A jet boat is a boat propel by a jet of water twisted out from the back of the craft. Unlike a powerboat or motorboat that uses a propeller in the water behind the boat; a jet boat draws the water from under the boat into a pump-jet inside the boat, and then expels it through a needle at the stern.
Jet boats were originally designed by Sir William Hamilton (who invented the water jet in 1954) for operation in the fast-flowing and shallow rivers of New Zealand, especially to overcome the problem of propellers striking rocks in such waters, although Italian inventor Second Camping had demonstrated a similar vessel as early as 1931 in Venice.
The difference between Campini's and Hamilton's inventions is that Campini's water jet had a very short lifetime in operation due to some unsolved material problems. Hamilton, unlike Camping, filed for a patent. Jet boats are extremely maneuverable, and many can, from full speed, be upturned and brought to a stop within their own length, in a maneuver known as a Hamilton turn.
Monday, May 28, 2007
Monday, April 2, 2007
Wain A wain is a type of horse-drawn, load-car...
Wain
A wain is a type of horse-drawn, load-carrying vehicle, used for agricultural purposes quite than transporting people, for example a haywain. It usually has four wheels but the term has now acquired slightly poetical connotation so is not always used with technological correctness. Though, a two-wheeled 'haywain' would be a hay cart, Compare with carriage.
Builders of wains were recognized as Wainwrights, just as the builders of carts were known as Cartwrights. These trades no longer are, but the terms survive as the surnames of children of those practicing these crafts.
The vehicle was the subject of John Constable's 1821 painting The Hay Wain. The painting, which was part of Constable's Gold Medal exhibit to Charles X, depicts a site in Suffolk, near Flat ford on the river Stour.
There are records of early short-distance flights from the 9th to 11th centuries, such as the parachute flight of Armen Firman, the glider flight of Abbas Ibn Firnas, and maybe earlier human-carrying kites from China.
The modern age of aviation began with the first untethered human lighter-than-air flight on November 21, 1783, in a hot air balloon intended by the Montgolfier brothers, and balloon flight became increasingly common over longer and longer distances throughout the 19th century, continuing to the present. On December 17, 1903, the Wright brothers flew the first successful powered, heavier-than-air flight, though their aircraft was not practical to fly for more than a short distance because of control problems. The widespread acceptance of ailerons made aircraft much easier to manage, and only a decade later, at the start of World War I, heavier-than-air powered aircraft had become practical for reconnaissance, artillery spotting, and even attacks against ground positions.
Aircraft began to transport people and cargo as designs grew larger and more dependable. Initially, lighter-than-air airships (also called dirigibles) were supposed to be the most practical means of air transportation of passengers. In the 1930s, however, the Douglas DC-3 became the first airliner that was profitable carrying passengers completely, starting the modern era of passenger airline service. Around the same time, the Hindenburg disaster of 1937 shattered airships' popularity (though there are periodic initiatives to revive their use). By the beginning of World War II, many towns and cities had built airports, and there were numerous capable pilots available. The war brought many innovations to aviation, as well as the first jet aircraft and the first liquid-fueled rockets.
A wain is a type of horse-drawn, load-carrying vehicle, used for agricultural purposes quite than transporting people, for example a haywain. It usually has four wheels but the term has now acquired slightly poetical connotation so is not always used with technological correctness. Though, a two-wheeled 'haywain' would be a hay cart, Compare with carriage.
Builders of wains were recognized as Wainwrights, just as the builders of carts were known as Cartwrights. These trades no longer are, but the terms survive as the surnames of children of those practicing these crafts.
The vehicle was the subject of John Constable's 1821 painting The Hay Wain. The painting, which was part of Constable's Gold Medal exhibit to Charles X, depicts a site in Suffolk, near Flat ford on the river Stour.
There are records of early short-distance flights from the 9th to 11th centuries, such as the parachute flight of Armen Firman, the glider flight of Abbas Ibn Firnas, and maybe earlier human-carrying kites from China.
The modern age of aviation began with the first untethered human lighter-than-air flight on November 21, 1783, in a hot air balloon intended by the Montgolfier brothers, and balloon flight became increasingly common over longer and longer distances throughout the 19th century, continuing to the present. On December 17, 1903, the Wright brothers flew the first successful powered, heavier-than-air flight, though their aircraft was not practical to fly for more than a short distance because of control problems. The widespread acceptance of ailerons made aircraft much easier to manage, and only a decade later, at the start of World War I, heavier-than-air powered aircraft had become practical for reconnaissance, artillery spotting, and even attacks against ground positions.
