THE ELECTRIC LIGHT.
[Illustration]
It has been stated that modern theory recognizes two classes of
electricity, the _Static_ and the _Dynamic_. The difference
is, however, solely noticeable in operation. Of the dynamic class there
can be no more common and striking example than the now almost universal
electric light. Yet, with a sufficient expenditure of chemicals and
electrodes, and a sufficient number of cells, electric lighting, either
arc or incandescent, can be as effectively accomplished as with the
current evolved by a powerful dynamo. [Footnote: As an illustration of
the day of beginnings, a few years ago the _thalus_, or lantern,
the pride of the rural Congressman, on the dome of the Capitol at
Washington was lighted by electricity, and an immense circular chamber
beneath the dome was occupied by hundreds of cells of the ordinary form
of battery. The lamps were of the incandescent variety, and what we now
know as the filament was platinum wire. Vacuum bulb, filament, carbon,
dynamo, were all unknown. But the current, and the heat of resistance,
and every fact now in use in electric lighting, were there in
operation.]
The reader will understand that modern dynamic electricity owes its
development to the principle of economy in production. Practical science
most effectively awakens from its lethargy at the call of commerce.
Nevertheless, from the earliest moment in which it became known that
electricity was akin to heat--that an interruption of the easy passage
of a current produced heat--the minds of men were busy with the question
of how to turn the tremendous fact to everyday use. Progress was slow,
and part of it was accidental. The great servant of modern mankind was
first an untrained one. It was a marked advance when the gaslights in a
theater could be all lighted at once by means of batteries and the spark
of an induction coil. The bottom of Hell Gate, in New York harbor, was
blown out by Gen. Newton by the same means, and would have been
impossible otherwise. But these were only incidents and suggestions.
The question was how to make this instantaneous spark _continuous_.
There was pondering upon the fact that the only difference between heat
and electricity is one of molecular arrangement. Heat is a molecular
motion like that of electricity, without the symmetry and harmony of
action electricity has. The vibrations of electricity are accomplished
rapidly, and without loss. Those of heat are slow, and greatly
radiated. _When a current of electricity reaches a place in the
conductor where it cannot pass easily, and the orderly vibrations of its
molecules are disturbed, they are thrown into the disorderly motion
known as heat._ So, when the conductor is not so good; when a large
wire is reduced suddenly to a small one; when a good conductor, such as
copper, has a section of resisting conduction, such as carbon; heat and
light are at once evolved at that point, and there is produced what we
know as the electric light. However concealed by machinery and devices,
and all the arrangements by which it is made more lasting, steady,
economical and automatic, it is no more nor less than this. _The
difference between heat and electricity is only a difference in the
rates of vibration of their molecules._ Whatever the theory as to
molecules, or essence, or actual nature and origin, the practical fact
that heat and light are the results of the circumstances described above
remains. This has long been known, and the question remained how to
produce an adequate current economically. The result was the machine we
know as the Dynamo.
The first electric light was very brief and brilliant and was made by
accident. Sir Humphrey Davy, in 1809, in pulling apart the two ends of
wires attached to a battery of two thousand small cells, the most
powerful generator that had been made to that time, produced a brief and
brilliant spark, the result of momentarily _imperfect contact._
Every such spark, produced since then innumerable times by accident, is
an example of electric lighting. There are now in use in the United
States some two million arc lights and nearly double that number of
incandescent.
There are two principal systems of electric lighting; one is by actually
burning away the ends of carbon-points in the open air. This is the
"arc." The other is by heating to a white heat a filament of carbon, or
some substance of high resistance, in a glass bulb from which the air
has been exhausted. This is the "incandescent."
[Illustration: THE INCANDESCENT LIGHT]
In the arc light the current passes across an _imperfect contact_,
and this imperfection consists in a gap of about one-sixteenth of an
inch between the extremities of two rods of carbon carrying a current.
This small gap is a place of bad conduction and of the piling up of
atoms, producing heat, burning, light. In the body of the lamp there are
appliances for the automatic holding apart of the two points of the
carbon, and the causing of them to continually creep together, yet never
touch. Many devices have been contrived to this end. With all theories
and reasons well known, and all effects accurately calculated, upon this
small arrangement depends the practical utility of the arc light. The
best arrangement is the invention of Edison, and is controlled most
ingeniously by the current itself, acting through the increased
difficulty of its passage when the two carbon-points are too far apart,
and the increased ease with which it flows when they are too near
together. The current, in leaping the small gap between the
carbon-points, takes a _curved_ path, hence the name "arc" light.
In passing from the positive to the negative carbon it carries small
particles of incandescent carbon with it, and consequently the end of
the positive carbon is hollowed out, while the end of the negative is
built up to a point.
The incandescent light is in principle the same as the arc, produced by
the same means and based upon the same principle of impediment to the
free passage of the current. It was first produced by heating with the
current to incandescence a fine platinum wire. As stated above,
electricity that quietly traverses a large wire will suddenly develop
great heat upon reaching a point where it is called upon to traverse, a
smaller one. Platinum was attempted for this place of greater resistance
because of its qualities. It does not rust, has a low specific heat, and
is therefore raised to a higher temperature with less heat imparted. But
it was a scarce and expensive material, and so long as it was heated to
incandescence in the open air, that is, so long as its heat was fed as
other heat is, by oxygen, it was slowly consumed. Platinum is no longer
in the field of electric lighting, and the substitute which takes its
place in the present incandescent lamp, and which is known as a
"filament," is not heated in contact with the air. The experiments and
endeavors that brought this result constitute the story of the
incandescent lamp.
