MISCELLANEOUS INVENTIONS
IT has been the endeavor in this narrative to group Edison's inventions
and patents so that his work in the different fields can be studied
independently and separately. The history of his career has therefore
fallen naturally into a series of chapters, each aiming to describe some
particular development or art; and, in a way, the plan has been helpful
to the writers while probably useful to the readers. It happens,
however, that the process has left a vast mass of discovery and
invention wholly untouched, and relegates to a concluding brief chapter
some of the most interesting episodes of a fruitful life. Any one who
will turn to the list of Edison patents at the end of the book will find
a large number of things of which not even casual mention has been made,
but which at the time occupied no small amount of the inventor's time
and attention, and many of which are now part and parcel of modern
civilization. Edison has, indeed, touched nothing that he did not in
some way improve. As Thoreau said: "The laws of the Universe are not
indifferent, but are forever on the side of the most sensitive," and
there never was any one more sensitive to the defects of every art and
appliance, nor any one more active in applying the law of evolution.
It is perhaps this many-sidedness of Edison that has impressed the
multitude, and that in the "popular vote" taken a couple of years ago
by the New York Herald placed his name at the head of the list of ten
greatest living Americans. It is curious and pertinent to note that a
similar plebiscite taken by a technical journal among its expert readers
had exactly the same result. Evidently the public does not agree with
the opinion expressed by the eccentric artist Blake in his "Marriage of
Heaven and Hell," when he said: "Improvement makes strange roads; but
the crooked roads without improvements are roads of Genius."
The product of Edison's brain may be divided into three classes. The
first embraces such arts and industries, or such apparatus, as have
already been treated. The second includes devices like the tasimeter,
phonomotor, odoroscope, etc., and others now to be noted. The third
embraces a number of projected inventions, partially completed
investigations, inventions in use but not patented, and a great many
caveats filed in the Patent Office at various times during the last
forty years for the purpose of protecting his ideas pending their
contemplated realization in practice. These caveats served their purpose
thoroughly in many instances, but there have remained a great variety of
projects upon which no definite action was ever taken. One ought to
add the contents of an unfinished piece of extraordinary fiction based
wholly on new inventions and devices utterly unknown to mankind. Some
day the novel may be finished, but Edison has no inclination to go
back to it, and says he cannot understand how any man is able to make a
speech or write a book, for he simply can't do it.
After what has been said in previous chapters, it will not seem so
strange that Edison should have hundreds of dormant inventions on his
hands. There are human limitations even for such a tireless worker as he
is. While the preparation of data for this chapter was going on, one of
the writers in discussing with him the vast array of unexploited things
said: "Don't you feel a sense of regret in being obliged to leave so
many things uncompleted?" To which he replied: "What's the use? One
lifetime is too short, and I am busy every day improving essential parts
of my established industries." It must suffice to speak briefly of a few
leading inventions that have been worked out, and to dismiss with
scant mention all the rest, taking just a few items, as typical and
suggestive, especially when Edison can himself be quoted as to them.
Incidentally it may be noted that things, not words, are referred to;
for Edison, in addition to inventing the apparatus, has often had to
coin the word to describe it. A large number of the words and phrases in
modern electrical parlance owe their origin to him. Even the "call-word"
of the telephone, "Hello!" sent tingling over the wire a few million
times daily was taken from Menlo Park by men installing telephones
in different parts of the world, men who had just learned it at
the laboratory, and thus made it a universal sesame for telephonic
conversation.
It is hard to determine where to begin with Edison's miscellaneous
inventions, but perhaps telegraphy has the "right of line," and Edison's
work in that field puts him abreast of the latest wireless developments
that fill the world with wonder. "I perfected a system of train
telegraphy between stations and trains in motion whereby messages could
be sent from the moving train to the central office; and this was the
forerunner of wireless telegraphy. This system was used for a number of
years on the Lehigh Valley Railroad on their construction trains. The
electric wave passed from a piece of metal on top of the car across
the air to the telegraph wires; and then proceeded to the despatcher's
office. In my first experiments with this system I tried it on the
Staten Island Railroad, and employed an operator named King to do the
experimenting. He reported results every day, and received instructions
by mail; but for some reason he could send messages all right when the
train went in one direction, but could not make it go in the contrary
direction. I made suggestions of every kind to get around this
phenomenon. Finally I telegraphed King to find out if he had any
suggestions himself; and I received a reply that the only way he could
propose to get around the difficulty was to put the island on a pivot
so it could be turned around! I found the trouble finally, and the
practical introduction on the Lehigh Valley road was the result. The
system was sold to a very wealthy man, and he would never sell any
rights or answer letters. He became a spiritualist subsequently, which
probably explains it." It is interesting to note that Edison became
greatly interested in the later developments by Marconi, and is an
admiring friend and adviser of that well-known inventor.
