Showing posts with label inventions. Show all posts
Showing posts with label inventions. Show all posts

Tuesday, January 17, 2023

Inventions have always been a driving force behind human progress

Inventions have always been a driving force behind human progress.

From the invention of the wheel to the latest technological advancements, inventions have shaped our world in countless ways. 

One of the most impactful inventions of all time is the printing press, invented by Johannes Gutenberg in the 15th century. This invention revolutionized the way information was disseminated, making it possible for books to be mass-produced and distributed to the masses. This led to an explosion of knowledge and education, and is considered one of the key factors in the development of the modern world.

 Another important invention is the steam engine, invented by James Watt in the 18th century. This invention powered the Industrial Revolution and led to the development of new forms of transportation, such as trains and steamboats, as well as the creation of new manufacturing processes. 

The invention of the telephone by Alexander Graham Bell in 1876 was another game-changer. It revolutionized communication and made it possible for people to talk to each other over long distances. In recent years, the invention of the internet has had an enormous impact on the way we live and work. It has made it possible for people to communicate and access information from anywhere in the world, and has greatly facilitated the growth of e-commerce and online business. 

All of these inventions have had a profound impact on society and have changed the way we live. From the printing press to the internet, they have all played a crucial role in shaping the world we live in today.

Saturday, October 18, 2014

Tungsten filament







The invention: 



Metal filament used in the incandescent light bulbs

that have long provided most of the world’s electrical lighting.





The people behind the invention:



William David Coolidge (1873-1975), an American electrical

engineer

Thomas Alva Edison (1847-1931), an American inventor








The Incandescent Light Bulb



The electric lamp developed along with an understanding of

electricity in the latter half of the nineteenth century. In 1841, the

first patent for an incandescent lamp was granted in Great Britain.A

patent is a legal claim that protects the patent holder for a period of

time from others who might try to copy the invention and make a

profit from it. Although others tried to improve upon the incandescent

lamp, it was not until 1877, when Thomas Alva Edison, the famous

inventor, became interested in developing a successful electric

lamp, that real progress was made. The Edison Electric Light

Company was founded in 1878, and in 1892, it merged with other

companies to form the General Electric Company.

Early electric lamps used platinum wire as a filament. Because

platinum is expensive, alternative filament materials were sought.

After testing many substances, Edison finally decided to use carbon

as a filament material. Although carbon is fragile, making it difficult

to manufacture filaments, it was the best choice available at the time.



The Manufacture of Ductile Tungsten



Edison and others had tested tungsten as a possible material for

lamp filaments but discarded it as unsuitable. Tungsten is a hard,

brittle metal that is difficult to shape and easy to break, but it possesses

properties that are needed for lamp filaments. It has the highest

melting point (3,410 degrees Celsius) of any known metal; therefore,

it can be heated to a very high temperature, giving off a

relatively large amount of radiation without melting (as platinum

does) or decomposing (as carbon does). The radiation it emits when

heated is primarily visible light. Its resistance to the passage of electricity

is relatively high, so it requires little electric current to reach

its operating voltage. It also has a high boiling point (about 5,900 degrees

Celsius) and therefore does not tend to boil away, or vaporize,

when heated. In addition, it is mechanically strong, resisting breaking

caused by mechanical shock.

William David Coolidge, an electrical engineer with the General

Electric Company, was assigned in 1906 the task of transforming

tungsten from its natural state into a form suitable for lamp filaments.

The accepted procedure for producing fine metal wires was

(and still is) to force a wire rod through successively smaller holes in

a hard metal block until a wire of the proper diameter is achieved.

The property that allows a metal to be drawn into a fine wire by

means of this procedure is called “ductility.” Tungsten is not naturally

ductile, and it was Coolidge’s assignment to make it into a ductile

form. Over a period of five years, and after many failures, Coolidge

and his workers achieved their goal. By 1911, General Electric

was selling lamps that contained tungsten filaments.