The result is due to the patient intelligence of the American scientist
and inventor, Thomas A. Edison. After all the absolute essentials of a
practical incandescent lamp had been thought out; after the qualities
and characteristics of the current were all known under the
circumstances necessary to its use in lighting, the practical
accomplishment still remained. Edison is said to have once worked for
several weeks in the making of a single loop-shaped carbon filament that
would bear the most delicate handling. This was then carefully carried
to a glass-worker to be inclosed in a bulb, and at the first movement he
broke it, and the work must be done over and done better. It finally
was. The little pear-shaped bulb with its delicate loop of filament,
which cost months of toil and experiment at first, is now a common
article, manufactured at an absurdly small cost, packed in barrelfuls
and shipped everywhere, and consumed by the million. A means has been
found for producing the vacuum of its interior rapidly, cheaply and
thoroughly, and the beautiful incandescent glow hangs in lines and
clusters over the civilized world. The phenomenon of incandescence
without oxygen seems peculiar to these lights alone. [Footnote: The
"electric field," previously explained, seemed to exist by giving a
magnetic quality to the surrounding air. It would be as true if one
should speak of a magnetized vacuum, since the same field would exist in
that as in surrounding air.]
So simple are great facts when finally accomplished that there remains
little to add on the subject of the mechanism of the electric light. The
two varieties, arc and incandescent, are used together as most
convenient, the large and very brilliant arc being especially adapted to
out-of-doors situations, and the gentler, steadier and more permanent
glow of the incandescent to interiors. The latter is also capable of a
modification not applicable to the arc. It can, in theaters and other
buildings, be "turned down" to a gentle, blood-red glow. The means by
which this is accomplished is ingenious and surprising, since it means
that the supply of electricity over a wire--seemingly the most subtle
and elusive essence on earth--may be controlled like a stream from a
cock, or the gas out of a burner. But this reduction of the current that
makes the red glow in the clusters in a theater is by no means the only
instance. The trolley-car, and even the common motor, may be made to
start very slowly, and the unseen current whose touch kills is fed to
its consumer at will.
[Illustration]
THE DYNAMO.--To the man who has been all his life thinking of the steam
engine as the highest and almost only embodiment of controlled
mechanical power, another machine, both supplementary to the steam
engine and far excelling it, whose familiar _burring_ sound is now
heard in almost every village in the United States and has become the
characteristic sound of modern civilization, must constitute a source of
continual question and surprise. To be accustomed to the dynamo, to look
upon it as a matter of course and a conceded fact, one must have come to
years of maturity and found it here.
Its practical existence dates back at furthest to 1870. Yet it is based
upon principles long since known, and can scarcely be said to be the
invention of any one mind or man. Its lineal ancestor was the
_magneto-electric machine_, in the early construction of which
figure the names of Siemens, Wilde, Ladd, and earlier and later
electricians. Kidder's medical battery used forty years ago or more, and
still used and purchasable in its first form, was a dynamo. A footnote
in a current encyclopedia states that: "An account of the
Magneto-electric machine of M. Gramme, in the London _Standard_ of
April 9th, 1873, confirmed by other information, leads to the belief
that a decided improvement has been made in these machines." The word
"dynamo" was then unknown. Later, Edison, Weston, Thompson, Hopkinson,
Ferranti and others appear as improvers in the mechanism necessary for
best developing a well-known principle, and many of these improvements
may be classed among original inventions. As soon as the
magneto-electric machine attained a size in the hands of experimenters
that took it out of the field of scientific toys it began to be what we
now know as a dynamo. A paragraph in the encyclopedia referred to says,
in speaking of Ladd, of London, "These developments of electric action
are not obtained without corresponding expenditure of force. The armatures
are powerfully attracted by the magnets, and must be forcibly pulled away.
Indeed, one of Wilde's machines, when producing a very intense electric
light, required about five horse power to drive it."
[Illustration: MAGNETO-ELECTRIC MACHINE. THE PREDECESSOR OF THE DYNAMO.]
Thus was the secret in regard to electric power unconsciously divulged
some twenty years ago.
In all nature there is no recipe for getting something for nothing. The
modern dynamo, apparently creating something out of nothing, like all
other machines _gives back only what is given to it_, minus a fair
percentage for waste, loss, friction, and common wear. Its advantages
amount to a miracle of convenience only. So far as power is concerned,
it merely transfers it for long distances over a single wire. So far as
light is considered, it practically creates it where wanted, in new and
convenient forms, with a new intensity and beauty, but with the same
expenditure of transmitted energy in the form of burned coal as would be
used in manufacturing the gas that was new, wonderful, and a luxury at
the beginning of the century.
The dynamo is the most prominent instance of actual mechanical utility
in the field of electrical induction. It seems almost incredible that
the apparently small facts discovered by Faraday, the bookbinder, the
employé of Sir Humphrey Davy at weekly wages the struggling experimenter
in the subtleties of an infant giant, should have produced such results
within sixty years. [Footnote: Faraday was not entirely alone in his
life of physical research. He was associated with Davy, and quarreled
with him about the liquefaction of chlorine and other gases, and was the
companion of Wallaston, Herschel, Brand, and others. In connection with
Stodart, he experimented with steel, with results still considered
valuable. The scientific world still speaks of his quarrel with Davy
with regret, since the personalities of great men should be free from
ordinary weaknesses. But Lady Davy was not a scientist, and while the
brilliant young mechanic was in her husband's employment for scientific
purposes she insisted upon treating him as a servant, whereat the
independence of thinking which made him capable of wandering in fields
unknown to conventionality and routine blazed into natural resentment.
The quarrel of 1823 must have been greatly augmented, in the lady's
eyes, in 1824, for in that year Faraday was made a member of the Royal
Society.