The earlier experiments with wireless telegraphy at Menlo Park were
made at a time when Edison was greatly occupied with his electric-light
interests, and it was not until the beginning of 1886 that he was
able to spare the time to make a public demonstration of the system
as applied to moving trains. Ezra T. Gilliland, of Boston, had become
associated with him in his experiments, and they took out several joint
patents subsequently. The first practical use of the system took place
on a thirteen-mile stretch of the Staten Island Railroad with the
results mentioned by Edison above.
A little later, Edison and Gilliland joined forces with Lucius J.
Phelps, another investigator, who had been experimenting along the same
lines and had taken out several patents. The various interests were
combined in a corporation under whose auspices the system was installed
on the Lehigh Valley Railroad, where it was used for several years. The
official demonstration trip on this road took place on October 6,
1887, on a six-car train running to Easton, Pennsylvania, a distance of
fifty-four miles. A great many telegrams were sent and received while
the train was at full speed, including a despatch to the "cable king,"
John Pender. London, England, and a reply from him. [17]
[Footnote 17: Broadly described in outline, the system
consisted of an induction circuit obtained by laying strips
of tin along the top or roof of a railway car, and the
installation of a special telegraph line running parallel
with the track and strung on poles of only medium height.
The train and also each signalling station were equipped
with regulation telegraphic apparatus, such as battery, key,
relay, and sounder, together with induction-coil and
condenser. In addition, there was a transmitting device in
the shape of a musical reed, or buzzer. In practice, this
buzzer was continuously operated at high speed by a battery.
Its vibrations were broken by means of a key into long and
short periods, representing Morse characters, which were
transmitted inductively from the train circuit to the pole
line, or vice versa, and received by the operator at the
other end through a high-resistance telephone receiver
inserted in the secondary circuit of the induction-coil.]
Although the space between the cars and the pole line was probably not
more than about fifty feet, it is interesting to note that in Edison's
early experiments at Menlo Park he succeeded in transmitting messages
through the air at a distance of 580 feet. Speaking of this and of
his other experiments with induction telegraphy by means of kites,
communicating from one to the other and thus from the kites to
instruments on the earth, Edison said recently: "We only transmitted
about two and one-half miles through the kites. What has always puzzled
me since is that I did not think of using the results of my experiments
on 'etheric force' that I made in 1875. I have never been able to
understand how I came to overlook them. If I had made use of my own work
I should have had long-distance wireless telegraphy."
In one of the appendices to this book is given a brief technical account
of Edison's investigations of the phenomena which lie at the root of
modern wireless or "space" telegraphy, and the attention of the reader
is directed particularly to the description and quotations there from
the famous note-books of Edison's experiments in regard to what he
called "etheric force." It will be seen that as early as 1875 Edison
detected and studied certain phenomena--i.e., the production of
electrical effects in non-closed circuits, which for a time made him
think he was on the trail of a new force, as there was no plausible
explanation for them by the then known laws of electricity and
magnetism. Later came the magnificent work of Hertz identifying the
phenomena as "electromagnetic waves" in the ether, and developing a
new world of theory and science based upon them and their production by
disruptive discharges.
Edison's assertions were treated with scepticism by the scientific
world, which was not then ready for the discovery and not sufficiently
furnished with corroborative data. It is singular, to say the least,
to note how Edison's experiments paralleled and proved in advance those
that came later; and even his apparatus such as the "dark box" for
making the tiny sparks visible (as the waves impinged on the receiver)
bears close analogy with similar apparatus employed by Hertz. Indeed, as
Edison sent the dark-box apparatus to the Paris Exposition in 1881,
and let Batchelor repeat there the puzzling experiments, it seems by no
means unlikely that, either directly or on the report of some friend,
Hertz may thus have received from Edison a most valuable suggestion, the
inventor aiding the physicist in opening up a wonderful new realm.
