Miscellaneous Inventions - 3

Miscellaneous Inventions - 3

  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

sub- stances 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.