Inventors and Inventions: Scientific Instruments and Industrial Machines

ANEMOMETER
The anemometer is a device that measures the speed of the wind (or other airflow, like in a wind tunnel). The first anemometer, a disc placed perpendicular to the wind, was invented in 1450 by the Italian architect Leon Battista Alberti. Robert Hooke, an English physicist, later reinvented the anemometer. In 1846, John Thomas Romney Robinson, an Irish physicist, invented the spinning-cup anemometer. In this device, cups are attached to a vertical shaft; when the cups spin in the wind, it causes a gear to turn.

ARCHIMEDES Archimedes (287-212 BC) was a prolific ancient Greek mathematician. Archimedes invented the water screw, a device for raising water using an encased screw open at both ends. The screw is set an an angle, and as the screw turns, water fills the air pockets and is transported upwards. The Archimedes screw is still in use today. Among his many accomplishments was the first description of the lever (around 260 BC). Levers are one of the basic tools; they were probably used in prehistoric times. Many of our basic tools use levers, including scissors (two class-1 levers), pliers (two class-1 levers), hammer claws (one class-1 lever), nutcrackers (two class-2 levers), and tongs (two class-3 levers). A Class 1 Lever. A Class 2 Lever. A Class 3 Lever. .

ASSEMBLY LINE Primitive assembly line production was first used in 1901 by Ransome Eli Olds (1864-1950), an early car-maker (he manufactured the Oldsmobile, the first commercially successful American car). Henry Ford (1863-1947) used the first conveyor belt-based assembly-line in his car factory in 1913-14 in Ford's Highland Park, Michigan plant. This type of production greatly reduced the amount of time taken to put each car together (93 minutes for a Model T) from its parts, reducing production costs. Assembly lines are now used in most manufacturing processes.

BAEKELAND, L.H. Leo Hendrik Baekeland (November 14, 1863 - February 23, 1944) was a Belgian-born American chemist who invented Velox photographic paper (1893) and Bakelite (1907), an inexpensive, nonflammable, versatile, and very popular plastic. For more information on Baekeland, click here.

BAKELITE Bakelite (also called catalin) is a plastic, a dense synthetic polymer (a phenolic resin) that was used to make jewelry, game pieces, engine parts, radio boxes, switches, and many, many other objects. Bakelite was the first industrial thermoset plastic (a material that does not change its shape after being mixed and heated). Bakelite plastic is made from carbolic acid (phenol) and formaldehyde, which are mixed, heated, and then either molded or extruded into the desired shape. Bakelite was patented in 1907 by the Belgian-born American chemist Leo Hendrik Baekeland (November 14, 1863 - February 23, 1944). The Nobel Prize winning German chemist Adolf von Baeyer had experimented with this material in 1872, but did not complete its development or see its potential. Baekeland operated the General Bakelite Company from 1911 to 1939 (in Perth Amboy, N.J., USA), and produced up to about 200,000 tons of Bakelite annually. Bakelite replaced the very flammable celluloid plastic that had been so popular. The bracelet above is made of "butterscotch" bakelite.

BAROMETER A barometer is a device that measures air (barometric) pressure. It measures the weight of the column of air that extends from the instrument to the top of the atmosphere. There are two types of barometers commonly used today, mercury and aneroid (meaning "fluidless"). Earlier water barometers (also known as "storm glasses") date from the 17th century. The mercury barometer was invented by the Italian physicist Evangelista Torricelli (1608 - 1647), a pupil of Galileo, in 1643. Torricelli inverted a glass tube filled with mercury into another container of mercury; the mercury in the tube "weighs" the air in the atmosphere above the tube. The aneroid barometer (using a spring balance instead of a liquid) was invented by the French scientist Lucien Vidie in 1843.