In this connection, indeed, it is very interesting to quote two great
authorities. In May, 1889, at a meeting of the Institution of Electrical
Engineers in London, Dr. (now Sir) Oliver Lodge remarked in a discussion
on a paper of his own on lightning conductors, embracing the Hertzian
waves in its treatment: "Many of the effects I have shown--sparks in
unsuspected places and other things--have been observed before. Henry
observed things of the kind and Edison noticed some curious phenomena,
and said it was not electricity but 'etheric force' that caused these
sparks; and the matter was rather pooh-poohed. It was a small part of
THIS VERY THING; only the time was not ripe; theoretical knowledge was
not ready for it." Again in his "Signalling without Wires," in giving
the history of the coherer principle, Lodge remarks: "Sparks identical
in all respects with those discovered by Hertz had been seen in recent
times both by Edison and by Sylvanus Thompson, being styled 'etheric
force' by the former; but their theoretic significance had not been
perceived, and they were somewhat sceptically regarded." During the same
discussion in London, in 1889, Sir William Thomson (Lord Kelvin), after
citing some experiments by Faraday with his insulated cage at the Royal
Institution, said: "His (Faraday's) attention was not directed to look
for Hertz sparks, or probably he might have found them in the interior.
Edison seems to have noticed something of the kind in what he called
'etheric force.' His name 'etheric' may thirteen years ago have seemed
to many people absurd. But now we are all beginning to call these
inductive phenomena 'etheric.'" With which testimony from the great
Kelvin as to his priority in determining the vital fact, and with the
evidence that as early as 1875 he built apparatus that demonstrated the
fact, Edison is probably quite content.
It should perhaps be noted at this point that a curious effect observed
at the laboratory was shown in connection with Edison lamps at the
Philadelphia Exhibition of 1884. It became known in scientific parlance
as the "Edison effect," showing a curious current condition or discharge
in the vacuum of the bulb. It has since been employed by Fleming in
England and De Forest in this country, and others, as the basis for
wireless-telegraph apparatus. It is in reality a minute rectifier of
alternating current, and analogous to those which have since been made
on a large scale.
When Roentgen came forward with his discovery of the new "X"-ray in
1895, Edison was ready for it, and took up experimentation with it on
a large scale; some of his work being recorded in an article in the
Century Magazine of May, 1896, where a great deal of data may be found.
Edison says with regard to this work: "When the X-ray came up, I made
the first fluoroscope, using tungstate of calcium. I also found that
this tungstate could be put into a vacuum chamber of glass and fused
to the inner walls of the chamber; and if the X-ray electrodes were let
into the glass chamber and a proper vacuum was attained, you could get a
fluorescent lamp of several candle-power. I started in to make a number
of these lamps, but I soon found that the X-ray had affected poisonously
my assistant, Mr. Dally, so that his hair came out and his flesh
commenced to ulcerate. I then concluded it would not do, and that it
would not be a very popular kind of light; so I dropped it.
"At the time I selected tungstate of calcium because it was
so fluorescent, I set four men to making all kinds of chemical
combinations, and thus collected upward of 8000 different crystals of
various chemical combinations, discovering several hundred different
substances which would fluoresce to the X-ray. So far little had come
of X-ray work, but it added another letter to the scientific alphabet.
