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April
Important dates in History
April 30: Electric Company
In 1883, the first U.S. three-wire central station for incandescent
lighting was incorporated. The plant was in Sunbury, Pennsylvania.
April 29: Wallace Hume Carothers
 (Born
April 27, 1896: Died April 29, 1937)
American chemist who developed nylon (1935), the first synthetic
polymer fibre to be spun from a melt. He produced this polyamide,
by condensation of adipic acid and hexamethylenediamine. He worked
for the duPont chemical company as head of organic chemistry research
from 1928. Through his study of long-chain molecules, now called
polymers, he also developed the first successful synthetic rubber,
neoprene (1931). He suffered from depression, and died by suicide
at the age of 41 before nylon had been commercially exploited. DuPont
produced nylon commercially from 1938 and laid the foundation of
the synthetic-fibre industry. Nylon proved outstanding in its properties
as a synthetic analog of silk.
April 28: J.
Willard Gibbs
(Born February 11, 1839: Died April 28, 1903)
Josiah Willard Gibbs was a theoretical physicist and chemist who
was one of the greatest scientists in the U.S. in the 19th century.
His application of thermodynamic theory converted a large part of
physical chemistry from an empirical into a deductive science.
April 27: Rolf
William Landauer
(Born February 4, 1927: Died April 27, 1999)
German-born American physicist whose discovery of what came to be
known as Landauer's principle (that the erasing of computer information
causes a loss of energy) led to the development of more efficient
computers.
April 26: Intergrated
Circuit
In 1961, the integrated circuit was patented by Robert Noyce (No.
2,981,877).
April 25: Anders
Celsius
 (Born
November 27, 1701: Died April 25, 1744)
Swedish astronomer, physicist and mathematician who is famous for
the temperature scale he developed. Celsius was born in Uppsala
where he succeeded his father as professor of astronomy in 1730.
It was there also that he built Sweden's first observatory in 1741.
He and his assistant Olof Hiortner discovered that aurora borealis
influence compass needles. Celsius' fixed scale (often called centigrade
scale) for measuring temperature defines zero degrees as the temperature
at which water freezes, and 100 degrees as the temperature at which
water boils. This scale, an inverted form of Celsius' original design,
was adopted as the standard and is still used in almost all scientific
work.
April 24: IBM-PC
In 1981, the first IBM personal computer was introduced.
April 23: Battery
In 1940, a leak-proof flashlight battery (Ray-o-Vac) was patented
in the U.S. by Herman Anthony (No. 2,198,423).
April 22: Gaston
Planté
(Born April 22, 1834: Died May 21, 1889)
French physicist who produced the first electric storage battery,
or accumulator, in 1859; in improved form, his invention is widely
used in automobiles.
April 21: Samuel
Slater
 (Born
June 9, 1768: Died April 21, 1835)
English-American mechanical engineer who founded the American cotton-textile
industry. Before immigrating to the U.S. in 1789, Slater apprenticed
with Jedediah Strutt (partner of Richard Arkwright) in England.
Once in the U.S., he found backing to build Arkwright's spinning
and carding machinery, with which he established the first successful
cotton mill in the U.S. as well as many others in the New England
region.
April 20: Ferdinand
Braum
(Born June 6, 1850: Died April 20, 1918)
German physicist who shared the Nobel Prize for Physics in 1909
with Guglielmo Marconi for the development of wireless telegraphy.
Braun is also known as the developer of the cathode-ray oscilloscope.
He demonstrated the first oscilloscope (Braun tube) in 1897, after
work on high-frequency alternating currents. Cathode-ray tubes had
previously been characterized by uncontrolled rays; Braun succeeded
in producing a narrow stream of electrons, guided by means of alternating
voltage, that could trace patterns on a fluorescent screen.
April 19: Zygmunt
Florenty von Wroblewski
(Born October 28, 1845: Died April 19, 1888)
Polish physicist who liquefied the "permanent gases" such
as nitrogen and carbon monoxide in larger quantities than previously
accomplished by Cailletet, whose method he improved. In 1883, he
achieved the static liquefaction of oxygen and air. He was the first
to liquify hydrogen. Although he achieved it only in a transient
fine mist, he published (1885) remarkably accurate data: critical
temperature 33 K, critical pressure, 13.3 atm and boiling point,
23 K (modern values 33.3 K, 12.8 atm, 20.3 K). He may also have
had a hint of strange electrical properties at very low temperatures,
but his research was cut short upon his accidental death.