Aircraft began to transport people and cargo as designs grew larger and more dependable. Initially, lighter-than-air airships (also called dirigibles) were supposed to be the most practical means of air transportation of passengers. In the 1930s, however, the Douglas DC-3 became the first airliner that was profitable carrying passengers completely, starting the modern era of passenger airline service. Around the same time, the Hindenburg disaster of 1937 shattered airships' popularity (though there are periodic initiatives to revive their use). By the beginning of World War II, many towns and cities had built airports, and there were numerous capable pilots available. The war brought many innovations to aviation, as well as the first jet aircraft and the first liquid-fueled rockets.
Wednesday, March 21, 2007
Carriage The standard definition of a carriage is...
Carriage
The standard definition of a carriage is a four-wheeled horse drawn personal passenger vehicle with leaf springs or leather robust for postponement, whether light, smart and fast or large and relaxed. Compare the public conveyance stagecoach, charabanc, and omnibus.
A medium that is not sprung is a wagon. An American buckboard or Conestoga wagon or "prairie schooner" was never taken for a carriage, but a waggonette was an enjoyment vehicle, with lengthways seats.
The word car meaning "wheeled vehicle", came from Norman French at the start of the 14th century; it was absolute to cover automobile in 1896.
In the British Isles and many Commonwealth countries, a railway carriage (also called a coach) is a railroad car planned and prepared for transporting passengers.
In the United States, a baby carriage is a wheeled transportation for recline infants (in English outside North America: perambulator or pram), often with a hood that can be adjusted to protect the baby from the sun.
The standard definition of a carriage is a four-wheeled horse drawn personal passenger vehicle with leaf springs or leather robust for postponement, whether light, smart and fast or large and relaxed. Compare the public conveyance stagecoach, charabanc, and omnibus.
A medium that is not sprung is a wagon. An American buckboard or Conestoga wagon or "prairie schooner" was never taken for a carriage, but a waggonette was an enjoyment vehicle, with lengthways seats.
The word car meaning "wheeled vehicle", came from Norman French at the start of the 14th century; it was absolute to cover automobile in 1896.
In the British Isles and many Commonwealth countries, a railway carriage (also called a coach) is a railroad car planned and prepared for transporting passengers.
In the United States, a baby carriage is a wheeled transportation for recline infants (in English outside North America: perambulator or pram), often with a hood that can be adjusted to protect the baby from the sun.
Monday, January 22, 2007
Lighthouse of Alexandria The Pharos of Alexandria...
Lighthouse of Alexandria
The Pharos of Alexandria was a lighthouse built in the 3rd century BC on the island of Pharos in Alexandria, Egypt to serve as that port's landmark, and later, a lighthouse. With a height variously estimated at between 115 and 135 metres it was among the tallest man-made structures on Earth for many centuries, and was identified as one of the Seven Wonders of the World by classical writers. It ceased operating and was largely destroyed as a result of two earthquakes in the 14th century AD; some of its remains were found on the floor of Alexandria's Eastern Harbour by divers in 1994. More of the remains have subsequently been revealed by satellite imaging.
Constructed from large blocks of light-colored stone, the tower was made up of three stages: a lower square section with a central core, a middle octagonal section, and, at the top, a circular section. At its apex was positioned a mirror which reflected sunlight during the day; a fire was lit at night. Extant Roman coins struck by the Alexandrian mint show that a statue of a triton was positioned on each of the building's 4 corners. A statue of Poseidon stood atop the tower during the Roman period.
The Pharos of Alexandria was a lighthouse built in the 3rd century BC on the island of Pharos in Alexandria, Egypt to serve as that port's landmark, and later, a lighthouse. With a height variously estimated at between 115 and 135 metres it was among the tallest man-made structures on Earth for many centuries, and was identified as one of the Seven Wonders of the World by classical writers. It ceased operating and was largely destroyed as a result of two earthquakes in the 14th century AD; some of its remains were found on the floor of Alexandria's Eastern Harbour by divers in 1994. More of the remains have subsequently been revealed by satellite imaging.
Constructed from large blocks of light-colored stone, the tower was made up of three stages: a lower square section with a central core, a middle octagonal section, and, at the top, a circular section. At its apex was positioned a mirror which reflected sunlight during the day; a fire was lit at night. Extant Roman coins struck by the Alexandrian mint show that a statue of a triton was positioned on each of the building's 4 corners. A statue of Poseidon stood atop the tower during the Roman period.
Tuesday, January 9, 2007
Conjoined twins Conjoined twins are monozygotic t...
