INCANDESCENT 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.

INTEGRATED CIRCUIT An integrated circuit (IC) or chip is a wafer of material to which impurities have been added (in just the right patterns) so that the entire chip is a circuit composed of many transistors. The chip (usually made of silicon or germanium) makes computational devices, like computers, very small and very inexpensive. IC's were invented independently in 1959 by Jack Kilby and Robert Noyce.

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.

IRON, ELECTRIC The electric iron was invented in 1882 by Henry W. Seeley, a New York inventor Seeley patented his "electric flatiron" on June 6, 1882 (patent no. 259,054). His iron weighed almost 15 pounds and took a long time to warm up.Other electric irons had also been invented, including one from France (1882), but it used a carbon arc to heat the iron, a method which was dangerous.

HADLEY, JOHN H. John Hadley (1682-1744) was an English mathematician and inventor who built the first reflecting telescope and invented an improved quadrant in 1731 (known as Hadley's quadrant). Hadley Rille, a long valley on the surface of the moon, was named for Hadley.

HARGREAVES, JAMES James Hargreaves (1720? - April 22, 1778) was an English weaver and spinner (he spun wool thread using a spinning wheel). He invented the spinning jenny, a hand-powered multiple spinning machine.The spinning jenny was much more efficient than the spinning wheel. With a spinning wheel, a person could produce only one yarn thread at a time. With Hargreaves' spinning jenny, a person could produce up to eight threads at once (it used one spinning wheel and 8 spindles on which threads were wound). The thread that the spinning jenny produced was coarse, and was only suited for filling material, but it was still quite a useful invention, and led the way to even better spinning devices. Hargreaves is said to have gotten the idea for his remarkable invention after his young daughter (named Jenny) overturned his spinning wheel. When it was upturned, it continued to spin, and Hargreaves realized that many spinning wheels could be positioned like this, creating a multiple-wheeled spinning machine. Hargreaves began selling spinning jenny's from his home, near Blackburn, Lancashire, England. After hearing of his invention, local spinners became fearful of losing their jobs and broke into Hargreaves' house, destroying his spinning jennies. He then moved to Nottingham, England (in 1768). Thomas James became Hargreaves' partner and they began a spinning mill which used spinning jennies (which could now produce even more threads per machine). Hargreaves patented the spinning jenny on July 12, 1770.

HAYAKAWA, TOKUJI The mechanical pencil was invented in 1915 by Tokuji Hayakawa (November 3, 1894-June 24, 1980). His first mechanical pencil was called the "Ever-Ready Sharp Pencil." Hayakawa had owned a metalworking shop in Tokyo, Japan, and in 1942, expanded his company and renamed it the Hayakawa Electric Industry Co.,Ltd. It was later called the Sharp Corporation (1970), and Hayakawa was appointed chairman.

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 Greeks never used this remarkable device for anything but a novelty. A steam engine designed for real work wasn't designed until 1690, when Dionysius Papin published plans for a for a high-pressure steam engine. Thomas Savery built the first steam engine in 1698. Wattlater improved the steam engine.

HOLMES, ARTHUR A geologic time scale is a diagram that details the history of the Earth's geology, noting major events like the formation of the Earth, the first life forms and mass extinctions. The first geologic time scale was proposed in 1913 by the British geologist Arthur Holmes (1890 - 1965). Holmes was also the first person to realize that the Earth was billions of years old (not millions, as had been previously believed). For a geologic time scale, click here.

HOPPER, GRACE M. Rear Admiral Grace Murray Hopper (1906 - 1992) was a US naval officer and mathematician who invented the computer compiler (called the A-O) in 1952. Her compiler revolutionized computer programming, automatically translating high-level instructions (easier to understand by people) into machine code (the cryptic, native language of the central processing unit). Hopper and a team developed the first user-friendly business programming language, COBOL (COmmon Business-Oriented Language). There is an unconfirmed story that Hopper determined than an error in the early Mark II computer was caused by a moth that was trapped in it; she then coined the term "computer bug."

