,
therefore, equivalent to the setting up of concentric magnetic whirls
around the axis of the wire, and anything that can do this will produce
an electric current. For example, if an inactive conducting wire is
moved through a magnetic field; it will have concentric circular whirls
set up around it; or, in other words, it will have a current generated
in it as a result of such motion. But to set up these whirls it is not
enough that the conducting wire be moved along the lines of force in the
field. In such a case no whirls are produced around the conductor. The
conductor must be moved so as to cut or pass through the lines of
magnetic force. Just what the mechanism is by means of which the cutting
of the lines of force by the conductor produces the circular magnetic
whirls around it, no man knows any more than he knows just what
electricity is; but this much we do know,--that to produce the circular
whirls or currents in a previously inactive conductor, the lines of
force of some already existing magnetic field must be caused to pass
through the conductor, and that the strength of the current so produced
is proportional to the number of lines of magnetic force cut in a given
time, say, per second; or, in other words, is directly proportional to
the strength of the magnetic field, and to the velocity and length of
the moving conductor.
Or, briefly recapitulating: Oersted showed that an electric current,
passed through a conducting circuit, sets up concentric circular whirls
around its axis; that is, an electric current invariably produces
magnetism; Faraday showed, that if the lines of magnetic force, or
magnetism, be caused to cut or pass through an inactive conductor,
concentric circular whirls will be set up around the conductor; that is,
lines of magnetic force passed across a conductor invariably set up an
electric current in that conductor.
The wonderful completeness of Faraday's researches into the production
of electricity from magnetism may be inferred from the fact that all
the forms of magneto-electric induction known to-day--namely,
self-induction, or the induction of an active circuit on itself; mutual
induction, or the induction of an active circuit on a neighboring
circuit; and electro-magnetic induction, and magneto-electric induction,
or the induction produced in conductors through which the magnetic flux
from electro and permanent magnets respectively is caused to pass--were
discovered and investigated by him. Nor were these investigations
carried on in the haphazard, blundering, groping manner that
unfortunately too often characterizes the explorer in a strange country;
on the contrary, they were singularly clear and direct, showing how
complete the mastery the great investigator had over the subject he was
studying. It is true that repeated failures frequently met him, but
despite discouragements and disappointments he continued until he had
entirely traversed the length and breadth of the unknown region he was
the first to explore.
Let us now briefly examine Faraday's many remaining discoveries and
inventions. Though none of these were equal to his great discovery, yet
many were exceedingly valuable. Some were almost immediately utilized;
some waited many years for utilization; and some have never yet been
utilized. We must avoid, however, falling into the common mistake of
holding in little esteem those parts of Faraday's work that did not
immediately result either in the production of practical apparatus, or
in valuable applications in the arts and sciences, or those which have
not even yet proved fruitful. Some discoveries and devices are so far
ahead of the times in which they are produced that several lifetimes
often pass before the world is ready to utilize them. Like immature or
unripe fruit, they are apt to die an untimely death, and it sometimes
curiously happens that, several generations after their birth, a
subsequent inventor or discoverer, in honest ignorance of their prior
existence, offers them to the world as absolutely new. The times being
ripe, they pass into immediate and extended public use, so that the
later inventor is given all the credit of an original discovery, and the
true first and original inventor remains unrecognized.
We will first examine Faraday's discovery of the relations existing
between light and magnetism. Though the discovery has not as yet borne
fruit in any direct practical application, yet it has proved of immense
value from a theoretical standpoint. In this investigation Faraday
proved that light-vibrations are rotated by the action of a magnetic
field. He employed the light of an ordinary Argand lamp, and polarized
it by reflection from a glass surface. He caused this polarized light to
pass through a plate of heavy glass made from a boro-silicate of lead.
Under ordinary circumstances this substance exerted no unusual action on
light, but when it was placed between the poles of a powerful
electro-magnet, and the light was passed through it in the same
direction as the magnetic flux, the plane of polarization of the light
was rotated in a certain direction.
Faraday discovered that other solid substances besides glass exert a
similar action on a beam of polarized light. Even opaque solids like
iron possess this property. Kerr has proved that a beam of light passed
through an extremely thin plate of highly magnetic iron has its plane of
polarization slightly rotated. Faraday showed that the power of rotating
a beam of polarized light is also possessed by some liquids. But what is
most interesting, in both solids and liquids, is that the direction of
the rotation of the light depends on the direction in which the
magnetism is passing, and can, therefore, be changed by changing the
polarity of the electro-magnet.