True friendship is a divine quality. To get a true friend is achievement rare now days. Someone is lucky if he gets a true friend. I am lucky enough to have true friend in Rakesh.' I value his friendship. He is really a true friend. We both are class fellows for last four years. Rakesh has many qualities of head and heart. He is an ideal student. He is very punctual in coming to school. He completes his home task regularly. His books and exercise note-books are very clean. Moreover he has a very good handwriting. His behaviour is a model for other students. He is very polite, good mannered and sweet tempered. He never promises anything wrong to others. I have never seen him losing his temper. His uniform is always neat and clean. Though he is not a very brilliant student yet he always tries to improve himself. more...

Raja Ram Mohan Roy was born on 22 May, 1778 at a time when our country was marred by various superstitions. He led our country from darkness to light. His father's name was Radha Kanta Roy and mother's name was Tarini Devi. His education started from the village school. He went to Kashi for studying Sanskrit. He also learned various languages like Arabic, French and English. He was a very good He encouraged promotion of education. He was rebellious by nature. He was awarded the title "Raja" by the Mughai Emperor. He did great work in the fields of education, politics and religion. He rendered a service of ten years in East India Company. Then he spent the rest of his life serving the people of India as a social reformer. He is remembered for his great work Sati Daho. He fought a great battle against the Sati custom, an more...

“To pinpoint the smallest fragments of the universe you have to build the biggest machine in the world." The Guardian The cyclotron was a subatomic particle accelerator that used a magnetic field to force the particles to move around a circular path in a thin, doughnut- shaped vacuum chamber, with a fixed frequency electric field for acceleration. This was then developed into the synchrotron, in which both the magnetic and the electrical fields could be varied. By decreasing the frequency of the applied voltage as the electrons move faster, the accelerating voltage and the orbiting particles could be synchronized. This phase stability ensured that the particles that were going too fast were accelerated less than those going too slowly, and the result was a stable cloud of particles that were gradually accelerated together. In 1945 two proposals for a synchrotron were put forward, one by Edwin McMillan (1907-1991) in the more...

"The use of these fireplaces in very many houses ...is a great saving of wood to the inhabitants." Benjamin Franklin, statesman and scientist Before inventing the lightning rod and bifocal lenses, American statesman and polymath Benjamin Franklin (1706-1790) had turned his attention to keeping peoples' homes warm and safe. In the eighteenth century many homes in the United States, built of wood and heated by open hearths, were at great risk of fire. This had concerned Franklin since at least 1735, when he organized the first volunteer fire department in his adopted home town of Philadelphia, Pennsylvania. He also called for building regulations to include minimum safety standards in fireplace design—modern standards are still based on them. In 1742 he designed a new stove that he called the "Pennsylvania fireplace"; it was later called the "Franklin stove" or "circulating fireplace." The stove was a box lined with metal that stood more...

Printing on demand (POD) has revolutionized the publishing world. The process, established in 2006 by Books on Demand, uses digital technology to print copies of a book once an order has been placed. POD is infinitely quicker and simpler to set up than conventional printing because the pages are stored electronically, eliminating the need for lithographic films or printing plates. It is also relatively cheap. Unit costs are higher per copy than with traditional printing methods, but POD offers lower costs per copy for small print runs after set-up costs are taken into account. POD books can be made available in either a traditional printed format or as an e-book. POD digital technology is rescuing many older and relatively obscure titles from oblivion by enabling them to remain available and in print. Cambridge University Press (CUP) has been using the process since 1998 and now has more than 10,000 titles more...

When telephonic communication systems were first invented, and few people actually owned a telephone with number buttons. Telephone calls would be connected via a human operator. You would lift a receiver, the switchboard operator would ask you for the number you wished to call, and he or she would plug a wire into the requisite part of the board to have you connected. However, as telephones became more popular, it became increasingly impractical to have humans connecting the calls by hand and so electromechanical switchboards were invented. Soon communications companies found that even this was not enough— there was so much telephonic traffic to deal with that they started to overload and seize up. It was Erna Schneider Hoover (b. 1926), a computer programmer with a PhD in mathematics and a specialist in symbolic logic, who struck upon the solution when she was working for Bell Laboratories in New Jersey. more...

"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...