HOT-AIR BALLOON A hot-air balloon is a balloon that is filled with hot air; it rises because hot air is less dense (lighter) than the rest of the air. Joseph and Jacques Etienne Montgolfier were two French bothers who made the first successful hot-air balloon. Their first balloon was launched in December, 1782, and ascended to an altitude of 985 ft (300 m). This type of hot-air balloon was called the Montgolfiére; it was made of paper and used air heated by burning wool and moist straw. The first passengers in a hot-air balloon were a rooster, a sheep, and a duck, whom the Montgolfier brothers sent up to an altitude of 1,640 ft (500 m) on September 19, 1783 (the trip lasted for 8 minutes); the animals survived the landing. This event was observed by King Louis XVI and Queen Marie Antoinette of France.

HOT DOGS Hot dogs began as sausages sold in buns. They were first sold from carts by German immigrants on the streets of New York City in the 1860s. The bun replaced a plate and made the hot dog easier to carry and eat. Sauerkraut was provided as a relish on the hot dog.

HOWE, ELIAS Elias Howe (1819-1867) was American inventor who patented an improved sewing machine in 1846. His revolutionary machine used two separate threads, one threaded through the needle, and one in a shuttle; it was powered by a hand crank. A sideways-moving needle with its eye at one end would pierce the fabric, creating a loop of thread on the other side; a shuttle would then push thread through the loop, creating a tight lock stitch. Earlier sewing machines used only one thread and a chain stitch that could unravel. Howe's business did not thrive. Others, like Isaac Singer made slight modifications in the machine and built successful businesses. Howe sued those who had infringed on his patent and won royalties on all machines sold (he was paid $5.00 for each sewing machine sold). Howe died the year his patent expired.

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 ofSaturn 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).

HYATT, JOHN WESLEY Celluloid is a plastic made from cellulose (it is derived from plants). This very flammable material was invented in 1869 by the American inventor John Wesley Hyatt (it was invented to be a substitute for the elephant ivory used for billiard balls). Celluloid was one the first plastics invented; it can be damaged by moisture.

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.

GABE, FRANCES Frances Gabe (actually, Frances G. Bateson) (1915-) invented and patented the self-cleaning house. Gabe, who lives in Newberg, Oregon, USA, disliked housework intensely. She designed and lives in a house in which each room has a 10-inch square, "Cleaning/ Drying/ Heating/ Cooling" device on the ceiling. To clean a room, all you have to do is push a button in a room, and the cleaning unit sends a powerful spray of soapy water around the room. It then rinses and blow-dries the room. Each room has a slightly-sloping floor, so the water would drain well. Frances stored valuable objects (and things that should not get wet) under glass. The house also has self-cleaning sinks, bathtubs and toilets. Her cupbord doubles as a dishwasher and her clothes are cleaned, dried and stored while hanging in the closet. Gabe holds 68 patents. Frances said, "Housework is a thankless, unending job, a nerve-tangling bore. Who wants it? Nobody! With my jaw set hard I was determined there had to be a better way!"

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.

GANT, ALLEN Pantyhose was invented in 1959 by Allen Gant of North Carolina, USA, in 1959. This new undergarment became popular as miniskirts were the fashion and soon came to replace nylon stockings held up with a garter belt (short skirts were not long enough to hide the bottom of the garter belt). Gant was associated with the Glen Raven Mills textile mill (he was a descendant of the founder of the mill, John Gant), the company that first manufactured pantyhose.

GAS MASK Garrett Augustus Morgan (March 4, 1877 - August 27, 1963), was an African-American inventor and businessman. He was the first person to patent a traffic signal. He also developed the gas mask (and many other inventions). Morgan used his gas mask (patent No. 1,090,936, 1914) to rescue miners who were trapped underground in a noxious mine. Soon after, Morgan was asked to produce gas masks for the US Army.For more information on Morgan, click here.