I don't know any thing about radium, and I have lots of company." The
Electrical Engineer of June 3, 1896, contains a photograph of Mr. Edison
taken by the light of one of his fluorescent lamps. The same journal
in its issue of April 1, 1896, shows an Edison fluoroscope in use by
an observer, in the now familiar and universal form somewhat like a
stereoscope. This apparatus as invented by Edison consists of a flaring
box, curved at one end to fit closely over the forehead and eyes, while
the other end of the box is closed by a paste-board cover. On the inside
of this is spread a layer of tungstate of calcium. By placing the
object to be observed, such as the hand, between the vacuum-tube and
the fluorescent screen, the "shadow" is formed on the screen and can be
observed at leisure. The apparatus has proved invaluable in surgery and
has become an accepted part of the equipment of modern surgery. In 1896,
at the Electrical Exhibition in the Grand Central Palace, New York City,
given under the auspices of the National Electric Light Association,
thousands and thousands of persons with the use of this apparatus in
Edison's personal exhibit were enabled to see their own bones; and the
resultant public sensation was great. Mr. Mallory tells a characteristic
story of Edison's own share in the memorable exhibit: "The exhibit
was announced for opening on Monday. On the preceding Friday all the
apparatus, which included a large induction-coil, was shipped from
Orange to New York, and on Saturday afternoon Edison, accompanied by
Fred Ott, one of his assistants, and myself, went over to install it so
as to have it ready for Monday morning. Had everything been normal, a
few hours would have sufficed for completion of the work, but on coming
to test the big coil, it was found to be absolutely out of commission,
having been so seriously injured as to necessitate its entire rewinding.
It being summer-time, all the machine shops were closed until Monday
morning, and there were several miles of wire to be wound on the coil.
Edison would not consider a postponement of the exhibition, so there was
nothing to do but go to work and wind it by hand. We managed to find
a lathe, but there was no power; so each of us, including Edison, took
turns revolving the lathe by pulling on the belt, while the other two
attended to the winding of the wire. We worked continuously all through
that Saturday night and all day Sunday until evening, when we finished
the job. I don't remember ever being conscious of more muscles in
my life. I guess Edison was tired also, but he took it very
philosophically." This was apparently the first public demonstration of
the X-ray to the American public.
Edison's ore-separation work has been already fully described, but the
story would hardly be complete without a reference to similar work
in gold extraction, dating back to the Menlo Park days: "I got up a
method," says Edison, "of separating placer gold by a dry process, in
which I could work economically ore as lean as five cents of gold to the
cubic yard. I had several car-loads of different placer sands sent to me
and proved I could do it. Some parties hearing I had succeeded in doing
such a thing went to work and got hold of what was known as the Ortiz
mine grant, twelve miles from Santa Fe, New Mexico. This mine, according
to the reports of several mining engineers made in the last forty years,
was considered one of the richest placer deposits in the United States,
and various schemes had been put forward to bring water from the
mountains forty miles away to work those immense beds. The reports
stated that the Mexicans had been panning gold for a hundred years out
of these deposits.
"These parties now made arrangements with the stockholders or owners of
the grant, and with me, to work the deposits by my process. As I had had
some previous experience with the statements of mining men, I concluded
I would just send down a small plant and prospect the field before
putting up a large one. This I did, and I sent two of my assistants,
whom I could trust, down to this place to erect the plant; and started
to sink shafts fifty feet deep all over the area. We soon learned that
the rich gravel, instead of being spread over an area of three by seven
miles, and rich from the grass roots down, was spread over a space of
about twenty-five acres, and that even this did not average more than
ten cents to the cubic yard. The whole placer would not give more than
one and one-quarter cents per cubic yard. As my business arrangements
had not been very perfectly made, I lost the usual amount."
Going to another extreme, we find Edison grappling with one of the
biggest problems known to the authorities of New York--the disposal of
its heavy snows. It is needless to say that witnessing the ordinary slow
and costly procedure would put Edison on his mettle. "One time when
they had a snow blockade in New York I started to build a machine with
Batchelor--a big truck with a steam-engine and compressor on it. We
would run along the street, gather all the snow up in front of us, pass
it into the compressor, and deliver little blocks of ice behind us
in the gutter, taking one-tenth the room of the snow, and not
inconveniencing anybody. We could thus take care of a snow-storm
by diminishing the bulk of material to be handled. The preliminary
experiment we made was dropped because we went into other things. The
machine would go as fast as a horse could walk."
Edison has always taken a keen interest in aerial flight, and has also
experimented with aeroplanes, his preference inclining to the helicopter
type, as noted in the newspapers and periodicals from time to time.