Originally, Coolidge attempted to mix powdered tungsten with a

suitable substance, form a paste, and squirt that paste through a die

to form the wire. The paste-wire was then sintered (heated at a temperature

slightly below its melting point) in an effort to fuse the

powder into a solid mass. Because of its higher boiling point, the

tungsten would remain after all the other components in the paste

boiled away. At about 300 degrees Celsius, tungsten softens sufficiently

to be hammered into an elongated form. Upon cooling, however,

tungsten again becomes brittle, which prevents it from being

shaped further into filaments. It was suggested that impurities in

the tungsten caused the brittleness, but specially purified tungsten

worked no better than the unpurified form.

Many metals can be reduced from rods to wires if the rods are

passed through a series of rollers that are successively closer together.

Some success was achieved with this method when the rollers

were heated along with the metal, but it was still not possible to

produce sufficiently fine wire. Next, Coolidge tried a procedure

called “swaging,” in which a thick wire is repeatedly and rapidly

struck by a series of rotating hammers as the wire is drawn past

them. After numerous failures, a fine wire was successfully produced

using this procedure. It was still too thick for lamp filaments,

but it was ductile at room temperature.

Microscopic examination of the wire revealed a change in the

crystalline structure of tungsten as a result of the various treatments.

The individual crystals had elongated, taking on a fiber like

appearance. Now the wire could be drawn through a die to achieve

the appropriate thickness. Again, the wire had to be heated, and if

the temperature was too high, the tungsten reverted to a brittle

state. The dies themselves were heated, and the reduction progressed

in stages, each of which reduced the wire’s diameter by a

thousandth of an inch.

Finally, Coolidge had been successful.Pressed tungsten bars

measuring 1/4 x 3/8x6 inches were hammered and rolled into rods 1/8

inch , or 125/1000 inc, in diameter.

The unit 1/1000 inch is often called a “mil.”

These rods were then swaged to approximately 30 mil and

then passed through dies to achieve the filament size of 25 mil or

smaller, depending on the power output of the lamp in which the

filament was to be used. Tungsten wires of 1 mil or smaller are now

readily available.







Impact



Ductile tungsten wire filaments are superior in several respects

to platinum, carbon, or sintered tungsten filaments. Ductile filament

lamps can withstand more mechanical shock without breaking.

This means that they can be used in, for example, automobile

headlights, in which jarring frequently occurs. Ductile wire can also

be coiled into compact cylinders within the lamp bulb, which makes

for a more concentrated source of light and easier focusing. Ductile

tungsten filament lamps require less electricity than do carbon filament

lamps, and they also last longer. Because the size of the filament

wire can be carefully controlled, the light output from lamps

of the same power rating is more reproducible. One 60-watt bulb is

therefore exactly like another in terms of light production.

Improved production techniques have greatly reduced the cost

of manufacturing ductile tungsten filaments and of light-bulb man-

ufacturing in general. The modern world is heavily dependent

upon this reliable, inexpensive light source, which turns darkness

into daylight.





See also : Fluorescent lighting; Memory metal; Steelmaking process.

Thursday, September 25, 2014

Tuberculosis vaccine







The invention: 



Vaccine that uses an avirulent (nondisease) strain

of bovine tuberculosis bacilli that is safer than earlier vaccines.





The people behind the invention:



Albert Calmette (1863-1933), a French microbiologist

Camille Guérin (1872-1961), a French veterinarian and

microbiologist

Robert Koch (1843-1910), a German physician and

microbiologist










Isolating Bacteria



Tuberculosis, once called “consumption,” is a deadly, contagious

disease caused by the bacterium Mycobacterium tuberculosis,

first identified by the eminent German physician Robert Koch in

1882. The bacterium can be transmitted from person to person by

physical contact or droplet infection (for example, sneezing). The

condition eventually inflames and damages the lungs, causing difficulty

in breathing and failure of the body to deliver sufficient oxygen

to various tissues. It can spread to other body tissues, where

further complications develop.Without treatment, the disease progresses,

disabling and eventually killing the victim. Tuberculosis

normally is treated with a combination of antibiotics and other

drugs.

