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N.Y. history would be considered incomplete if it did not include all events
from the beginning. Hence, since radio is based on electricity, our chronology
must begin with the ancient days, with the "discovery" of the peculiar spark
producing properties of amber when this material was rubbed on a piece of
cloth or fur. Similarly, knowledge of magnetic attraction in lodestone,
which also dates back to the days of the ancients, was an epochal event;
inasmuch as both of these "accidents" were responsible for the later discovery
and refinement of electrical laws and principles, which served as the foundation
upon which "wireless" was built.
While no exact dates are available, the earliest histories
mention the phenomena surrounding amber and the lodestone, as far
back as 600 B.C. In that era, it is chronicled, Thales discovered
mysterious sparks which resulted when rubbing the mineral amber,
and which we now know to be "static electricity." Since
the greek word for amber is "electrum," when the
experiment was repeated many centuries later, so that more might
be known regarding its cause and effect, it served as the root
for a new word---electricity.>
During the long interim, strange and fantastic superstitions
were conceived concerning static electricity and magnetism. The
philosophers of the early days theorized quite a bit, but did
very little experimenting; and what was know was handed down from
generation to generation with elaboration and no attempt at
justification by, at least, trial-and-error experiments.
Consequently, we find such fallacies, based more on hearsay, as
"garlic odor destroys the magnetic potency of the lodestone
or the compass." This myth lasted through the early
centuries clear up to 1544, when the famous trearise on Physics
by Philip Melanchthon included mention of it. After that time,
numerous controversies sprang up, pro and con, until 1646 when it
received its death blow from Sir Thomas Browne. This astute
physician-scientist refused to take anybody's word for it,
and actually performed experiments with magnetized iron and
"garlick juice"----thus definitely disproving the
centuries-old superstition.
Similary, numerous theories were created concerning amber and
diamonds; among them the most notable that iron rubbed with a
diamond became a magnet, and that diamonds when rubbed would
attract bits of paper and particles of dust. Another English
scientist, Dr. William Gilbert, outraged at what he termed
"chattering of barbers," undertook to disprove these
theories by actual experiment. To his discomfiture, he found that
the rubbibg of diamonds did cause them to attract bits of
paper; but he discovered also that practically everything he
rubbed, except metals, became thus
"electrified."
This led Gilbert to compile a huge list of materials which
could be "electrified," including such items as
"true jewels and paste imitations, sulphur, sealing wax,
rock salt, alum, resin," etc. It was this gentleman who gave
the name "electric" to this effect, and later on, in
1675, Robert Boyle, in his "Mechanical Production of
Electricity," coined or derived the word
"electricity" from it. More important, however, is
Gilbert's invention of the "electroscope," which he
probably used to test the various materials enumerated in his
lengthy compilation. Also, he too set a precedent by conducting
actual experiments before publishing scientific information,
refusing to accept hearsay as fact.
With the beginning of electricity, came a new era in
scientific research; from then on, scientists have resorted to
trial and tests to confirm their theories. Back into the darkness
were dispelled the mysteries and superstitions of the ancients.
Electricity was born, and new fields were open to conquest.
Perhaps that is why some chronologers refer to Gilbert as the
"Father of Electricity." At any rate, since this period
marks the inception o=f scientific electricity, because gradual
elimination of rumors, guesswork and superstition, our chronology
begins with the date 1600. Without question, scientific work of
importance in this field was reported earlier than this period,
and this fact is now acknowledged to avoid confusion, discussion
and unnecessary arguments.
1600
Dr. William Gilbert, physician to Queen Elizabeth, and
scientist. Invented the "electroscope," consisting of a
straw which was pivoted like a compass needle, and which
indicated the approach of a charged body. Disproved many myths,
and compiled a list of materials which could be electrified by
rubbibg. Coined the word "Electric", from the Greek
root for amber---"Electrum." Conceived the earth as a
huge magnet, with magnetic poles and a field of magnetic force
about it-- thus laying a positive foundation for many scientific
discoveries to come later.