The following statement from him refers to a type of aeroplane of great
novelty and ingenuity: "James Gordon Bennett came to me and asked that
I try some primary experiments to see if aerial navigation was feasible
with 'heavier-than-air' machines. I got up a motor and put it on the
scales and tried a large number of different things and contrivances
connected to the motor, to see how it would lighten itself on the
scales. I got some data and made up my mind that what was needed was a
very powerful engine for its weight, in small compass. So I conceived of
an engine employing guncotton. I took a lot of ticker paper tape, turned
it into guncotton and got up an engine with an arrangement whereby I
could feed this gun-cotton strip into the cylinder and explode it inside
electrically. The feed took place between two copper rolls. The copper
kept the temperature down, so that it could only explode up to the point
where it was in contact with the feed rolls. It worked pretty well;
but once the feed roll didn't save it, and the flame went through and
exploded the whole roll and kicked up such a bad explosion I abandoned
it. But the idea might be made to work."
Turning from the air to the earth, it is interesting to note that the
introduction of the underground Edison system in New York made an appeal
to inventive ingenuity and that one of the difficulties was met as
follows: "When we first put the Pearl Street station in operation, in
New York, we had cast-iron junction-boxes at the intersections of all
the streets. One night, or about two o'clock in the morning, a policeman
came in and said that something had exploded at the corner of William
and Nassau streets. I happened to be in the station, and went out to see
what it was. I found that the cover of the manhole, weighing about 200
pounds, had entirely disappeared, but everything inside was intact. It
had even stripped some of the threads of the bolts, and we could never
find that cover. I concluded it was either leakage of gas into the
manhole, or else the acid used in pickling the casting had given off
hydrogen, and air had leaked in, making an explosive mixture. As this
was a pretty serious problem, and as we had a good many of the manholes,
it worried me very much for fear that it would be repeated and the
company might have to pay a lot of damages, especially in districts
like that around William and Nassau, where there are a good many people
about. If an explosion took place in the daytime it might lift a few of
them up. However, I got around the difficulty by putting a little bottle
of chloroform in each box, corked up, with a slight hole in the cork.
The chloroform being volatile and very heavy, settled in the box and
displaced all the air. I have never heard of an explosion in a manhole
where this chloroform had been used. Carbon tetrachloride, now made
electrically at Niagara Falls, is very cheap and would be ideal for the
purpose."
Edison has never paid much attention to warfare, and has in general
disdained to develop inventions for the destruction of life and
property. Some years ago, however, he became the joint inventor of
the Edison-Sims torpedo, with Mr. W. Scott Sims, who sought his
co-operation. This is a dirigible submarine torpedo operated by
electricity. In the torpedo proper, which is suspended from a long
float so as to be submerged a few feet under water, are placed the small
electric motor for propulsion and steering, and the explosive charge.
The torpedo is controlled from the shore or ship through an electric
cable which it pays out as it goes along, and all operations of varying
the speed, reversing, and steering are performed at the will of the
distant operator by means of currents sent through the cable. During the
Spanish-American War of 1898 Edison suggested to the Navy Department the
adoption of a compound of calcium carbide and calcium phosphite, which
when placed in a shell and fired from a gun would explode as soon as it
struck water and ignite, producing a blaze that would continue several
minutes and make the ships of the enemy visible for four or five miles
at sea. Moreover, the blaze could not be extinguished.
Edison has always been deeply interested in "conservation," and much
of his work has been directed toward the economy of fuel in obtaining
electrical energy directly from the consumption of coal. Indeed, it
will be noted that the example of his handwriting shown in these volumes
deals with the importance of obtaining available energy direct from the
combustible without the enormous loss in the intervening stages that
makes our best modern methods of steam generation and utilization so
barbarously extravagant and wasteful. Several years ago, experimenting
in this field, Edison devised and operated some ingenious pyromagnetic
motors and generators, based, as the name implies, on the direct
application of heat to the machines. The motor is founded upon the
principle discovered by the famous Dr. William Gilbert--court physician
to Queen Elizabeth, and the Father of modern electricity--that the
magnetic properties of iron diminish with heat. At a light-red heat,
iron becomes non-magnetic, so that a strong magnet exerts no influence
over it. Edison employed this peculiar property by constructing a small
machine in which a pivoted bar is alternately heated and cooled. It
is thus attracted toward an adjacent electromagnet when cold and is
uninfluenced when hot, and as the result motion is produced.
