ELECTRICITY.
In 1900 the real nature of electricity appears to be as unknown as it
was in 1800.
Franklin in the eighteenth century defined electricity as consisting of
particles of matter incomparably more subtle than air, and which
pervaded all bodies. At the close of the nineteenth century electricity
defined as “simply a form of energy which imparts to material substances
a peculiar state or condition, and that all such substances partake more
or less of this condition.”
These theories and the late discovery of Hertz that electrical energy
manifests itself in the form of waves, oscillations or vibrations,
similar to light, but not so rapid as the vibrations of light,
constitute about all that is known about the nature of this force.
Franklin believed it was a single fluid, but others taught that there
were two kinds of electricity, positive and negative, that the like
kinds were repulsive and the unlike kinds attractive, and that when
generated it flowed in currents.
Such terms are not now regarded as representing actual varieties of this
force, but are retained as convenient modes of expression, for want of
better ones, as expressing the conditions or states of electricity when
produced.
Electricity produced by friction, that is, developed upon the surface of
a body by rubbing it with a dissimilar body, and called frictional or
static electricity, was the only kind produced artificially in the days
of Franklin. What is known as galvanism, or animal electricity, also
takes its date in the 18th century, to which further reference will be
made. Since 1799 there have been discovered additional sources, among
which are voltaic electricity, or electricity produced by chemical
action, such as is manifested when two dissimilar metals are brought
near each other or together, and electrical manifestations produced by a
decomposing action, one upon the other through a suitable medium;
inductive electricity, or electricity developed or induced in one body
by its proximity to another body through which a current is flowing;
magnetic electricity, the conversion of the power of a magnet into
electric force, and the reverse of this, the production of magnetic
force by a current of electricity; and thermal electricity, or that
generated by heat. Electricity developed by these, or other means in
contra-distinction to that produced by friction, has been called
dynamic; but all electric force is now regarded as dynamic, in the sense
that forces are always in motion and never at rest.
Many of the manifestations and experiments in later day fields which, by
reason of their production by different means, have been given the names
of discovery and invention, had become known to Franklin and others, by
means of the old methods in frictional electricity. They are all,
however, but different routes leading to the same goal. In the midst of
the brilliant discoveries of modern times confronting us on every side
we should not forget the honourable efforts of the fathers of the
science.
We need not dwell on what the ancients produced in this line. It was a
single fact only:--The Greeks discovered that amber, a resinous
substance, when rubbed would attract lighter bodies to it.
In 1600 appeared the father of modern electricity--Dr. Gilbert of
Colchester, physician to Queen Elizabeth. He revived the one experiment
of antiquity, and added to it the further fact that many substances
besides amber, when rubbed, would manifest the same electric condition,
such as sulphur, sapphire, wax, glass and other bodies. And thus he
opened the field of electrodes. He was the first to use the terms,
electricity, electric and electrode, which he derived from the word
_elektron_, the Greek name for amber. He observed the actions of
magnets, and conjectured the fundamental identity of magnetism and
electricity. He arranged an electrometer, consisting of an iron needle
poised on a pivot, by which to note the action of the magnet. This was
about the time that Otto von Guericke of Magdeburg, Germany, was born.
He became a “natural” philosopher, and for thirty-five years was
burgomaster of his native town. He invented the air-pump, and he it was
who illustrated the force of atmospheric pressure by fitting together
two hollow brass hemispheres which, after the air within them had been
exhausted, could not be pulled apart. He also invented a barometer, and
as an astronomer suggested that the return of comets might be
calculated. He invented and constructed the first machine for generating
electricity. It consisted of a ball of sulphur rotated on an axis, and
which was electrified by friction of the hand, the ball receiving
negative electricity while the positive flowed through the person to the
earth. With this machine “he heard the first sound and saw the first
light in artificially excited electricity.” The machine was improved by
Sir Isaac Newton and others, and before the close of that century was
put into substantially its present form of a round glass plate rotated
between insulated leather cushions coated with an amalgam of tin and
zinc, the positive or vitreous electricity thus developed being
accumulated on two large hollow brass cylinders with globular ends,
supported on glass pillars. Gray in 1729 discovered the conductive power
of certain substances, and that the electrical influence could be
conveyed to a distance by means of an insulated wire. This was the first
step towards the electric telegraph.
Dufay, the French philosopher and author, who in 1733-1737 wrote the
_Memoirs of the French Academy_, was, it seems, the first to observe
electrical attractions and repulsions; that electrified resinous
substances repelled like substances while they attracted bodies
electrified by contact with glass; and he, therefore, to the latter
applied the term _vitreous_ electricity and to the former the term
_resinous_ electricity. In 1745 Prof. Muschenbroeck of Leyden University
developed the celebrated Leyden jar. This is a glass jar coated both
inside and outside with tinfoil for about four-fifths of its height. Its
mouth is closed with a cork through which is passed a metallic rod,
terminating above in a knob and connected below with the inner coating
by a chain or a piece of tinfoil. If the inner coating be connected with
an electrical machine and the outer coating with the earth, a current of
electricity is established, and the inner coating receives what is
called a positive and the outer coating a negative charge. On connecting
the two surfaces by means of a metallic discharger having a
non-conducting handle a spark is obtained. Thus the Leyden jar is both a
collector and a condenser of electricity. On arranging a series of such
jars and joining their outer and inner surfaces, and connecting the
series with an electrical machine, a battery is obtained of greater or
less power according to the number of jars employed and the extent of
supply from the machine.
The principle of the Leyden jar was discovered by accident. Cuneus, a
pupil of Muschenbroeck, was one day trying to charge some water in a
glass bottle with electricity by connecting it with a chain to the
sparking knob of an electrical machine. Holding the bottle in one hand
he arranged the chain with the other, and received a violent shock. His
teacher then tried the experiment himself, with a still livelier and
more convincing result, whereupon he declared that he would not repeat
the trial for the whole Kingdom of France.
When the science of static electricity was thus far developed, with a
machine for generating it and a collector to receive it, many
experiments followed. Charles Morrison in 1753, in the _Scots Magazine_,
proposed a telegraph system of insulated wires with a corresponding
number of characters to be signalled between two stations. Other schemes
were proposed at different times down to the close of the century.
Franklin records among several other experiments with frictional
electricity accumulated by the Leyden jar battery the following results,
produced chiefly by himself: The existence of an attractive and a
repulsive action of electricity; the restoration of the equilibrium of
electrical force between electrified and non-electrified bodies, or
between bodies differently supplied with the force; the electroscope, a
body charged with electricity and used to indicate the presence and
condition of electricity in another body; the production of work, as the
turning of wheels, by which it was proposed a spit for roasting meat
might be formed, and the ringing of chimes by a wheel, which was done;
the firing of gunpowder, the firing of wood, resin and spirits; the
drawing off a charge from electrified bodies at a near distance by
pointed rods; the heating and melting of metals; the production of
light; the magnetising of needles and of bars of iron, giving rise to
the analogy of magnetism and electricity.