BATTERY A battery is a device that converts chemical energy into electrical energy. Each battery has two electrodes, an anode (the positive end) and a cathode (the negative end). An electrical circuit runs between these two electrodes, going through a chemical called an electrolyte (which can be either liquid or solid). This unit consisting of two electrodes is called a cell (often called a voltaic cell or pile). Batteries are used to power many devices and make the spark that starts a gasoline engine. Alessandro Volta was an Italian physicist invented the first chemical battery in 1800. Storage batteries are lead-based batteries that can be recharged. In 1859, the French physicist Gaston Plante (1834-1889) invented a battery made from two lead plates joined by a wire and immersed in a sulfuric acid electrolyte; this was the first storage battery. The dry cell is a an improved voltaic cell with a cylindrical zinc shell (the zinc acts as both the cathode and the container) that is lined with an ammonium chloride (the electrolyte) saturated material (and not a liquid). The dry cell battery was developed in the 1870s-1870s by Georges Leclanche of France, who used an electrolyte in the form of a paste. Edison batteries (also called alkaline batteries) are an improved type of storage battery developed by Thomas Edison. These batteries have an alkaline electrolyte, and not an acid. For more information on the battery, click here.

BUNSEN BURNER The laboratory Bunsen burner was invented by Robert Wilhelm Bunsen in 1855. Bunsen (1811-1899) was a German chemist and teacher. He invented the Bunsen burner for his research in isolating chemical substances - it has a high-intensity, non-luminous flame that does not interfere with the colored flame emitted by chemicals being tested. For more information on Bunsen, click here.

CASSEGRAIN TELESCOPE A Cassegrain telescope is a wide-angle reflecting telescope with a concave mirror that receives light and focuses an image. A second mirror reflects the light through a gap in the primary mirror, allowing the eyepiece or camera to be mounted at the back end of the tube. The Cassegrain reflecting telescope was developed in 1672 by the French sculptor Sieur Guillaume Cassegrain. A correcting plate (a lens) was added in 1930 by the Estonian astronomer and lens-maker Bernard Schmidt (1879-1935), creating the Schmidt-Cassegrain telescope which minimized the spherical aberration of the Cassegrain telescope.

CELLOPHANE Cellophane is a thin, transparent, waterproof, protective film that is used in many types of packaging. It was invented in 1908 by Jacques Edwin Brandenberger, a Swiss chemist. He had originally intended cellophane to be bonded onto fabric to make a waterproof textile, but the new cloth was brittle and not useful. Cellophane proved very useful all alone as a packaging material. Chemists at the Dupont company (who later bought the rights to cellophane) made cellophane waterproof in 1927.

CELSIUS, ANDERS Anders Celsius (1701-1744) was a Swedish professor of astronomy who devised the Celsius thermometer. He also ventured to the far north of Sweden with an expedition in order to measure the length of a degree along a meridian, close to the pole, later comparing it with similar measurements made in the Southern Hemisphere. This confirmed that that the shape of the earth is an ellipsoid which is flattened at the poles. He also cataloged 300 stars. With his assistant Olof Hiorter, Celsius discovered the magnetic basis for auroras.

COMPOUND MICROSCOPE Zacharias Janssen was a Dutch lens-maker who invented the first compound microscope in 1595 (a compound microscope is one which has more than one lens). His microscope consisted of two tudes that slid within one another, and had a lens at each end. The microscope was focused by sliding the tubes. The lens in the eyepiece was bi-convex (bulging outwards on both sides), and the lens of the far end (the objective lens) was plano-convex (flat on one side and bulging outwards on the other side). This advanced microscope had a 3 to 9 times power of magnification. Zacharias Janssen's father Hans may have helped him build the microscope.

DA VINCI, LEONARDO Leonardo da Vinci (1452-1519) was an Italian inventor, artist, architect, and scientist. Da Vinci had an interest in engineering and made detailed sketches of the airplane, the helicopter (and other flying machines), the parachute, the submarine, the armored car, the ballista (a giant crossbow), rapid-fire guns, the centrifugal pump (designed to drain wet areas, like marshes), ball bearings, the worm gear (a set of gears in which many teeth make contact at once, reducing the strain on the teeth, allowing more pressure to be put on the mechanism), and many other incredible ideas that were centuries ahead of da Vinci's time. For some da Vinci art coloring pages, click here For more information on da Vinci, click here.

DAVY, HUMPHRY Sir Humphry Davy (1778-1829) was an English scientist who invented the first electric light in 1800. He experimented with electricity and invented an electric battery. When he connected wires from his battery to two pieces of carbon, electricity arced between the carbon pieces, producing an intense, hot, and short-lived light. This is called an electric arc. Davy also invented a miner's safety helmet and a process to desalinate sea water. Davy discovered the elements boron, sodium, aluminum (whose name he later changed to aluminium), and potassium.