1646
Sir Thomas Browne, English physician and author. Performed
many experiments with lodestone and magnetism, refuting many idle
superstitions by actual trial. Actually tried to make the first
"wireless" by employing two compasses with the alphabet
written about them (although credit for the idea must be given to
a predecessor, one John Baptista Porta). He imagined that, if the
two needles were magnetized together, then separated, the turning
of one to indicate some letter of the alphabet would cause the
indicator on the second dial to move to a similar position; thus
envisioning a means of communication without any intervening
medium. The second compass indicator, however, did not budge from
its North-pointing position, remaining as he said "like the
pillars of Hercules." Nevertheless, the thought of
communicating between persons over a distance, hitherto more or
less a figment of the imagination that inspired very few people
in the centuries before, became an intriguing thought in the
minds of many scientists of that time.
1672
Otto von Guericke, German burgomaster of Magdeburg. Famous
for the "Magdeburg experiment" with which he proved
atmospheric pressure, and entertained king and princes. Built an
"electric" generating device of a globe of sulphur
mounted on an axle and turned by a crank. The globe was rubbed by
the dry palm of the hand as it rotated, after some little
friction, the globe was sufficiently electrified to attract
particles. This machine was, of course, a generator only of
static electricity, not current electricity which we now use.
While experimenting with this device, he discovered that the
particles after they had been attracted would in a short while be
repelled. At this time we know that the particles assumed a like
charge to that of the sulphur ball and, when this condition
occurred, the particles were repelled because "like charges
ree each other." But the poor burgomaster was laying the
foundation for our knowledge by chasing a repelled feather around
the room with a heavy globe of sulphur in his arms. In his
pursuit of the feather, he noticed that the feather was repelled
by a lit candle on the table, and then "flew back to the
sulphur globe as a sort of guard." Von Guericke attributed
human attributes to a feather when, in reality, he had observed
the fact of electronic emission without knowing it; nearly three
more centuries elapsed before anyone knew more about this
phenomenon. What really happened to the feather was that its
charge was dissipated and the changed by the electron stream from
the candle and, consequently, was now attracted to the globe
which had repelled it before. His experiments resulted in further
discoveries but, as with all pioneering work performed with
little or no background, satisfactory explanations for some of
the phenomena he encountered were not available. He heard and saw
the tiny discharges which resulted when he generated static
electricity with his globe, but he didn't associate it with
lightning and thunder. That discovery was to wait until
Franklin's experiment with the kite.
1729
Stephen Gray, Englishman. By experimenting with charged
bodies, Gray discovered the effect and the differences of what we
now know to be conductors and insulators, as regards conveying or
transmitting charged impulses. About this same time, Dufay, a
Frenchman, conducted similar experiments but along more elaborate
lines. He, evidently, was versed in Gray's accomplishments
because his work seemed to be in the nature of proving or
disproving Gray's discoveries. In the course of his
experiments he found that metal wires or wet objects were the
best conductors, though the most difficult to electrify, while
those easiest to electrify were the best supporters or insulators
of the charged impulses. In fact, he built a line, a quarter mile
long, which consisted of wet held up on glass tubes and
determined that it was an excellent means of conveying a charged
impulse from one end to the other. This was probably the first
transmission or electric line, and consequently an important
discovery.
1745
Pieter Van Musschenbroek, of Leyden, Holland. Invented the
Leyden jar, after discovering it in an accidential but most
interesting manner. It must be remembered that the scientists of
this period were still playing around with friction apparatus,
since no other means for generating electricity had been
discovered. Musschenbroek had the thought that electricity could
be bottled or, rather, confined within a bottle so that it could
be used at some later time. Whether the idea was original with
him is hard to determine, since histories vary. At any rate, the
idea was that, if water were placed within a bottle and then
charged by means of a frictional-electric producing machine, the
charge would remain in the corked or stoppered bottle because
glass is a good insulating material. Fate took a hand the day
Musschenbroek was conducting the experiment. He was turning the
crank of the electric-producing machine, while his assistant,
Cunaeus, was holding the jar with one hand and with the other
trying to draw off sparks from the gun barrel. The circuit
consisted of the gun barrel connected to the friction machine and
also to a brass wire which entered the jar, partly filled with
water. Had Cunaeus placed the jar on a table, nothing would have
happened, and the condenser might not have been heard of today.
