April 30: Electron
In 1897, at the Royal Institution Friday Evening Discourse, Joseph John Thomson (1856-1940) first announced the existence of electrons (as they are now named). Thomson told his audience that earlier in the year, he had made a surprising discovery. He had found a particle of matter a thousand times smaller than the atom. He called it a corpuscle, meaning "small body." Although Thomson was director of the Cavendish Laboratory at the University of Cambridge, and one of the most respected scientists in Great Britain, the scientists present found the news hard to believe. They thought the atom was the smallest and indivisible part of matter that could exist. Nevertheless, the electron was the first elementary particle to be discovered.

April 29: Rubber patent
In 1820, Thomas Hancock's first patent was dated. It was for the application of rubber in clothing where some elasticity was useful, such as braces (suspenders) or slip-on boots. Thus began his wish to find uses for rubber, which until then had limited worth due to its poor properties, being hard and liable to crack in winter cold and sticky in summer heat. Later, he invented a "masticator" which fed waste rubber through a spiked roller rotating in a hollow cyclinder and produced a homogeneous mass of solid rubber resulting from the pressure appled and heat generated during the process. When rolled into sheets or compacted into blocks, the product was suitable to make various articles. Thus, he became the founder of the British rubber industry.

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: 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 26: Sir Owen Willians Richardson
(Born April 26, 1879: Died February 15, 1959).
English physicist who was awarded the Nobel Prize for Physics in 1928 for "his work on the thermionic phenomenon [electron emission by hot metals] and especially for the discovery of the law named after him." This effect is why a heated filament in a vacuum tube releases a current of electrons to travel an anode, which was essential for the development of such applications as radio amplifiers or a TV cathode ray tube. Richardson's law mathematically relates how the electron emission increases as the absolute temperature of the metal surface is raised. He also conducted research on photoelectric effects, the gyromagnetic effect, the emission of electrons by chemical reactions, soft X-rays, and the spectrum of hydrogen.

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: Emilio Segrè
(Born February 1, 1905: Died April 22, 1989)
Italian-born American physicist who was cowinner, with Owen Chamberlain of the United States, of the Nobel Prize for Physics in 1959 for the discovery of the antiproton, an antiparticle having the same mass as a proton but opposite in electrical charge.

April 21: Samuel Slater
(Born June 17, 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: Karl Alex Müller
(Born April 20, 1927)
Swiss physicist who, along with J. Georg Bednorz, was awarded the 1987 Nobel Prize for Physics for their joint discovery of superconductivity in certain substances at higher temperatures than had previously been thought attainable. They startled the world by reporting superconductivity in a layered, ceramic material at a then-record-high temperature of 33 degrees above absolute zero. Their discovery set new research worldwide into related materials that yielded dozens of new superconductors, eventually reaching a transition temperature of 135 kelvin.

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. Wroblewski died as a result of burns in a fire started when he overturned a kerosene lamp in his laboratory.

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: Jean Perrin
(Born September 30, 1871: Died April 17, 1942)
Jean-Baptiste Perrin was a French physicist who, in his studies of the Brownian motion of minute particles suspended in liquids, verified Albert Einstein's explanation of this phenomenon and thereby confirmed the atomic nature of matter. Using a gamboge emulsion, Perrin was able to determine by a new method, one of the most important physical constants, Avogadro's number (the number of molecules of a substance in so many grams as indicated by the molecular weight, for example, the number of molecules in two grams of hydrogen). The value obtained corresponded, within the limits of error, to that given by the kinetic theory of gases. For this achievement he was honoured with the Nobel Prize for Physics in 1926.

April 16: Thomas Blanchard
(Born June 24, 1788: Died April 16, 1864):
American inventor who made major contributions to the development of machine tools.