Franklin, who had gone thus far, and who also had drawn the lightning
from the clouds, identified it as electricity, and taught the mode of
its subjection, felt chagrined that more had not been done with this
subtle agent in the service of man. He believed, however, that the
day-spring of science was opening, and he seemed to have caught some
reflection of its coming light. Observing the return to life and
activity of some flies long imprisoned in a bottle of Madeira wine and
which he restored by exposure to the sun and air, he wrote that he
should like to be immersed at death with a few friends in a cask of
Madeira, to be recalled to life a hundred years thence to observe the
state of his country. It would not have been necessary for him to have
been embalmed that length of time to have witnessed some great
developments of his favorite science. He died in 1790, and it has been
said that there was more real progress in this science in the first
decade of the nineteenth century than in all previous centuries put
together.
Before opening the door of the 19th century, let us glance at one more
experiment in the 18th:
While the aged Franklin was dying, Dr. Luigi Galvani of Bologna, an
Italian physician, medical lecturer, and learned author, was preparing
for publication his celebrated work, _De viribus Electricitatis in Motu
Musculari Commentarius_, in which he described his discovery made a few
years before of the action of the electric current on the legs and
spinal column of a frog hung on a copper nail. This discovery at once
excited the attention of scientists, but in the absence of any immediate
practical results the multitude dubbed him the “frog philosopher.” He
proceeded with his experiments on animals and animal matter, and
developed the doctrine and theories of what is known as animal or
galvanic electricity. His fellow countryman and contemporary, Prof.
Volta of Pavia, took decided issue with Galvani and maintained that the
pretended animal electricity was nothing but electricity developed by
the contact of two different metals. Subsequent investigations and
discoveries have established the fact that both theories have truth for
their basis, and that electricity is developed both by muscular and
nervous energy as well as by chemical action. In 1799 Volta invented his
celebrated pile, consisting of alternate disks of copper and zinc
separated by a cloth moistened with a dilute acid; and soon after an
arrangement of cups--each containing a dilute acid and a copper and a
zinc plate placed a little distance apart, and thus dispensing with the
cloth. In both instances he connected the end plate of one kind with the
opposite end plate of the other kind by a wire, and in both arrangements
produced a current of electricity. To the discoveries, experiments, and
disputes of Galvani and Volta and to those of their respective
adherents, the way was opened to the splendid electrical inventions of
the century, and the discovery of a new world of light, heat, speech and
power. The discoveries of Galvani and Volta at once set leading
scientists at work. Fabroni of Florence, and Sir Humphry Davy and
Wollaston of England, commenced interesting experiments, showing that
rapid oxidation and chemical decomposition of the metals took place in
the voltaic pile.
By the discoveries of Galvani the physicians and physiologists were
greatly excited, and believed that by this new vital power the nature of
all kinds of nervous diseases could be explored and the remedy applied.
Volta’s discovery excited the chemists. If two dissimilar metals could
be decomposed and power at the same time produced they contended that
practical work might be done with the force. In 1800 Nicholson and
Carlisle decomposed water by passing the electric current through the
same; Ritter decomposed copper sulphate, and Davy decomposed the
alkalies, potash and soda. Thus the art of electrolysis--the
decomposition of substances by the galvanic current, was established.
Later Faraday laid down its laws. Naturally inventions sprung up in new
forms of batteries. The pile and cup battery of Volta had been succeeded
by the trough battery--a long box filled with separated plates set in
dilute acid. The trough battery was used by Sir Humphry Davy in his
series of great experiments--1806-1808--in which he isolated the
metallic bases, calcium, sodium, potassium, etc. It consisted of 2000
double plates of copper and zinc, each having a surface of 32 square
inches. With this same trough battery Davy in 1812 produced the first
electric carbon light, the bright herald of later glories.
Among the most noted new batteries were Daniell’s, Grove’s and Bunsen’s.
They are called the “two fluid batteries,” because in place of a single
acidulated bath in which the dissimilar metals were before placed, two
different liquid solutions were employed.
John Frederick Daniell of London, noted for his great work,
_Meteorological Essays_, and other scientific publications, and as
Professor of Chemistry in King’s College, in 1836, described how a
powerful and constant current of electricity may be continued for an
unlimited period by a battery composed of zinc standing in an acid
solution and a sheet of copper in a solution of sulphate of copper.
Sir William Robert Grove, first an English physician, then an eminent
lawyer, and then a professor of natural philosophy, and the first to
announce the great theory of the Correlation of Physical Forces, in 1839
produced his battery, much more powerful than any previous one, and
still in general use. In it zinc and platinum are the metals used--the
zinc bent into cylindrical form and placed in a glass jar containing a
weak solution of sulphuric acid, while the platinum stands in a porous
jar holding strong nitric acid and surrounded by the zinc. Among the
electrical discoveries of Grove were the decomposition by electricity of
water into free oxygen and hydrogen, the electricity of the flame of the
blow-pipe, electrical action produced by proximity, without contact, of
dissimilar metals, molecular movements induced in metals by the electric
current, and the conversion of electricity into mechanical force.
Robert Wilhelm Bunsen, a German chemist and philosopher and scientific
writer, who invented some of the most important aids to scientific
research of the century, who constructed the best working chemical
laboratory on the continent and founded the most celebrated schools of
chemistry in Europe, invented a battery, sometimes called the carbon
battery, in which the expensive pole of platinum in the Grove battery is
replaced by one of carbon. It was found that this combination gave a
greater current than that of zinc and platinum.
A great variety of useful voltaic batteries have since been devised by
others, too numerous to be mentioned here. There is another form of
battery having for its object the storing of energy by electrolysis, and
liberating it when desired, in the form of an electric current, and
known as an accumulator, or secondary, polarization, or storage battery.
Prof. Ritter had noticed that the two plates of metal which furnished
the electric current, when placed in the acid liquid and united, could
in themselves furnish a current, and the inventing of _storage_
batteries was thus produced. The principal ones of this class are
Gustave Planté’s of 1860 and M. Camille Faure’s of 1880. These have
still further been improved. Still another form are the _thermo-electric
batteries_, in which the electro-motive force is produced by the joining
of two different metals, connecting them by a wire and heating their
junctions. Thus, an electric current is obtained directly from heat,
without going through the intermediate processes of boiling water to
produce steam, using this steam to drive an engine, and using this
engine to turn a dynamo machine to produce power.
But let us retrace our steps:--As previously stated, Franklin had
experimented with frictional electricity on needles, and had magnetised
and polarised them and noticed their deflection; and Lesage had
established an experimental telegraph at Geneva by the same kind of
electricity more than a hundred years ago. But frictional electricity
could not be transmitted with power over long distances, and was for
practical purposes uncontrollable by reason of its great diffusion over
surfaces, while voltaic electricity was found to be more intense and
could be developed with great power along a wire for any distance. Fine
wires had been heated and even melted by Franklin by frictional
electricity, and now Ritter, Pfaff and others observed the same effect
produced on the conducting wires by a voltaic current; and Curtet, on
closing the passage with a piece of charcoal, produced a brilliant
light, which was followed by Davy’s light already mentioned.