The pyromagnetic generator is based on the same phenomenon; its aim
being of course to generate electrical energy directly from the heat of
the combustible. The armature, or moving part of the machine, consists
in reality of eight separate armatures all constructed of corrugated
sheet iron covered with asbestos and wound with wire. These armatures
are held in place by two circular iron plates, through the centre of
which runs a shaft, carrying at its lower extremity a semicircular
shield of fire-clay, which covers the ends of four of the armatures.
The heat, of whatever origin, is applied from below, and the shaft being
revolved, four of the armatures lose their magnetism constantly, while
the other four gain it, so to speak. As the moving part revolves,
therefore, currents of electricity are set up in the wires of the
armatures and are collected by a commutator, as in an ordinary dynamo,
placed on the upper end of the central shaft.
A great variety of electrical instruments are included in Edison's
inventions, many of these in fundamental or earlier forms being devised
for his systems of light and power, as noted already. There are numerous
others, and it might be said with truth that Edison is hardly ever
without some new device of this kind in hand, as he is by no means
satisfied with the present status of electrical measurements. He holds
in general that the meters of to-day, whether for heavy or for feeble
currents, are too expensive, and that cheaper instruments are a
necessity of the times. These remarks apply more particularly to what
may be termed, in general, circuit meters. In other classes Edison
has devised an excellent form of magnetic bridge, being an ingenious
application of the principles of the familiar Wheatstone bridge, used
so extensively for measuring the electrical resistance of wires; the
testing of iron for magnetic qualities being determined by it in the
same way. Another special instrument is a "dead beat" galvanometer which
differs from the ordinary form of galvanometer in having no coils or
magnetic needle. It depends for its action upon the heating effect of
the current, which causes a fine platinum-iridium wire enclosed in a
glass tube to expand; thus allowing a coiled spring to act on a pivoted
shaft carrying a tiny mirror. The mirror as it moves throws a beam of
light upon a scale and the indications are read by the spot of
light. Most novel of all the apparatus of this measuring kind is the
odoroscope, which is like the tasimeter described in an earlier chapter,
except that a strip of gelatine takes the place of hard rubber, as
the sensitive member. Besides being affected by heat, this device is
exceedingly sensitive to moisture. A few drops of water or perfume
thrown on the floor of a room are sufficient to give a very decided
indication on the galvanometer in circuit with the instrument.
Barometers, hygrometers, and similar instruments of great delicacy can
be constructed on the principle of the odoroscope; and it may also be
used in determining the character or pressure of gases and vapors in
which it has been placed.
In the list of Edison's patents at the end of this work may be noted
many other of his miscellaneous inventions, covering items such as
preserving fruit in vacuo, making plate-glass, drawing wire, and
metallurgical processes for treatment of nickel, gold, and copper ores;
but to mention these inventions separately would trespass too much on
our limited space here. Hence, we shall leave the interested reader to
examine that list for himself.
From first to last Edison has filed in the United States Patent
Office--in addition to more than 1400 applications for patents--some
120 caveats embracing not less than 1500 inventions. A "caveat" is
essentially a notice filed by an inventor, entitling him to receive
warning from the Office of any application for a patent for an invention
that would "interfere" with his own, during the year, while he is
supposed to be perfecting his device. The old caveat system has now been
abolished, but it served to elicit from Edison a most astounding record
of ideas and possible inventions upon which he was working, and many
of which he of course reduced to practice. As an example of Edison's
fertility and the endless variety of subjects engaging his thoughts, the
following list of matters covered by ONE caveat is given. It is needless
to say that all the caveats are not quite so full of "plums," but this
is certainly a wonder.
Forty-one distinct inventions relating to the phonograph, covering
various forms of recorders, arrangement of parts, making of records,
shaving tool, adjustments, etc.
Eight forms of electric lamps using infusible earthy oxides and brought
to high incandescence in vacuo by high potential current of several
thousand volts; same character as impingement of X-rays on object in
bulb.
A loud-speaking telephone with quartz cylinder and beam of ultra-violet
light.
Four forms of arc light with special carbons.
A thermostatic motor.
A device for sealing together the inside part and bulb of an
incandescent lamp mechanically.
Regulators for dynamos and motors.
Three devices for utilizing vibrations beyond the ultra violet.