Koch developed his approach for identifying bacterial pathogens

(disease producers) with simple equipment, primarily microscopy.

Having taken blood samples from diseased animals, he would

identify and isolate the bacteria he found in the blood. Each strain of

bacteria would be injected into a healthy animal. The latter would

then develop the disease caused by the particular strain.

In 1890, he discovered that a chemical released from tubercular

bacteria elicits a hypersensitive (allergic) reaction in individuals

previously exposed to or suffering from tuberculosis. This chemical,

called “tuberculin,” was isolated from culture extracts in which tubercular

bacteria were being grown.

When small amounts of tuberculin are injected into a person subcutaneously

(beneath the skin), a reddened, inflamed patch approximately

the size of a quarter develops if the person has been exposed

to or is suffering from tuberculosis. Injection of tuberculin into an

uninfected person yields a negative response (that is, no inflammation).

Tuberculin does not harm those being tested.







Tuberculosis’s Weaker Grandchildren





The first vaccine to prevent tuberculosis was developed in 1921

by two French microbiologists, Albert Calmette and Camille Guérin.

Calmette was a student of the eminent French microbiologist Louis

Pasteur at Pasteur’s Institute in Paris. Guérin was a veterinarian

who joined Calmette’s laboratory in 1897. At Lille, Calmette and

Guérin focused their research upon the microbiology of infectious

diseases, especially tuberculosis.

In 1906, they discovered that individuals who had been exposed to

tuberculosis or who had mild infections were developing resistance to

the disease. They found that resistance to tuberculosis was initiated by

the body’s immune system. They also discovered that tubercular bacteria

grown in culture over many generations become progressively

weaker and avirulent, losing their ability to cause disease.

From 1906 through 1921, Calmette and Guérin cultured tubercle

bacilli from cattle. With proper nutrients and temperature, bacteria

can reproduce by fission (that is, one bacterium splits into two bacteria)

in as little time as thirty minutes. Calmette and Guérin cultivated

these bacteria in a bile-derived food medium for thousands of

generations over fifteen years, periodically testing the bacteria for

virulence by injecting them into cattle. After many generations, the

bacteria lost their virulence, their ability to cause disease. Nevertheless,

these weaker, or “avirulent” bacteria still stimulated the animals’

immune systems to produce antibodies. Calmette and Guérin

had successfully bred a strain of avirulent bacteria that could not

cause tuberculosis in cows but could also stimulate immunity against

the disease.

There was considerable concern over whether the avirulent strain

was harmless to humans. Calmette and Guérin continued cultivating

weaker versions of the avirulent strain that retained antibody-

stimulating capacity. By 1921, they had isolated an avirulent antibody-

stimulating strain that was harmless to humans, a strain they

called “Bacillus Calmette-Guérin” (BCG).

In 1922, they began BCG-vaccinating newborn children against

tuberculosis at the Charité Hospital in Paris. The immunized children

exhibited no ill effects from the BCG vaccination. Calmette and

Guérin’s vaccine was so successful in controlling the spread of tuberculosis

in France that it attained widespread use in Europe and

Asia beginning in the 1930’s.



Impact



Most bacterial vaccines involve the use of antitoxin or heat- or

chemical-treated bacteria. BCG is one of the few vaccines that use

specially bred live bacteria. Its use sparked some controversy in

the United States and England, where the medical community

questioned its effectiveness and postponed BCG immunization

until the late 1950’s. Extensive testing of the vaccine was performed

at the University of Illinois before it was adopted in the

United States. Its effectiveness is questioned by some physicians to

this day.

Some of the controversy stems from the fact that the avirulent,

antibody-stimulating BCG vaccine conflicts with the tuberculin

skin test. The tuberculin skin test is designed to identify people

suffering from tuberculosis so that they can be treated. A BCGvaccinated

person will have a positive tuberculin skin test similar

to that of a tuberculosis sufferer. If a physician does not know that

a patient has had a BCG vaccination, it will be presumed (incorrectly)

that the patient has tuberculosis. Nevertheless, the BCG

vaccine has been invaluable in curbing the worldwide spread of

tuberculosis, although it has not eradicated the disease.