As it was, his hand formed one plate and, while Musschenbroek
cranked the machine, the improised condenser eventually became
charged up---and then Cunaeus must have thought the world had
come to an end! The tremendous spark which resulted caused the
entire charge to pass through his body---and the records have it
that Cunaeus was incapacitated for two full days. Another
scientist of that period, Nollet by name, heard of the experiment
and, unwilling to be a subject for experiment himself, got
together approximately two hundred soldiers, had them all join
hands in a large circle, and then, in much the same manner as
Musschenbrock and Cunaeus had done, sent a severe charge through
them. The fact that they all jumped instantly and strenuously
pleased him immensely, and gave him much to marvel at. Naturally
boyh Mussechenbroek and Nollet tried to figure out what had
caused the effect, and it wasn't for some time that a
definite conclusion was arrived at. They found that, when they
placed the jar of water on a table, it would refuse to be
electrified (since the other plate of the condenser was lacking)
and that, only when the hand was placed around the jar, could the
phenomenon be repeated. But volunteers for the experiment were
probably lacking; so eventually it was discovered that placing
the jar over a metal plate seemed to do as well. Later on, an
outside tinfoil covering was substituted, with improved results,
and for many years this was the actual construction of Leyden
jars---the grandaddy of all condensers.
1751
Benjamin Franklin, American statesman, philosopher and, last
but by no means least, scientist. Practically everyone is
familiar with Franklin's kite and lightning experiment---but
perhaps too familiar with this phase of his work and not so well
versed in his other scientific endeavors. Some of his deductions
have played an important role in the development of electricity
since he employed the same methodical precision and calm logic
which made him famous as a statesman and philosopher. Franklin
established the law of conservation of the electric charge; that
there are a Positive and Negative kind of electricity; that
lightning and thunder are related to the crashings and sparks
obtained when electrically-charged bodies became discharged. He
invented the lightning rod, to prevent the great damage done to
property by lightning, and sent the suggestion to the Royal
Society in London---but was ridiculed for it. His theories led to
his followers' discovery that air may be substituted as the
dielectric in place of glass in construction of a Leyden jar, as
well as that "like charges repel and unlike charges
attract"---which is now axiomatic.
1780
Aloysius Galvani, Italian professor of anatomy. Up to his
time, only two means for obtaining electricity were known; one by
means of the frictional machine, the other from the clouds, as
discovered by Franklin. Galvani (by accident, it is reported),
noticed that an electrical charge applied to a dead frog's
nerve would make it kick and struggle as if it were very much
alive. Continuing his experiments along this line, he found that
a number of frogs he had prepared and suspended on his balcony
would respond to lightning flashes in similar manner and that,
even before the storm , if a frog's leg happened to touch the
iron part of his balcony, the twitching muscular movement would
occur. Later on, he determined that any two metals joined
together, so that one touched a leg muscle and the other a leg
nerve, would cause the muscular twitching. Galvani then reasoned
that the muscle was akin to a Leyden jar, and that the
electricity was a fluid which made a circuit through the metallic
conductors back to the muscle again. He called the
"fluid" animal electricity; but true galvanic
electricity, as caused by two dissimilar metals in contact, was
not recognized by Galvani who theorized that the electricity
originated in the frog's leg.
1790
Alessandro Volta, Italian professor. Shortly after
Galvani's experiments, Volta devised what we now know as the
"voltaic pile," consisting of a pile of alternate zinc
and copper discs (each pair of discs being seperated by a
moistened pasteboard disc and termed a "couple"); so
that, by using quite an aggregation or large pile of discs, a
distinct shock was obtained when the finger tips were placed on
each end of the pile. The disadvantage of this arrangement was
that, when the pasteboard discs dried out, the voltage
diminished. Consequently Volta devised copper and zinc strips,
joined at the ends and placed in seperate jars containing a weak
acid solution. Now we have the first real battery---a unit
destined to be of great help to future inventors and scientists
in their explorations into the realm of electricity. In honor of
this discovery, Volta's name was immortalized when, later on,
the volt was the name given to the unit of electrical
force.
1800
Nicholson and Carlisle, English experimenters. Set up a
voltaic pile and showed that water could be decomposed into
it's elements, hydrogen and oxygen, by passing an electric
current through it. Known now as the electrolysis of
water.
1820
Hans Christian Oersted, Dane. Professor at Copenhagen. For
thirteen years Professor Oersted had experimented with
electricity and its effect on the compass needle, having read
Benjamin Franklin's reports that there was some effect and
relation between the two. While lecturing to a class, Oersted had
his attention called to the wavering of a compass needle,
whenever a switch was thrown which connected to a volyaic pile.