GAYETTY, JOSEPH Joseph Gayetty invented toilet paper in 1857. His new toilet paper was composed of flat sheets. Before Gayetty's invention, people tore pages out of mail order catalogs - before catalogs were common, leaves were used. Unfortunately, Gayetty's invention failed. Walter Alcock (of Great Britain) later developed toilet paper on a roll ( instead of in flat sheets). Again, the invention failed.In 1867, Thomas, Edward and Clarence Scott (brothers from Philadelphia, Pennsylvania, USA) were successful at marketing toilet paper that consisted of a small roll of perforated paper . They sold their new toilet paper from a push cart - this was the beginning of the Scott Paper Company.

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.

GEOLOGIC TIME SCALE A geologic time scale is a diagram that details the history of the Earth's geology, noting major events like the formation of the Earth, the first life forms and mass extinctions. The first geologic time scale was proposed in 1913 by the British geologist Arthur Holmes (1890 - 1965). Holmes was also the first person to realize that the Earth was billions of years old (not millions, as had been previously believed). For a geologic time scale, click here.

GERSTENZANG, LEO The Q-tip was invented in the 1920's Leo Gerstenzang (a Polish-born American). His wife had used a toothpick with cotton stuck on the end to clean their baby's ears, and Leo invented Q-tips to replace her jury-rigged invention. Gerstenzang's original Q-tips consisted of a wooden stick swathed in cotton at both ends; much later, the wood was replaced by white cardboard. Gerstenzang started the Infant Novelty Company to sell Q-tips (which he then called Baby Gays); in 1926, he changed the name of his product to Q-Tips® Baby Gays. The Q stood for "quality". Eventually, the name changed to Q-tips. Doctors today advise that you should not use Q-tips to clean inside your ears. Q-tips, however, have many other uses, including cleaning small areas (like jewelry or the space between computer keys), applying glue, spreading paint, etc.

GLASSES Eyeglasses with convex lenses for correcting farsighted vision were probably invented in Italy around the year 1268-1284, perhaps by Salvino D'Armate of Pisa or by Alessandro Spina of Florence. Early glasses were also made in China around the same time. The earliest glasses did not have arms; they perched on the bridge of the nose. Eyeglasses with concave lenses for nearsightedness (or myopia) were not invented until the 1400s.Glasses with arms were invented in the 1600s. Bifocals (combining convex and concave lenses to correct both nearsightedness and farsightedness) were invented by Benjamin Franklin around 1775. Glasses with hinged arms were invented in 1752 by James Ayscough. Ayscough also made the first sunglasses (glasses with green- or blue-tinted lenses). Polarizing filters (which are very effective at filtering out glare) were invented by Edwin H. Land (and patented in 1929). Katherine J. Blodgett (1898-1979) invented a micro-thin barium stearate lens coating that made glass completely nonreflective and "invisible" (patent #2,220,660, March 16, 1938).

GLOBE Martin Behaim (1459-1537) was a German mapmaker, navigator, and merchant who made the earliest globe, called the "Nürnberg Terrestrial Globe". It was made during the years 1490-1492; the painter Georg Glockendon helped in the project. Behaim had previously sailed to Portugal as a merchant (in 1480). He had advised King John II on matters concerning navigation. He accompanied the Portuguese explorer Diogo Cam (Cão) on a 1485-1486 voyage to the coast of West Africa; during this trip, the mouth of the Congo River was discovered. After returning to Nürnberg in 1490, Behaim began construction of his globe (which was very inaccurate as compared to other maps from that time, even in the areas in which Behaim had sailed). It was once thought that Behaim's maps might have influenced Columbus and Magellan; this is now discounted. Behaim may have also developed an astrolabe. Behaim's globe is now in the German National Museum in Nürnberg.

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.