EDISON, THOMAS ALVA Thomas Alva Edison (1847-1931) was an American inventor (also known as the Wizard of Menlo Park) whose many inventions revolutionized the world. His work includes improving the incandescent electric light bulb and inventing the phonograph, the phonograph record, the carbon telephone transmitter, and the motion-picture projector. Edison's first job was as a telegraph operator, and in the course of his duties, he redesigned the stock-ticker machine. The Edison Universal Stock Printer gave him the capital ($40,000) to set up a laboratory in Menlo Park, New Jersey, to invent full-time (with many employees). Edison experimented with thousands of different light bulb filaments to find just the right materials to glow well, be long-lasting, and be inexpensive. In 1879, Edison discovered that a carbon filament in an oxygen-free bulb glowed but did not burn up for quite a while. This incandescent bulb revolutionized the world. For more information on Edison, click here.

ELION, GERTRUDE Gertrude Belle Elion (January 23, 1918 - February 21, 1999) was a Nobel Prize winning biochemist who invented many life-saving drugs, including 6-mercaptopurine (Purinethol) and 6-thioguanine (which fight leukemia), Imuran, Zovirax, and many others. Elion worked at Burroughs-Wellcome (now called Glaxo Wellcome) for decades (beginning in 1944) with George Hitchings and Sir James Black, with whom she shared the Nobel Prize. She is named on 45 patents for drugs and her work has saved the lives of thousands of people.

ENIAC ENIAC stands for "Electronic Numerical Integrator and Computer." It was one of the first all-purpose, all-electronic digital computers. This room-sized computer was built by the physicist John William Mauchly (Aug. 30, 1907 - Jan. 8, 1980) and the electrical engineer John Presper Eckert, Jr. (April 9, 1919 - June 3, 1995) at the University of Pennsylvania. They completed the machine in November, 1945. For more information on ENIAC, click here.

FARNSWORTH, PHILO T. Philo Taylor Farnsworth (1906-1971) was an American inventor. Farnsworth invented many major major components of the television, including power, focusing systems, synchronizing the signal, contrast, controls, and scanning. He also invented the radar systems, cold cathode ray tube, the first baby incubator and the first electronic microscope. Farnsworth held over 300 patents.

FOUCAULT, JEAN Jean Bernard Léon Foucault (1819-1868) was a French physicist who invented the gyroscope (1852) and the Foucault pendulum (1851). A gyroscope is essentially a spinning wheel set in a movable frame. When the wheel spins, it retains its spatial orientation, and it resists external forces applied to it. Gyroscopes are used in navigation instruments (for ships, planes, and rockets). Foucault was the first person to demonstrate how a pendulum could track the rotation of the Earth (the Foucault pendulum) in 1851. He also showed that light travels more slowly in water than in air (1850) and improved the mirrors of reflecting telescopes (1858).

FRANKLIN, BENJAMIN Benjamin Franklin (January 17, 1706-April 17, 1790) was an American statesman, writer, printer, and inventor. Franklin experimented extensively with electricity. In 1752, his experiments with a kite in a thunderstorm (never do this, many people have died trying it!) led to the development of the lightning rod. Franklin started the first circulating library in the colonies in 1731. He also invented bifocal glasses and the Franklin stove. The idea of daylight savings time was first proposed by Benjamin Franklin in 1784. For more information on Franklin, click here.

GALILEI, GALILEO Galileo Galilei (1564-1642) was an Italian mathematician, astronomer, and physicist. Galileo found that the speed at which bodies fall does not depend on their weight and did extensive experimentation with pendulums. In 1593 Galileo invented the thermometer. In 1609, Galileo was the first person to use a telescope to observe the skies (after hearing about Hans Lippershey's newly-invented telescope). Galileo discovered the rings of Saturn (1610), was the first person to see the four major moons of Jupiter (1610), observed the phases of Venus, studied sunspots, and discovered many other important phenomena. For more information on Galileo, click here.

GEIGER COUNTER The Geiger counter (sometimes called the Geiger-Muller counter) is a device that detects ionizing radioactivity (including gamma rays and X-rays) - it counts the radioactive particle that pass through the device. The German nuclear physicist Hans Wilhelm Geiger (Sept. 30, 1882- Sept. 24, 1945) developed the device from 1908-12. At that time, Geiger was an assistant to the British physicist Ernest Rutherford (1871-1937). [Geiger's work helped Rutherford discover that radioactive elements can transform into other elements and that atoms have a nucleus]. In 1928, the Geiger counter was improved by the German physicist E. Walther Muller.