In his lectures and public experiments he was greatly assisted by a man
now almost forgotten, an "intelligent artilleryman" named Andersen. This
unknown soldier with a taste for natural science doubtless had his
reward in the exquisite pleasure always derived from the personal
verification of facts hitherto unknown. There is often a pecuniary
reward for the servant of science. Just as often there is not, and the
work done has been the same.
It was on Christmas morning, 1821, that Faraday first succeeded in
making a magnetic needle rotate around a wire carrying an electric
current. He was the discoverer of benzole, the basis of our modern
brilliant aniline dyes. In 1831 he made the discovery he had been
leading to for many years--that of magneto-electric induction. All we
have of electricity that is now a part of our daily life is the result
of this discovery.
Faraday was born in 1791, and died August, 1867, in a house presented to
him by Victoria, who had not the same opinion of his relations to the
aristocracy that Lady Davy seems to have had. His insight into science
was something explainable only on the supposition that he was gifted
with a kind of instinct. He was a scientific prophet. A man who could,
in 1838, foresee the ocean cable, and describe those minute difficulties
in its working that all in time came true, must be classed as one of the
great, clear, intuitive intellects of his race. He was in youth
apprenticed to a bookbinder, "and many of the books he bound he read." A
line in his indentures says: "In consideration of his faithful service,
no premium is to be given." When these words were written there was no
dream that the "faithful service" should be for all posterity.]
[Illustration: Faraday's Spark. Striking the leg of a horseshoe magnet
with an iron bar wound with insulated wire causes a contact between
loose end of wire and small disc, and a spark.
Faraday's First Magneto-Electric Experiment. A horseshoe magnet passed
near a bent soft iron wound with insulated wire caused an induced
current in the wire.
TWO OF FARADAY'S EARLY EXPERIMENTS IN INDUCTION.]
He who made the first actual machine to evolve a current in compliance
with Faraday's formulated laws was an Italian named Pixü, in 1832. His
machine consisted of a horseshoe magnet set on a shaft, and made to
revolve in front of two cores of, soft iron wound with wire, and having
their ends opposite the legs of the magnet. Shortly after Pixü, the
inventors of the times ceased to turn the magnet on a shaft, and turned
the iron cores instead, because they were lighter. In like manner, the
huge field magnets of a modern dynamo are not whirled round a stationary
armature, but the armature is whirled within the legs of the magnet with
very great rapidity. The next step was to increase the number of magnets
and the number of wire-wound iron cores--bobbins. The magnets were made
compound, laminated; a large number of thin horseshoe magnets were laid
together, with opposite poles touching. These were all comparatively
small machines--what we now, with some reason, regard as having been
toys whose present results were rather long in coming.
[Illustration: THE SIEMENS' ARMATURE AND WINDING. THE FIRST STEP TOWARD
THE MODERN DYNAMO.]
Then came Siemens, of Berlin, in 1857. He was probably the first to wind
the iron core, what we now call the _armature_, with wire from end
to end, _lengthwise_, instead of round and round as a spool. This
resulted, of course, in the shaft of the armature being also placed
crosswise to the legs of the magnet, as it is in the modern dynamo. One
of the ends of the wire used in this winding was fastened to the axle of
the armature, and the other to a ring insulated from the shaft, but
turning with it. Two springs, one bearing on the shaft and the other on
the ring, carried away the current through wires attached to them.
Siemens also originated the mechanical idea of hollowing out the legs of
the magnet on the inside for the armature to turn in close to the
magnet, almost fitting. It was the first time any of these things had
been done, and their author probably had no idea that they would be
prominent features of the dynamo of a little later time, in all
essentials closely imitated.
[Illustration: DIAGRAM OF SHAFT, SPLIT RING AND "BRUSHES."]
It will be guessed from what has been previously said on the subject of
induction that the currents from such an electro-magnetic machine would
be alternating currents, the impulses succeeding each other in alternate
directions. To remedy this and cause the currents to flow always in the
same direction, the "_commutator_" was devised. The ring mentioned
above was split, and the two springs both bore upon it, one on each
side. The ends of the wires were both fastened to this ring. The springs
came to be known as "brushes." The effect was that one of them was in
the insulated space between the split halves of the ring while the other
was bearing on the metal to which the wire was attached. This action was
alternate, and so arranged that the current carried away was always
direct. When an armature has a winding of more than one wire, as the
practical dynamo always has, the insulated ring is divided into as many
pieces as there are wires, and the two brushes act as above for the
entire series.
Pacinotti, of Florence, constructed a magneto-electric machine in which
the current flows always in one direction without a commutator. It has
what is known as a _ring armature_, and is the mother of all
dynamos built upon that principle. It is exceedingly ingenious in
construction, and for certain purposes in the arts is extensively used.
A description of it is too technical to interest others than those
personally interested in the class of dynamo it represents.
Wilde, of Manchester, England, improved the Siemens machine in 1866 by
doing that which is the feature that makes possible the huge "field
magnet" of the modern dynamo, which is not a magnet at all, strictly
speaking. He caused the current, after it had been rectified by the
commutator, to return again into coils of wire round the legs of his
field magnets, as shown in the diagram. This induced in them a new
supply of magnetism, and this of course intensified the current from the
armature. It is true he had a separate smaller magneto-electric machine,
with which he evolved a current for the coil around the legs of the
field magnet of a greatly larger machine upon which he depended for his
actual current, and that he did not know, although he was practically
doing the same thing, that if he should divert this current made by the
larger machine itself back through the coils of its field magnet, he
would not need the extra small machine at all, and would have a much
more powerful current.
[Illustration: SIMPLEST FORM OF DYNAMO]
And here arises a difference and a change of name. All generating
machines to this date had been called "_Magneto-electric_" because
they used _permanent_ steel magnets with which to generate a
current by the whirling of the bobbin which we now call an armature. The
time came, led to by the improvement of Wilde, in which those steel
permanent magnets were no longer used. Then the machine became the
"_dynamo-electric_" machine, and leaving off one word, according to
our custom, "_dynamo_."
Siemens and Wheatstone almost simultaneously invented so much of the
dynamo as was yet incomplete. It has "cores"--the parts that answer to
the legs of a horseshoe magnet--of soft iron, sometimes now even of cast
iron. These, at starting, possess very little magnetism--practically
none at all--yet sufficient to generate a very weak current in the
coils, windings, of the armature when it begins to turn. This weak
current, passing through the windings of the field magnet, makes these
still stronger magnets, and the effect is to evolve a still stronger
current in the armature. Soon the full effect is reached. The big iron
field magnet, often weighing some thousands of pounds, is then the same
as a permanent steel horseshoe magnet, which would hardly be possible at
all. One who has watched the installation of a dynamo, knowing that
there is nowhere near any ordinary source of electricity, and has seen
its armature begin to whirl and hum, and then in a few moments the
violet sparklings of the brushes and the evident presence of a powerful
current of electricity, is almost justified in the common opinion that
the genius of man has devised a machine to _create_ something out
of nothing. It is true that a _starting_ quantity of electricity is
required. It exists in almost every piece of iron. Sometimes, to hasten
first action, some cells of a galvanic battery are used to pass a
current through the coils of the field magnet. After the first use there
is always enough magnetism remaining in them during rest or stoppage to
make a dynamo efficient after a few moments operation.
[Illustration: PACINOTTI'S RING-ARMATURE DYNAMO.]
This is the dynamo in principle of action. The varieties in construction
now in use number scores, perhaps hundreds. Some of them are monsters in
size, and evolve a current that is terrific. They are all essentially
the same, depending for action upon the laws illustrated in the simplest
experiment in induced electricity. One of the best known of the modern
machines is Edison's, represented in the picture at the head of this
article. In it the field magnet--answering to the horseshoe magnet of
the magneto-electric machine--is plainly distinguishable to the
unskilled observer. It is not even solid, but is made of several pieces
bolted together. Its legs are hollowed at the ends to admit closely the
armature which turns there. There are valuable peculiarities in its
construction, which, while complying in all respects with the dynamo
principle, utilize those principles to the best mechanical advantage. So
do others, in other respects that did not occur even to Edison, or were
not adopted by him. Probably the modern dynamo is the most efficient,
the most accurately measurable, the least wasteful of its power, and the
most manageable, of any power-machine so far constructed by man for
daily use.
The motor.--This is the twin of the dynamo. In all essentials the two
are of the same construction. A difference in the arrangement of the
terminals of the wire coils or the wrappings of armature and field
magnet, makes of the one a dynamo and of the other a motor.
Nevertheless, they are separate studies in electrical science. Practice
has brought about modified constructions, as in the case of the dynamo.
The differences between the two machines, and their similarities as
well, may be explained by a general brief statement.
_It is the work of the dynamo to convert mechanical energy into the
form of electrical energy. The motor, in turn, changes this electrical
energy back again into mechanical energy._
Where the electric light is produced by the dynamo current no motor
intervenes. The current is converted into heat and light by merely
having an impediment, a restriction, a narrowness, interposed to its
free passage on a conducting wire, as heretofore explained, very much as
water in a pipe foams and struggles at a narrow place or an obstruction.
Where mechanical movements are to be produced by the dynamo current the
motor is always the intermediate machine. In the dynamo the armature is
rotated by steam power, producing an electrical energy in the form of a
powerful current transmitted by a wire. In the motor the armature, in
turn, _is rotated by_ this current. It is but another instance of
that ability to work backwards--to reverse a process--that seems to
pervade all machines, and almost all processes. I have mentioned steam
power, and, consequently, the necessary burning of coal and expenditure
of money in producing the dynamo current. The dynamo and motor are not
necessarily economical inventions, but the opposite when the force
produced is to be transmitted again, with some loss, into the same
mechanical energy that has already been produced by the burning of coal
and the making of steam. Across miles of space, and into places where
steam would not be possible, the power is invisibly carried. Suggestions
of this convenience--stated cases--it is not necessary to cite. The
fact is a prominent one, to be noted everywhere.
And it may be made a mechanical economy. The most prominent instance of
this is the new utilization of Niagara as a turbine water-power with
which to whirl the armatures of gigantic dynamos, using the power thus
obtained upon motors, and in the production of light and the
transmission of power to neighboring cities.
The discovery of the possibility of transmitting power by a wire, and
converting it again into mechanical energy, is a strange story of the
human blindness that almost always attends an acuteness, a thinking
power, a prescience, that is the characteristic of humanity alone, but
which so often stops short of results. This discovery has been
attributed to accident alone; the accident of an employé mistaking the
uses of wires and fastening their ends in the wrong places. But a French
electrician thus describes the occurrence as within his own experience.
His name is Hypolyte Fontaine.
But let us first advert to the forgetfulness of the man who really
invented the machine that was capable of the opposite action of both
dynamo and motor. This was the Italian, Pacinotti. [Footnote: Moses G.
Farmer, an American, and celebrated in his day for intelligent
electrical researches, is claimed to have made the first reversible
motor ever contrived. A small motor made by Farmer in 1847, and
embodying the electro-dynamic principle was exhibited at the great
exposition at Chicago in 1893. If the genealogy of this machine remains
undisputed it fixes the fact that the discovery belongs to this country,
and to an American.] He mentioned that his machine could be used either
to generate a current of electricity on the application of motive power
to its armature, or to produce motive power on connecting it with a
source of electricity. Yet it did not occur to him to definitely
experiment with two of his machines for the purpose of accomplishing
that which in less than twenty years has revolutionized our ideas and
practice in transmitted force. He did not suggest that two of his
machines could be run together, one as a generator and the other as a
motor. He did not think of its advantages with the facilities for it, of
his own creation, in his hands.