After the classroom students had departed, he investigated the
phenpmenon---finally ascertaining that, when the compass needle
was placed along the wire, there was a deflection, with the
compass needle coming to a stationary position when it was across
the wire. When the compass was placed above the wire, the
needle turned one way, when placed under the wire it
turned the other way. This was the basis for determining magnetic
lines of force, and without doubt the foundation for measuring or
indicating electrical instruments. In this same year, the
chronicles have it, one week after Oersted made the
aforementioned discovery, Andre Marie Ampere, French scientist,
made the important discovery that two parallel wires carrying an
electric current but free to move, attract each other if currents
travel in the same direction, and repel each other if they travel
in opposite directions. Also, he determined not only that a wire
carrying an electric current would attract a magnetized needle,
but that the needle would also attract the wire. Today we find
the unit of current, the ampere, named in his
honor.
1826
George Simon Ohm, Bavaria. His outstanding accomplishment is
the law which now bears his name: "A current flowing in any
closed circuit is proportional to the force or voltage and
inversely proportional to the resistance of the wire." Today
we express Ohm's Law simply by mathematical means,
viz., I=E/R.
1831
Joseph Henry, American physicist, improved the electromagnet
(developed by Arago in 1820) by using silk-covered wire, which
allowed the use of many layers of turns. First to employ
insulated wire, which permitted him to make coil-magnets large
enough to lift several pounds. The unit of inductance, the
henry, is named for him.
1832-1837
Samuel F.B. Morse, American artist, created the electric
telegraph system and conceived a "code" which permitted
transmission and reception of messages. This Morse
Code---still used in wired telegraphy---was soon adopted for
use in the earlier transmission and reception of wireless
messages.
1825-1867
Michael Faraday. English. Since it is very difficult to
assign accurately the various dates for Faraday's numerous
inventions and discoveries, we herewith list the period of his
activity. In 1824 Faraday became a Fellow of the Royal Institute,
but his fame as a scientist had preceded this date. He died in
1867; and in the interim his discoveries were the most complete,
numerous and productive of any contemporary scientist's. They
deal with every phase of the sciences, physics, chemistry,
mechanics, electro-chemistry and electricity. His first
explorations in the field of electricity resulted in the basic
principle of the electric motor. Faraday reasoned that, if an
electric current in wire causes a magnetized needle to rotate,
the a magnet should cause a wire carrying current to do likewise.
He proved his reasoning by suspending a conductor, so that it
could rotate between magnetic poles. He formulated the laws of
magnetic induction, which finally ledhim to invent the first
electric generator; as a matter of fact, he built many models,
each time improving them. Heinvented the induction coil which was
later improved by Ruhmkorff, a French-man; and also the
transformer, which operated from alternating current and,
consequently, did not need the interrupter device for starting
and stopping the current. In fact, Faraday discovered alternating
current; and the experiment now shown in high schools, for
producing electricity by plunging a bar magnet into a coil of
wire, was conceived by this most brilliant of all inventors. He
made astudy of condensers, discovered different dielectrics that
may be employed, and analyzed the relative merits of
each---finally tabulating this data so that today we have the
"dielectric constant" for each insulating material and
can be guided accordingly. He coined many electrical terms now in
use.
1865
James Clerk Maxwell, Scottish. Elaborated mathematically what
is known as the "electromagnetic theory of light",
although the thought was conceived by Faraday. This theory says
that light, electric waves and magnetic waves, of varying
frequency, travel in the same medium, namely---ether. Since ether
permeates all matter, a current may exist in and about a
conductor, but is essentially guided by
light.