April 18: Sir
John Ambrose Fleming
(Born November 29, 1849: Died April 18, 1945)
 English
engineer who made numerous contributions to electronics, photometry,
electric measurements, and wireless telegraphy. In 1904, he discovered
the one directional current effect between a positively biassed
electrode, which he called the anode, and the heated filament in
an evacuated glass tube; the electrons flowed from filament to anode
only. Fleming called the device a diode because it contained two
electrodes, the anode and the heated filament. He noted that when
an alternating current was applied, only the positive halves of
the waves were passed - that is, the wave was rectified (from a.c.
to d.c.). It would also take a radio frequency wave and produce
d.c.corresponding to the on and off of the Morse code transmitted
signals.
April 17: Benjamin
Franklin
Born January 17, 1706: Died April 17, 1790)
American printer and publisher, author, inventor and scientist,
and diplomat. He become widely known in European scientific circles
for his reports of electrical experiments and theories. He invented
a stove, still being manufactured, to give more warmth than open
fireplaces; the lightning rod and bifocal eyeglasses also were his
ideas. Grasping the fact that by united effort a community may have
amenities which only the wealthy few can get for themselves, he
helped establish institutions people now take for granted: a fire
company, a library, an insurance company, an academy, and a hospital.
In some cases these foundations were the first of their kind in
North America.
April 16: Ferdinand
Gotthold Eisenstein
(Born April 16, 1823: Died October 11, 1852)
German mathematician whose work on the theory of elliptic functions
and on quadratic and cubic forms led to theorems for quadratic and
biquadratic residues, a reciprocity theorem for cubic residues,
cyclotomy, and quadratic partition of prime numbers.
April 15: Johannes
Stark
 (Born
April 15, 1874: Died June 21, 1957)
German physicist who won the 1919 Nobel Prize for Physics for his
discovery in 1913 that an electric field would cause splitting of
the lines in the spectrum of light emitted by a luminous substance;
the phenomenon is called the Stark effect.
April 14: ENIAC proposed to Army
 In
1943, a proposal for an electronic computer was submitted to colleagues
at the U.S. Army's Ballistics Research Laboratory by John Grist
Brainerd, director of research at the University of Pennsylvania's
Moore School, where the proposal was written by John Mauchly. In
May 1943, the Army contracted the Moore School to build ENIAC, the
first electronic computer. Although ENIAC was not finished until
after the war had ended, it nevertheless marked a major step forward
in computing.
April 13: Microscope
In 1625, the word "microscope" was coined as a suggested
term in a letter written by Johannes Faber of Bamberg, Germany,
to Federigo Cesi, Duke of Aquasparata and founder of Italy's Accademia
dei Lincei (Academy of the Lynx). This academy, possibly the world's
first scientific society took its name after the animal for its
exceptional vision.
April 12: Theory
of Relativity
In 1923, American scientists studying Einstein's Theory of Relativity
found further evidence in support of its correctness.
April 11: Hydrogen-cooled
generator
In 1941, the first hydrogen-cooled electrical generator for outdoor
installation in the U.S. was put into operation. Built by the General
Electric Company for the city of Glendale, Cal., it was rated 20,000
kW and cost $391,669. It was mounted on an open deck.* (The first
GE-built, hydrogen-cooled indoor generator started operation started
on October 12, 1937). In modern hydrogen-cooled turbo-generators,
hydrogen is used as a coolant fluid. The stator core is direct cooled
with hydrogen, for example, at a pressure of 3-6 bar. The advantage
of hydrogen is a high thermal conductivity and lower friction than
air-cooled generators, thus more efficient operation, lower fuel
consumption, highest output capacity, and lowest operating cost.
April 10: Frank
Stephen Baldwin
(Born April 10, 1838: Died April 8, 1925)
Inventor best-known for his development of the Monroe calculator.
April 9: Thomas
Johann Seeback
(Born April 9, 1770: Died December 10, 1831)
 German
physicist who discovered (1821) that an electric current flows between
different conductive materials that are kept at different temperatures,
known as the Seebeck effect. It is the basis of the thermocouple
and is considered the most accurate measurement of temperature.
