Al-

Arabic definite article, meaning “the.” It often prefixes Arabic proper nouns, especially place-names; an example is Al-Jazirah (Arabic: “The Island”), the name of an interfluvial region in The Sudan. The article is often used in lowercase form, hence al-Jazirah. Reference works, including Encyclopædia Britannica, often alphabetize names beginning with al- under the main part

Arabic Language

Arabic is the language of the Qur'an (or Koran, the sacred book of Islam) and the religious language of all Muslims. Literary Arabic, usually called Classical Arabic, is essentially the form of the language

Earth, Measurement of the field

Magnetic fields can be measured in various ways. The simplest measurement technique still employed today involves the use of the compass, a device consisting of a permanently magnetized needle that is balanced to pivot in the horizontal plane. In the presence of a magnetic field and in the absence of gravity, a magnetized needle aligns itself exactly along the

Epicureanism

In a strict sense, the philosophy taught by Epicurus (341–270 BC). In a broad sense, it is a system of ethics embracing every conception or form of life that can be traced to the principles of his philosophy. In ancient polemics, as often since, the term was employed with an even more generic (and clearly erroneous) meaning as the equivalent of hedonism, the doctrine that pleasure or

Huguenot

Any of the Protestants in France in the 16th and 17th centuries, many of whom suffered severe persecution for their faith. The origin of the name is uncertain, but it appears to have come from the word aignos, derived from the German Eidgenossen (confederates bound together by oath), which used to describe, between 1520 and 1524, the patriots of Geneva hostile to the duke of Savoy. The

Undersea Cable

Also called  Marine Cable,   assembly of conductors enclosed by an insulating sheath and laid on the ocean floor for the transmission of messages. Undersea cables for transmitting telegraph signals antedated the invention of the telephone; the first undersea telegraph cable was laid in 1850 between England and France. The Atlantic was spanned in 1858 between Ireland and Newfoundland, but the cable's

Chalcocite

A sulfide mineral that is one of the most important ores of copper. Valuable occurrences include deposits of sulfide minerals at Ely, Nev., and Morenci, Ariz., where other components of the original rock have been dissolved away; it is also found with bornite in the sulfide veins of Tsumeb, Namibia, and Butte, Mont. For detailed physical properties, see sulfide mineral