See also:



Antibacterial drugs; Birth control pill; Penicillin; Polio vaccine (Sabin);

Polio vaccine (Salk)












Tuesday, August 26, 2014

Transistor radio







The invention:



 Miniature portable radio that used transistors and

created a new mass market for electronic products.









The people behind the invention:



John Bardeen (1908-1991), an American physicist

Walter H. Brattain (1902-1987), an American physicist

William Shockley (1910-1989), an American physicist

Akio Morita (1921-1999), a Japanese physicist and engineer

Masaru Ibuka (1907-1997), a Japanese electrical engineer and

industrialist





A Replacement for Vacuum Tubes



The invention of the first transistor by William Shockley, John

Bardeen, andWalter H. Brattain of Bell Labs in 1947 was a scientific

event of great importance. Its commercial importance at the time,

however, was negligible. The commercial potential of the transistor

lay in the possibility of using semiconductor materials to carry out

the functions performed by vacuum tubes, the fragile and expensive

tubes that were the electronic hearts of radios, sound amplifiers,

and telephone systems. Transistors were smaller, more rugged,

and less power-hungry than vacuum tubes. They did not suffer

from overheating. They offered an alternative to the unreliability

and short life of vacuum tubes.

Bell Labs had begun the semiconductor research project in an effort

to find a better means of electronic amplification. This was

needed to increase the strength of telephone signals over long distances.

Therefore, the first commercial use of the transistor was

sought in speech amplification, and the small size of the device

made it a perfect component for hearing aids. Engineers from the

Raytheon Company, the leading manufacturer of hearing aids, were

invited to Bell Labs to view the new transistor and to help assess the

commercial potential of the technology. The first transistorized consumer

product, the hearing aid, was soon on the market. The early

models built by Raytheon used three junction-type transistors and

cost more than two hundred dollars. They were small enough to go

directly into the ear or to be incorporated into eyeglasses.

The commercial application of semiconductors was aimed largely

at replacing the control and amplification functions carried out by

vacuum tubes. The perfect vehicle for this substitution was the radio

set. Vacuum tubes were the most expensive part of a radio set

and the most prone to break down. The early junction transistors

operated best at low frequencies, and subsequently more research

was needed to produce a commercial high-frequency transistor.

Several of the licensees embarked on this quest, including the Radio

Corporation of America (RCA), Texas Instruments, and the Tokyo

Telecommunications Engineering Company of Japan.



Perfecting the Transistor



The Tokyo Telecommunications Engineering Company of Japan,

formed in 1946, had produced a line of instruments and consumer

products based on vacuum-tube technology. Its most successful

product was a magnetic tape recorder. In 1952, one of the founders

of the company, Masaru Ibuka, visited the United States to learn

more about the use of tape recorders in schools and found out that

Western Electric was preparing to license the transistor patent.With

only the slightest understanding of the workings of semiconductors,

Tokyo Telecommunications purchased a license in 1954 with

the intention of using transistors in a radio set.

The first task facing the Japanese was to increase the frequency

response of the transistor to make it suitable for radio use. Then a

method of manufacturing transistors cheaply had to be found. At

the time, junction transistors were made from slices of germanium

crystal. Growing the crystal was not an exact science, nor was the

process of “doping” it with impurities to form the different layers of

conductivity that made semiconductors useful. The Japanese engineers

found that the failure rate for high-frequency transistors was

extremely high. The yield of good transistors from one batch ran as

low as 5 percent, which made them extremely expensive and put the

whole project in doubt. The effort to replace vacuum tubes with

components made of semiconductors was motivated by cost rather

than performance; if transistors proved to be more expensive, then

it was not worth using them.

Engineers from Tokyo Telecommunications again came to the

United States to search for information about the production of

transistors. In 1954, the first high-frequency transistor was produced

in Japan. The success of Texas Instruments in producing the

components for the first transistorized radio (introduced by the Regency

Company in 1954) spurred the Japanese to greater efforts.

