Tuesday, February 27, 2007

Minerals and rocks

A mineral is a obviously occurring, inorganic solid with a definite chemical composition and a crystalline structure. A rock is an collective of one or more minerals. (A rock may also include organic remains and mineraloids.) Some rocks are mostly composed of just one mineral. For example, limestone is a sedimentary rock composed almost wholly of the mineral calcite. Other rocks have many minerals, and the specific minerals in a rock can vary widely. Some minerals, like quartz, mica or feldspar are general, while others have been found in only one or two locations worldwide. The vast majority of the rocks of the Earth's crust consist of quartz, feldspar, mica, chlorite, kaolin, calcite, epidote, olivine, augite, hornblende, magnetite, hematite, limonite and a few other minerals.Over half of the mineral species identified are so rare that they have only been found in a handful of samples, and many are known from only one or two small grains.
Commercially costly minerals and rocks are referred to as industrial minerals. Rocks from which minerals are mined for economic purposes are referred to as ores (the rocks and minerals that remain, after the desired mineral has been separated from the ore, are referred to as tailings).

Thursday, February 22, 2007

The Institution of Engineers

The Institution of Engineers (IEI) was established by Sir Thomas Holland and others in Madras in 1920. In 1935, it obtained the Royal Charter from King George V to promote and move ahead the art, science and practice of engineering and technology in India.
The first President of the Institution was Sir Thomas R J Ward. Sir Thomas Guthrie Russell played a key role in the winning petition for a Royal Charter. The current President is Prof S C Naik.
The organization has been prominent amongst the founder members of the Commonwealth Engineers' Council and the Federation of Engineering Institutions of South and Central Asia. The Institution has a conditional membership of the Engineers Mobility Forum since 2003.
Today, the Institution is head-quartered in Kolkata, with 94 state and local centres. With half a million members, it is one of the biggest professional bodies in the English-speaking world. Life corporate members of the Institution are accredited with the Chartered Engineer title.

Sunday, February 18, 2007

Historiography

Historiography has a number of associated meanings. It can refer to the history of historical learning, its methodology and practices (the history of history). It can also refer to a particular body of historical writing (for example, "medieval historiography during the 1960s" means "medieval history written during the 1960s"). Historiography can also be in use to mean historical theory or the study of past writing and memory. As a meta-level analysis of descriptions of the past, this third conception can relate to the first two in that the analysis usually focuses on the narratives, interpretations, worldview, use of evidence, or method of presentation of other historians.

Friday, February 09, 2007

Jewellery

Jewellery is factually any piece of fine material used to decorate oneself. Although in earlier times jewellery was created for more convenient uses, such as wealth storage and pinning clothes together, in recent times it has been used almost completely for beautification. The first pieces of jewellery were made from likely materials, such as bone and animal teeth, shell, wood and engraved stone. Jewellery was often made for people of high importance to show their status and, in many cases, they were covered with it.Jewellery is made out of almost every material recognized and has been made to garnish nearly every body part, from hairpins to toe rings and many more types of jewellery. While high-quality and artistic pieces are made with gemstones and valuable metals, less pricey costume jewellery is made from less-valuable materials and is mass-produced.Form and function Kenyan man exhausting tribal beads.Over time, jewellery has been used for a number of reasons: Currency, wealth display and storage, purposeful Symbolism Protection and Artistic display Most cultures have at some point had a practice of observance large amounts of wealth stored in the form of jewellery. Numerous cultures move wedding dowries in the form of jewelry, or create jewelry as a means to store or display coins. on the other hand, jewellery has been used as a currency or trade good; a mostly poignant example being the use of slave beads.
In creating jewellery, a variety of gemstones, coins, or other valuable items can be used, often set into precious metals. Common expensive metals used for modern jewellery include gold, platinum or silver, although alloys of nearly every metal known can be encountered in jewellery -- bronze, for example, was common in Roman times. Most gold jewellery is made of an alloy of gold, the purity of which is affirmed in karats, indicated by a number followed by the letter K. For example, ordinary gold jewellery ranges from 10K (41.7% pure gold) to 22K (91.6% pure gold), while 24K (99.9% pure gold) is considered too soft for jewellery use. Platinum alloys variety from 900 (90% pure) to 950 (95.0% pure). The silver used in jewellery is usually sterling silver, or 92.5% fine silver.Other generally used materials include glass, such as merged glass or enamel; wood, often carved or turned; shells and other natural animal substances such as bone and ivory; natural clay, polymer clay, and even plastics.
Jewellery and society
One universal issue is control over who could wear what jewellery, a point which indicate the powerful symbolism the wearing of jewellery evoked. In ancient Rome, for instance, only convinced ranks could wear rings; later, sumptuary laws dictated who could wear what type of jewellery; again based on rank. Cultural dictate have also played a important role; for example, the wearing of earrings by Western men was considered "effeminate" in the 19th and early 20th centuries. on the other hand, the jewellery industry in the early 20th century launched a crusade to popularize wedding rings for men — which caught on — as well as appointment rings for men , going so far as to make a false history and claim that the practice had Medieval roots. By the mid 1940s, 85% of weddings in the U.S. feature a double-ring ceremony, up from 15% in the 1920s.Religion has also played a role: Islam, for instance, consider the wearing of gold by men as a social taboo,and many religions have edicts against extreme display.