Science Projects And Inventions

At the heart of a quartz watch is a 4-mm bar of quartz piezoelectric crystal that is made to vibrate by applying a small voltage. The crystal is laser trimmed so that it oscillates exactly 32,768 times per second. Higher-frequency crystals would need too large a driving current and guickly drain a watch battery, and lower-frequency ones would be physically too large. The signal, one cycle per second, either drives a second hand or triggers an LCD (liquid crystal display). Quartz is used because it has a very low coefficient of thermal expansion and thus is not affected by changes in the weather. A fairly standard mass- produced quartz watch typically gains or loses less than one second per day. The first quartz oscillator was produced in 1921. By 1927 Warren Marrison, a telecommunications engineer at Bell Laboratories in Canada, had made the first quartz clock. Unfortunately, its valve-driven counting more...

"Getting information off the Internet is like taking a drink from a fire hydrant" Mitchell Kapor, software designer In 1963, the Advanced Research Project Agency (ARPA) unit, set up by the U.S. Defense Department, began to build a computer network. Driven by fear of the Soviet nuclear threat, it aimed to link computers at different locations, so researchers could share data electronically without having fixed routes between them, making the system less vulnerable to attacks—even nuclear ones. Data was converted into telephone signals using a modem (modulator-demodulator), developed at AT&T in the late 1950s. In the 1.960s, key advances were made, including "packet switching"—the system of packaging, labeling, and routing data that enables it to be delivered across the network between machines. Paul Baran (b. 1926) proposed this system, which broke each message down into tiny chunks. These would be fired into the network, which would then route ("switch") the more...

Michael Faraday (1791-1867), one of Britain's foremost physicists, is most famous for discovering principles relating to magnetic induction and the relationship between magnetism and electricity. But Faraday was also an inventive lecturer and actually initiated the tradition of the Christmas lectures at the Royal Institution (the lectures still go on to this day and are televised in the United Kingdom). Faraday even has the honor of having a unit of measurement named after him; the farad is a unit of electrical capacitance. However, an achievement of this scientist that much less often finds its way into the history books is that he also invented the toy balloon. Faraday's career began not in physics but in chemistry. He was appointed as a chemicals assistant at the Royal Institution and performed experiments in this capacity, investigating chlorine and the nature of gases. It was while researching the properties of hydrogen that Faraday more...

"Demeter, goddess of agriculture, ate Pelop's shoulder, but [made him] a prosthetic ivory shoulder." Ampuloves, History of prosthetic The earliest written reference to an artificial limb occurs in an epic Indian poem, the "Rig-Veda," which was compiled between 3500 and 1800 B.C.E. Written in Sanskrit, the poem includes a description of the amputation of the warrior Queen Vishpla's leg during battle. Later fitted with an iron prosthesis by the Ashvins (celestial physicians), she returned to combat. Most authorities doubt the story of Queen Vishpla, and turn to the Histories of Herodotus for the first plausible reference to a prosthetic limb. Herodotus describes how, in the mid sixth century B.C.E., Hegesistratus of Elis, a Persian soldier and seer imprisoned by the Spartans, was sentenced to death, and cut off part of his foot to escape from the stocks. Hegesistratus fashioned a wooden prosthesis to help walk the 30 miles (48 km) more...

“... embracing the fracture with a pair of hot tongs and closing so tight till the weld leans out..." Vannoccio Biringuccio, sixteenth-century writer Welding is the process of joining pieces of metal with heat, pressure, or a combination of both, so that they completely fuse together. The first instance of welding is thought to have been in the smelting of iron ore to create wrought iron, some of the earliest evidence of which was discovered in a Hattic tomb in northern Anatolia, dated to around 2500 B.C.E. Lumps of the iron ore were heated in furnaces until the impurities melted into a slag, trapped in pores in the still solid iron. The hot piece was then hammered to expel the liquid slag and weld together the particles of surrounding iron. Similar methods of heating and hammering were used to join separate pieces of iron, and examples of this were discovered in more...