M. Fontaine states that at the Vienna Exposition of 1873 there was a
Gramme machine intended to be operated by a primary battery, to show
that the Gramme was capable of being worked by a current, and, as there
was also a second machine of the same kind there, of also generating
one. These two machines were to demonstrate this range of capacity as
_separately worked_, one by power, the other with a battery. There
was, then, no intention of coupling them together as late as 1873, with
the means at hand and the suggestion almost unavoidable. The dynamo and
motor had not occurred to any one. But M. Fontaine states that he failed
to get the primary (battery) current in time for the opening, and was
troubled by the dilemma. Then the idea occurred to him, as he could do
no better, to work one of the machines with a current "deprived," partly
stolen, from the other, as a temporary measure. A friend lent him the
necessary piece of wire, and he connected the two machines. The machine
used as a motor was connected with a pumping apparatus, and when the
machine intended as a generator started, and this make-shift,
temporarily-stolen current was carried to the acting motor, the action
of the last was so much more vigorous than was intended that the water
was thrown over the sides of the tank. Fontaine was forced to remedy
this excessive action by procuring an additional wire of such length
that its resistance permitted the motor to work more mildly and throw
less water. This accidentally established the fact of distance,
convenience, a revolution in the power of the industrial world. Fontaine
states that Gramme had previously told him that he had done the same
thing with his machines. The idea was never patented. Neither Pacinotti,
who invented the machine originally, nor Gramme, one of the great names
of modern electricity, nor this skilled practical electrician, Fontaine,
who had charge of the exhibit of the Gramme system at Vienna, considered
the fact of the transmission of concentrated power over a thin wire to a
great distance as one of value to its inventor or to the industries of
mankind. With the motor and the dynamo already made, it was an accident
that brought them together after all.
* * * * *
It may be amusing, if not useful, to spend a moment in reviewing of the
efforts of men to utilize the power of the electrical current in
mechanics before the day of the dynamo and a motor, and while yet the
electric light was an infant in the nursery of the laboratory. They knew
then, about 1835 to 1870, of the laws of induction as applied to the
electro-magnet, or in small machines the generating power, so called, of
the magneto-electric arrangement embodied, as a familiar example, in
Kidder's medical battery. There is a long list of those inventors,
American and European. The first patent issued for an American
electro-motor was in 1837, to a man named Thomas Davenport, of Brandon,
Vt. He was a man far ahead of his times. He built the first electric
railroad ever seen, at Springfield, Mass., in 1835, and considering the
means, whose inadequacy is now better understood by any reader of these
lines than it then was by the deepest student of electricity, this first
railroad was a success. Davenport came as near to solving the problem of
an electric motor as was possible without the invention of Pacinotti.
Following this there were many patents issued for electro-magnetic
motors to persons residing in all parts of the country, north and south.
One was made by C. G. Page, of the Smithsonian Institute, in which the
motive power consisted in a round rod, acting as a plunger, being pulled
into the space where the core would be in an ordinary electro-magnet,
and thereby working a crank. [Footnote: The _National
Intelligencer_, a prominent Washington newspaper, said with reference
to Page's motor "He has shown that before long electro-magnetic action
will have dethroned steam and will be the adopted motor," etc. This was
an enthusiasm not based upon any fact then known about a machine not
even in the line of the present facts of electro-dynamics.] A large
motor of this kind is alleged, in 1850, to have developed ten horse
power. It was actually applied to outdoor experiment as a car-motor on
an actual railroad track, and was efficient for several miles. But it
carried with it its battery-cells, and they were disarranged and stirred
by the jolting, and being made of crockeryware were broken. The
chemicals cost much more than fuel for steam, and there could be no
economical motive for further experiment. It was a huge toy, as the
entire sum of electrical science was until it was made useful first in
the one instance of the telegraph, and long after that date the use of
the electro-magnet, with a cam to cut off and turn on again the current
at proper intervals, which was the one principle of all attempts, was a
repeated and invariable failure. That which was wanted and lacking was
not known, and was finally discovered and successively developed as has
been described.
Electric railroads.--There was an instance of almost simultaneous
invention in the case of the first practical electric railroads. S. D.
Field, Dr. Siemens, and Thomas A. Edison all applied for patents in
1880. Of these, Field was first in filing, and was awarded patents. The
combined dynamo and motor were, of course, the parents of the practical
idea. Field's patents covered a motor in or under the car, operated by a
current from a stationary source of electricity--of course a dynamo.
These first electric roads had the current carried on the rail. They
were partially successful, but there was something wrong in the plan,
and that something was induction by the earth. Later came, as a remedy
for this, the "Trolley" system; the trolley being a small, grooved wheel
running upon a current-carrying wire overhead. The question of how best
to convey a current to the car-motor is a serious one, doubtless at this
moment occupying the attention of highly-trained intelligence
everywhere. The motor current is one of high power, and as such
intractable; and it is in the character of this current, rather than in
methods of insulation, that the remedy for the much-objected-to overhead
wire is to be found. It will be remembered that all the phenomena of
induction are _unhindered by insulation_.
Aside from the current-carrying problem, the electric road is
explainable in all its features upon the theory and practice of the
dynamo and motor. It is merely an application of the two machines. The
last is, in usual practice, under the car, and geared to the truck-axle.