GOODE, SARAH S. Sarah E. Goode was a businesswoman and inventor. Goode invented the folding cabinet bed, a space-saver that folded up against the wall into a cabinet. When folded up, it could be used as a desk, complete with compartments for stationery and writing supplies. Goode owned a furniture store in Chicago, Illinois, and invented the bed for people living in small apartments. Goode's patent was the first one obtained by an African-American woman inventor (patent #322,177, approved on July 14, 1885).

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.

GUILLOTINE Many, many people were being executed during the French Revolution, and Dr. Joseph-Ignace Guillotin (1738-1821) suggested that decapitation would be a more humane method for execution. Experiments with cadavers (dead people) were done. The device that we call the guillotine was invented; it is a tall wooden framework with a hole to keep a person's head still and a large falling blade. Although he did not invent the machine we call the guillotine, Guillotin's name is forever attached to it. The guillotine was first was used on April 25, 1792 at the Place de Grève (the victim was a highway man). The most famous victims of the guillotine include the deposed French King Louis XVI and his extravagant wife Queen Marie Antoinette, who were beheaded on January 21, 1793. The guillotine was used in France until 1981, when capital punishment was abolished.

GUNPOWDER Gunpowder was invented in China, probably during the 1000's. Gunpowder is composed of about 75 percent saltpeter (potassium nitrate), 15 percent powdered charcoal, and 10 percent sulphur. The Chinese used gunpower to make fireworks and signals, and later to make weapons of war.For more information on this invention, click here.

GUTENBERG, JOHANNES Johannes Gutenberg (the 1300's-1468) was a German craftsman, inventor, and printer who invented the first printing press with movable type in 1450. This invention revolutionized printing, making it simpler and more affordable. Gutenberg produced dies (molds) for easily producing individual pieces of metal type that could be made, assembled, and later reused. Gutenberg's new press could print a page every three minutes. This made printed material available to the masses for the first time in history. Religious materials were the majority of the early printed materials. The use of printing presses began the standardization of spelling.

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.

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

FERRIS WHEEL The Ferris Wheel is a large amusement-park ride that is made of a giant, vertical, metal wheel that slowly turns around. The wheel is equipped with hanging compartments for people, who ride around in a circle, going far above the ground. The Ferris Wheel was invented by the Pittsburgh, Pennsylvania bridge-builder George Washington Gale Ferris Jr. (1859-1896) . The first Ferris wheel was opened on June 21, 1893 at the Chicago World's Fair. This Ferris wheel was 250 feet tall (the diameter of the wheel) - this is about the height of a 25 story building! It had 36 wooden cars that could each seat 40 people, and hold another 20 standing people plus a conductor. Each car was 27 feet long, 13 feet wide, and 9 feet tall. A total of 2000 people could ride the wheel at one time. The wheel was powered by two 1,000 horsepower engines and weighed over 4,000 tons. It cost 50 cents per ride. This same Ferris wheel was later used at the St. Louis exposition in 1904, but was scrapped in 1906. Ferris wheels are now common at amusement parks around the world - most are much smaller than the original.

FIREWORKS Gunpowder was invented in China, probably during the 1000's. Gunpowder is composed of about 75 percent saltpeter (potassium nitrate), 15 percent powdered charcoal, and 10 percent sulphur. The Chinese used gunpower to make fireworks and signals, and later to make weapons of war.For more information on this invention, click here.

FLEMING, SANDFORD The Earth is divided into 24 time zones so that everyone in the world can be on roughly similar schedules (like noon being roughly when the sun is highest in the sky). The idea to divide the Earth into time zones was proposed by the Canadian railway planner and engineer Sir Sandford Fleming in the late 1870s.For a more information on time zones, click here.