A great variety of methods for coating incandescent lamp filaments with
silicon, titanium, chromium, osmium, boron, etc.
Several methods of making porous filaments.
Several methods of making squirted filaments of a variety of materials,
of which about thirty are specified.
Seventeen different methods and devices for separating magnetic ores.
A continuously operative primary battery.
A musical instrument operating one of Helmholtz's artificial larynxes.
A siren worked by explosion of small quantities of oxygen and hydrogen
mixed.
Three other sirens made to give vocal sounds or articulate speech.
A device for projecting sound-waves to a distance without spreading and
in a straight line, on the principle of smoke rings.
A device for continuously indicating on a galvanometer the depths of the
ocean.
A method of preventing in a great measure friction of water against the
hull of a ship and incidentally preventing fouling by barnacles.
A telephone receiver whereby the vibrations of the diaphragm are
considerably amplified.
Two methods of "space" telegraphy at sea.
An improved and extended string telephone.
Devices and method of talking through water for considerable distances.
An audiphone for deaf people.
Sound-bridge for measuring resistance of tubes and other materials for
conveying sound.
A method of testing a magnet to ascertain the existence of flaws in the
iron or steel composing the same.
Method of distilling liquids by incandescent conductor immersed in the
liquid.
Method of obtaining electricity direct from coal.
An engine operated by steam produced by the hydration and dehydration of
metallic salts.
Device and method for telegraphing photographically.
Carbon crucible kept brilliantly incandescent by current in vacuo, for
obtaining reaction with refractory metals.
Device for examining combinations of odors and their changes by rotation
at different speeds.
From one of the preceding items it will be noted that even in the
eighties Edison perceived much advantage to be gained in the line of
economy by the use of lamp filaments employing refractory metals in
their construction. From another caveat, filed in 1889, we extract the
following, which shows that he realized the value of tungsten also for
this purpose. "Filaments of carbon placed in a combustion tube with a
little chloride ammonium. Chloride tungsten or titanium passed through
hot tube, depositing a film of metal on the carbon; or filaments of
zirconia oxide, or alumina or magnesia, thoria or other infusible oxides
mixed or separate, and obtained by moistening and squirting through a
die, are thus coated with above metals and used for incandescent lamps.
Osmium from a volatile compound of same thus deposited makes a filament
as good as carbon when in vacuo."
In 1888, long before there arose the actual necessity of duplicating
phonograph records so as to produce replicas in great numbers, Edison
described in one of his caveats a method and process much similar to
the one which was put into practice by him in later years. In the
same caveat he describes an invention whereby the power to indent on
a phonograph cylinder, instead of coming directly from the voice, is
caused by power derived from the rotation or movement of the phonogram
surface itself. He did not, however, follow up this invention and put it
into practice. Some twenty years later it was independently invented
and patented by another inventor. A further instance of this kind is
a method of telegraphy at sea by means of a diaphragm in a closed
port-hole flush with the side of the vessel, and actuated by a
steam-whistle which is controlled by a lever, similarly to a Morse key.
A receiving diaphragm is placed in another and near-by chamber, which is
provided with very sensitive stethoscopic ear-pieces, by which the
Morse characters sent from another vessel may be received. This was
also invented later by another inventor, and is in use to-day, but will
naturally be rivalled by wireless telegraphy. Still another instance
is seen in one of Edison's caveats, where he describes a method of
distilling liquids by means of internally applied heat through electric
conductors. Although Edison did not follow up the idea and take out a
patent, this system of distillation was later hit upon by others and is
in use at the present time.
In the foregoing pages of this chapter the authors have endeavored
to present very briefly a sketchy notion of the astounding range of
Edison's practical ideas, but they feel a sense of impotence in being
unable to deal adequately with the subject in the space that can be
devoted to it. To those who, like the authors, have had the privilege
of examining the voluminous records which show the flights of his
imagination, there comes a feeling of utter inadequacy to convey to
others the full extent of the story they reveal.
The few specific instances above related, although not representing a
tithe of Edison's work, will probably be sufficient to enable the reader
to appreciate to some extent his great wealth of ideas and fertility
of imagination, and also to realize that this imagination is not only
intensely practical, but that it works prophetically along lines of
natural progress.