GREGORY, JAMES James Gregory (1638-1675), a Scottish mathematician, invented the first reflecting telescope in 1663. He published a description of the reflecting telescope in "Optica Promota," which was published in 1663. He never actually made the telescope, which was to have used a parabolic and an ellipsoidal mirror.

GODDARD, ROBERT Robert Hutchings Goddard (October 5, 1882-August 10, 1945) was an American physicist and inventor who is known as the father of modern rocketry. In 1907, Goddard proved that a rocket's thrust can propel it in a vacuum. In 1914, Goddard received two U.S. patents: for liquid-fueled rockets and for two- to three-stage rockets that use solid fuel. In 1919, Goddard wrote a scientific article, "A Method of Reaching Extreme Altitudes," describing a high-altitude rocket; it was published in a Smithsonian report. Goddard's many inventions were the basis upon which modern rocketry is based. After many years of failed attempts and public ridicule, Goddard's first successful rocket was launched on March 16, 1926 from a relative's farm in Auburn, Massachusetts. It was a liquid-fueled 10-ft. rocket that he called Nell. The flight lasted 2 1/2 seconds; the rocket flew a distance of 184 feet and achieved an altitude of 41 feet. Goddard soon moved to Roswell, New Mexico, where he developed more sophisticated multi-stage rockets, rockets with fins (vanes) to steer them (1932), a gyro control device to control the rocket (1932), and supersonic rockets (1935). In 1937, Goddard launched the first rocket with a pivotable motor on gimbals using his gyro control device. Altogether, Robert Goddard had 214 patents. For more information on Goddard, click here.

GYROSCOPE A gyroscope is essentially a spinning wheel set in a movable frame. When the wheel spins, it retains its spatial orientation, and it resists external forces applied to it. Gyroscopes are used in navigation instruments (for ships, planes, and rockets). Jean Bernard Léon Foucault (1819-1868), a French physicist, invented the gyroscope in 1852.

HERON The steam engine was invented by Heron, an ancient Greek geometer and engineer from Alexandria. Heron lived during the first century AD and is sometimes called Hero. Heron made the steam engine as a toy, and called his device "aeolipile," which means "wind ball" in Greek. The steam was supplied by a sealed pot filled with water and placed over a fire. Two tubes came up from the pot, letting the steam flow into a spherical ball of metal. The metallic sphere had two curved outlet tubes, which vented steam. As the steam went through the series of tubes, the metal sphere rotated. The aeolipile is the first known device to transform steam power into rotary motion. The Greeks never used this remarkable device for anything but a novelty. A steam engine designed for work wasn't built until 1698 (built by the British inventor, Thomas Savery). Watt later improved the steam engine.

HUYGENS, CHRISTIAN Christian Huygens (1629-1695) was a Dutch physicist and astronomer who developed new methods for grinding and polishing glass telescope lenses (about 1654). With his new, powerful telescopes, he identified Saturn's rings and discovered Titan, the largest moon of Saturn in 1655. Huygens also invented the pendulum clock in 1656 (eliminating springs), wrote the first work on the calculus of probability (De Ratiociniis in Ludo Aleae, 1655), and proposed the wave theory of light (Traité de la lumiere, 1678).

HYDE, IDA HENRIETTA Ida Henrietta Hyde (1857-1945) was an American physiologist who invented the microelectrode in the 1930's. The microelectrode is a small device that electrically (or chemically) stimulates a living cell and records the electrical activity within that cell. Hyde was the first woman to graduate from the University of Heidelberg, to do research at the Harvard Medical School and to be elected to the American Physiological Society.

INTERCHANGEABLE PARTS Clock makers used the idea of interchangeable parts since the early 1700's. In 1790, the French gunsmith Honoré Blanc demonstrated his muskets entirely made from interchangeable parts; the French government didn't like the process (since with this process, anyone could manufacture items, and the government lost control), so it was stopped. The idea of interchangeable parts was introduced to American gun manufacturing by Eli Whitney (1765-1825) in 1798. The concept of interchangeable manufacturing parts helped modernize the musket industry (and mass production in general). Whitney made templates for each separate part of the musket (an early gun). The workers then used the template when chiseling the part. Whitney was an American inventor and engineer who also invented the cotton gin.