As early as 1802 an Italian savant, Gian D. Romagnosi of Trent, learning
of Volta’s discovery, observed and announced in a public print the
deflection of the magnetic needle when placed near a parallel conductor
of the galvanic current. In the years 1819 and 1820 so many brilliant
discoveries and inventions were made by eminent men, independently and
together, and at such near and distant places, that it is hard telling
who and which was first. It was in 1819 that the celebrated Danish
physicist, Oersted of Copenhagen, rediscovered the phenomena that the
voltaic current would deflect a magnetic needle, and that the needle
would turn at right angles to the wire. In 1820 Prof. S. C. Schweigger
of Halle discovered that this deflecting force was increased when the
wire was wound several times round the needle, and thus he invented the
magnetising helix. He also then invented a galvano-magnetic indicator (a
single-wire circuit) by giving the insulated wire a number of turns
around an elongated frame longitudinally enclosing the compass needle,
thus multiplying the effect of the current upon the sensitive needle,
and converting it into a practical _measuring_ instrument--known as the
galvanometer, and used to observe the strength of currents. In the same
year Arago found that iron filings were attracted by a voltaic charged
wire; and Arago and Davy that a piece of soft iron surrounded spirally
by a wire through which such a current was passed would become magnetic,
attract to it other metals while in that condition, immediately drop
them the instant the current ceased, and that such current would
permanently magnetise a steel bar. The elements of the _electro-magnet_
had thus been produced. It was in that year that Ampère discovered that
magnetism is the circulation of currents of electricity at right angles
to the axis of the needle or bar joining the two poles of the magnet. He
then laid down the laws of interaction between magnets and electrical
currents, and in this same year he proposed an electric-magneto
telegraph consisting of the combination of a voltaic battery, conducting
wires, and magnetic needles, one needle for each letter of the alphabet.
The discoveries of Ampère as to the laws of electricity have been
likened to the discovery of Newton of the law of gravitation.
Still no practical result, that is, no useful machine, had been produced
by the electro-magnet.
In 1825 Sturgeon of England bent a piece of wire into the shape of a
horse-shoe, insulated it with a coating of sealing wax, wound a fine
copper wire around it, thus making a helix, passed a galvanic current
through the helix, and thus invented the first practical electro-magnet.
But Sturgeon’s magnet was weak, and could not transmit power for more
than fifty feet. Already, however, it had been urged that Sturgeon’s
magnet could be used for telegraphic purposes, and a futile trial was
made. In the field during this decade also labored the German professors
Gauss and Weber, and Baron Schilling of Russia. In 1829 Prof. Barlow of
England published an article in which he summarised what had been done,
and scientifically demonstrated to his own satisfaction that an
electro-magnetic telegraph was impracticable, and his conclusion was
accepted by the scientific world as a fact. This was, however, not the
first nor the last time that scientific men had predicted
impracticabilities with electricity which afterwards blossomed into full
success. But even before Prof. Barlow was thus arriving at his
discouraging conclusion, Prof. Joseph Henry at the Albany Institute in
the State of New York had commenced experiments which resulted in the
complete and successful demonstration of the power of electro-magnetism
for not only telegraph purposes but for almost every advancement that
has since been had in this branch of physics. In March 1829 he exhibited
at his Institute the magnetic “spool” or “bobbin,” that form of coil
composed of tightly-wound, silk-covered wire which he had constructed,
and which since has been universally employed for nearly every
application of electro-magnetism, of induction, or of magneto-electrics.
And in the same year and in 1830 he produced those powerful magnets
through which the energy of a galvanic battery was used to lift hundreds
of tons of weight.
In view of all the facts now historically established, there can be no
doubt that previous to Henry’s experiments the means for developing
magnetism in soft iron were imperfectly understood, and that, as found
by Prof. Barlow, the electro-magnet which then existed was inapplicable
and impracticable for the transmission of power to a distance. Prof.
Henry was the first to prove that a galvanic battery of “intensity” must
be employed to project the current through a long conductor, and that a
magnet of one long wire must be used to receive this current; the first
to magnetise a piece of soft iron at a distance and call attention to
its applicability to the telegraph; the first to actually sound a bell
at a distance by means of the electro-magnet; and the first to show that
the principles he developed were applicable and necessary to the
practical operation of an effective telegraph system.
Sturgeon, the parent of the electro-magnet, on learning of Henry’s
discoveries and inventions, wrote: “Professor Henry has been enabled to
produce a magnetic force which totally eclipses every other in the whole
annals of magnetism; and no parallel is to be found since the miraculous
suspension of the celebrated oriental impostor in his iron coffin.”
(_Philosophical Magazine and Annals_, 1832.)
The third decade was now prepared for the development of the telegraph.
As to the telegraph in its broadest sense, as a means for conveying
intelligence to a distance quickly and without a messenger, successful
experiments of that kind have existed from the earliest times:--from the
signal fires of the ancients; from the flag signals between ships at
sea, introduced in the seventeenth century by the Duke of York, then
Admiral of the English fleet, and afterwards James II of England; from
the semaphore telegraph of M. Chappe, adopted by the French government
in 1794, consisting of bars pivoted to an upright stationary post, and
made to swing vertically or horizontally to indicate certain signals;
and from many other forms of earlier and later days.
As to electricity as an agent for the transmission of signals, the idea
dates, as already stated, from the discovery of Stephen Gray in 1729,
that the electrical influence could be conveyed to a distance by the
means of an insulated wire. This was followed by the practical
suggestions of Franklin and others. But when, as we have seen, voltaic
electricity entered the field, electricity became a more powerful and
tractable servant, and distant intelligent signals became one of its
first labors.
The second decade was also made notable by the discovery and
establishment by George Simon Ohm, a German professor of Physics, of the
fundamental mathematical law of electricity: It has been expressed in
the following terms: (a) the current strength is equal to the
electro-motive force divided by the resistance; (b) the force is equal
to the current strength multiplied by the resistance; (c) the resistance
is equal to the force divided by the current strength.
The historical development and evolution of the telegraph may be now
summarized:--
1. The discovery of galvanic electricity by Galvani--1786-1790.
2. The galvanic or voltaic battery by Volta in 1800.
3. The galvanic influence on a magnetic needle by Romagnosi (1802)
Oersted (1820).
4. The galvanometer of Schweigger, 1820--the parent of the needle
system.
5. The electro-magnet by Arago and Sturgeon--1820-1825--the parent of
the magnet system.
Then followed in the third decade the important series of steps in the
evolution, consisting of:--
_First_, and most vital, Henry’s discovery in 1829 and 1830 of the
“intensity” or spool-wound magnet, and its intimate relation to the
“intensity” battery, and the subordinate use of an armature as the
signalling device.