1865
Dr. Mahlon Loomis, American dentist. The inventions of the
previous years in the field of electricity had brought about the
electric generator, batteries, the telegraph, are lights, a
trans-Atlantic cable and many other devices which were a great
boom to humanity. But man is always continuously striving to
improve as well as explore, and so we find Loomis, a Washington
dentist, conducting experiments and applying for a patent on a
method for transmitting and receiving messages whereby the
earth's atmosphere is used as one conductor. Strangely, he
not only wanted to send messages as aformentioned, but also to do
away with batteries or generators, since he was acquainted with
the fact that the atmosphere is continuously charged with
electricity. Operating on the theory that the higher the level,
the greater the charge would be, Loomis sent up kites 18 miles
apart, from two high mountains in West Virginia. The kites,
covered with large squares of copper screen or gauze, were
connected to the ground by strings within which fine copper wires
were enclosed. The wire from each kite string was connected to
one side of a galvanometer, the other side of which Loomis held
in readiness, so that he could establish a connection to a coil
buried in the earth. The receiving station connection, between
meter and earth coil was always closed; and, whenever the circuit
was closed at the transmitting end wonder of all wonders--the
galvanometer at the receiving station actually dipped! This and
other numerous similar tests were conducted in the presence of
reputable witnesses; and Loomis almost got an appropriation of
$50,000 from Congress, to develop his
invention.
1875
In 1875 the microphone (or magnetic transducer, which
functions optionally as an earphone) was invented by Alexander
Graham Bell. About 2 years later D. E. Hughes invented the carbon
microphone.
1879
David Edward Hughes, English. Discovered an arrangement which
consisted of a stick of wood covered with powdered copper; when
placed in an electrical circuit the copper particles would cohere
when a spark was made.
1885
Sir William Preece and A. W. Heaviside, Englishmen. These two
gentlemen sent signals to each other over a distance of 1,000
yards. The means employed consisted of two telegraph lines
paralleling each other, with a telephone receiver in the
receiving side. The telegraph signals could be clearly heard in
the phone receiver, without actual connection between the two,
due to what is known induction or, in common telephone
parlance, "cross-talk."
1887-1888
Heinrich Hertz, German. It will be noted that the dedication
to Olt Time Radio begins with this date since, in reality,
Hertz's experiments paved the way for Marconi's work in
this field. Some prefer to call Hertz the "Father of
Radio"; and that he deserves more than ordinary recognition,
for his work in this field is indicated by the fact that radio
waves are commonly referred to as "Hertzian Waves".
Hertz first became intrigued with this problem when he studied
Maxwell's theories concerning ligt, magnetism and electrical
waves. In an attempt to gain further data on this theory, Hertz
actually set up the first spark transmitter and receiver. The
transmitter consisted of a Leyden jar and a coil of wire, the
ends of which were left open so that a small gap was formed. For
the receiver he employed a similar coil, with a gap arrangement,
located in the opposite side of the room. When the Leyden jar was
charged sufficiently, it discharged through the gap in the wire
coil; and the oscillating waves thus generated were launched into
the ether of the room, and swept across the receiving coil
causing sparks to fly across the gap in the receiving coil, Hertz
measured the velocity of these waves and found that they were the
same as that of light, 186,000 miles per second; also measured
their length and, subsequently, substained Maxwell's
theories.
1892
Edouard Branly, French. Inventor of the coherer, which was
later destined to play so large a part in the practical reception
of wireless waves by Marconi. The coherer was not named as such
until later, nor was it basically conceived by Branly, since
Hughes had employed a similar device as mentioned previously.
Branly, however, made the device as Marconi was to use it,
consisting of a tube containing loose zinc and silver filings,
and plugs to make contact to each end. Since the filings would
echere (stick together) after the first spark was received, a
means of seoerating them for the next signal was necessary.
Popoff (Russian) conceived the idea of employing the vibrator and
hammer of an ordinary electric bell in the circuit of the coherer
so that, almost the instant the filings cohered, the hammer would
strike the tube and cause them to "discohere."
1893
Nikola Telsa, Serbian. Suggested a means of wireless
communication which utilized the earth as a conductor and created
stationary electrical waves on it. Invented the Telsa coil,
which, in effect, created high-frequency oscillations of a broad
nature (hence was in reality a broad wireless transmitter) but,
since he made no effort to detect them, allowed the golden
opportunity of being the first to discover wireless slip by. By
1905, he had devised a means of wireless communication from his
earlier experiments, but the Marconi system was well established
by that time.
