Archives May 2013

"Today, centrifugal pumps and compressors have reached efficiency levels above 90 percent." Abraham Engeda, Michigan State University The centrifugal pump works by drawing in a fluid (a liquid or gas) at the center of a cylindrical chamber that contains a rotating impeller with vanes. This forces the fluid to rotate outward toward the wall of the cylinder before flowing into an outlet pipe. The rotation of the fluid causes the liquid to leave with a higher velocity and pressure than when it entered. The centrifugal pump was invented by French scientist Denis Papin in 1689 as he attempted to solve the problem of ventilating mines. Papin's device was used to pump air through mines and was also applied to furnaces, where it was known as the Hessian bellows. The basic centrifugal pump was improved by John Appold, who carried out an exhaustive study on the effect of blade shape on more...

No office is complete without a fax machine, so you would probably think that it was a modern invention. But the earliest facsimile machine was actually invented thirty years before the telephone, in 1842. Today faxes run a sheet of paper through rolls, using optical chips to record the image. These chips did not exist until the late 1960s, but machines using photoelectric cells, invented by Edouard Belin in 1907, sent the light and dark parts of a picture as electrical pulses. By 1902 Arthur Korn had already invented a similar machine. Even earlier, in 1898, Ernest A. Hummel invented the copying telegraph, which sent pictures between major newspapers in the United States. But long before Hummel there was a way to transmit images. In 1855 Giovanni Caselli made the pantelegraph, synchronizing the sending and receiving machines with an electronic heartbeat and sending pulses between them. But even this was more...

A visit to a hill station is worth enjoying during the summer vacation. There is heat over the plains. People like to go to hill stations to refresh themselves. It was terribly hot in June. School work could not be done properly. Students were all looking forward to holidays. When our school broke up for summer vacation on the 3rd of June, we felt a great relief. My father made a programme to go to Mussorie. I requested him to spend a few days at Haridwar also. He agreed to my request. On 12th June we left Jalandhar by the Dehradun Passenger. We reached Haridwar the next day in the morning. We stayed there in a rented hut. Haridwar is a beautiful town with lots of temples. It is situated on the bank of the holy Ganges. It is considered as a holy place of the Hindus and presents a more...

Sand casting with molten metal ranks as one of the oldest of the manufacturing technologies. For many years it was a dark art and its mysteries were known only to a select few. A sixteenth-century Italian metallurgist and arms maker, Vannoccio Biringuccio (1480-c. 1539), would change this with his seminal work, De la pirotechnia (1540). Published in Venice a year after Biringuccio's death, the book is a veritable enclyclopedia of metallurgical knowledge and constitutes some of the earliest printed information on sand casting and foundry techniques in general. Born in Siena, Biringuccio, under the patronage of an Italian merchant politician and part-time tyrant, Pandolfo Petrucci, traveled widely throughout Italy and Germany, accumulating the information and experiences that he would summarize in his book. During a typical sand-casting operation, a model or "pattern" of the item to be cast is positioned in a frame. Sand, moistened to bind it together, is more...

The roar of a chain saw is a sound that is hard to separate from images of destruction and violence. Horror movies and wildlife documentaries have taught us that chain saws are, in general, a "bad thing." For maintenance workers and lumberjacks in the 1920s,the invention of the chain saw was undoubtedly a blessing. It is possible that early chain saws were in use before World War I, although there is little solid evidence for this and it was not until World War II that Andreas StihI's (1896-1973) "hand held mobile chain saw," invented in 1927, came into its own. German troops used the saws for making quick progress through wooded areas. When the Allies caught wind of this, they promptly dropped a bomb on the Germans' chain saw factory—but not before stealing a saw for themselves so that they could copy it. StihI's original chain saw was equal in more...

"Get in a supply of taffeta... and you will see one of the most astonishing sights In the world." Joseph Montgolfier in a letter to his brother At 1:45 p.m., November 21, 1783, in the courtyard of the Chateau de la Muette on the outskirts of Paris, the balloon constructed by brothers Joseph-Michael (1740-1810) and Jacques-Etienne de Montgolfier (1745-1799) made its first manned flight. Piloted by a young scientist named Jean-Francois Pilatre de Rozier and an army officer, the Marquis d'Adlandes, the flight high over the city lasted for twenty-five minutes and came to the ground on the Butte-aux-Cailles, 10 miles (16 km) from where it had started. The Montgolfiers' inspiration came from watching a fire burning and speculating as to the "force" that caused the sparks, smoke, and embers to rise. They constructed a large envelope from taffeta, lit a fire beneath the opening, and watched as it rose more...

There are many types of animals found around the world. Some are very big and some very small. The elephant is the largest animal living today and the strongest too. It has thick legs, huges sides and back, large hanging ears, small tail, little eyes, long white tusks and above all long nose called trunk. The trunk is the elephant's peculiar feature, and  it puts it to various uses. It draws up water by it and can squirt it all over its body like a shower bath; picks leaves  from the trees and puts them into mouth. Elephants look very clumsy and heavy. Elephants are found in India and Africa. The African elephant differs in some respects from the Indian; it is larger, stronger, with longer tusks and bigger ears. In fact the two are considered to be of different species. In both the countries, they live in herds in more...

While other ancient civilizations were playing with balls made of stitched-up cloth or cow bladders, the people of Mesoamerica (present-day Mexico and Central America) were playing a game of life and death using balls made from a processed rubber. By adding the juice of the morning glory vine to latex (raw liquid rubber) harvested from the native rubber tree {Castilla elastica), they created balls that had great bounce. As early as 1600 B.C.E., the Mesoamericans used this method to make resilient rubber balls that defied the natural brittleness of solid latex. Their amalgamation could be shaped into any conceivable form, but would harden within minutes, making it impossible to reshape the object afterward. They used this process for a variety of artifacts and produced balls of different sizes, the biggest being larger than a volleyball and weighing up to eight pounds (3.6 kg). These were then used in ritual ball more...

"Ancient masons... could carve marble at more than double the speed of today's craftsmen." Evan Hadingon, Smithsonian Magazine Chisel-like tools have been dated to the Paleolithic era, which stretches across a vast expanse of evolutionary time, from before the first Homo sapiens to roughly 10,000 B.C.E. During this time humans were making and refining stone tools, which became gradually more specialized overtime. Other materials were also used, and bone chisels from around 30,000 B.C.E. have been uncovered in Southern France, near the village of Aurignac. Although very difficult to date exactly, it is thought that by about 7500 B.C.E., what we would recognize today as a chisel was in fairly common use. By the time of the Bronze Age, chisels had become quite varied and included gouges—chisels with curved blades—and tanged chisels, where the blade is connected to the handle by a collar. The Greek architect Manolis Korres believes the more...

The barber is a very useful and important member of the society. He makes us look clean and decent in appearance. It is good that he is not regarded mean and untouchable. In villages, the barber is paid in the form of fixed quantity of corn at the harvest time. This quantity depends upon the members of the family. This corn is generally enough for him for the whole year. Besides this, on happy occasions and ceremonies, he is given gifts of clothes and money by his customers. He goes from village to village and shaves the people and cuts their hair once or twice a month. The village barber is well and happy. In towns and cities there are shops of barbers known as hair cutting saloons. People go to these shops and get themselves shaved and have their hair cut. These shops are beautifully decorated with looking glass, more...