Conjoined twins
Conjoined twins are monozygotic twins, whose bodies are joined together at birth. This occurs where the single zygote of identical twins fails to separate completely, and the zygote starts to split after day 13 following fertilization. This condition occurs in about 1 in 50,000 human pregnancies. Most conjoined twins are now evaluated for surgery to attempt to separate them into separate functional bodies. The degree of difficulty rises if a vital organ or structure is shared between twins, such as brain, heart or liver.
A chimera is an ordinary person or animal except that some of his or her parts actually came from his or her twin. A chimera may arise either from identical twin fetuses, or from dizygotic fetuses, which can be identified by chromosomal comparisons from various parts of the body. The number of cells derived from each fetus can vary from one part of the body to another, and often leads to characteristic mosaicism skin colouration in human chimeras. A chimera may be a hermaphrodite, composed of cells from a male twin and a female twin.
Conjoined twins are monozygotic twins, whose bodies are joined together at birth. This occurs where the single zygote of identical twins fails to separate completely, and the zygote starts to split after day 13 following fertilization. This condition occurs in about 1 in 50,000 human pregnancies. Most conjoined twins are now evaluated for surgery to attempt to separate them into separate functional bodies. The degree of difficulty rises if a vital organ or structure is shared between twins, such as brain, heart or liver.
A chimera is an ordinary person or animal except that some of his or her parts actually came from his or her twin. A chimera may arise either from identical twin fetuses, or from dizygotic fetuses, which can be identified by chromosomal comparisons from various parts of the body. The number of cells derived from each fetus can vary from one part of the body to another, and often leads to characteristic mosaicism skin colouration in human chimeras. A chimera may be a hermaphrodite, composed of cells from a male twin and a female twin.
Tuesday, January 2, 2007
Wildlife The term wildlife refers to living organ...
Wildlife
The term wildlife refers to living organisms that are not in any way artificial or domesticated and which survive in natural habitats. Wildlife can refer to flora but more usually refers to fauna. Wildlife is a very general term for life in ecosystems. Deserts, rainforests, plains, and other areas including the most built-up urban sites all have distinct forms of wildlife.
Humans have historically tended to split civilization from wildlife in a number of ways; besides the obvious difference in vocabulary, there are differing expectations in the legal, social, and moral sense. This has been a reason for debate during recorded history. Religions have often declared certain animals to be sacred, and in modern times concern for the environment has aggravated activists to protest the exploitation of wildlife for human benefit or entertainment. Literature has also made use of the traditional human separation from wildlife.
The term wildlife refers to living organisms that are not in any way artificial or domesticated and which survive in natural habitats. Wildlife can refer to flora but more usually refers to fauna. Wildlife is a very general term for life in ecosystems. Deserts, rainforests, plains, and other areas including the most built-up urban sites all have distinct forms of wildlife.
Humans have historically tended to split civilization from wildlife in a number of ways; besides the obvious difference in vocabulary, there are differing expectations in the legal, social, and moral sense. This has been a reason for debate during recorded history. Religions have often declared certain animals to be sacred, and in modern times concern for the environment has aggravated activists to protest the exploitation of wildlife for human benefit or entertainment. Literature has also made use of the traditional human separation from wildlife.
Wednesday, December 27, 2006
Etymology of India India, as a country and nation...
Etymology of India
India, as a country and nation, has three principal names, in both official and popular usage, each of which is historically and culturally important. All three originally designated a single entity comprise all the modern nations of the Indian subcontinent. The first Article of the Constitution of India, which deals with the official name, states that "India, that is Bharat, shall be a union of states." Thus, not only in usage but officially India and Bharat are both accorded primary status? The name India is derived from the river Indus.
The innovative name of the river came from the fact that in the north-west of the subcontinent, there are seven main tributaries of the one river. The local inhabitants therefore called it Sapta-Sindhu, meaning the seven rivers. As the seven tributaries are part of the one river, the whole river system came to be known in time as Sindhu. In general, Sindhu also means any river or water body in Sanskrit.
India, as a country and nation, has three principal names, in both official and popular usage, each of which is historically and culturally important. All three originally designated a single entity comprise all the modern nations of the Indian subcontinent. The first Article of the Constitution of India, which deals with the official name, states that "India, that is Bharat, shall be a union of states." Thus, not only in usage but officially India and Bharat are both accorded primary status? The name India is derived from the river Indus.
The innovative name of the river came from the fact that in the north-west of the subcontinent, there are seven main tributaries of the one river. The local inhabitants therefore called it Sapta-Sindhu, meaning the seven rivers. As the seven tributaries are part of the one river, the whole river system came to be known in time as Sindhu. In general, Sindhu also means any river or water body in Sanskrit.
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