_Second_, Gauss’s improvement in 1833 (or probably Schilling’s
considerably earlier) of reducing the electric conductors to a single
circuit by the ingenious use of a dual sign so combined as to produce a
true alphabet.
_Third_, Weber’s discovery in 1833 that the conducting wires of an
electric telegraph could be efficiently carried through the air without
any insulation except at their points of support.
_Fourth_, Daniell’s invention of a “constant” galvanic battery in 1836.
_Fifth_, Steinheil’s remarkable discovery in 1837 that the earth may
form the returning half of a closed galvanic circuit, so that a single
conducting wire is sufficient for all telegraphic purposes.
_Sixth_, Morse’s adaptation of the armature and electro-magnet of Henry
as a recording instrument in 1837 in connection with his improvement in
1838 on the Schilling, Gauss and Steinheil alphabets by employing the
simple “dot and dash” alphabet in a single line. He was also assisted by
the suggestions of Profs. Dana and Gale. To which must be added his
adoption of Alfred Vail’s improved alphabet, and Vail’s practical
suggestions in respect to the recording and other instrumentalities.
To these should be added the efforts in England, made almost
simultaneously with those of Morse, of Wheatstone and Cook and Davy, who
were reaching the same goal by somewhat different routes.
Morse in 1837 commenced to put the results of his experiments and
investigations in the form of caveats, applications and letters patent
in the United States and in Europe. He struggled hard against
indifference and poverty to introduce his invention to the world. It was
not until 1844 that he reduced it to a commercial practical success. He
then laid a telegraph from Washington to Baltimore under the auspices of
the United States Government, which after long hesitation appropriated
$30,000 for the purpose. It was on the 24th day of May, 1844, that the
first formal message was transmitted on this line between the two cities
and recorded by the electro-magnet in the dot and dash alphabet, and
this was immediately followed by other messages on the same line.
Morse gathered freely from all sources of which he could avail himself
knowledge of what had gone before. He was not a scientific discoverer,
but an inventor, who, adding a few ideas of his own to what had before
been discovered, was the first to combine them in a practical useful
device. What he did as an inventor, and what anyone may do to constitute
himself an inventor, by giving to the world a device which is useful in
the daily work of mankind, as distinguished from the scientific
discoverer who stops short of successful industrial work, is thus stated
by the United States Supreme Court in an opinion sustaining the validity
of his patents, after all the previous art had been produced before
it:--
“Neither can the inquiries he made nor the information or advice he
received from men of science in the course of his researches impair his
right to the character of an inventor. No invention can possibly be
made, consisting of a combination of different elements of power,
without a thorough knowledge of the properties of each of them, and the
mode in which they operate on each other. And it can make no difference
in this respect, whether he derives his information from books, or from
conversation with men skilled in the science. If it were otherwise, no
patent in which a combination of different elements is used would ever
be obtained, for no man ever made such an invention without having first
obtained this information, unless it was discovered by some fortunate
accident. And it is evident that such an invention as the
electro-magnetic telegraph could never have been brought into action
without it; for a very high degree of scientific knowledge and the
nicest skill in the mechanic arts are combined in it, and were both
necessary to bring it into successful operation. The fact that Morse
sought and obtained the necessary information and counsel from the best
sources, and acted upon it, neither impairs his rights as an inventor
nor detracts from his merits.”--_O’Reilly vs. Morse, 5 Howard_.
The combination constituting Morse’s invention comprised a main wire
circuit to transmit the current through its whole length whenever
closed; a main galvanic battery to supply the current; operating keys to
break and close the main circuit; office circuits; a circuit of
conductors and batteries at each office to record the message there;
receiving spring lever magnets to close an office circuit when a current
passes through the main circuit; adjusting screws to vary the force of
the main current; marking apparatus, consisting of pointed pieces of
wire, to indent dots and lines upon paper; clockwork to move the paper
indented; and magnet sounders to develop the power of the pointer and of
the armatures to produce audible distinguishable sounds.
It was soon learned by operators how to distinguish the signs or letters
sent by the length of the “click” of the armature, and by thus reading
by sound the reading of the signs on paper was dispensed with, and the
device became an electric-magnetic acoustic telegraph.
What is known as the Morse system has been improved, but its fundamental
principles remain, and their world-wide use constitute still the daily
evidence of the immense value of the invention to mankind.
Before the 1844 reduction to practice, Morse had originated and laid the
first submarine telegraph. This was in New York harbour in 1842. In a
letter to the Secretary of the United States Treasury, August 10, 1843,
he also suggested the project of an Atlantic telegraph.
While Henry was busy with his great magnets and Morse struggling to
introduce his telegraph, Michael Faraday was making those investigations
and discoveries which were to result in the application of electricity
to the service of man in still wider and grander fields.
Faraday was a chemist, and Davy’s most brilliant pupil and efficient
assistant. His earliest experiments were in the line of electrolysis.
This was about 1822, but it was not until 1831 that he began to devote
his brilliant talents as an experimentalist and lecturer wholly to
electrical researches, and for a quarter of a century his patient,
wonderful labours and discoveries continued. It has been said that
“although Oersted was the discoverer of electro-magnetism and Ampère its
expounder, Faraday made the science of magnets electrically what it is
at the present day.”
Great magnetic power having been developed by passing a galvanic current
around a bar of soft iron, Faraday concluded that it was reasonable to
suppose that as mechanical action is accompanied by an equal amount of
reaction, electricity ought to be evolved from magnetism.
“It was in 1831 that Faraday demonstrated before the Royal Society that
if a magnetized bar of steel be introduced into the centre of a helix of
insulated wire, there is at the moment of introduction of the magnet a
current of electricity set up in a certain direction in the insulated
wire forming the helix, while on the withdrawal of the magnet from the
helix a current in an opposite direction takes place.
“He also discovered that the same phenomenon was to be observed if for
the magnet was substituted a coil of insulated wire, through which the
current from a voltaic element was passing; and further that when an
insulated coil of wire was made to revolve before the poles of a
permanent magnet, electric currents were induced in the wires of the
coil.”--_Journal of the Society of Arts._
On these discoveries were based the action of all magneto-dynamo
electric machines--machines that have enabled the world to convert the
energy of a steam engine in its stall, or a distant waterfall, into
electric energy for the performance of the herculean labours of lighting
a great city, or an ocean-bound lighthouse, or transporting quickly
heavy loads of people or freight up and down and to and fro upon the
earth.
As before stated, Faraday was also the first to proclaim the laws of
electrolysis, or electro-chemical decomposition. He expressed conviction
that the forces termed chemical affinity and electricity are one and the
same. Subsequently the great Helmholtz, having proved by experiment that
in the phenomena of electrolysis no other force acts but the mutual
attractions of the atomic electric charges, came to the conclusion,
“that the very mightiest among the chemical forces are of electric
origin.”
Faraday having demonstrated by his experiments that chemical
decomposition, electricity, magnetism, heat and light, are all
inter-convertible and correlated forces, the inventors of the age were
now ready to step forward and put these theories at work in machines in
the service of man. Faraday was a leader in the field of discovery. He
left to inventors the practical application of his discoveries.
