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). 

LEONARDO DA VINCI

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.

THOMAS ALVA EDISON

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. 

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. 

GALILEO GALILEI

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. 

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.

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.

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").

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."

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