1895-1900
Guglielmo Marconi, Italian. Considering the inventions and
research of previous years, it is with no great suprise that we
determine that scientists of this era looked upon Marconi as an
interloper and one of audacity. In 1895, Marconi conducted
experiments with Hertzian waves, and was able to send and receive
messages over a distance of a mile and a quarter. He employed the
coherer in- vented by Branley, with Popoff's automatic tapper
for decohering after a signal was received. In fact his apparatus
differed very slightly from that of his predecessors when he
applied for and was granted his first patent in England in 1896
for wireless telegraphy. From then on, however, Marconi made
rapid strides in the advancement of the art, being successful in
transmitting and receiving messages between two warships over a
distance of 12 miles. In this year, Marconi was successful in
enlisting the financial backing of a number of wealthy English-
men, and formed the Wireless Telegraph and Signal Company; he was
made a director of this company and placed in charge of all
development work although he was then but 23 years old. In 1899,
he adapted to wireless, Sir Oliver Lodge's principles of
syntomy, or tuning of circuits, perfecting it and obtaining a
patent in 1900. It was a remarkable step forward in wireless
transmission and reception, since it eliminated the interference
of stations transmitting simultaneously, a problem of no mean
proportions until that time. In 1899, Marconi was successful in
covering distances up to 74 miles with his instruments, and ship
and shore stations began to install his equipment. His activities
and progress with wireless filtered through to America, and in
1899 he was invited to this country by the New York Herald
which engaged him to report the international yacht races held in
October of that year. Marconi accepted for another reason, he
wanted to interest the United States Navy in his equipment in the
hope that it would make large purchases and thus help
commercially exploit wireless. To facilitate matters,
representatives of the British company financed and incorporated
the Wireless Telegraph Company of America, to take care of the
Marconi interests in this country. Marconi then went ahead with
the transmission and reception of the yacht race results, and an
amazed American public obtained the news as to who had won, long
before the ships had returned to port. From this angle
Marconi's efforts were thoroughly successful, but not so with
the Navy. In demonstrations, the official witnesses were
considerably impressed by the efficiency of his equipment,
although in their reports mention was made of the interference
obtained when two transmitters were operating. Marconi, with the
success of his experiments with Lodge's syntony or tuning
still fresh in his mind, specified that this defect could be
overcome. The deciding factor, however, against Marconi's
equipment was the terms of his proposed contract, which the Navy
definitely rejected. Thus, for a while, no further real progress
was made in wireless in this country. Marconi, in the meantime,
had gone back to England to continue with his experiments and
make further rapid advances in the art of wireless communication.
His famous Trans- Atlantic transmission of the letter
"S" is described elsewhere in this
chronicle.
1900-1905
Reginald A. Fessenden, and Lee DeForest, Americans. These two
gentlemen were the outstanding American contributors to the art
of wireless in its earlier days, and to each has been applied the
appellation of "father of American radio". Fessenden,
while fully acquainted with Marconi's wireless equipment
---having experimented with these devices---was more interested
in radio- telephony. He knew that Marconi's system was
adapted only to damped-wave transmission and that, as such, would
not tolerate super-imposing on it voice or further irregular
waves. Consequently, he began to experiment with continuous
wave transmissions (now know as C.W.), which led to his
perfecting an arc transmitter. However, the coherer would not
receive the voice impulses modulated on the oscillating wave
produced by the arc; so, remembering his electricity and
chemistry. Fessenden created the electrolytic detector,
which allowed current to flow in only one direction. It consisted
of a small aluminum cup, filled with a solution of acid and water
into which a fine silver wire dipped which was tremendous
improvement over the coherer, and increased the receiver's
efficiency considerably. Later on, Fessenden conceived the idea
of employing an alternator, similar to a regular A.C.
generator---but with a frequency much higher than 120 cycles--to
an antenna (similar to the arc transmitter's) and thus
eliminating the spark gaps and arcs which wasted so much power.
While at the time he was laughed at, his idea was in the future
to play a very important part in the progress of
radio.
Meanwhile, deForest was experimenting with wireless, and in
1901 built an outfit less cumbersome and more efficient than
Marconi's. He, too, employed the electrolytic detector, which
caused between him and Fesenden considerable legal conflict which
later was determined in Fessenden's favor. DeForest secured
some financial backing and formed the American DeForest Wireless
Telegraph Company. With this company he commenced manufacturing
equipment, some of which he sold to the Army. Unfortunately, the
company depended upon stock promotion for capital to finance its
development work, and soon it was in financial difficulties that
hampered it from getting into the commercial communications
field. In this same period, 1904 to be exact, J. Ambrose Fleming,
English. developed his 2-element (diode) "valve" while
employed by Marconi. He remembered Edison's experiments and
the so-called "Edison efect"--since he had been a
scientific adviser to the Edison Electric Light Company of
America---and hence it occurred to him that the phenomenon could
be employed to advantage as a detector of radio waves. This
invention was to enjoy only a short life, inasmuch as
deForest's discovery of the 3-element (triode) or audion tube
was soon to follow.
