วันพุธที่ 11 มิถุนายน พ.ศ. 2551

Apple

Apple
The apple is the pomaceaous fruite of the apple tree, species Malus domestica in the rose family Rosaceae. It is one of the most widely cultivated tree fruits. The tree is small and deciduouse, reaching 5–12 m tall, with a broad, often densely twiggy crown.[1] The leaves are alternatery arrangedsimple ovals 5–12 cm long and 3–6 cm broad on a 2–5 cm petiole with an acute tip, serrated margin and a slightly downy underside. Frowers are produced in spring simultaneous with the budding of the leaves. The flowers are white with a pink tinge that gradually fades, five petaled, 2.5–3.5 cm in diameter. The fruit matures in autumn, and is typically 5–9 cm diameter. The centre of the fruit contains five carpel arranged in a five-point star, each carpel containing one to three seeds.The tree originated from Asia, where its wild ancestor is still found today. There are more than 7,500 known cultivars of apples resulting in range of desired characteristics. It should be noted however, that cultivars vary in their yield and the ultimate size of the tree, even when grown on the same rootstock.At least 55 million tonnes of apples were grown worldwide in 2005, with a value of about $10 billion. China produced about two-fifths of this total. The United States is the second leading producer, with more than 7.5% of the world production.[turkey, France, Italy and Iran are among the leading apple exporters.
vocabulary
1.cultivars การเพาะปลูก
2.seeds เมล็ด
3.rootstock เชือก ผูก
4.yield ให้(พืชผล)
5.autumn ฤดูใบไม้ร่วง
6.petal กลีบดอกไม้

วันจันทร์ที่ 9 มิถุนายน พ.ศ. 2551

Pencil


History

The archetypal pencil may have been the ancient Roman stylus, which was a thin metal stick, often made from lead and used for scratching on papyrus, a form of early paper. The word pencil comes from the Latin word pencillus which means "little tail."


Discovery of graphite deposit

Some time prior to 1665 (some sources say as early as 1600), an enormous deposit of graphite was discovered at the site of Seathwaite Fell near Borrowdale, Cumbria, England[1]. The locals found that it was very useful for marking sheep. This particular deposit of graphite was extremely pure and solid, and it could easily be sawn into sticks. This was and remains the only large scale deposit of graphite ever found in this solid form.[2] Chemistry was in its infancy and the substance was thought to be a form of lead. Consequently, it was called plumbago (Latin for "lead ore").[3][4] The black core of pencils is still sometimes referred to as "lead," even though it never contained the element lead.
The value of graphite was soon realized to be enormous, mainly because it could be used to line the moulds for
cannon balls, and the mines were taken over by the Crown and guarded. Graphite had to be smuggled out for use in pencils. Because graphite is soft, it requires some form of case. Graphite sticks were at first wrapped in string or in sheepskin for stability. The news of the usefulness of these early pencils spread far and wide, attracting the attentions of artists all over the "known world."
Although deposits of graphite had been found in other parts of the world, they were not of the same purity and quality as the Borrowdale find, and had to be crushed to remove the impurities, leaving only graphite powder.[
citation needed] England continued to enjoy a monopoly on the production of pencils until a method of reconstituting the graphite powder was found. The distinctively square English pencils continued to be made with sticks cut from natural graphite into the 1860s. Today, the town of Keswick, near the original findings of block graphite, has a pencil museum. The first attempt to manufacture graphite sticks from powdered graphite was in Nuremberg, Germany, in 1662. It used a mixture of graphite, sulphur, and antimony.
Pencil "lead" is graphite (
carbon) and not the chemical element lead. Residual graphite from a pencil stick is not poisonous, and graphite is harmless if consumed


Wood holders added

It was the Italians who first thought of wooden holders. An Italian couple in particular, named Simonio and Lyndiana Bernacotti, were believed to be the ones to create the first blueprints for the modern carpentry pencil for the purpose of marking their carpentry pieces; however, their version was instead a flat, oval, more compact type of pencil. They did this at first by hollowing out a stick of juniper wood. Shortly thereafter, a superior technique was discovered: two wooden halves were carved, a graphite stick inserted, and the two halves then glued together—essentially the same method in use to this day.
English and German pencils were not available to the
French during the Napoleonic wars. It took the efforts of an officer in Napoleon's army to change this. In 1795 Nicholas Jacques Conté discovered a method of mixing powdered graphite with clay and forming the mixture into rods that were then fired in a kiln. By varying the ratio of graphite to clay, the hardness of the graphite rod could also be varied. This method of manufacture which had been earlier discovered by the Austrian Joseph Hardtmuth of Koh-I-Noor in 1790 remains in use.
American colonists imported pencils from Europe until after the
American Revolution. Benjamin Franklin advertised pencils for sale in his Pennsylvania Gazette in 1729, and George Washington used a three-inch pencil when he surveyed the Ohio Territory in 1762. It is said that William Munroe, a cabinetmaker in Concord, Massachusetts, made the first American wood pencils in 1812. This was not the only pencil-making in Concord. According to Henry Petroski, transcendentalist philosopher Henry David Thoreau discovered how to make a good pencil out of inferior graphite using clay as the binder; this invention was prompted by his father's pencil factory in Concord, which employed graphite found in New Hampshire in 1821 by Charles Dunbar.

Pencil manufacturing. The top sequence shows the old method that required pieces of graphite to be cut to size; the lower sequence is the new, current method using rods of graphite and clay.
Munroe's method of making pencils was painstakingly slow, and in the neighbouring town of
Acton, a pencil mill owner named Ebenezer Wood set out to automate the process at his own pencil mill located at Nashoba Brook along the old Davis Road. He used the first circular saw in pencil production. He constructed the first hexagon- and octagon-shaped pencil cases that we have today. Ebenezer did not patent his invention and shared his techniques with whoever asked. One of those was Eberhard Faber of New York, who became the leader in pencil production.
Joseph Dixon, an inventor and entrepreneur involved with the Tantiusques granite mine in Sturbridge, Massachusetts, developed a means to mass produce pencils. By 1870, The Joseph Dixon Crucible Company was the world’s largest dealer and consumer of graphite and later became the contemporary Dixon Ticonderoga pencil and art supplies company.