The name 'Bodmin Moor' is fairly recent, invented in 1813. It was formerly known as Fowey Moor after the River Fowey which rises within it. Since the mid 18th century Bodmin Moor has been crossed by the trunk road now known as the A30.
Dramatic granite tors rise from the rolling moorland: the best known are Brown Willy, the highest point in Cornwall at , and Rough Tor at . Considerable areas of the moor are poorly drained and form marshes (in hot summers these can dry out). The rest of the moor is mostly rough pasture or overgrown with heather and other low vegetation.
The Moor contains about 500 farm holdings with around 10,000 beef cows, 55,000 breeding ewes and 1,000 horses and ponies. Most of the moor is a Site of Special Scientific Interest (SSSI) and has been officially designated an Area of Outstanding Natural Beauty (AONB), as part of Cornwall AONB.
Bodmin Moor is the source of several of Cornwall's rivers: they are mentioned here anti-clockwise from the south.
Inland waters on the moor include Dozmary Pool (Cornwall's only natural inland lake) and
three reservoirs, Colliford Lake, Siblyback Lake and Crowdy reservoir which supply water for a large part of the county's population.
Amphipod
The Amphipods are an order of malacostracan crustaceans. They have no carapace.
The name "amphipoda" means "different-footed". Unlike isopods, where all the legs are alike, amphipods have different appendage types.
Of the 7,000 species, 5,500 are classified into one suborder, the Gammaridea. The rest are in two or three other suborders.
Amphipods range in size from 0.1 to 34 centimetres (0.04 to 13 inches) and are mostly detritivores or scavengers. They live in almost all aquatic environments; 750 species live in caves and the order also includes terrestrial animals and sandhoppers such as "Talitrus saltator". The largest amphipods live on the sea floor, seven kilometres down.
Mature females bear a "marsupium", or brood pouch, which holds her eggs while they are fertilised, and until the young are ready to hatch. As a female ages, she produces more eggs in each brood. Mortality is around 25%–50% for the eggs. There are no larval stages; the eggs hatch directly into a juvenile form, and sexual maturity is generally reached after 6 moults.
Converter (metallurgy)
A converter is a chemical reactor which turns raw iron into steel.
Raw iron called "pig iron" which is the product of blast furnace, contains up to 4% of carbon. It is too hard and brittle for meaningful use. The carbon must first be burned off the iron to produce steel. This process is called "conversion" and the reactor a "converter".
The first converter was invented by Sir Henry Bessemer in 1856. He built a pear-shaped large vessel with nozzles (tuyeres) for air in the bottom. Hot molten pig iron from blast furnace was poured in the converter, and then air was pumped in at the bottom with high pressure. The result was a loud noise and a flame of up to 20 metres off the mouth of the converter. After ten minutes all the pig iron had become steel. The Bessemer converter was the first successful reactor on converting pig iron into steel, and the era of steel began. Steel was now plentiful and cheap.
However, steel becomes better if only oxygen is blown in. Air contains nitrogen, which is harmful for some steel grades. A modern converter called basic oxygen furnace uses pure oxygen instead of air. It was invented 1949 in Austria.
The modern basic oxygen converter is a large pumpkin-shape vessel which is made from steel and lined with refractories such as calcium oxide and magnesium oxide line so the vessel can withstand the high temperature of molten metal.
Molten pig iron and scrap are loaded in the converter. The scrap usually is rusty and contains oxygen, so some of the rust reacts with the pig iron, burning the carbon away and creating heat which melts the scrap. Once all scrap has melted, a special pipe called "oxygen lance" is lowered in the pig iron, and a very fast and sharp blow of oxygen is blasted in. The oxygen burns all the carbon away and mixes the liquid steel thoroughly. Once all carbon has been burned away, some extra carbon is inserted to raise the contents to desired level. The result is liquid steel, which is then tapped away and taken to rolling mill to produce steel products.
Fellowship
Fellowship may refer to:
Tuning fork
A tuning fork is a sound resonator which is a two-pronged fork. The prongs, called tines, are made from a U-shaped bar of metal (usually steel). This bar of metal can move freely. It resonates at a specific constant pitch when set vibrating by striking it against an object. It sounds a pure musical tone after waiting a moment to allow some high overtone sounds to die out. The pitch depends on the length of the two prongs. Its main use is as a standard of pitch to tune other musical instruments, and in some tests of hearing.
The tuning fork was invented in 1711 by British musician John Shore. He was the Sergeant Trumpeter to the court, who had musical parts written for him by the composers George Frideric Handel and Henry Purcell.
The fork shape produces a very pure tone. Most of the vibrational energy is at the fundamental frequency, with very few overtones (harmonics). This is not the case with other resonators. The reason for this is that the frequency of the first overtone is about 5/2 = 25/4 = 6¼ times the fundamental (about 2½ octaves above it). By comparison, the first overtone of a vibrating string is only one octave above the fundamental. So when the fork is struck, little of the energy goes into the overtone modes; they also die out correspondingly faster, leaving the fundamental. It is easier to tune other instruments with this pure tone, when listening to compare with the tone of each other instrument.
Another reason for using the fork shape is that, when it vibrates in its principal mode, the handle vibrates up and down as the prongs move apart and together. There is a node (point of no vibration) at the base of each prong. The handle motion is small, allowing the fork to be held by the handle without damping the vibration, but it allows the handle to transmit the vibration to a resonator (like the hollow rectangular box often used), which amplifies the sound of the fork. Without the resonator (which may be as simple as a table top to which the handle is pressed), the sound is very faint. The reason for this is that the sound waves produced by each fork prong are 180° out of phase with the other, so at a distance from the fork they interfere and largely cancel each other out. If a sound absorbing sheet is slid in between the prongs of a vibrating fork, reducing the waves reaching the ear from one prong, the volume heard will actually increase, due to a reduction of this cancellation.
Commercial tuning forks are normally tuned to the correct pitch at the factory, but they can be retuned by filing material off the prongs. Filing the ends of the prongs raises the pitch, while filing the inside of the base of the prongs lowers it.
The most common tuning fork sounds the note of A = 440 Hz. This is the standard concert pitch, used as tuning note by some orchestras. It is the pitch of the violin's second string, the first string of the viola, and an octave above the first string of the cello, all played open. Tuning forks used by orchestras between 1750 and 1820 mostly had a frequency of A = 423.5 Hz, although there were many forks and many slightly different pitches. Standard tuning forks are available for all the musical pitches within the central octave of the piano, and other pitches. Well-known manufacturers of tuning forks include Ragg and John Walker, both of Sheffield, England.
The frequency of a tuning fork depends on its dimensions and the material from which is made:
Where: