Archives November 2013

"The first stone... fell with such weight and force upon a building that a great part... was destroyed." Marco Polo, The Travels of Marco Polo(c.1298) The word catapult came from two Greek words: kata, meaning "downward," and pultos, which refers to a small circular shield. Katapultos was taken to mean "shield piercer." The weapon was said to have been invented in 399 B.C.E. in the Sicilian city of Syracuse and, according to Archimedes, was. derived from a composite bow, which was similar to the crossbow. Early catapults had a central lever with a counterweight at the opposite end to the projectile basket. Torsion-powered catapults entered into common use in Greece and Macedon around 330 B.C.E. Alexander the Great used them to provide cover on the battlefield as well as during sieges. The Chinese, Greeks, and Romans used various types of catapults. The ballista, built for Philip of Macedon, was similar more...

Science has gifted us so many wonderful things that have affected our style of living and made life easy going. Computer is one of them that have played an important role in improving the conditions of advanced nations. We can effectively realize our dreams through proper use of computers. India declared its computer policy in November 1984. It has opened a new beginning of computer revolution in the history of India. The first computer in India was built in 1966 by Tata Institute of Fundamental Research. After a while Bhabha Atomic Research Centre added to computers in a series. Computers are now manufactured on a commercial basis. This   given a further momentum to the computer  revolution in India. The establishment of the Electronics Corporation of India was a momentous event. The use of electronics will not accentuate the problem of unemployment. On the other hand it will provide employment more...

Dating back to 1839, the daguerreotype is one of the oldest known forms of photography. It was the first process that did not require excessively long exposure times, making it ideal for portrait photography. Louis Daguerre (1787-1851) had been trying since 1829 to capture the images he viewed through his camera obscura, a wood box that produced an image on a sheet of frosted glass via a lens at one end. In 1839, after a decade of painstaking work, he presented his daguerreotypes to a joint session of the Academic des Sciences and the Academic des Beaux-Arts. The pictures included images of shells, fossils, and a dead spider, photographed through a microscope. The process for developing the pictures was long and laborious. The plates had to be prepared from a sheet of copper coated with a thin layer of silver. The silver surface had to be polished until it was more...

"I was famous for my kites; and my sleds were the envy... of all the boys in town." Margaret Knight Margaret Knight(1838-1914) was one of the first American women to be awarded a patent. She was a prolific inventor from the age of twelve, when an accident in a textile mill prompted her to design a safety feature to protect workers from the looms. The flat-bottomed paper bag, however, is her most widely remembered invention, as it endures to this day. Knight was working in a paper-bag factory after the American Civil War when she saw the need for a different kind of bag. The factory produced flat bags, more like envelopes, which were unsuitable for bulky items. Square, flat-bottomed bags could be made, but only by hand. Although she had little education, Knight—after studying the factory machinery—built a working wooden prototype of a machine at home. Understanding that she more...

As recently as the 1950s, people with sight clouded by cataracts would slowly go blind with no hope of a cure. Today, in most cases, a cataract sufferer's eyesight can be restored to what it was when they were a teenager in an operation taking just thirty minutes. The man responsible for this incredible breakthrough was British ophthalmologist Harold Ridley (1906-2001), although he had to battle for this achievement to be recognized by his peers. During World War II Ridley treated pilots with injuries caused by shards of Perspex® from their cockpits being lodged in the eye. He noticed that the Perspex® did not react with the eye and realized that, its inert quality, combined with its lightness and optical properties, made it ideal for the construction of replacement lenses for damaged eyes. He confided this information to optical scientist John Pike, who helped design and make the first-ever intraocular more...

"He [Seymour Cray] is the Thomas Edison of the supercomputing industry." Larry L. Smarr, physicist Imagine if you could revolutionize the design of computers and leave the competition standing; U.S. inventor Seymour Cray (1925-1996) made a habit of doing just that. In 1972, with a long history of extending the reach of computer technology already behind him, Cray set up the Cray Research company to concentrate on building a powerful computer. His design for the Cray 1 was the first major commercial success in supercomputing. It was essentially a giant microprocessor capable of completing 133 million floating-point operations per second with an 8- megabyte main memory The secret to its immense speed was Cray's own vector register technology and its revolutionary "C" shape, which meant its integrated circuits could be packed together as tightly as possible. It produced an immense amount of heat and it needed a complex Freon-based cooling more...

"Political power...  grows out of the barrel of a gun...” Mao Zedong, political leader The basic mechanism from which the traditional flintlock originated is thought to have first appeared on a firearm made for King Louis XIII of France. The name of the French courtier Marin Le Bourgeoys appears on the flintlock, and it is thought to have been made in about 1612. The flintlock works as follows. First, the hammer of the gun, which holds a piece of flint, is pulled back or rotated to the half-cock position. Gunpowder is poured into the barrel, followed by ammunition— often a steel ball—and both are pressed into position with a ramrod. A small amount of finely ground gunpowder is then placed in a compartment below the hammer, known as the flashpan. The hammer is then pulled back or rotated to the full-cock position, and the gun is ready to be fired. more...

“... the only standard in worldwide use in the automotive industry." David Beecroft, Society of Automotive Engineers There is a part on all cars and bicycles whose design has not changed in more than a century: the tire valve. It was created by August Schrader (b. 1820), a German immigrant who owned rubber depots and warehouses in Manhattan. He became intimately linked with the rubber industry, making molds and brass fittings for Goodyear and the Union India Rubber Company. In 1890 Schrader received a request to research and develop an airtight seal for the newly developed pneumatic tire. Two years later, August and his son George applied for a patent for the Schrader tire valve. The valve consists of a small brass air tube with its outside surface threaded like a screw. The hollow tube contains a metal pin in its center, running parallel to the tube. Screwing a pump more...

"There are, Indeed, few merrier spectacles than that of many windmills bickering together..." Robert Louis Stevenson, writer The early history of the windmill is much contested, and it is not known for sure when or where it first appeared. Some date it as far back as Babylonia in the seventeenth century B.C.E., while others claim it was not until 200 B.C.E. that wind power was used to pump water in China and mill cereal in Persia. It is, however, reliably documented that windmills were widespread in Persia by the seventh century C.E. They ground grain between millstones rotated by wind blowing on woven reed sails mounted around a vertical axis. The earliest European windmills were built in France and England in the twelfth century and are thought by some to have been the result of a transfer of knowledge from the returning Crusaders. However, the horizontal-axis mills of northern Europe more...

Until the 1980s, most commercial audio recordings were made according to analog principles, with the original sound modulated onto another medium, the physical characteristics of which are directly related to the original sound. In contrast, digital recording sees the original sound converted to digital information and stored as a series of 1s and 0s—known as "bits." Although the principles of digital recording were already in place in the late 1930s, it was not until 1975 that a usable commercial system was developed, when Dr. Thomas Stockham (1933-2004) established Soundstream, Inc., the first dedicated digital recording company. The original audio was passed through an Analog-Digital-Converter (ADC), converted to 16-bit audio, and stored on a 1-inch (2.54 cm) Honeywell tape deck. To play back the sound, the digital information was passed through a Digital-Analog- Converter (DAC). The system offered the highest quality sound without any of the problems of analog recording. Mechanical more...