JANSKY, KARL Karl Gothe Jansky (1905-1949) was an American radio engineer who pioneered and developed radio astronomy. In 1932, he detected the first radio waves from a cosmic source - in the central region of the Milky Way Galaxy.

JANSSEN, ZACHARIAS Zacharias Janssen was a Dutch lens-maker who invented the first compound microscope in 1595 (a compound microscope is one which has more than one lens). His microscope consisted of two tudes that slid within one another, and had a lens at each end. The microscope was focused by sliding the tubes. The lens in the eyepiece was bi-convex (bulging outwards on both sides), and the lens of the far end (the objective lens) was plano-convex (flat on one side and bulging outwards on the other side). This advanced microscope had a 3 to 9 times power of magnification. Zacharias Janssen's father Hans may have helped him build the microscope.

KARLE, ISABELLA L. Isabella Helen Lugoski Karle (1921- ) is a American physical chemist who invented new methods of X-ray Crystallography. She used electron diffraction and then x-ray diffraction to study the structure of molecules. Karle developed a three-dimensional modeling process, enabling her to identify and show the structures of hundreds of complex and important molecules (including alkaloids, ionophores, steroids, toxins, and peptides [amino acid compounds]). Because of Karle's process, the number of published molecular analyses has jumped from about 150 to over 10,000 per year. Karle received the National Medal of Science in 1995. Karle is a senior scientist and head of the Naval Research Laboratory's (NRL) x-ray diffraction section in the Laboratory for the Structure of Matter. Karle's husband, Jerome Karle, is a Nobel Prize winner in chemistry.

KELVIN Lord Kelvin (William Thomson, 1824 - 1907) designed the Kelvin scale, in which 0 K is defined as absolute zero and the size of one degree is the same as the size of one degree Celsius. Water freezes at 273.16 K; water boils at 373.16 K. For more information on Kelvin, click here.

LATIMER, LEWIS H. Lewis Howard Latimer (1848-1928) was an African-American inventor who was a member of Edison's research team, which was called "Edison's Pioneers." Latimer improved the newly-invented incandescent light bulb by inventing a carbon filament (which he patented in 1881). For more information on Lewis Howard Latimer, click here.

LEVERS Levers are one of the basic tools; they were probably used in prehistoric times. Levers were first described about 260 BC by the ancient Greek mathematician Archimedes (287-212 BC). Many of our basic tools use levers, including scissors (two class-1 levers), pliers (two class-1 levers), hammer claws (one class-1 lever), nutcrackers (two class-2 levers), and tongs (two class-3 levers). A Class 1 Lever. A Class 2 Lever. A Class 3 Lever. .

LIGHT BULB The first incandescent electric light was made in 1800 by Humphry Davy, an English scientist. He experimented with electricity and invented an electric battery. When he connected wires to his battery and a piece of carbon, the carbon glowed, producing light. This is called an electric arc. Much later, in 1860, the English physicist Sir Joseph Wilson Swan (1828-1914) was determined to devise a practical, long-lasting electric light. He found that a carbon paper filament worked well, but burned up quickly. In 1878, he demonstrated his new electric lamps in Newcastle, England. The inventor Thomas Alva Edison (in the USA) experimented with thousands of different filaments to find just the right materials to glow well and be long-lasting. In 1879, Edison discovered that a carbon filament in an oxygen-free bulb glowed but did not burn up for 40 hours. Edison eventually produced a bulb that could glow for over 1500 hours. The incandescent bulb revolutionized the world. For more information, click here.

LIPPERSHEY, HANS Hans Lippershey (1570?-1619) was a German-born Dutch lens maker who demonstrated the first refracting telescope in 1608, made from two lenses; he applied for a patent for this optical refracting telescope (using 2 lenses) in 1608, intending it for use as a military device.

McCOY, ELIJAH Elijah McCoy (1843 or 1844-1929) was a mechanical engineer and inventor. McCoy's high-quality industrial inventions (especially his steam engine lubricator) were the basis for the expression "the real McCoy," meaning the real, authentic, or high-quality thing. For more information on Elijah McCoy, click here. For a cloze activity on McCoy, click here.

