Italian genius Leonardo da Vinci (1452-1519) is best known as a painter, anatomist, sculptor and architect. His paintings The Last Supper and Mona Lisa are among the most famous of all time. But he is also hailed as one of the greatest inventors who ever lived. Among his notebooks he left plans for countless advanced machines, often with descriptions written in secret mirror writing. Many of them were never built, but they anticipated modern inventions, often by hundreds of years. They include the following:
Air conditioner, Alarm clock, Ball-bearings, chemical and biological warfare, clock with minute and four hands, crane, diving suit and diving bell, double –hull ship, dredging machine, flying machine, gas mask, gears, giant catapults and crossbows, helicopter, lifebelt, magnetic compass, mechanical musical instruments, milometer, multi-barreled machine gun, one-person battleship, parachute, pedometer (for measuring walking distance), revolving stage, screw-making machine, shrapnel bomb, spectacles, steam engine, tank-like armored vehicle, telescope, water clock, water turbine
Friday, June 26, 2009
Tuesday, June 23, 2009
Something about Mangoes Seeds
Mangoes can easily propagate from seeds. But to ensure good quality, ‘inarching’ or simple grafting is commonly practiced in most states of the country. A shoot from a suitable parent tree is united to a potted seedling. This graft is carefully nursed for about one year and is then planted out in the garden. Here, it gradually grows into a graceful dome-shaped form, and four years after, the tree is ready to bear fruits. The grafted tree bears good fruits for about fifty years. On the other hand, a seedling tree—grown out of a seed—takes about ten years to bear fruits but has a longer fruitive period than the grafted one.
The tree grows well in humid as well as dry climates. Rain, fog or cloudy weather at the time of flowering affect fruit-setting. Similarly, heavy rains during the maturing and ripening of the fruit cases damage to the crop. In South India, the tree starts flowering in December-January while in North India, flowering takes place late—mid February to mid March. After flowering, it takes about ninety days for the fruit of ripen.
The tree grows well in humid as well as dry climates. Rain, fog or cloudy weather at the time of flowering affect fruit-setting. Similarly, heavy rains during the maturing and ripening of the fruit cases damage to the crop. In South India, the tree starts flowering in December-January while in North India, flowering takes place late—mid February to mid March. After flowering, it takes about ninety days for the fruit of ripen.
Sunday, June 21, 2009
How many kinds of mangoes are cultivated in India?
It is estimated that about a thousand varieties of mangoes are grown in various parts of India, each variety characterized by its own peculiar taste and flavor. The number of wild varieties is unknown. Of the cultivated kind, thirty varieties of are commercially well known. Some of them are the Duseheri or Dashehari; the Langra and the Chausa of the North; the Alphonso and the Kalepad of the west; the Baneshan (Bangan-Palli); the Jahangir (Umdra); the Imam Pasand and Neelum of the South and south-east; and the Gulab-Khan and the Malda of the east. Quite often one single variety assumes several different names as orchardists like to consider each seedling as a new ‘variety’ and to Christen it with exotic new name. One can call it by any name, but a mango is always delicious.
Although the mango is now cultivated in several countries of the world, no where else has it achieved the prime position it enjoys in India. It occupies about 70% of the total area under fruit cultivation in this country. The State of Uttar Pradesh has the largest area under mango cultivation where 150 varieties of mangoes are grown. Bihar comes next followed by Andhra Pradesh.
Although the mango is now cultivated in several countries of the world, no where else has it achieved the prime position it enjoys in India. It occupies about 70% of the total area under fruit cultivation in this country. The State of Uttar Pradesh has the largest area under mango cultivation where 150 varieties of mangoes are grown. Bihar comes next followed by Andhra Pradesh.
Thursday, June 18, 2009
Another four elements
Helium
Helium is twice as heavy as hydrogen, but it is still only one seventh the weight of air. Unlike hydrogen does not burn, so it is used in modern airships.
Lithium
Lithium was discovered in 1817 by Swedish scientists Johan August Arfvedson. It takes its name from the Latin word for rock, although it is actually a metal. Lithium is so light (42 times lighter than the heaviest element, osmium) and so soft that it can be easily cut with a knife. It floats because it is half as heavy as water, and lighter than some types of wood. It is used to make lithium batteries.
Potassium and sodium
Both are discovered in 1807 by Sir Humphry Davy. Both are metals that are lighter than water. In a laboratory, potassium is usually kept in paraffin because if it comes into contact with water it releases hydrogen and generate so much heat that it catches fire.