1906
DeForest's Audion. Here is the mightiest radio
invention of all! It consisted only of the insertion of a grid
between the filament and plate of Fleming's
"valve", yet this addition of a third element so
revolutionized radio that today we must be grateful for its
conception. While the power or ability of the audion tube as an
amplifier or generator of oscillations had not as yet been
recognized, its merit as a detector was soon proven. Despite this
invention, and other meritorious work in the wireless field
DeForest's finances were in extremely poor shape. To obtain
the necessary capital, he was forced to sell stock in his
company, but somehow an unwilling public could not be interested.
Later on, in 1912, to obtain funds for himself and his company
DeForest sold the rights to the Audion amplifier to the American
Telephone and Telegraph Co., for a paltry sum compared to
it's actual worth.
1907
First Crystal Detector, by G.W. Pickard. Up to this time, the most
popular detector was the electrolytic type; the coherer, while still somewhat
used, having been found unstable and insensitive. The Fleming valve was never
really popularized, because of its insensitivity to weak impulses. Consequently
the development of the crystal detector marks another great stride in the
development of radio. While the first employed silicon as the mineral, it was
later determined that galena, iron pyrites, and many other minerals (even carborundum)
also are efficient. It was extremely effective as a detector of feeble irregular
impulses (modulated C.W., damped waves) although somewhat critical in the adjustment
of the "catwhisker". Because of its inexpensiveness, it was the most popular of
all detectors until the advent of cheap commercial audions, and was to a great
extent responsible for increased activity and interest in wireless or radio
(these terms are synonymous).
1909
S. S. Republic and Jack Binns. By this year, practically all large ocean-
going vessels had been equipped with wireless apparatus, since it served as a
means of contact with land. Fortunately so, for on January 23rd of this year the
White Star liner Republic rammed the Florida off Nantucket Island,
and commenced immediately to sink. Jack Binns, the wireless operator on the
Republic, broadcast his famous "CQD" (now "SOS") which brought rescue
ships that saved all but 6 of the entire crew and passengers. This drama, so
tense and poignant, was reported to the entire world, and created such a favorable
impression on the public's mind that wireless was definately established for
ship communication.
1911
To be continued....
1920
Pittsburgh radio station KDKA broadcasts the Harding-Cox
presidential election returns, ushering in a new era of radio
broadcasts directed at a home audience.
1922
Approximately 250,000 home radio receivers are
manufactured in the U.S.
1924
RCA brings out the first super-heterodyne radio, developed
by Edwin H. Armstrong.
1927
RCA releases a new generation of alternating current
tubes, making possible "light socket" powered radios
with enclosed power supplies. The need for cumbersome batteries
is eliminated.
1929
4.5 million radio receivers are manufactured in the
U.S.
1933
FM is invented by Edwin H. Armstrong.
1935
Octal base metal envelope vacuum tubes are introduced.
1939
Loktal base tubes are introduced.
1940
Miniature tubes are introduced, making smaller radio
cabinets possible.
1941
13 million radios are manufactured in the U.S.
1942-1945
U.S. involvement in World War 2 brings a halt to
production of home radio receivers as manufacturers shift their
focus to supporting the war effort.
1947
Scientists at Bell Laboratories develop the transistor.
1961
FCC approves FM stereo broadcasting, which spurs FM development.
1962
United States radio stations begin broadcasting in stereophonic sound.
1986
In Europe, FM radio stations begin to use the subcarrier signal of FM radio
to transmit digital data. This RDS (radio data system) is used to transmit
messages on display screens to radios.
1993
In the US, FM radio stations begin to use the RDS already in place in Europe.
2001
XM Officially Launches the First U.S. Digital Satellite Radio Service.
2002
Digital Radio starts being broadcast in Europe by the BBC.
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