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: Internet spam
In 1994, the first Internet spamming program was used by an attorney in Arizona. Laurence Canter created the software program, a simple Perl script, that flooded Usenet message board readers with a notice for the "Green Card Lottery" to solicit business for his law firm of Canter & Siegel (with wife, Martha Siegel.) The reaction from the online community was vigorously critical, condemning such a form of advertising. Thousands of recipients complained, but a new, burgeoning business of unsolicited mass Internet advertising had been spawned. The term "spam" was coined from a sketch in the "Monty Python's Flying Circus" BBC television show in which a waitress offered a menu full of variations of spam to an unwilling patron.

April 11: Electricity lecture
In 1751, Ebenezer Kinnersley advertised in the Pennsylvania Gazette that he was to give a lecture on "The Newly Discovered Electrical Fire." His lectures were the first of the kind in America or Europe. The announcement read: "Notice is hereby given to the Curious, that Wednesday next, Mr. Kinnersley proposes to begin a course of experiments on the newly discovered Electrical Fire, containing not only the most curious of those that have been made and published in Europe, but a considerable number of new ones lately made in this city, to be accompanied with methodical Lectures on the nature and properties of that wonderful element." Thus, Kinnersley was one of the earliest popularizers of science.

April 10: Paul-Louis-Toussaint Héroult
(Born April 10, 1863: Died May 9, 1914)
French chemist who invented the electric-arc furnace, widely used in making steel; and, independently of the simultaneous work of Charles M. Hall of the United States, devised the electrolytic process for preparing aluminum. This process made low-priced aluminum available for the first time, securing the widespread use of the metal and its alloys.

April 9: J. Presper Eckert, Jr.
(Born April 9, 1919: Died June 3, 1995)
John Presper Eckert, Jr. was an American engineer and coinventor of the first general-purpose electronic computer, a digital machine that was the prototype for most computers in use today. In 1946, Eckert with John W. Mauchly fulfilled a government contract to build a digital computer to be used by the U.S. Army for military calculations. They named it ENIAC for Electronic Numerical Integrator and Computer. By 1949, they had started a manufacturing company for their BINAC computer. This was followed by a business oriented computer, UNIVAC (1951), which was put to many uses and spurred the growth of the computer industry. By 1966 Eckert held 85 patents, mostly for electronic inventions.

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: Telegraph
In 1885, Granville T. Woods, a prolific black American inventor, patented an "Apparatus for Transmission of Messages by Electricity," No. 315,368. In the following years he introduced numerous innovations for use on railroads, applying electricity for telegraphy, brakes, overhead conductors, controls and an electric railway.

April 6: Horst L. Störmer
(Born April 6, 1949)
Horst Ludwig Störmer is a German-born American physicist who shared (with Daniel C. Tsui and Robert B. Laughlin) the 1998 Nobel Prize in Physics for the discovery "of a new form of quantum fluid with fractionally charged excitations." By experiment using extremely powerful magnetic fields and low temperatures, in 1982, Störmer and Tsui found that electrons acting together in strong magnetic fields can form new types of "particles", with charges that are fractions of electron charges. Within a year. Laughlin made a theoretical analysis explaining their result.

April 5: Ivar Giaever
(Born April 5, 1929)
Norwegian-born American physicist who, for his experimental discoveries regarding tunneling phenomena in superconductors, shared the Nobel Prize for Physics in 1973 with Leo Esaki and Brian Josephson for work in solid-state physics. Giaever demonstrated (1960) the tunneling of electrons through a sandwich with an extremely thin oxide layer surrounded with metal either in superconducting state on both sides or in superconducting state on one side and in normal state on the other side. This gave direct evidence for the so called energy gap in a superconductor (predicted by Bardeen et al., in 1972). Later, Giaever developed the method into a very powerful and accurate spectroscopy to study the detailed properties of superconductors.

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: Aluminium process
In 1889, Charles M. Hall patented an inexpensive electrolytic process to extract aluminium from its ore (No. 400,655). Although aluminum is the most abundant metal in the earth's crust, it is not found naturally in pure form, and thus it must be separated from its surrounding ore.

April 1: François-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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