Science Projects And Inventions

The ability to focus clearly on nearby objects— accommodation—decreases with age. This is known as presbyopia. It explains why older people tend to hold books at arm's length. Bifocals are glasses incorporating two lenses for each eye. The lower section of each glass corrects for presbyopia, bringing nearby objects into focus. American statesman Benjamin Franklin (1706- 1790) is normally credited with the invention of bifocals—although no one knows for sure who devised them, or when they did so. Franklin, and a few others, may have been wearing bifocals since the 1760s, but the first mention he makes of his "double spectacles" is in a letter dated August 21,1784. Franklin certainly did much to publicize bifocals and, as a man of science—and of poor eyesight—he certainly understood the principles behind their function. Each "lens" of Franklin's bifocal glasses consisted of two distinct pieces of glass, but toward the end of the more...

William Gascoigne (1612-44) was an English mathematician and astronomer, renowned for making scientific instruments. He was intrigued by the vernier scale and saw its potential for measuring the angular distances between stars. In circa 1635, while working on precision optics, he noticed that a thread from a spider's web had become trapped at the exact focal point of two lenses, and that he could therefore see it sharply. This inspired him to create a thin marker that could be placed at the focal point of a lens. He added a second linear marker so that, when he looked through his telescope lens, two parallel lines could be seen within the field of view. One of the markers he linked to a very fine screw thread, which could be used to adjust the distance between the two markers—the other of which would remain fixed. As the angular size of the field more...

It is likely that you will not have given much thought to how glass is made. In fact, it is very difficult to make flat glass to the standard needed for uses such as shop windows, cars, and mirrors. Or at least it was before Sir Alastair Pilkington (1920-1995) created the float process in 1959 in the United Kingdom. He was a technical engineer at the glass manufacturers Pilkington Brothers (no relation) and it took him seven years to perfect his technique. Before this, the plate process, first developed by English engineer Henry Bessemer in 1848, was used. But this process was expensive because it resulted in distortion and marking of the glass, which had to be corrected by polishing. In the float process, the melted glass mixture. traditionally made of a combination of silica, sodium carbonate, calcium oxide, magnesium oxide, and aluminum oxide, is poured onto a bath of more...

The effects of aspirinlike substances have been known since ancient times. Romans recorded the use of willow bark as a means of fighting fever. In the early nineteenth century it was discovered that the leaves and bark of the willow tree contain a substance called salicylic acid. Although salicylic acid reduced pain and fever, it also produced severe stomach upsets. In 1832 French chemist Charles Frederic Gerhardt tried 'to eliminate these side effects by combining salicylic acid with acetyl chloride. But he found the process too time-consuming and gave up. In 1899 German chemist Felix Hoffmann (1868-1946), who worked for the Bayer pharmaceutical company, became aware of Gerhardt's work and sought the drug to relieve his father's arthritis symptoms. Hoffmann simplified the method and came up with acetylsalicylic acid. Hoffmann took a small phial home for his father, who had his first pain-free night for years. Hoffmann named the drug more...

“For much of history, investment casting was confined to sculpture and works of art." European Investment Casters' Federation Investment casting is one of the oldest metalworking practices, occurring as long ago as 3000 B.C.E., and remains vital in producing very specific, one-piece metal designs. Today, the process is used to produce complex parts for nuclear power plants, but thousands of years ago essentially the same method was used to produce small metal ornaments and statues. Civilizations such as the Egyptians and the Mesopotamians used the investment casting—or "lost wax"—process to create small idols or jewelry with intricate patterns. The intended shape and design of each object was first sculpted from natural beeswax, and then coated with several layers of thick and heat-resistant plaster. This mold was then heated, the wax inside melted and drained out, and molten metal was poured into the resulting hollow space. After cooling, the plaster was more...

It may not be the most eye-catching of names, but the superheterodyne receiver vastly improved radio technology in the early twentieth century by filtering out unwanted radio signals. The "superhet," as it is commonly called, is the invention of Edwin Howard Armstrong (1890-1954). While working on ways to amplify radio signals during World War I, he hit upon a cunning idea. An incoming radio signal is mixed with an internal signal generated by the receiver (known as a local oscillator). The two signals are multiplied together. This creates two new signals: One is the sum of the two originals, and one is the difference. So, if you have an incoming radio frequency at 5 MHz and a local oscillator at 4 MHz, signals will be seen at 9 MHz and 1 MHz, This is known as heterodyning. A filter can be used to remove any signal that does not fit more...

Hybrid vehicles have two different types of engines running in parallel—usually a gasoline or diesel engine to provide most of the motive force and an electric motor, powered by batteries, for additional assistance. The main advantages of hybrids are a reduction in carbon dioxide emissions and increased fuel efficiency due to the use of regenerative braking to recharge the battery (these batteries are sometimes referred to as onboard rechargeable energy storage systems). Fuel can also be saved by switching off the gasoline or diesel engine when coasting or stationary in traffic. The major breakthrough was made by Victor Wouk (1919-2005), the brother of the novelist Herman Wouk. Victor, an electrical engineer, was spurred into action by the Federal Clean Car Incentive Program of 1970. After founding a company called Petro-Electric Motors Ltd. with a chemist friend, Charles Rosen, in 1974 they adapted a Buick Skylark as a gasoline/electric hybrid that more...

“... next to agriculture, [shelter] is the most necessary to man. One must eat, one must have shelter." Philip Johnson, architect The earliest evidence for built shelter appears to have been constructed by Homo heidelbergensis, who lived in Europe between around 800,000 B.C.E. and 200,000 B.C.E. Anthropologists are uncertain whether these were ancestors of Homo sapiens (humans) or Homo neanderthalensis (Neanderthals) or both. At the French site of Terra Amata, which dates back around 400,000 years, archeologists have found what they believe to be the foundations of large oval huts. One of these shows evidence of fire in a hearth, although other archeologists postulate that natural processes could be responsible. Archeology on sites from hundreds of thousands of years ago is complicated. Claims of the discovery of built shelters in Japan from more than 500,000 years ago were discredited in 2000. In fact, all evidence for humans in Japan before 35,000 more...

Modern   meteorology   depends   hugely   on radiosondes, and hundreds of these balloon-borne instrument packages are released daily from weather stations all over the world. The sonde collects data up to a height of 18 miles (30 km), while being tracked in position using radar. The real-time data is continuously transmitted back to Earth by radio and the position of the sonde as time passes indicates the wind speed. Rising at the rate of about 0.2 miles (0.3 km) per minute, the flight usually takes about two hours. Silk weather balloons were first used to collect data in 1892 by the French scientist Gustave Hermite. In 1901 these were replaced by sealed rubber balloons. These burst when they reached a height of 12 miles (20 km), and the instrument package parachuted to the ground. The rest was left somewhat to chance because the flight records were picked up more...

Gyrocompasses have two great advantages over magnetic needle compasses: They point to the spin pole of Earth as opposed to the magnetic pole; and they are completely unaffected by the ferrous metal of a ship's hull or the magnetic fields produced by electrical currents running through nearby wires. Their main component is a motorized, fast-spinning, damped, gimballed wheel. When this wheel is not spinning exactly in the plane containing Earth's spin axis, an interaction between the angular momentum of the wheel and the angular momentum of Earth produces a restoring torque that pushes the wheel back into the true north-south orientation. A ship's gyrocompass is mounted in a complex set of gimbals that isolate the instrument from the ever- present pitching, yawing, and rolling. Aircraft gyrocompasses are even more complicated due to the higher velocity of the plane and the speedy changes in altitude during takeoff and landing. German scientist more...