It is also a key component of the semi-conductor, the foundation
of the modern computer business. Seebeck's work was the basis of
German physicist Georg Simon Ohm (1789-1854) discoveries in electricity
and of French physicist Jean Charles Athanase Peltier (1785-1845),
whose Peltier effect became well known as a way to use electricity
to freeze water (air conditioning, refrigeration).
April 8: Johann
Salamo Christoph Schweigger
 (Born
April 8, 1779: Died September 6, 1857)
German physicist who invented the galvanometer (1820), a device
to measure the strength of an electric current. He developed the
principle from Oersted's experiment (1819) which showed that current
in a wire will deflect a compass needle. Schweigger realized that
suggested a basic measuring instrument, since a stronger current
would produce a larger deflection, and he increased the effect by
winding the wire many times in a coil around the magnetic needle.
He named this instrument a "galvanometer" in honour of
Luigi Galvani, the professor who gave Volta the idea for the first
battery. Seebeck (1770-1831) named the innovative coil, Schweigger's
multiplier. It became the basis of moving coil instruments and loudspeakers.
April 7: Erik
Ivar Fredholm
(Born April 7, 1866: Died August 17, 1927)
Swedish mathematician who founded modern integral equation theory.
April 6: Teflon
In 1938, Du Pont researcher Roy J. Plunkett and his technician Jack
Rebok accidentally discovered the chemical compound polytetrafluoroethylene
(PTFE) that was later marketed as Teflon. Plunkett was researching
chemical reactions of the gas perfluoroethylene in order to synthesize
new types of refrigerant gases. Rebok found an apparently defective
cylinder of this gas, since no pressure was found when the valve
was opened, even though the cyclinder weight was the same as full
cylinders. Rebok suggested sawing it open to investigate. Inside
was a slippery white powder. Plunkett found it had unusual properties,
a wonderful solid lubricant in powdered form, was chemically inert
and had a very high melting point. He realized it was formed by
an unexpected polymerization.
April 5: Faraday
Lecture
In 1881, Hermann von Helmholtz presented The Faraday Lecture
before the Fellows of the Chemical Society in London. His topic
was The Modern Development of Faraday's Conception of Electricity.
Helmholtz recognized Faraday as being the person who most advanced
the general scientific method, saying "His principal aim was
to express in his new conceptions only facts, with the least possible
use of hypothetical substances and forces."
April 4: Zénobe-Théophile
Gramme
(Born April 4, 1826: Died January 20, 1901)
French electrical engineer and inventor (1869) of the Gramme dynamo,
a continuous-current electrical generator that gave principal impetus
to the development of electric power. In 1870 he invented a continuous-current
dynamo with a ring armature (a ring of soft iron around which were
placed insulated copper coils). This produced much higher voltages
than other dynamos of the time and was the first high-voltage direct-current
generator practical for mass production and distribution. Driven
by steam-engines, they were immediately successful and were used
for a variety of purposes, including factory lighting, electroplating,
and lighthouses. With these dynamos, the era of large-scale electrical
engineering began.
April 3: First
cell phone call
In 1973, the first portable phone call was placed by inventor Martin
Cooper. The phone was 10
inches in height, 3 inches deep and an inch-and-a-half wide and
weighed 30-oz. Since then, cell phones have shrunk to a mere palm-size
weighing 4-oz, and are used by a billion people around the world.
Cooper's first ''shoebox'' phone replaced a car phone of the time
that weighed more than 30 pounds and cost thousands of dollars.
A car phone owner had to drill a hole in his car to install the
antenna and most of the phone sat in the trunk. A control unit with
a handset was placed inside the car.
April 2: Walter
Chrysler
(Born April 2, 1875: Died August 18, 1940)
Walter P(ercy) Chrysler was the industrialist, inventor and manufacturer
who founded the Chrysler Corporation (1925), and developed the six-cylinder
engine.
April 1: Francois-Marie
Raoult
(Born May 10, 1830: Died April 1, 1901)
French chemist who formulated a law on solutions (called Raoult's
law) that made it possible to determine the molecular weights of
dissolved substances.
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