The beaver (Castor) is the only genus of the family Castoridae. The family contains a single genus, Castor, with two species: Castor canadensis, found in the New World, and Castor fibre, found in the Old World. Both species are semi-aquatic rodents noted for the building of dams. The two species differ chiefly in the shape of the nasal bones and are so much alike that some authorities consider them to be varieties of the same species. They are large rodents; the average adult beaver weighs about 16 kg, but specimens as heavy as 40 kg have been found, and some extinct beavers were almost bear- like in size. The beaver is usually about 76 centimetres long and stands less than 30 centimetres high, with a broad, flat, scaly tail about 25 centimetres long.
The body is plump, the back arched, the neck thick, the hind feet webbed, and all the digits clawed. The fur is usually reddish- brown above and lighter or greyish below. The eyes are small and the nostrils closable. The skull is massive, with marked ridges for fixing the muscles that work the jaws. The two front teeth on either jaw are like those of other rodents, wearing away more rapidly behind so as to leave a sharp, enamelled chisel edge. With these the beaver can cut down large trees. It usually selects trees five to 20 centimetres in diameter, but it can fell trees with diameters as large as 76 cm.
Beavers have a pair of anal scent glands, called castors, that secrete a musk-like substance called castoreum, probably for marking territories. The animals tend to be monogamous and have a life span of 20 years or more. The female has one litter a year, usually of two to four young.
Beavers are social animals and in areas where food is abundant and the locality secluded, the number of families in a beaver community can be rather large. The so-called beaver lodge is a unique structure. Three distinct kinds exist, their differences depending on whether they are built on islands, on the banks of ponds, or on the shores of lakes. The island lodge consists of a central chamber, with its floor a little above the level of the water, and with two entrances. One of these, the 'wood entrance', is a straight incline rising from the water, opening into the floor of the hut. The other approach, the 'beaver entrance', is more abrupt in its descent to the water.
The lodge itself is an oven-shaped house of sticks, grass, and moss, woven together and plastered with mud. The room inside is carpeted with bark, grass, and wood chips, sometimes with special store rooms adjoining. The pond lodge is built either a short way back from the edge of the bank, or partly hanging over it, with the front wall built up from the bottom of the pond. The lakelodge is built on the shelving shores of lakes. Dams are used by beavers to widen the area and increase the depth of water around their homes and are constructed either of sticks and poles or more firmly and solidly of mud, brushwood, and stones. As time goes by the beaver repairs and adds to the dam. Floating material lodges there, and vegetation growing on the top adds its roots to the strength of the dam. Frequently the beaver builds a smaller dam downstream in order to back up some water against the original dam and thus decrease the pressure of water on it from the other side. The dams are about 1.5 metres high, usually more than three metres wide at the base, and narrow at the top. A beaver dam more than 300 metres long was found in Rocky Mountain National Park, Colorado.
Beaver ponds eventually fill with sediment, and the animals move to a new location. The abandoned area becomes good meadowland. Beaver dams also help control runoff. Although the beaver is a powerful swimmer, it has difficulty dragging over the ground the logs and branches it needs for building and for food. Colonies of beavers therefore often dig canals from the pond to a grove of trees. Such canals are up to one metre wide and deep and often a few hundred metres long. The timber is then readily floated down the canal toward the pond.
Beavers have long been exploited for their fur, and for many years during the 18th and 19th centuries hundreds of thousands of beaver skins were exported to Europe from North America annually. The animals were also sometimes destroyed because of the damage they did to forests and the flooding occasionally caused by dams. Ceaseless slaughter led to near extinction of beavers in both Europe and North America. The beaver is almost extinct in Europe, but is becoming re-established in Canada and in protected areas of the USA. Research Beaver
The hazel is a shrub and sometimes small tree of the genus Corylus, sub-family Corylaceae, family Betulaceae, found in Europe, North Africa, Asia, and North America.. The leaves are roundish-cordate, alternate and shortly petiolate. The bark is reddish-brown and smooth. The plant is monoecious, the male flowers are clustered in pendulous catkins, the female flowers are arranged in erect, short, bud-like spikes with protruding red styles. The fruit is a hard, brown, rounded nut (filbert), enclosed by an irregularly lobed green involucre.
The European hazel (Corylus Avellana) produces the nuts called filberts, and grows best in a tolerably dry soil. It bears male and female flowers, the former composing cylindrical catkins. The hazel-nut oil is little inferior in flavour to that of almonds. Hazel branches form excellent walking-sticks, fishing-rods, etc, and the wood produces good charcoal, often employed by painters.
The American hazel (Corylus. americana) very much resembles the European. The roots are used by cabinet-makers for veneering; and in Italy the chips were formerly sometimes put into turbid wine for the purpose of fining it.