By the time Isaac Fenn was granted a patent, in 1765, for his distance-measuring hodometer, the device had existed, in various forms and with various names, for centuries. In Roman times it was called an odometer and comprised little more than a wheel that could be pushed along, coupled to a mechanical system for counting the number of revolutions the wheel made, and thus the distance it had traveled. The eighteenth and nineteenth century saw the mapping of India and the division of vast tracts of land into farms in regions such as the United States and Australia. Reasonably accurate surveying and distance measurement became important. The surveyor's perambulator wheel (the "waywiser" or trundle wheel) was in everyday use. The accuracy of this device was good on a smooth surface such as a pavement or macadamed road. On rough terrain, such as farmland, wheel bounce and slippage became a problem more...

Superconductors are materials that have no electrical resistance, so electricity can flow through them with out any loss. The superconductivity phenomenon was first discovered in 1911 by researchers in Germany who used solid mercury as their conducting material. Superconductivity was at first seen only in certain substances when supercooled to temperatures close to absolute zero, or -459°F (-273°C)—the coldest temperature theoretically possible. In 1986 Georg Bednorz (b. 1950) and Alex Muller (b. 1927), both researchers at IBM, discovered a new type of superconducting material, copper oxide perovskites, that could superconduct at -396°F (-238°C). Paul Chu, at the University of Houston, improved on this by bringing the superconducting temperature up to a relatively balmy -296°F (-182°C). For the first time, superconductivity could be made to occur at temperatures in the range of liquid nitrogen. The discovery quickly led to a huge meeting of physicists in New York, a meeting that became more...

Superconductors are materials that have no electrical resistance, so electricity can flow through them with out any loss. The superconductivity phenomenon was first discovered in 1911 by researchers in Germany who used solid mercury as their conducting material. Superconductivity was at first seen only in certain substances when supercooled to temperatures close to absolute zero, or -459°F (-273°C)—the coldest temperature theoretically possible. In 1986 Georg Bednorz (b. 1950) and Alex Muller (b. 1927), both researchers at IBM, discovered a new type of superconducting material, copper oxide perovskites, that could superconduct at -396°F (-238°C). Paul Chu, at the University of Houston, improved on this by bringing the superconducting temperature up to a relatively balmy -296°F (-182°C). For the first time, superconductivity could be made to occur at temperatures in the range of liquid nitrogen. The discovery quickly led to a huge meeting of physicists in New York, a meeting that became more...

In 1821 the Estonian physicist Thomas J. Seebeck made an accidental discovery: Not only does a potential (that is, voltage) difference exist between the two ends of an electrical conductor if these ends are at different temperatures, but also the voltage is a direct function of the temperature difference. If a circuit is made of a uniform material, the net loop voltage is zero. If, however, two different metallic conductors, such as platinum and palladium, are connected, a positive voltage is produced. The thermocouple, after being calibrated using the melting points of certain pure substances such as lead (621.68°F/327.6°C), silver (1,762°F/961°C), and nickel (2,647°F/1,453°C), can measure temperatures nearly up to the melting points of its two components. The Italian physicist Leopoldo Nobili (1784-1845) was slightly less ambitious and used a series of antimony bismuth bars to construct a thermopile in 1829. This was used to investigate infrared radiation and was more...

In 1797, Robert Fulton (1765-1815), a Pennsylvania- born artist and inventor, offered to build a submarine for the French, who were then engaged in a bitter war with Britain. He proposed to use the vessel to sink Royal Navy warships blockading French ports. The French government hesitated to become involved in what they regarded as a dishonorable style of warfare. Undeterred, Fulton went ahead with developing his machine, gaining French financial backing after Napoleon made himself First Consul in 1799. Fulton's "mechanical Nautilus" was launched on the River Seineat Rouen in 1800. Its inventor described it as "six and a half meters long and two meters wide... built entirely of wood." It had a mast and sail for propulsion on the surface, which were lowered when it submerged by filling its water tanks. The crew of two to four could stay underwater for around four hours thanks to a supply more...