A more modern mechanical improvement is to make the axle the shaft of
the motor armature. When the motor has used the current it passes by
most systems into the rail and the ground. By others there is a
"metallic circuit"--two wires. Many men whose interest and occupation
leads them to a study of such matters know that the use of electricity,
instead of steam locomotion, is merely a question of time on all
railroads. I have said elsewhere that the actual age of electricity had
not yet fully come. It seems to us now that we have attained the end;
that there is little more to know or to do. But so have all the
generations thought in their day. In the field of electricity there are
yet to come practical results of which one may have some foreshadowings
in the experiments of men like Tesla, which will make our present times
and knowledge seem tame and slow.
Electrolysis.--In all history, fire has been the universal practical
solvent. It has been supplanted by the electrical current in some of the
most beautiful and useful phenomena of our time. Electrolysis is the
name of the process by which fluid chemicals are decomposed by the
current.
A familiar early experiment in electrolysis is the decomposition of
water--a chemical composed of oxygen and hydrogen, though always thought
of and used as a simple, pure fluid. If the poles of a galvanic battery
are immersed in water slightly mixed with sulphuric acid to favor
electrical action, these poles will become covered with bubbles of gas
which presently rise to the surface and pass off. These bubbles are
composed of the two constituents of water, the oxygen rising from the
positive and the hydrogen from the negative pole. Particles of the
substance decomposed are transferred, some to one pole and some to the
other; and, therefore, electrolysis is always practiced in a fluid in
order that this transference may more readily occur.
The quantity of _electrolyte_--the substance decomposed--that is
transferred in a given time is in proportion to the strength of the
current. When this electrolyte is composed of many substances a current
will act a little on all of them, and the quantity in which the
elementary bodies appear at the poles of the current depends upon the
quantities of the compounds in the liquid, and on the relative ease with
which they yield to the electrical action.
The electrolytic processes are not the mere experiments a brief
description of them would indicate, but are among the important
processes for the mechanical products of modern times. The extensive
nickel-plating that became a permanent fad in this country on the
discovery of a special process some years ago, is all done by
electrolysis. The silver plating of modern tableware and table cutlery,
as beautiful and much less expensive than silver, and the fine finish of
the beautiful bronze hardware now used in house-furnishing, are the
results of the same process. Some use for it enters into almost every
piece of fine machinery, and into the beautifying or preserving of
innumerable small articles that are made and used in unlimited quantity.
The process and its principle is general, but there are many details
observed in the actual work of electroplating which interest only those
engaged. One of the most usual of these is that of making an
electrotype. This may mean the making of an exact impression of a medal,
coin, or other figure, or a depositing of a coating of the same on any
metallic surface. Formerly the faces of the types used in printing were
very commonly faced with copper to give them finish and a wearing
quality. Even fresh, natural fruits that have been evenly coated with
plumbago may be covered with a thin shell of metal. A silver head may be
placed on the wood of a walking stick, precisely conforming on the
outside to the form of the wood within.
The deposit of metal in the electrotyping process always takes place at
the negative pole--the pole by which the current passes out of the fluid
into its conductor. This is the "_cathode_." The other is the
"_anode_." The "bath," as the fluid in which the process is
accomplished is called, for silver, gold or platinum contains one
hundred parts of water, ten of potassium cyanide, and one of the cyanide
of whichever of those metals is to be deposited. The articles to be
plated are suspended in this bath and the battery-power, varying in
intensity according to circumstances, is applied. After removal they are
buffed and finished. A varying detail is practiced for different metals,
and the current now commonly used is from a dynamo. [Footnote: Among
modern modifications of the dynamic current, is its use, modified by
proper appliances, for the telegraph and the telephone circuits of
cities and the larger towns. Every electric current may now be safely
attributed to that source, and from the same circuit and generator all
modifications may be produced at once.]
The origin of electrolysis is said to be with Daniell, who noticed the
deposit of copper while experimenting with the battery that bears his
name. Jacobi, at St. Petersburg, first published a description of the
process in 1839. The Elkingtons were the first to actually put the
process into commercial practice.
It would be interesting now, were it apropos, to describe the seemingly
very ancient processes by which our ancestors gilded, plated, were
deceived and deceived others, previous to about 1845. For those things
were done, and the genuineness of life has by no means been destroyed by
the modern ease with which a precious metal may be deposited upon one
utterly base. A contemplation of the moral side of the subject might
lead at once to the conclusion that we could now spare one of the least
in actual importance of the processes of the all-pervading and wonderful
essence that alike makes the lightning-stroke and gilds the plebeian pin
that fastens a baby's napkin. But from any other view we could not now
dispense with anything electricity does.
General facts.--The names of many of the original investigators of
electrical phenomena are perpetuated in the familiar names of electrical
measurements. For, notwithstanding its seeming subtlety, there is no
force in use, or that has ever been used by men, capable of being so
definitely calculated, measured, determined beforehand, as electricity
is. As time passes new measurements are adopted and named, some of them
being proposed as lately as 1893. An instance of the value of some of
these old determinations of a time when all we now know of electrical
science was unknown, may be given in what is known as Ohm's Law. Ohm was
a native of Erlangen, in Bavaria, and was Professor of Physics at
Munich, where he died in 1874. He formulated this Law in 1827, and it
was translated into English in 1847. He was recognized at the time, and
was given the Copley medal of the Royal Society of London. The Law--for
by that distinctive name is it still called, though the name "Ohm," also
expresses a unit of measurement--is that _the quantity of current that
will pass through a conductor is proportional to the pressure and
inversely proportional to the distance_. That is:
Current = Pressure / Resistance.