Much of their engineering and research work was directed at the

manufacture and quality control of transistors. In 1955, they introduced

their transistor radio, the TR-55, which carried the brand

name “Sony.” The name was chosen because the executives of the

company believed that the product would have an international appeal

and therefore needed a brand name that could be recognized

easily and remembered in many languages. In 1957, the name of the

entire company was changed to Sony.



Impact



Although Sony’s transistor radios were successful in the marketplace,

they were still relatively large and cumbersome. Ibuka saw a

consumer market for a miniature radio and gave his engineers the

task of designing a radio small enough to fit into a shirt pocket. The

realization of this design—“Transistor Six”—was introduced in 1957.

It was an immediate success. Sony sold the radios by the millions,

and numerous imitations were also marketed under brand names

such as “Somy” and “Sonny.” The product became an indispensable

part of popular culture of the late 1950’s and 1960’s; its low cost enabled

the masses to enjoy radio wherever there were broadcasts.

The pocket-sized radio was the first of a line of electronic consumer

products that brought technology into personal contact with

the user. Sony was convinced that miniaturization did more than

make products more portable; it established a one-on-one relationship

between people and machines. Sony produced the first alltransistor

television in 1960. Two years later, it began to market a

miniature television in the United States. The continual reduction in

the size of Sony’s tape recorders reached a climax with the portable

tape player introduced in the 1980’s. The SonyWalkman was a marketing

triumph and a further reminder that Japanese companies led

the way in the design and marketing of electronic products.





John Bardeen





The transistor reduced the size of electronic circuits and at

the same time the amount of energy lost from them as heat.

Superconduction gave rise to electronic circuits with practically

no loss of energy at all. John Bardeen helped unlock the secrets

of both.

Bardeen was born in 1908 in Madison,Wisconsin, where his

mother was an artist and his father was a professor of anatomy

at the University ofWisconsin. Bardeen attended the university,

earning a bachelor’s degree in electrical engineering in 1928

and a master’s degree in geophysics in 1929. After working as a

geophysicist, he entered Princeton University, studying with

Eugene Wigner, the leading authority on solid-state physics,

and received a doctorate in mathematics and physics in 1936.

Bardeen taught at Harvard University and the University of

Minnesota until World War II, when he moved to the Naval

Ordnance Laboratory. Finding academic salaries too low to

support his family after the war, he accepted a position at Bell

Telephone Laboratories. There, with Walter Brattain, he turned

William Shockley’s theory of semiconductors into a practical

device—the transfer resistor, or transistor.

He returned to academia as a professor at the University of

Illinois and began to investigate a long-standing mystery in

physics, superconductivity, with a postdoctoral associate, Leon

Cooper, and a graduate student, J. Robert Schrieffer. In 1956

Cooper made a key discovery—superconducting electrons

travel in pairs. And while Bardeen was in Stockholm, Sweden,

collecting a share of the 1956 Nobel Prize in Physics for his work

on transistors, Schrieffer worked out a mathematical analysis of

the phenomenon. The theory that the three men published since

became known as BCS theory from the first letters of their last

names, and as well as explain superconductors, it pointed toward

a great deal of technology and additional basic research.

The team won the 1972 Nobel Prize in Physics for BCS theory,

making Bardeen the only person to ever win two Nobel Prizes

for physics. He retired in 1975 and died sixteen years later.





See also :  Compact disc; FM radio; Radio; Radio crystal sets; Television;

Transistor;



Further Reading



Handy, Roger, Maureen Erbe, and Aileen Antonier. Made in Japan:

Transistor Radios of the 1950s and 1960s. San Francisco: Chronicle

Books, 1993.



Marshall, David V. Akio Morita and Sony. Watford: Exley, 1995.

Morita, Akio, with Edwin M. Reingold, and Mitsuko Shimomura.

Made in Japan: Akio Morita and Sony. London: HarperCollins, 1994.









Nathan, John. Sony: The Private Life. London: HarperCollins-

Business, 2001.