METER (and the METRIC SYSTEM) The metric system was invented in France. In 1790, the French National Assembly directed the Academy of Sciences of Paris to standardize the units of measurement. A committeee from the Academy used a decimal system and defined the meter to be one 10-millionths of the distance from the equator to the Earth's Pole (that is, the Earth's circumference would be equal to 40 million meters). The committee consisted of the mathematicians Jean Charles de Borda (1733-1799), Joseph-Louis Comte de Lagrange (1736-1813), Pierre-Simon Laplace (1749-1827), Gaspard Monge (1746 -1818), and Marie Jean Antoine Nicholas Caritat, the Marquis de Condorcet (1743-1794) The word meter comes from the Greek word metron, which means measure. The centimeter was defined as one-hundredth of a meter; the kilometer was defined as 1000 meters. The metric system was passed by law in France on August 1, 1793. In 1960, the definition of the meter changed to 1,650,763.73 wavelengths of of the orange-red radiation of krypton 86. In 1983, the meter was redefined as 1/299,792,458 of the distance that light travels in one second in a vacuum. For the metric unit of mass, the gram was defined as the mass of one cubic centimeter of pure water at a given temperature. In common usage and in commerce, grams are used as a unit of weight.

MICROELECTRODE Ida Henrietta Hyde (1857-1945) was an American physiologist who invented the microelectrode in the 1930's. The microelectrode is a small device that electrically (or chemically) stimulates a living cell and records the electrical activity within that cell. Hyde was the first woman to graduate from the University of Heidelberg, to do research at the Harvard Medical School and to be elected to the American Physiological Society.

MICROSCOPE The microscope may have been invented by eyeglass makers in Middelburg, The Netherlands, invented sometime between 1590 and 1610. Hans and his son Zacharias Janssen are mentioned in the letters of William Boreel ( the Dutch envoy to the Court of France) as having invented a 20X magnification microscope. Robert Hooke used an early microscope to observe slices of cork (bark from the oak tree) using a 30X power compound microscope. He published his observations in "Microgphia" in 1665. In 1673, Antony van Leeuwenhoek discovered bacteria, free-living and parasitic microscopic protists, sperm cells, blood cells, etc., using a 300X power single lens microscope. Click here for a microscope printout to label. Click here for a microscope definition worksheet to print.

NOBEL, ALFRED Alfred Bernhard Nobel (1833-1896) was a Swedish inventor and industrialist. Nobel invented many powerful and relatively safe explosives and explosive devices, including the "Nobel patent detonator" (it detonated nitroglycerin using a strong electrical shock instead of heat, 1863), dynamite (1867), blasting gelatin (guncotton plus nitroglycerin, 1875), and almost smokeless blasting powder (1887). Nobel also made inventions in the fields of electrochemistry, optics, biology, and physiology. Nobel left much of his fortune to award prizes (the Nobel prizes) each year to people who made advancements in Physics, Chemistry, Physiology/Medicine, Literature, and Peace.

PASTEUR, LOUIS Louis Pasteur (1822-1895) was a French chemist and inventor. Pasteur studied the process of fermentation, and postulated that fermentation was produced by microscopic organisms (other than yeast), which Pasteur called germs. He hypothesized that these germs might be responsible for some diseases. Pasteur disproved the notion of "spontaneous generation " which stated that organisms could spring from nothing; Pasteur showed that organisms came form other, pre-existing organisms. Applying his theories to foods and drinks, Pasteur invented a heating process (now called pasteurization) which sterilizes food, killing micro-organisms that contaminate it.

RADIO TELESCOPE A radio telescope is a metal dish that gathers radio waves from space. Radio astronomy involves exploring space by examining radio waves from outer space. Radio astronomy was pioneered by Karl G. Jansky, who in 1932 first detected radio waves from a cosmic source - in the central region of the Milky Way Galaxy. Gote Reber (a ham radio operator) made the first true radio telescope (using a 32-foot diameter parabolic dish to focus the radio waves) after reading of Jansky's discoveries. One example of a radio telescope is the Very Large Array (VLA) in New Mexico.

REFLECTING TELESCOPE A reflecting (or Newtonian) telescope uses two mirrors to magnify what is viewed. The reflecting telescope was first described by James Gregory in 1663.

REFRACTING TELESCOPE A refracting telescope uses two lenses to magnify what is viewed; the large primary lens does most of the magnification. The first refracting telescope was invented by Hans Lippershey in 1608.