Prof. Henry in America was, contemporaneously with Faraday, developing
electricity by means of magnetic induction.
In 1832, Pixii, a philosophical instrument-maker of Paris, and Joseph
Saxton, an American then residing in London, invented and constructed
magneto-machines on Faraday’s principle of rendering magnetic a core of
soft iron surrounded with insulated wire from a permanent magnet, and
rapidly reversing its polarity, which machines were used to produce
sparks, decompose liquids and metals, and fire combustible bodies.
Saxton’s machine was the well-known electric shock machine operated by
turning a crank. A similar device is now used for ringing telephone call
bells.
Prof. C. G. Page of Washington and Ruhmkorff of Paris each made a
machine, well known as the Ruhmkorff coil, by which intense
electro-magnetic currents by induction were produced. The production of
electrical illumination was now talked of more than ever. Scientists and
inventors now had two forms of electrical machines to produce light: the
voltaic battery and the magneto-electric apparatus. But a period of
comparative rest took place in this line until 1850, when Prof. Nollet
of Brussels made an effort to produce a powerful magneto-electric
machine for decomposing water into its elements of hydrogen and oxygen,
which gases were then to be used in producing the lime light; and a
company known as “The Alliance” was organized at Paris to make large
machines for the production of light.
We have seen that Davy produced a brilliant electric light with two
pieces of charcoal in the electric circuit of a voltaic battery. Greener
and Staite revived this idea in a patent in 1845. Shortly after Nollet’s
machine, F. H. Holmes of England improved it and applied the current
directly to the production of electric light between carbon points. And
Holmes and Faraday in 1857 prepared this machine for use.
On the evening of December 8, 1858, the first practical electric light,
the work of Faraday and Holmes, flashed over the troubled sea from the
South Foreland Lighthouse. On June 6, 1862, this light was also
introduced into the lighthouse at Dungeness, England. The same light was
introduced in French lighthouses in December, 1863, and also in the work
on the docks of Cherbourg. At this time Germany was also awake to the
importance of this invention, and Dr. Werner Siemens of Berlin was at
work developing a machine for the purpose into one of less cost and of
greater use. Inventors were not yet satisfied with the power developed
from either the voltaic battery or the magneto-electric machine, and
continued to improve the latter.
In 1867, the same year that Faraday died, and too late for him to
witness its glory, came out the most powerful magneto-electric machine
that had yet been produced. It was invented by Wilde of London, and
consisted of very large electro-magnets, or field magnets, receiving
their electric power from the “lines of force” discovered by Faraday,
radiating from the poles of a soft iron magnet, combined with a small
magneto-electric machine having permanent magnets, and by which the
current developed in the smaller machine was sent through the coils of
the larger magnets. By this method the magnetic force was vastly
multiplied, and electricity was produced in such abundance as to fuse
thick iron wire fifteen inches long and one-fourth of an inch in
diameter, and to develop a magnificent arc light. Quickly succeeding the
Wilde machine came independent inventions in the same direction from
Messrs. G. Farmer of Salem, Mass., Alfred Yarley and Prof. Charles
Wheatstone of England, and Dr. Siemens of Berlin, and Ladd of America.
These inventors conceived and put in practice the great idea of
employing the current from an electro-magnetic machine to excite its own
electric magnet. They were thus termed “self-exciting.” The idea was
that the commutator (an instrument to change the direction, strength or
circuit of the current) should be so connected with the coils of the
field magnets that all or a part of the current developed in the
armature would flow through these coils, so that all permanent magnets
might be dispensed with, and the machine used to excite itself or charge
its own field magnets without the aid of any outside charging or feeding
mechanism.
Mr. Z. Gramme, of France, a little later than Wilde made a great
improvement. Previously, machines furnished only momentary currents of
varying strength and polarity; and these intermittent currents were hard
to control without loss in the strength of current and the frequent
production of sparks. Gramme produced a machine in which, although as in
other machines the magnetic field of force was created by a powerful
magnet, yet the armature was a ring made of soft iron rods, and
surrounded by an endless coil of wire, and made to revolve between the
poles of the magnet with great rapidity, producing a constant current in
one direction. By Faraday’s discovery, when the coil of the closed
circuit was moved before the poles of the magnet, the current was
carried half the time in one direction and half in the other,
constituting what is called an alternating current. Gramme employed the
commutator to make the current direct instead of alternating.
Dynamo-electric machines for practical work of many kinds had now been
born and grown to strength.
In addition to these and many other electrical machines this century has
discovered several ways by which the electricity developed by such
machines may be converted into light. I. By means of two carbon
conductors between which passes a series of intensely brilliant sparks
which form a species of flame known as the _voltaic arc_, and the heat
of which is more intense than that from any other known artificial
source. II. By means of a rod of carbon or kaolin, strip of platinum or
iridium, a carbon filament, or other substance placed between two
conductors, the resistance opposed by such rod, strip, or filament to
the passage of the current being so great as to develop heat to the
point of incandescence, and produce a steady white and pure light.
Attempts also have been made to produce illumination by what is called
stratified light produced by the electric discharge passing through
tubes containing various gases. These tubes are known as Geissler tubes,
from their inventor. Still another method is the production of a
continuous light from a vibratory movement of carbon electrodes to and
from each other, producing a bright flash at each separation, and
maintaining the separations at such a rate that the effect of the light
produced is continuous. But these additional methods do not appear as
yet to be commercially successful.
It must not be overlooked that before dynamo-magneto-electric machines
were used practically in the production of the electric light for the
purposes of illumination, the voltaic battery was used for the same
purpose, but not economically.
The first private dwelling house ever lighted in America, or doubtless
anywhere else, by electricity, was that of Moses G. Farmer, in Salem,
Massachusetts, in the year 1859. A voltaic battery furnished the current
to conducting wires which led to two electric lamps on the mantel-piece
of the drawing-room, and in which strips of platinum constituted the
resisting and lighting medium. A soft, mild, agreeable light was
produced, which was more delightful to read or sew by than any
artificial light ever before known. Either or both lamps could be
lighted by turning a button, and they were maintained for several weeks,
but were discontinued for the reason that the cost of maintaining them
was much greater than of gas light.
It was in connection with the effective dynamo-electric apparatus of
M. Gramme above referred to that the electric candle invented by
M. Paul Jablochoff became soon thereafter extensively employed for
electric lighting in Paris, and elsewhere in Europe. This invention,
like the great majority of useful inventions, is noted for its
simplicity. It consists of two carbon pencils placed side by side and
insulated from each other by means of a thin plate of some refractory
material which is a non-conductor at ordinary temperatures, but which
becomes a conductor, and consequently a light, when fused by the action
of a powerful current. Plaster of Paris was found to be the most
suitable material for this purpose, and the light produced was soft,
mellow, slightly rose-coloured, and quite agreeable to the eye.