Transposing the terms of the equation we may get an expression for
either of those elements, current, pressure, or resistance, in the terms
of the other two. This relation holds true and is accurate in every
possible case and condition of practical work. This remarkable precision
and definiteness of action has made possible the creation of an
extensive school of electrical testing, by which we are not only enabled
to make accurate measurement of electrical apparatus and appliances, but
also to make determinations in _other_ fields by the agency of
electricity. When an ocean cable is injured or broken the precise
location of the trouble is made _by measuring the electrical
resistance of the parts on each side of the injury_.
The magnitudes of measurements of electricity are expressed in the
following convenient electrical units:
The VOLT (named from Volta) equals a unit of _pressure_ that is
equal to one cell of a gravity battery.
The OHM, as a unit of measurement, equals a unit of _resistance_
that is equivalent to the resistance of a hundred feet of copper wire
the size of a pin.
The AMPÈRE (named from Ampère, 1775-1836, author of a "Collection of
Observations on Electro-Dynamics" and other works, and a profound
practical investigator) equals a unit of _current_ equivalent to
the current which one Volt of pressure will produce through one Ohm of
wire (or resistance).
The Coulomb (1736--inventor of the means of measuring electricity called
the "Torsion balance," and general early investigator) equals a unit of
_quantity_ of one Ampere flowing for one second.
The Farad (from Faraday, the discoverer of the laws of Induction, see
_ante_), equals that unit of _capacity_ which is the capacity
for holding one Coulomb. Death current.--What is now spoken of as the
"Death Current" is one that will instantly overcome the "resistance" of
the human, or animal, body. It is a current of from one to two thousand
Volts--about the same as that used in maintaining the large arc lights.
This question of the killing capacity of the current became officially
prominent some years ago, upon the passage by the legislature of the
State of New York of a statute requiring the death penalty to be
inflicted by means of electricity. The object was to deter evildoers by
surrounding the penalty with scientific horror, [Footnote: Hence also
the new lingual atrocity, the word "electrocute," derived from "execute"
by decapitation and the addition of "electro"] and the idea had its
origin in the accidents which formerly occurred much more frequently
than now. The "death current" is now almost everywhere, though the care
of the men who continually work about "live" wires has grown to be much
like that of men who continually handle firearms or explosives, and
accidents seldom happen. At first it was apparently difficult for the
general public to appreciate the fact that the silent and
harmless-looking wires must be avoided. There was suddenly a new and
terrific power in common use, and it was as slender, silent and
unobtrusive as it was fatal.
Insulation of the hands by the use of rubber gloves, and extreme care,
are the means by which those who are called "linemen"--a new
industry--protect themselves in their occupation. But there is a new
commandment added to the list of those to be memorized by the
body-politic. "Do not tread upon, drive over, or touch _any_ wire."
It may be, and probably is, harmless. But you cannot positively
know. [Footnote: It is a common trait of general human nature to refuse
to learn save by the hardest of experiences, and so far as the crediting
of statements is concerned, to at first believe everything that is not
true, and reject most that is. The supernatural, the phenomena of
alleged witchcraft and diabolism, and of "luck," "hoodoo," "fate," etc.,
find ready disciples among those who reject disdainfully the results of
the working of natural law. When the railroads were first built across
the plains the Indians repeatedly attempted to stop moving trains by
holding the ends of a rope stretched across the track in front of the
engine, and with results which greatly surprised them When the lines
were first constructed in northern Mexico the Mexican peasant could not
be induced to refrain from trying personal experiments with the new
power, and scores of him were killed before he learned that standing on
the track was dangerous. In the United States the era of accidents
through indifference to common-looking wires has almost passed, but for
some years the fatality was large because people are always governed by
appearances connected with _previous_ notions, until _new_
experiences teach them better.]
INSTRUMENTS OF MEASUREMENT.--Some of the most costly and beautiful of
modern scientific instruments are those used in the measurements and
determinations of electrical science. There are many forms and varieties
for every specific purpose. Electrical measurement has become a
department of physical science by itself, and a technical, extensive and
varied one. Already the electrical specialist, no more an original
experimenter or investigator than the average physician is, has become
professional. He makes plans, submits facts, estimates cost, and states
results with almost certainty.
ELECTRICITY AS AN INDUSTRY.--Immense factories are now devoted to the
manufacture of electrical goods exclusively. Large establishments in
cities are filled with them. The installation of the electric plant in a
dwelling house is done in the same way, and as regularly, as the
plumbing is. Soon there must be still another enlargement, since the
heating of houses through a wire, and the kitchen being equipped with
cooking utensils whose heat is for each vessel evolved in its own
bottom, is inevitable.
The following are some of the facts, in figures, of the business side of
electricity in the United States at the present writing. In 1866, about
twenty years after the establishment of the telegraph, but with a
population of only a little more than half the present, there were
75,686 miles of telegraph wire in use, and 2,520 offices. In 1893 there
were 740,000 miles of wire, and more than 20,000 offices. The receipts
for the year first named are unknown, but for 1893 they were about
$24,000,000. The expenses of the system for the same year were
$16,500,000.
The telephone, an industry now about sixteen years old, had in 1893, for
the Bell alone, over 200,000 miles of wire on poles, and over 90,000
miles of wire under ground. The instruments were in 15,000 buildings.
There were 10,000 employés, and 233,000 subscribers. All companies
combined had 441,000 miles of wire. Ninety-two millions of dollars were
invested in telephone _fixtures_.
In 1893, the average cost of a telegram was thirty-one and one
six-tenths cents, and the average alleged cost of sending the same to
the companies was twenty-two and three-tenths cents, leaving a profit of
nine and three-tenths cents on every message. It must be remembered that
with mail facilities and cheapness that are unrivalled, the telegraph
message is always an extraordinary mode of communication; an emergency.