ROENTGEN, WILHELM VON X-rays were discovered in 1895 by Wilhelm Konrad von Roentgen (1845-1923). Roentgen was a German physicist who described this new form of radiation that allowed him to photograph objects that were hidden behind opaque shields. He even photographed part of his own skeleton. X-rays were soon used as an important diagnostic tool in medicine. Roentgen called these waves "X-radiation" because so little was known about them.

SCHMIDT-CASSEGRAIN TELESCOPE A Schmidt-Cassegrain telescope (SCT) is a wide-angle reflecting telescope with a correcting lens that minimizes spherical aberration and a concave mirror that receives light and focuses an image. A second mirror reflects the light through a gap in the primary mirror, allowing the eyepiece or camera to be mounted at the back end of the tube. The Cassegrain telescope (named for the French sculptor Sieur Guillaume Cassegrain) was developed in 1672; the correcting plate (a lens) was added in 1930 by the Estonian astronomer and lens-maker Bernard Schmidt (1879-1935).

STEAM ENGINE The steam engine was invented by Heron, an ancient Greek geometer and engineer from Alexandria. Heron lived during the first century AD and is sometimes called Hero. Heron made the steam engine as a toy, and called his device "aeolipile," which means "wind ball" in Greek. The steam was supplied by a sealed pot filled with water and placed over a fire. Two tubes came up from the pot, letting the steam flow into a spherical ball of metal. The metallic sphere had two curved outlet tubes, which vented steam. As the steam went through the series of tubes, the metal sphere rotated. The aeolipile is the first known device to transform steam power into rotary motion. The Greeks never used this remarkable device for anything but a novelty. A steam engine designed for work wasn't built until 1698 (built by the British inventor, Thomas Savery). Watt later improved the steam engine.

SWAN, JOSEPH WILSON The first practical electric light bulb was made in 1878 simultaneously (and independently) by Joseph Wilson Swan and Thomas Alva Edison. Sir Joseph Wilson Swan (1828-1914) was an English physicist who was determined to devise a practical, long-lasting electric light. After many years of experimentation, he found that a carbon paper filament worked well, but burned up quickly. In 1878, he demonstrated his new electric lamps in Newcastle, England.

TELESCOPE A telescope is a device that lets us view distant objects. Early telescopes (and most today) used glass lenses and/or mirrors to detect visible light. Some modern telescopes gather images from different parts of the electromagnetic spectrum, from radio waves to gamma rays. Most telescopes are located on Earth, but others are in space. For a more information on telescopes, click here.

TESLA, NIKOLA Nikola Tesla (1856-1943) was a Serbian-American inventor who developed the radio, fluorescent lights, the Tesla coil (an air-core transformer that generates a huge voltage from high-frequency alternating current), remote-control devices, and many other inventions; Tesla held 111 patents. Tesla developed and promoted the uses of alternating current (as opposed to direct current, which was promoted fiercely by Thomas Edison and General Electric). Tesla briefly worked with Thomas Edison. The unit of magnetic induction is named for Tesla; a tesla (abbreviated T) is equal to one weber per square meter. For a page on Tesla, click here.

Galileo Galilei THERMOMETER The Thermometer was invented by Galileo Galilei in 1593. His thermometer consisted of water in a glass bulb; the water moved up and down the bulb as the temperature changed. The sealed thermometer was invented in 1641 by the Grand Duke Ferdinand II. He used a glass tube containing alcohol, which freezes well below the freezing point of water (alcohol freezes at -175°F=-115°C). He sealed the tube to exclude the influence of air pressure. Mercury was later substituted for the alcohol, and then Daniel Gabriel Fahrenheit (1686-1736), a German physicist, used mercury plus a chemical solution that kept the mercury from sticking to the tube of the thermometer (in 1714). Fahrenheit also expanded the thermometer's scale (in 1724); on his scale, the temperature of boiling water is 212°F and the freezing point of water is 32°F. Anders Celsius Anders Celsius, a Swedish astronomer, invented the Celsius (or Centigrade) scale in 1742, putting the freezing point of water at 0° and the boiling point at 100°. Lord Kelvin Lord Kelvin (William Thomson, 1824 - 1907) designed the Kelvin scale in which 0 K is defined as absolute zero and the size of one unit is the same as the size of one degree Celsius. Water freezes at 273.16 ;K; water boils at 373.16 K.