It having been found that carbon was better adapted for lighting
purposes than platinum or other metals, by reason of its greater
radiating power for equal temperatures, and still greater infusibility
at high temperatures, inventors turned their attention to the production
of the best carbon lamp.
The two pointed pieces of hard conducting carbon used for the separated
terminals constitute the voltaic arc light--a light only excelled in
intense brilliancy by the sun itself. It is necessary in order to make
such a light successful that it should be continuous. But as it is found
that both carbons waste away under the consuming action of the intense
heat engendered by their resistance to the electric current, and that
one electrode, the positive, wastes away twice as fast as the opposite
negative electrode, the distance between the points soon becomes too
great for the current longer to leap over it, and the light is then
extinguished. Many ingenious contrivances have been devised for
correcting this trouble, and maintaining a continuously uniform distance
between the carbons by giving to them a self-adjusting automatic action.
Such an apparatus is called a _regulator_, and the variety of regulators
is very great. The French were among the first to contrive such
regulators,--Duboscq, Foucault, Serrin, Houdin, and Lontin invented most
useful forms of such apparatus. Other early inventors were Hart of
Scotland, Siemens of Germany, Thompson and Houston of England, and
Farmer, Brush, Wallace, Maxim, and Weston and Westinghouse of America.
Gramme made his armature of iron rods to prevent its destruction by
heat. Weston in 1882 improved this method by making the armature of
separate and insulated sheets of iron around which the coil is wound.
The arc light is adapted for streets and great buildings, etc.; but for
indoor illumination, when a milder, softer light is desirable, the
_incandescent_ light was invented, and this consists of a curved
filament of carbon about the size of a coarse horsehair, seated in a
bulb of glass from which the air has been exhausted. In exhausted air
carbon rods or filaments are not consumed, and so great ingenuity was
exercised on that line. Among the early noted inventors of incandescent
carbon filament lamps were Edison and Maxim of New York, Swan, and
Lane-Fox of England.
Another problem to be solved arose in the proposed use of arc lamps upon
an extended scale, or in series, as in street lighting, wherein the
current to all lamps was supplied by a single wire, and where it was
found that owing to the unequal consumption of the carbons some were
burning well, some poorly, and some going out. It was essential,
therefore, to make each lamp independent of the resistance of the main
circuit and of the action of the other lamps, and to have its regulating
mechanism governed entirely by the resistance of its own arc. The
solution of this difficult problem was the invention by Heffner von
Alteneck of Germany, and his device came into use wherever throughout
the world arc lamps were operated. Westinghouse also improved the direct
alternating system of lighting by one wire by the introduction of two
conducting wires parallel to each other, and passing an interrupted or
alternating current through one, thereby inducing a similar and always
an alternating current through the other. Brush adopted a three-wire
system; and both obtained a uniform consumption of the carbons.
In a volume like this, room exists for mention only of those inventions
which burn as beacon lights on the tallest hills--and so we must now
pass on to others.
Just as Faraday was bringing his long series of experimental researches
to a close in 1856-59, and introducing the fruits of his labours into
the lighthouses of England, Cyrus W. Field of New York had commenced his
trials in the great scheme of an ocean cable to “moor the new world
alongside the old,” as John Bright expressed it. After crossing the
ocean from New York to England fifty times, and baffled often by the
ocean, which broke his cables, and by the incredulous public of both
hemispheres, who laughed at him, and by electricity, which refused to do
his bidding, he at last overcame all obstacles, and in 1866 the cable
two thousand miles in length had been successfully stretched and
communication perfected. To employ currents of great power, the cable
insulation would have been disintegrated and finally destroyed by heat.
Therefore only feeble currents could be used. But across that long
distance these currents for many reasons grew still weaker. The
inventor, Sir William Thomson, was at hand to provide the remedy. First,
by his _mirror galvanometer_. A needle in the shape of a small magnet
and connected to the current wires, is attached to the back of a small
concave mirror having a hole in its centre; opposite the mirror is
placed a graduated scale board, having slits through it, and a lighted
lamp behind it. The light is thrown through the slits across to the hole
at the center of the mirror and upon the needle. The feeblest imaginable
current suffices to deflect the needle in one direction, which throws
back the little beam of light upon it to the graduated front of the
scale. When the current is reversed the needle and its shadow are
deflected in the other direction, and so by a combination of right and
left motions, and pauses, of the spots of light to represent letters,
the message is spelled out. Second, a more expeditious instrument called
the _syphon recorder_. In this the galvanometer needle is connected to a
fine glass syphon tube conducting ink from a reservoir on to a strip of
paper which is drawn under the point of the tube with a uniform motion.
The irregular movements given the galvanometer needle by the varying
current are clearly delineated on the paper. Or in writing very long
cables the point of the syphon may not touch the paper, but the ink by
electrical attraction from the paper is ejected from the syphon upon the
paper in a succession of fine dots. The irregular lines of dots and
dashes were translated into words in accordance with the principles of
the Morse telegraph.
An instrument was exhibited at the Centennial International Exhibition
at Philadelphia in 1876, which was considered by the judges “the
greatest marvel hitherto achieved by the electric telegraph.” Such was
the language used both by Prof. Joseph Henry and Sir Wm. Thomson, and
concurred in by the other eminent judges from America, Germany, France,
Austria and Switzerland. This instrument was the _Telephone_. It
embodied, for the practical purpose of transmitting articulate speech to
distances, the union of the two great forces,--sound and electricity. It
consisted of a method and an apparatus. The apparatus or means consisted
of an electric battery circuit, a transmitting cone placed at one end of
the line into which speech and other vocal sounds were uttered, a
diaphragm against which the sounds were projected, an armature secured
to or forming a part of the diaphragm, an electro-magnet loosely
connected to the armature, a wire connecting this magnet with another
precisely similar arrangement of magnet, armature, diaphragm, and cone,
at the receiving end. When speech was uttered in the transmitter the
sound vibrations were received on the diaphragm, communicated to the
electricised armature, from thence by induction to the magnet and the
connecting wire current, which, undulating with precisely the same form
of sound vibrations, carried them in exactly the same form to the
receiving magnet. They were then carried through the receiving armature
and reproduced on the receiving diaphragm, with all the same
characteristics of pitch, loudness and quality.
The inventor was Alexander Graham Bell, by nativity a Scotchman, then a
resident of Canada, and finally a citizen of the United States. His
father was a teacher of vocal physiology at Edinburgh, and he himself
became a teacher of deaf mutes. This occupation naturally led him to a
thorough investigation of the laws of sound. He acknowledged the aid he
received from the great work of Helmholtz on the _Theory of Tone_. His
attention was called to sounds transmitted and reproduced by the
electric current, especially by the ease with which telegraph operators
read their messages by the duration of the “click” of their instruments.