These few figures may serve to give the reader a dim idea of the
importance to which the most ordinary and general of the branches of
electrical industry have grown in the United States.
MEDICAL ELECTRICITY.--For more than fifty years the medical fraternity
in regular practice persisted in disregarding all the claims made for
the electric current as a therapeutic agent. In earlier times it was
supposed to have a value that supplanted all other medical agencies.
Franklin seems to have been one of the earliest experimenters in this
line, and to have been successful in many instances where his brief
spark from the only sources of the current then known were applicable to
the case. The medical department of the science then fell into the hands
of charlatans, and there is a natural disposition to deal in the
wonderful, the miraculous or semi-miraculous, in the cure of disease.
Divested of the wonder-idea through a wider study and greater knowledge
of actual facts, electricity has again come forward as a curative agent
in the last ten years. Instruction in its management in disease is
included in the curriculum of almost every medical school, and most
physicians now own an outfit, more or less extensive, for use in
ordinary practice. To decry and utterly condemn is no longer the custom
of the steady-going physician, the ethics of whose cloth had been for
centuries to condemn all that interfered with the use of drugs, and
everything whose action could not be understood by the examples of
common experience, and without special study outside the lines of
medical knowledge as prescribed.
Perhaps the developments based upon the discoveries of Faraday have had
much to do with the adoption of electricity as a curative agent. The
current usually used is the Faradic; the induced alternate current from
an induction coil. This is, indeed, the current most useful in the
majority of the nervous derangements in the treatment of which the
current is of acknowledged utility.
In surgery the advance is still greater. "Galvano-cautery" is the
incandescent light precisely; the white-hot wire being used to cut off,
or burn off, and cauterize at the same time, excrescences and growths
that could not be easily reached by other means than a tube and a small
loop of platinum wire. A little incandescent lamp with a bulb no bigger
than a pea is used to light up and explore cavities, and this advance
alone, purely mechanical and outside of medical science, is of immense
importance in the saving of life and the avoidance of human suffering.
It may be added that there is nothing magical, or by the touch, or
mysterious, in the treatment of disease by the electrical current. The
results depend upon intelligent applications, based upon reason and
experience, a varied treatment for varying cases. Nor is it a remedy to
be applied by the patient himself more than any other is. On the
contrary, he may do himself great injury. The pills, potions, powders
and patent medicines made to be taken indiscriminately, and which he
more or less understands, may be still harmful yet much safer. Even the
application of one or the other of the two poles with reference to the
course of a nerve, may result in injury instead of good.
INCOMPLETE POSSIBILITIES.--There are at least two things greatly desired
by mankind in the field of electrical science and not yet attained. One
of these, that may now be dismissed with a word, is the resolving of the
latent energy of, say a ton of coal, into electrical energy without the
use of the steam engine; without the intervention of any machine. For
electricity is not manufactured; not created by men in any case. It
exists, and is merely gathered, in a measure and to a certain extent
confined and controlled, and sent out as a _concentrated form of
energy_ on its various errands. Should a means for the concentration
of this universally diffused energy be found whereby it could be made to
gather, by the new arrangement of some natural law such as places it in
enormous quantities in the thundercloud, a revolution that would
permeate and visibly change all the affairs of men would take place,
since the industrial world is not a thing apart, but affects all men,
and all institutions, and all thought.
The other desideratum, more reasonable apparently, yet far from present
accomplishment, is a means of storing and carrying a supply of
electricity when it has been gathered by the means now used, or by any
means.
THE STORAGE BATTERY is an attempt in this last direction. The name is
misleading, since even in this attempt electricity is in no sense
"stored," but a chemical action producing a current takes place in the
machine. The arrangement is in its infancy. Instances occur in which,
under given circumstances, it is more or less efficient, and has been
improved into greater efficiency. But many difficulties intervene, one
of which is the great weight of the appliances used, and another,
considerable cost. The term "storage battery" is now infrequently used,
and the name "secondary" battery is usually substituted. The principle
of its action is the decomposing of combined chemicals by the action of
a current applied from a stationary generator or dynamo, and that these
chemicals again unite as soon as they are allowed to do so by the
completing of a circuit, _and in re-combining give off nearly as much
electricity as was first used in separating them._ The action of the
secondary, "storage," battery, once charged, is like that of a primary
battery. The current is produced by chemical action. Two metals outside
of the solution contained in a primary battery cell, but under differing
physical conditions from each other, will yield a current. A piece of
polished iron and a piece of rusty iron, connected by a wire, will yield
a small current. Rusty lead, so to speak, so connected with bright lead,
has a high electromotive force. Oxygen makes lead rusty, and hydrogen
makes it bright. Oxygen and hydrogen are the two gases cast off when
water is subjected to a current. (See _ante_ under
_Electrolysis_) So Augustin Planté, the inventor of as much as we
yet have of what is called a storage or secondary battery, suspended two
plates of lead in water, and when a current of electricity was passed
through it hydrogen was thrown off at one plate, making it bright, and
oxygen at the other plate, peroxydizing its surface. When the current
was removed the altered plates, connected by a wire, would send off a
current which was in the opposite direction from the first, and this
would continue until the plates were again in their original condition.
This is the principle and mode of action of the storage battery. So far
it has assumed many forms. Scores of modifications have been invented
and patented. The leaden plates have taken a variety of forms, yet have
remained leaden plates, one cleaned and the other fouled by the
electrolytic action of a current, and giving off an almost equivalent
current again by the return process. The arrangement endures for several
repetitions of the process, but is finally expensive and always
inconvenient. The secondary battery, in its infancy, as stated, presents
now much the same obstacles to commercial use the galvanic, or primary,
battery did before the induced current had become the servant of man.