Before the Fourdrinier machine, paper was made one sheet at a time using a screen-bottomed frame and a mold, or vat, of wet pulp. Lifting the frame through the pulp allowed the water to drain, leaving pulp on the screen. The pulp layer was then pressed and dried. The size of a single shaet was restricted to how large a frame could be handled manually. Paper production was a skilled affair undertaken by craftsmen, often working in guilds. But by the eighteenth century, an increased demand for paper, and a desire to circumvent the paper makers' guild, prompted Frenchman Nicholas-Louis Robert (1761- 1828) to design a machine that would automate the process and produce a seamless length of paper, via a continuous belt of cloth-covered, wire-mesh screen. After much experimentation and testing, Robert's machine received a French patent in January 1799, but the design still needed development. The political situation more...

Rail travel is one of the safest ways to get around in the modern age. The pioneer responsible for much of this safety record was the visionary inventor and industrialist George Westinghouse (1846-1914). Before he invented his revolutionary air brake, slowing and stopping a train was an exercise fraught with risk. Each separate car of the train needed its own brakeman to manually operate brakes on its own set of wheels. Accidents caused by uncoordinated braking were frequent and Westinghouse realized that the poor safety of trains was holding up the whole industrialization of the United States. He spent several years working on a replacement for brakemen's manual labor. Various models failed until, in 1868, he found a solution. He placed an air compressor inside the train driver's cabin and connected long air hoses to it. These hoses traveled the length of the train and were attached to brakes on more...

We all know that kindness is a great virtue and an important duty of man. But most men take it in a limited sense and think that it is enough if they are kind to their fellow men only. Other creatures, birds and beasts too feel pain and we should be kind to them. All living creatures—men, birds and beasts are the creation of God. So He is their common father. It must, therefore, be His desire that the virtue of kindness should be extended to all these creatures alike. No doubt that man has become the lord of the world by virtue of his intellect. But that is the stronger reason why he should be kind to his weaker fellow creatures. We often forget our duty and treat animals cruelly, even those that do us good. Let us take the case of the cow. It gives us milk, the more...

The cluster bomb has courted controversy since its induction in modern warfare in 1939. A conventional bomb consists of a single container carrying an explosive charge that is designed to explode upon impact. The cluster bomb differs through the addition of an outer casing carrying dozens of small bomblets. The casing splits open in mid-air, releasing a shower of smaller bomblets that impact over a broad area. Often dropped by parachute, cluster bombs are highly versatile, if not particularly accurate. They can wreak havoc on soft or unarmored targets such as airfields and formations of men; cluster bombs containing shrapnel are able to pierce armored tanks and penetrate concrete. Cluster bombs really came to the fore during the Vietnam War. U.S. forces carpet- bombed the dense forests of Vietnam, Laos, and Cambodia with cluster bombs carrying chemical weapons such as napalm. The bombs were designed to set fire to the more...

"When the plumbers and sanitary engineers had done their work... diseases began to vanish." Lewis Thomas, medical researcher and essayist It was probably more the need to get rid of foul smells than an understanding of the health hazards of human waste that led to the first proper sewage systems. While most early settlements grew up next to natural waterways—-into which waste from latrines was readily channeled—the emergence of major cities exposed the inadequacy of this approach. Early civilizations, like that of the Babylonians, dug cesspits below floor level in their houses and created crude drainage systems for removing storm water. But it was not until around 2500 B.C.E. in the Indus Valley that networks of precisely made brick-lined sewage drains were constructed along the streets to convey waste from homes. Toilets in homes on the street side were connected directly to these street sewers and were flushed manually with more...

India is a great country having extensive borders. Its total borderline is nearly 15000 kms. Its northen frontier stretches from Kashmir and goes up to Arunachal Pradesh and Assam, touching the border of Burma and Bangladesh. On the periphery of India, lie many countries. In the north, Kashmir is surrounded by Afghanistan, Pakistan, Tibet and China. Ladakh is the tri-junction where the frontiers of these three countries kiss each other. Afghanistan is though now friendly towards India, Pakistan and China are hostile. Along the entire Himalayan range lies the kingdom of Bhutan. The Himalayan kingdom has a benevolent king. Its customs, costumes, religion and manners are quite akin to India. There is the beautiful Himalayan kingdom of Nepal. Nepal is a country, situated in the heart of the mighty  Himalayas. Its capital is Kathmandu. Kathmandu is a lovely valley. India and Nepal are closely linked culturally and historically. The borders more...

Introduction. Today, India is facing a lot of problems. But population problem is worst from all of them. Due to this problem we fall short of our resources. The countries having limited population are fully developed in nil the sectors. India is a great country. It has 2.4% area of the whole world. At the time of our independence in 1947, the population of our country was merely 33 crore but now we have crossed more than one thousand millions. Present Indian position. Indian population has increased four times .since our independence. We stand in the second position after China in world population. It will create havoc if it continues to increase at the same  rate in next twenty-five years. Due to this population problem in India, all our plannings or policies become unsuccessful. Reasons of population explosion. In India, the main reason behind  this grim problem is illiteracy. The more...

"I wanted to work in the visible spectrum... and everybody else was working in the infrared." Nick Holonyak The LED (light-emitting- diode) is a semiconductor device. All semiconductors have a variable ability to conduct electric current because of impurities (caused by trace chemical additives) in their structure. An N-type impurity adds an extra electron to the semiconductor, and a P-type impurity provides an electron hole. Electrons, negatively charged particles, naturally move from areas with many electrons (negative) to areas with few electrons (positive). In a diode, an N-type material is placed next to a. P-type one, and the two are sandwiched between electrodes. This setup only allows electric current (a stream of electrons) to flow in one direction, from the N-type side's electrode to the P-type side's electrode. When an electron drops into an electron hole, it releases energy in the form of a photon. As a result, when electrons more...

In India, the legislature at the central level is called Parliament. The Indian Parliament is bicameral. It consists of  two houses. The lower house is called the Lok Sabha or the House of the people. The upper house is called the Raiya  Sabha or the council of States. The President of India is .in integral part of the Indian Parliament. The two houses of  Parliament  are constituted in different ways. They do not enjoy equal powers. The first elected Parliament came into in  April 1952. Lok Sabha, as the name itself signifies, is the body representative of the people. It consists of members of directly elected by the people. The maximum strength of Lok sabha  has been fixed at 552. Out of these, 530 members are has  by the people from different states and to 20 members are  elected from the union territories. Besides, the President In the power to more...

Being a woman in science in the early 1900s was difficult for American neurophysiologist Ida Hyde (1857-1945). Born in Davenport, Iowa, to German immigrant parents, she struggled to find a university that would accept her. She eventually earned a bachelor's degree at Cornell University and later became the first woman to earn a PhD in science at the University of Heidelberg, in Germany. Despite this, Hyde was still not acknowledged for her invention of the microelectrode until after her death. Since then, the microelectrode has revolutionized neuro-physiology. Hyde's electrode was so small that at the time her methods were among the first capable of studying single cells. Hyde's research focused on the breathing mechanism and nervous systems of a range of organisms, from grasshoppers to humans. During her research, she invented the microelectrode so that she could deliver electrical or chemical stimuli to a cell and record the electrical activity more...