The witch hazel or wych hazel, Hamamelis virginica, is a shrub or small tree of a different natural order, the Hamamelidaceae. It is a native of the United States, and healing properties have long been ascribed to it both by the Indians and the settlers. A liquid prepared from it is said to be useful as an application to wounds, stanching the bleeding and promoting healing, being applied also to bruises, sprains, bleeding piles, in internal bleeding, etc. There arc several officinal preparations of the witch-hazel, especially a fluid extract and a tincture. The former American patent medicine, Pond's Extract, owed its chief properties to the witch-hazel. Research Hazel
Elihu Burritt (also known as the learned blacksmith) was an American writer and anti-slavery campaigner. He was born in 1810 at New Britain, Connecticut and died in 1879. He was apprenticed to a blacksmith, but, conceiving a strong desire for knowledge, he began to read English literature, and with great diligence and perseverance at length acquired proficiency not only in the ancient, but also most of the modern languages of Europe. He afterwards came into public notice as a lecturer on behalf of temperance, the abolition of slavery and war, etc, and In 1842 he established the 'Christian Citizen' in the interests of international peace and the abolition of slavery. In 1848 the first International Peace Congress was held under his guidance at Brussels. In 1865 he was consular agent at Birmingham. In 1868 he returned to live on his farm in America, and died March 7, 1879. His best-known writings are Sparks from the Anvil; Thoughts and Things at Home and Abroad; Chips from Many Blocks; etc. Research Elihu Burritt
Chips Rafferty (John William Goffage) was an Australian actor, producer and writer. He was born in 1909 at Broken Hill, New South Wales, and died in 1971. Research Chips Rafferty
Michael Bryant CBE was an English actor. He was born in 1928 at London and died in 2002. Primarily a stage actor, he has also appeared in several films including the 1969 'Goodby Mr Chips' and television series including playing the role of 'Squadron Leader Marsh' in the 1970's television series 'Colditz'. He was awarded the CBE in 1988 for his services to British theatre. Research Michael Bryant
The Cobalt RAQ was a series of low-cost servers based on the Linux operating system, first produced in 1996 by the Cobalt Microserver company. The servers proved very popular with Internet service Providers and smaller businesses and in 2000 Sun Microsystems purchased the company.
The Cobalt RaQ is a series of 1U rack mount server products that were developed by Cobalt Networks, Inc based upon a modified Red Hat Linux Operating System with a proprietary GUI for server management. Original RaQ systems were equipped with MIPS CPUs but later models used AMD K6-2 chips and then eventually Intel Pentium III CPUs for the final models. Th original RAQ1 was fitted with a 150 Mhz MIPS RM5230 CPU, the RAQ 2 with a 250 Mhz MIPS RM5231 CPU, the RAQ 3 with a 300 Mhz AMD K6 3DCPU, the RAQ4 with a 450 Mhz AMD K6-2 CPU, the RAQ XTR with an Intel Pentium IIICPU originally running at 733 or 933 Mhz and later 850 Mhz or 1 Ghz, and the final RAQ550 model was fitted with a 1 Ghz or 1.26 Ghz Intel Pentium III processor.In 2006 Sun decided to end production and support for the RAQ series of servers. Research Cobalt RAQ
A computer is a programmable, usually electronic, device. The modern computer is generally accepted to have been invented during the 19th century by the mathematician Charles Babbage.
Computers are of two distinct types: analog and digital. Analog computers operate by manipulating electrical potentials, voltage in simple terms. Digital computers operate on fixed values, usually the binary code of one and zero. Modern computers are generally digital, and certainly all personal computers are digital.
Early digital computers used electrical relays as their two-state (binary) devices - two-state, they were either 'on' or 'off'. These early digital computers were first made during the 1940's, were large and were used for military purposes and in a few research laboratories. They were unreliable due to the unreliability of the physical contacts of the relays, and were very low speed - compared to modern computers. During the 1950's valves or vacuum tubes replaced relays in digital computers, and by the 1960's they in turn were replaced by transistors - enabling a computer with the power of one which filled a room in the 1950's to be built which would fit in a shoe box. Transistors were in turn replaced by the integrated circuit or 'silicon chip', allowing computers to be made even smaller and smaller.
In 1980 Sir Clive Sinclair revolutionised computing with the invention of the ZX80 domestic micro computer, and a year later marketed the ZX81, the first computer to be built with just four siliconchips. Shortly afterwards the personal computer or PC emerged aimed at the business market. Research Computer
Core was an old-fashioned type of computer memory, made from doughnut-shaped
cores about 0.01 inch in diameter. These could be magnetized to store information, each holding one binary digit. Core memories were superseded in the 1970s by memories that use integrated circuits, often called siliconchips.
The Probert Encyclopaedia was designed, edited and programed by
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Abbreviations
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