FORD, HENRY Henry Ford (1863-1947) was an American engineer and industrialist who used the first conveyor belt-based assembly-lines in his car factory, revolutionizing factory production. Ford manufactured affordable cars and paid high wages to his factory workers, allowing workers to buy the cars they made. After early work as a machinist, Ford built a gasoline engine in 1893. In 1896, Ford built a "horseless carriage," which he called the "Quadricycle," which means "four wheels" (others, including Charles Edgar and J. Frank Duryea, Elwood Haynes, Hiram Percy Maxim, and Charles Brady King had built earlier "horseless carriage"). In 1899, Ford formed the Detroit Automobile Company (which was later called the Henry Ford Company and then the Cadillac Motor Car Company). Ford introduced the Model T in October 1908; it was a great success (every Model T was painted black). Ford introduced conveyor belt-based assembly-line factory production and a $5 daily wage in 1913-14 in Ford's Highland Park, Michigan plant (primitive assembly line production had been started in 1901 by Ransome Eli. Olds, another early car-maker). 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.

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).

FOUNTAIN PEN Lewis E. Waterman was an American inventor and insurance salesman who developed a relatively leak-proof fountain pen; he patented his new invention in 1884 and revolutionized writing. Before his fountain pen, pen tips had to be tipped into ink after every few words. Waterman put an ink reservoir in the pen above the pen's metal nib (point). This reservoir would hold enough ink for a few pages of writing. There were many problems in developing the fountain pen, especially the difficulty of controlling the flow of the ink. Putting a sealed reservoir above the nib wouldn't let the ink flow, but if it wasn't sealed, all the ink would flow at once. Waterman used capillary action to replace the ink in the rubber sac with air so that the ink flowed smoothly but did not flow all at once. Also, the metals in the ink dissolved the steel pen nib, so Waterman used an iridium-plated gold nib. Waterman was also the first person to place a clip on the cap of the pen.

FOX, SAMUEL Samuel Fox (1815 - 1887), an English inventor and manufacturer, invented the steel ribbed umbrella in 1852 (the ribs of the umbrella hold the fabric in place - wood or whale bone had been used as ribs before Fox's invention). Fox started the "English Steels Company," which manufactured his new umbrella.

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.

FROEBEL, WILHELM A. Friedrich Wilhelm August Froebel (also written Fröbel) (1782-1852) was a German educator and educational reformer who invented the kindergarten (which means "garden of children"). He opened the first kindergarten in Bad Blankenburg (near Keilhau) in 1837. Froebel founded a kindergarten training school at Liebenstein, Germany in 1849. After some conflicts and mistaken charges of treason, the German government banned the establishment of kindergartens in 1851. In 1860, the government repealed the ban, and kindergartens re-opened (unfortunately, this was after Froebel's death). Froebel's kindergartens included pleasant surroundings, self-motivated activity, play, music, and the physical training of the child.

EASTMAN, GEORGE George Eastman (1854-1932) was an American inventor who made many improvements in photography. Eastman invented the dry plate method in 1879; this was an improvement in the wet plate process photographic process). He founded the Eastman Dry Plate company in 1881, located in Rochester, New York. Eastman and William Walker invented flexible roll film in 1882, eliminating the necessity of using cumbersome glass plates for photography. Eastman produced the first simple, all-purpose, fixed-focus camera in 1888, which sold for $25.00; this was the first KODAK Camera . By 1900, Eastman Kodak was producing a camera that cost only one dollar. Early cameras took round pictures. To get the film developed, the photographer had to send the entire camera to the Rochester factory. The company name was changed to Eastman Kodak Company in 1892, and is still one of the largest photographic companies in the world.

ECKERT, JOHN PRESPER 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.

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.

ELECTRIC IRON The electric iron was invented in 1882 by Henry W. Seeley, a New York inventor Seeley patented his "electric flatiron" on June 6, 1882 (patent no. 259,054). His iron weighed almost 15 pounds and took a long time to warm up.Other electric irons had also been invented, including one from France (1882), but it used a carbon arc to heat the iron, a method which was dangerous.

ELEVATOR BRAKE Elisha Graves Otis (1811-1861) invented the elevator brake, which greatly improved the safety of elevators. He used a ratchet on a spring to catch the elevator in the event of an accident (like a broken cable).In 1854, at the Crystal Palace Exposition in New York, Otis demonstrated how safe his elevator was by cutting the elevator's cable with an ax, and the elevator car stayed where it was in the shaft. Otis' invention spurred the development of skyscrapers, changing the look of cities around the world forever.