TORRICELLI, EVANGELISTA Evangelista Torricelli (1608 - 1647) was an Italian physicist who invented the mercury barometer (in 1643) and made improvements to the microscope. Torricelli was a pupil of Galileo. Torricelli inverted a glass tube filled with mercury into another container of mercury; the mercury in the tube "weighs" the air in the atmosphere above the container. A barometer is a device that measures air (barometric) pressure. It measures the weight of the column of air that extends from the instrument to the top of the atmosphere. There are two types of barometers commonly used today, mercury and aneroid (meaning "fluidless").

VIDIE, LUCIEN Lucien Vidie was a French scientist who invented the aneroid barometer in 1843. A barometer is a device that measures air (barometric) pressure. It measures the weight of the column of air that extends from the instrument to the top of the atmosphere. There are two types of barometers commonly used today, mercury and aneroid (meaning "fluidless"). The aneroid barometer uses a spring balance instead of a liquid; it is easy to transport and easy to construct.

VON ROENTGEN, WILHELM X-rays were discovered in 1895 by Wilhelm Konrad von Roentgen (1845-1923). Roentgen was a German physicist who described this new form of radiation that allowed him to photograph objects that were hidden behind opaque shields. He even photographed part of his own skeleton. X-rays were soon used as an important diagnostic tool in medicine. Roentgen called these waves "X-radiation" because so little was known about them.

WATT, JAMES James Watt (1736-1819) was a Scottish inventor and engineer. In 1765, Watt revolutionized the steam engine, redesigning it so that it was much more efficient and four times as powerful as the old Newcomen steam engines. Watt's engines did not waste steam (heat), and had a separate condenser. Watt partnered with the businessman and factory owner Matthew Boulton in 1772, helping to promote Watt's ideas commercially. Watt also invented a method for converting the up-and-down piston movement into rotary motion (the "sun-and-planet" gear), allowing a greater number of applications for the engine. Watt produced this rotary-motion steam engine in 1781; it was used for many applications, including draining mines, powering looms in textile factories, powering bellows, paper mills, etc. It helped power the Industrial Revolution. Watt coined the term "horsepower," which he used to convey the power of his engines; Watt calculated how many horses it would take to do the work of each engine. One horsepower equals 33,000 foot-pounds of work per minute; it is the power required to lift a total of 33,000 pounds one foot in one minute. Parliament granted Watt a patent on his steam engine in 1755, making Watt a very wealthy man. In 1882 (long after Watt's death), the British Association named the unit of electrical power the "watt."

WU, CHIEN-SHIUNG Dr. Chien-Shiung Wu (Shanghai, China, May 31, 1912 - New York, USA, February 16, 1997) was a nuclear physicist who studied beta-decay (a weak interaction in which one of the neutrons in the nucleus of an atom decays into a proton and an electron; the proton enters the nucleus, forming an isotope, and the electron is emitted as a beta-particle). In 1956, Madam Wu did experiments showing that parity is not conserved in weak interactions (demonstrating parity violation in the nuclear beta decay in cobalt 60). Her experiments supported T. D. Lee and C. N. Yang's revolutionary idea that parity was not conserved in weak interactions (parity conservation had been a basic assumption in physics). Madam Wu worked on the Manhattan Project (a secret US project during World War 2 to develop an atomic bomb in order to defeat Hitler), developing a process for separating the uranium isotopes U235 and U238 by gaseous diffusion. She also helped develop more sensitive Geiger counters (devices that detect radiation). Madam Wu also studied the molecular changes in hemoglobin associated with sickle-cell anemia.

X-RAY X-rays were discovered in 1895 by Wilhelm Konrad von Roentgen (1845-1923). Roentgen was a German physicist who described this new form of radiation that allowed him to photograph objects that were hidden behind opaque shields. He even photographed part of his own skeleton. X-rays were soon used as an important diagnostic tool in medicine. Roentgen called these waves "X-radiation" because so little was known about them.

YALE JR., LINUS
Linus Yale Jr. (1821-1868) was an American mechanical engineer and manufacturer who developed the cylinder pin-tumbler lock (and other key and combination locks). Yale's father, Linus Yale, had invented an earlier pin-tumbler lock in 1848; the son's lock used a smaller, flat key with serrated edges (like the ones we still use today). There is no connection between Linus Yale and Yale University.

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