He knew of the old device of a tightly-stretched string or wire between
two little boxes. He had read the publication of Prof. C. G. Page, of
America, in 1837, on the _Production of Galvanic Music_, in which was
described how musical notes were transmitted and reproduced by an
interrupted magnetic circuit. He became acquainted with the experimental
musical telephonic and acoustic researches of Reis, and others of
Germany, and those of celebrated scientists in France, especially the
phonautograph of Scott, a delicate instrument having a cone membrane and
pointer, and used to reproduce on smoked glass the waves of sound. He
commenced his experiments with magneto instruments in 1874, continued
them in 1875, when he succeeded in reproducing speech, but poorly, owing
to his imperfect instruments, and then made out his application, and
obtained a patent in the United States in July, 1876.
Like all the other remarkable inventions recorded in these pages, this
“marvel” did not spring forth as a sudden creation, but was a slow
growth of a plant derived from old ideas, although it blossomed out
suddenly one day when audible sounds were accidentally produced upon an
apparatus with which he was experimenting.
It is impossible here to narrate the tremendous conflict that Bell now
encountered to establish his title as first inventor, or to enumerate
the multitude of improvements and changes made which go to make up the
successful telephone of to-day.
The messages of the voice are carried on the wings of electricity
wherever any messages are carried, except under the widest seas, and
this difficulty inventors are now seeking to overcome.
The story of the marvellous inventions of the century in electricity is
a fascinating one, but in length and details it is also marvellous, and
we must hasten unwillingly to a close. Numerous applications of it will
be mentioned in chapters relating to other arts.
In the generation of this mighty force improvements have been made, but
those of greatest power still involve the principles discovered by
Faraday and Henry seventy years ago. The ideas of Faraday of the “lines
of force”--the magnetic power streaming from the poles of the magnet
somewhat as the rays of heat issue on all sides from a hot body, forming
the magnetic field--and that a magnet behaves like an electric current,
producing an electric wave by its approach to or recession from a coil
of wire, joined with Henry’s idea of increasing the magnetising effect
by increasing the number of coils around the magnet, enter into all
powerful dynamo electric machines of to-day. In them the lines of force
must flow around the frame and across the path of the armature; and
there must be a set of conductors to cut the lines of force twice in
every revolution of the cylinder carrying the armature from which the
current is taken.
When machines had been produced for generating with some economy
powerful currents of electricity, their use for the world’s business
purposes rapidly increased. Among such applications, and following
closely the electric lighting, came the _electric railway_. A substitute
for the slow animal, horse, and for the dangerous, noisy steam horse and
its lumbering locomotive and train, was hailed with delight. Inventors
came forward with adaptations of all the old systems they could think of
for the purpose, and with many new ones. One plan was to adapt the
storage battery--that silent chemical monster which carries its own
power and its own machine--and place one on each car to actuate a motor
connected to the driving wheels. Another plan was to conduct the current
from the dynamo machine at its station along the rails on one side of
the track to the motor on the car and the return current on the opposite
track; another was to carry the current to the car on a third rail
between the track, using both the other rails for the return; another to
use an overhead wire for the current from the dynamo, and connect it
with the car by a rod, one end of which had a little wheel or trolley
running on the overhead wire, to take up the current, the other end
being connected by a wire to the car motor; another plan to have a
trench made leading from the central station underneath the track the
whole length of the line, and put into this trench conducting wires from
the dynamo, to one of which the car motor should be connected by a
trolley rod or “brush,” extending down through a central slot between
the rails of the track to carry the electric supply into the motor. In
all these cases a lever was supplied to cut off communication between
the conducting wire and the motor, and a brake lever to stop the car.
All of these plans have been tried, and some of them are still being
tried with many improvements in detail, but not in principle.
The first electrical railway was constructed and operated at Berlin in
1879, by Messrs Siemens and Halske. It was two thousand seven hundred
feet long and built on the third rail system. This was an experiment but
a successful one. It was followed very soon by another line near Berlin
for actual traffic; then still another in Saxony. At the Paris
Exposition in 1881, Sir Wm. Siemens had in operation a road about one
thousand six hundred feet in length, on which it is estimated
ninety-five thousand passengers were conveyed in seven weeks. Then in
the next year in London; and then in the following year one in the
United States near New York, constructed by Edison. And thus they
spread, until every important town and city in the world seems to have
its electric plant, and its electric car system, and of course its
lighting, telephone and telegraph systems.
In 1882 Prof. Fleeming Jenkin of England invented and has put to use a
system called _Telpherage_, by which cars are suspended on an overhead
wire which is both the track and electrical conductor. It has been found
to be advantageous in the transportation of freight from mines and other
places to central stations.
With the coming of the electric railway, the slow, much-abused horse,
the puffing steam engine blowing off smoke and cinders through the
streets, the great heavy cars, rails and roadbeds, the dangerous
collisions and accidents, have disappeared.
The great problems to solve have related to generation, form,
distribution and division of the electric current at the dynamos at the
central stations for the purposes of running the distant motors and for
furnishing independent supplies of light, heat, sound and power. These
problems have received the attention of the keenest inventors and
electrical engineers and have been solved.
The description of the inventions made by such electrical magicians as
Thomas Edison and Nikola Tesla would fill volumes.
The original plan of sending but one message over a wire at a time has
also been improved; and duplex, quadruplex and multiplex systems have
been invented (by Stearns, Farmer, Edison and others) and applied, which
have multiplied the capacity of the telegraphs, and by which even the
alleged all-talk-at-the-same-time habit of certain members of the great
human family can be carried on in opposite directions on the same wire
at the same time between their gatherings in different cities and
without a break.
To understand the manner of multiplying messages or signals on the same
line, and using apparently the same electric current to perform
different operations, the mind must revert to the theory already
referred to, that a current of electricity does not consist of a stream
of matter flowing like water through a conductor in one direction, but
of particles of subtle ether, vibrating or oscillating in waves from and
around the conductor which excites them; that the vibration of this line
of waves proceeds at the rate of many thousand miles per second, almost
with the velocity of waves of light, with which they are so closely
related; that this wave current is susceptible of being varied in
direction and in strength, according to the impulse given by the initial
pressure of the transmitting and exciting instrument; and that some wave
currents have power by reason of their form or strength to penetrate or
pass others coming from an opposite direction. So that in the multiplex
process, for instance, each transmission having a certain direction or
strength and its own set of transmitting and receiving instruments, will
have power to give its own peculiar and independent signal or message.
Apparently there is but one continuous current, but in reality each
transmission is separated from the others by an almost inconceivably
short interval of time.
Among the inventions in the class of Telegraphy should also be mentioned
the dial and the printing systems. Ever since the electric telegraph was
invented, attempts have been made to use the electric influence to
operate either a pointer to point out the letters of the message sent on
a dial, or to print them on a moving strip of paper; and also to
automatically reproduce on paper the handwriting of the sender or writer
of the message. The earliest efforts were by Cooke and Prof. Wheatstone
of London, in 1836-37; but it was not until 1839, after Prof. Henry had
succeeded in perfecting the electromagnet, that dial and printing
telegraphs were successfully produced. Dial telegraphs consist of the
combination with magnets, armatures and printed dial plate of a
clock-work and a pointer, means to set the pointer at the communicating
end (which in some instances has been a piano keyboard) to any letter,
the current operating automatically to indicate the same letters at the
receiving end. These instruments have been modified and improved by
Brequet and Froment of France, Dr. Siemens and Kramer, and Siemens and
Halske of Germany, Prof. Wheatstone of England, Chester and Hamblet of
America, and others. They have been used extensively upon private and
municipal lines both in Europe and the United States.