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.

EPPERSON, FRANK The popsicle was invented by 11-years-old Frank Epperson in 1905. Epperson (1894-?) lived in San Francisco, California. Epperson had left a fruit drink out overnight (with a stirrer in it), and it froze, making a new treat. His frozen treat was originally called the Epsicle. Epperson got a patent on his "frozen ice on a stick" many years later, in 1923. The Epsicle was later renamed the popsicle. Epperson also invented the twin popsicle (with two sticks so it could be shared by two children), Fudgsicle, Creamsicle and Dreamsicle.

ESCALATOR An escalator is a moving stairway that helps people move easily from floor to floor in building. The escalator was invented by the American inventor Jesse W. Reno in 1891. On his "inclined elevator," passengers rode on an wedge-shaped supports attached to a conveyor belt at an incline of about 25 degrees. The original elevator had a stationary handrail (which was soon replaced with a moving handrail).Horizontal steps were added to the escalator by Georg A. Wheeler and Charles D. Seeberger (who bought Wheeler's patent) in the late 1890's. The Otis company later bought the patents for the escalator and marketed it worldwide. The word escalator was first used at the Paris Exposition of 1900, when the Otis Company exhibited the moving stairway.

EYEGLASSES Eyeglasses with convex lenses for correcting farsighted vision were probably invented in Italy around the year 1268-1284, perhaps by Salvino D'Armate of Pisa or by Alessandro Spina of Florence. Early glasses were also made in China around the same time. The earliest glasses did not have arms; they perched on the bridge of the nose. Eyeglasses with concave lenses for nearsightedness (or myopia) were not invented until the 1400s.Glasses with arms were invented in the 1600s. Bifocals (combining convex and concave lenses to correct both nearsightedness and farsightedness) were invented by Benjamin Franklin around 1775. Glasses with hinged arms were invented in 1752 by James Ayscough. Ayscough also made the first sunglasses (glasses with green- or blue-tinted lenses). Polarizing filters (which are very effective at filtering out glare) were invented by Edwin H. Land (and patented in 1929). Katherine J. Blodgett (1898-1979) invented a micro-thin barium stearate lens coating that made glass completely nonreflective and "invisible" (patent #2,220,660, March 16, 1938).

DAVENPORT, THOMAS Thomas Davenport (July 9, 1802 -July 6, 1851) was an American blacksmith and inventor who established the first commercially successful electric streetcar. Davenport, from Vermont, invented an electric motor in 1834 and began a small electric railway in 1835. He patented a device for "Improvements in propelling machinery by magnetism and electromagnetism" in 1837 (his electric railway). Davenport later started a workshop in New York City, New York, and published a journal on electromagnetism (it was printed on a press that was powered by motors which he devised).

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.

DICKSON, EARLE Bandages for wounds had been around since ancient times, but an easy-to-use dressing with an adhesive was invented by Earle Dickson (a cotton buyer at the Johnson & Johnson company). Dickson perfected the BAND-AID® in 1920, making a small, sterile adhesive bandage for home use. Dickson invented the BAND-AID® for his wife, who had many kitchen accidents and needed an easy-to-use wound dressing. Dickson was rewarded by the Johnson & Johnson company by being made a vice-president of the company.

DIONYSIUS THE ELDER The catapult was invented in ancient Greece (in 399 BC) by Dionysius the Elder of Syracuse. The catapult is a device that hurls heavy objects or arrows over a large distance. The Romans later added wheels to the catapult to make it more maneuverable. Also called the ballista, this device was a major weapon of warfare for well over a thousand years. A double-armed catapult (also called the trebuchet) was invented by Mariano Taccola of Siena during the Middle Ages, about AD 1400.