Helium is twice as heavy as hydrogen, but it is still only one seventh the weight of air. Unlike hydrogen does not burn, so it is used in modern airships.
Lithium
Lithium was discovered in 1817 by Swedish scientists Johan August Arfvedson. It takes its name from the Latin word for rock, although it is actually a metal. Lithium is so light (42 times lighter than the heaviest element, osmium) and so soft that it can be easily cut with a knife. It floats because it is half as heavy as water, and lighter than some types of wood. It is used to make lithium batteries.
Potassium and sodium
Both are discovered in 1807 by Sir Humphry Davy. Both are metals that are lighter than water. In a laboratory, potassium is usually kept in paraffin because if it comes into contact with water it releases hydrogen and generate so much heat that it catches fire.
Sunday, June 14, 2009
1980s and 1990s
By 1981 the ARPA network had 213 hosts (sites to which users could connect). A new host was added approximately every 20 days. In 1982 a common language called TCP/IP was invented which allowed all internet computers to communicate with each other and the network was first called an internet. In the 19802s many more people and businesses began to use computers. The internet began to be used commercially, as well as by governments and universities.
In 1991 the World Wide Web (www) was created. It combined words, pictures and sounds in a system that ordinary people could easily understand and use. By 1994 approximately 40 million people were connected to the internet. They could exchange information, sell goods, and work form any computer with a phone call. The rolling stones rock group even broadcast a concert over the internet. Schools started using the internet as an electronic library. By 1996 users in almost 150 countries around the world were connected to the internet
In 1991 the World Wide Web (www) was created. It combined words, pictures and sounds in a system that ordinary people could easily understand and use. By 1994 approximately 40 million people were connected to the internet. They could exchange information, sell goods, and work form any computer with a phone call. The rolling stones rock group even broadcast a concert over the internet. Schools started using the internet as an electronic library. By 1996 users in almost 150 countries around the world were connected to the internet
Wednesday, June 10, 2009
The heaviest elements
Osmuim
Osmium is the heaviest element of all (22.61g per cubic centimeter). It was discovered by the British chemist Smithson Tennant in 1803. He named it after the Greek word for smell because it smelt bad. Osmium is twice as heavy as lead – so heavy that a cubic foot (0.028317 cubic meters) weighs 640ks, as much as ten average people! A football made of osmium would weigh 126 kg, or much as two adults. Osmium is also very hard, and is used to make hard-wearing points, such as the nibs of fountain pens.
Platinum
Platinum was used before anyone realized that it was an element. It weighs almost as much as osmium (21.45g per cubic centimeter) and is also used in catalytic converters in cars to reduce the pollution from exhaust gases.
Plutonium
Plutonium was discovered in 1941 and is heavy and highly radioactive metal. It is used as a nuclear fuel and in nuclear weapons - a kilogram of plutonium produces an explosion equivalent to 20,000 tonnes of TNT.
Osmium is the heaviest element of all (22.61g per cubic centimeter). It was discovered by the British chemist Smithson Tennant in 1803. He named it after the Greek word for smell because it smelt bad. Osmium is twice as heavy as lead – so heavy that a cubic foot (0.028317 cubic meters) weighs 640ks, as much as ten average people! A football made of osmium would weigh 126 kg, or much as two adults. Osmium is also very hard, and is used to make hard-wearing points, such as the nibs of fountain pens.
Platinum
Platinum was used before anyone realized that it was an element. It weighs almost as much as osmium (21.45g per cubic centimeter) and is also used in catalytic converters in cars to reduce the pollution from exhaust gases.
Plutonium
Plutonium was discovered in 1941 and is heavy and highly radioactive metal. It is used as a nuclear fuel and in nuclear weapons - a kilogram of plutonium produces an explosion equivalent to 20,000 tonnes of TNT.
Tuesday, June 2, 2009
Elements on Earth
There is calcium in the Earth and sea in the form of calcium carbonate. Sodium exists in the form of sodium chloride, the salt in the sea and on our tables. The quantities of both calcium and sodium are so vast that these elements are considered unlimited. Some elements are mined and used in industry. Iron is the most common, followed by magnesium. There are quite small amounts of some precious metals on earth, which is why they are so valuable. For example, there are about one million tones of silver and 15,000 tonnes of gold. Elements are constantly being taken from Earth, but new discoveries are being made. We are still some way from running out of even the rarest elements. Element 98 was given the name Californium by the four scientists who discovered it in 1950. They were working at the University of California at Berkeley, and named the element for both the state and their university.