The type-printing telegraph was coeval with the dial, and originated
with Morse and Vail as early as 1837. The printing of the characters is
effected in various ways; sometimes by clockwork mechanism and sometimes
by the direct action of an electromagnet. Wheatstone exhibited one in
1841. House of Vermont invented in 1845-1846 the first printing
telegraph that was brought into any extensive use in the United States.
Then followed that of David E. Hughes of Kentucky in 1855, aided by his
co-inventor George M. Phelps of Troy, New York, and which was
subsequently adopted by the French government, by the United Kingdom
Telegraph Co. of Great Britain, and by the American Telegraph Co in the
United States. The system was subsequently greatly improved by Hughes
and others. Alexander Bain of Edinburgh in 1845-46 originated the modern
automatic chemical telegraph. In this system a kind of punch was used to
perforate two rows of holes grouped to represent letters on a strip of
paper conducted over a metal cylinder and arranged so as to permit
spring levers to drop through the perforations and touch the cylinder,
thus forming an electrical contact; and a recording apparatus consisting
of a strip of paper carried through a chemical solution of an acid and
potash and over a metal roller, and underneath one or two styles, or
pens, which pens were connected by live wires with the poles of two
batteries at the sending station. The operation is such that colored
marks upon the paper were made by the pens corresponding precisely to
the perforations in the strip at the sending station. Siemens,
Wheatstone and others also improved this system; but none of these
systems have as yet replaced or equalled in extensive use the Morse key
and sounder system, and its great acoustic advantage of reading the
messages by the click of the instrument. The type-printing system,
however, has been recently greatly improved by the inventions of Howe,
C. L. Buckingham, Fiske and others in the United States. Special
contrivances and adaptations of the telegraph for printing stock reports
and for transmitting fire alarm, police, and emergency calls, have been
invented.
The erection of tall office and other buildings, some to the height of
more than twenty stories, made practicable by the invention of the
elevator system, has in turn brought out most ingenious devices for
operating and controlling the elevators to insure safety and at the same
time produce economy in the motive power.
The utility of the telephone has been greatly increased by the
inventions of Hughes and Edison of the _microphone_. This consists, in
one form, of pieces of carbon in loose contact placed in the circuit of
a telephone. The very slightest vibrations communicated to the wood are
heard distinctly in the telephone. By these inventions and certain
improvements not only every sound and note of an opera or concert has
been carried to distant places, but the slightest whispers, the minute
movements of a watch, even the tread of a fly, and the pressure of a
finger, have been rendered audible.
By the aid of the electric current certain rays of light directed upon
the mineral selenium, and some other substances, have been discovered to
emit musical sounds.
So wonderful and mysterious appear these communications along the
electric wire that each and every force in the universe seems to have a
voice awaiting utterance to man. The hope is indulged that by some such
means we may indeed yet receive the “touch of a vanished hand and the
sound of a voice that is still.”
In 1879 that eminent English scientist, Prof. Wm. Crookes, published his
extensive researches in electrical discharges as manifested in glass
tubes from which the air had been exhausted. These same tubes have
already been referred to as Geissler tubes, from the name of a young
artist of Bonn who invented them. In these tubes are inclosed various
gases through which the sparks from an induction coil can be passed by
means of platinum electrodes fused into the glass, and on the passage of
the current a soft and delicately-tinted light is produced which streams
through the tube from pole to pole.
In 1895, Wm. Konrad Roentgen, professor of Physics in the Royal
University of Würzburg, while experimenting with these Crookes and
Geissler tubes, discovered with one of them, which he had covered with a
sort of black cardboard, that the rays emanating from the same and
impinging on certain objects would render them self-luminous, or
fluorescent; and on further investigation that such rays, unlike the
rays of sunlight, were not deflected, refracted or condensed; but that
they proceeded in straight lines from the point at which they were
produced, and penetrated various articles, such as flesh, blood, and
muscle, and thicknesses of paper, cloth and leather, and other
substances which are opaque to ordinary light; and that thus while
penetrating such objects and rendering them luminous, if a portion of
the same were of a character too dense to admit of the penetration, the
dark shadow of such obstacle would appear in the otherwise luminous
mass.
Unable to explain the nature or cause of this wonderful revelation,
Roentgen gave to the light an algebraic name for the unknown--the X
rays.
This wonderful discovery, at first regarded as a figment of scientific
magic, soon attracted profound attention. At first the experiments were
confined to the gratification of curiosity--the interior of the hand was
explored, and on one occasion the little mummified hand of an Egyptian
princess folded in death three or four thousand years ago, was held up
to this light, and the bones, dried blood, and muscle of the ancient
Pharaohs exhibited to the startled eyes of the present generation. But
soon surgery and medicine took advantage of the unknown rays for
practical purposes. The location of previously unreachable bullets, and
the condition of internal injuries, were determined; the cause of
concealed disease was traced, the living brain explored, and the
pulsations of the living heart were witnessed.
Retardation of the strength of the electric current by the inductive
influence of neighboring wires and earth currents, together with the
theory that the electric energy pervades all space and matter, gave rise
to the idea that if the energy once established could be set in motion
at such point above the ordinary surface of the earth as would free this
upper current from all inductive disturbance, impulses of such power
might be conveyed from one high point and communicated to another as to
produce signals without the use of a conducting wire, retaining only the
usual batteries and the earth connection. On July 30th, 1872, Mahlen
Loomis of Washington, D. C., took out a patent for “the utilization of
natural electricity from elevated points” for telegraphic purposes,
based on the principle mentioned, and made successful experiments on the
Blue Ridge mountains in Virginia near Washington, accounts of which were
published in Washington papers at the time; but being poor and receiving
no aid or encouragement he was compelled to give it up. Marconi of Italy
has been more successful in this direction, and has sent electric
messages and signals from high stations over the English Channel from
the shores of France to England. So that now wireless telegraphy is an
established fact.
It is certainly thrilling to realize that there is a mysterious, silent,
invisible and powerful mechanical agent on every side of us, waiting to
do our bidding, and to lend a hand in every field of human labour, and
yet unable to be so used without excitement to action and direction in
its course by some master, intermediate between itself and man. The
principal masters for this purpose are steam and water power. A small
portion of the power of the resistless Niagara has been taken, diverted
to turn the machinery which excites electricity to action, and this
energy in turn employed to operate a multitude of the most powerful
motors and machines of many descriptions.
So great is the might of this willing agent that at a single turn of the
hand of man it rushes forth to do work for him far exceeding in wonder
and extent any labour of the gods of mythological renown.