DISHWASHER The first dishwasher was patented in 1850 by Joel Houghton; his machine was a hand-turned wheel that splashed water on dishes - unfortunately, it wasn't very effective at washing dishes. The first working automatic dishwasher was invented by Mrs. Josephine Garis (W. A.) Cochran, of Shelbyville, Illinois, in 1889. Her dishwasher was a wooden tub with a wire basket in it - the dishes went in the basket, and rollers rotated the dishes. As a handle on the tub was turned, hot, soapy water was sprayed into the tub, cleaning the dishes. Cochran's machine was first shown at the 1893 World's Fair in Chicago, Illinois. At first, her machine was only bought by some restaurants and hotels. Cochran's small company was eventually associated with the KitchenAid company. The dishwasher didn't become widespread as a labor-saving machine until the 1960s.

DISPOSABLE DIAPER The disposable diaper was invented in 1950 by Marion Donovan. Her first leak-proof diaper was a plastic-lined cloth diaper. Donovan then developed a disposable diaper. She was unsuccessful at selling her invention to established manufacturers, so she started her own company.

DONOVAN, MARION Marion Donovan (1917-1998) was an American mother, inventor, and architect who invented the disposable diaper in 1950. Her first leak-proof diaper were fast-selling "Boaters," plastic-lined cloth diapers (diapers lined with pieces cut from a shower curtain, and later with surplus parachute nylon). Donovan then developed a completely disposable diaper. She was unsuccessful at selling this invention to established manufacturers, so she started her own company, which she later sold. Donovan produced many other consumer-based inventions and held more than a dozen patents

DORTICUS, CLATONIA JOAQUIN Clatonia Joaquin Dorticus was an African-American inventor who received many patents. He invented an apparatus for applying dyes to the sides of the soles and heels of shoes (patent # 535,820, March 19, 1895), a machine for embossing (contouring the paper of) photographs (patent # 537,442, April 16, 1895), a device that helped develop photographs (patent # 537,968, April 23, 1895), and a leak stopper for hoses (patent # 629,315, July 18, 1899).

DOWNING, PHILIP B. The street letter drop mailbox with a hinged door that closed to protect the mail was invented by Philip B. Downing. Downing, an African-American inventor, patented his new device on October 27, 1891 (US Patent # 462,093).

DREW, CHARLES RICHARD Dr. Charles Richard Drew (1904-1950) was an American medical doctor and surgeon who started the idea of a blood bank and a system for the long-term preservation of blood plasma (he found that plasma kept longer than whole blood). His ideas revolutionized the medical profession and have saved many, many lives.For more information on Dr, C. R. Drew, click here.

DREW, RICHARD Richard G. Drew (1899-1980) invented masking tape and clear adhesive tape (also called cellophane tape or Scotch tape). Drew was an engineer for the 3M company (the Minnesota Mining and Manufacturing).Drew's first tape invention was a masking tape made for painters in 1923 (this tape was designed to help painters paint a straight border between two colors). This early masking tape was a wide paper tape with adhesive on only the edges of the tape - not in the middle. Drew made an improved tape called Scotch (TM) Brand Cellulose Tape in 1930. This tape was a clear, all-purpose adhesive tape that was soon adopted worldwide. The first tape dispenser with a built-in cutting edge was invented in 1932 by John A. Borden, another 3M employee.

DUTCH CHOCOLATE Coenraad Johannes Van Houten (1801-1887) was a Dutch chemist and chocolate manufacturer who in 1828 invented the process that is used to turn roasted cacao beans (the source of chocolate) into cocoa powder (this process is now called Dutching, Dutch processing or alkalinisation). His method was an inexpensive way of removing much of the cocoa butter from the nib (center) of the beans, using a hydraulic press, and adding alkaline salts (potassium carbonate or sodium carbonate) so that the cocoa powder would mix readily with water or milk (the alkali neutralized the acidic chocolate). The resulting cocoa powder can be used to make chocolate milk and other delicacies.