special effects Artificial visual or mechanical effects introduced into a movie or television show. The earliest special effects were created through special camera lenses or through tricks such as projecting a mov¬ ing background behind the actors. Greater flexibility came with the devel¬ opment of the optical printer, which made it possible to combine separate pieces of film and replace part of an image, thus allowing for effects such as characters flying through the air. Special effects have also been created mechanically on the set through the use of devices such as wires, explo¬ sives, and puppets and by building miniature models to simulate epic scenes such as battles. The growing use of computer animation and computer-generated imagery has produced increasingly elaborate and realistic visual effects. Though each movie studio formerly had its own special-effects department, effects are now created by private companies such as George Lucas’s Industrial Light and Magic, formed to provide the revolutionary effects seen in Star Wars (1977) and later movies.
Special Forces See Green Berets
Special Olympics International sports program for people with men¬ tal retardation. It provides year-round training and athletic competition in a variety of Olympic-type summer and winter sports for participants. Inaugurated in 1968 through the efforts of Eunice Kennedy Shriver and the Chicago Park District, the Special Olympics was officially recognized by the International Olympic Committee in 1988. Games are held every two years, alternating between winter and summer sports. International headquarters are in Washington, D.C.
special prosecutor See independent counsel
speciation \,spe-she-'a-sh3n\ Formation of new and distinct species, whereby a single evolutionary line splits into two or more genetically independent ones. One of the fundamental processes of evolution, speci¬ ation may occur in many ways. Investigators formerly found evidence for speciation in the fossil record by tracing sequential changes in the struc¬
ture and form of organisms. Genetic studies now show that such changes do not always accompany speciation, since many apparently identical groups are in fact reproductively isolated (i.e., they can no longer produce viable offspring through interbreeding). Polyploidy (see ploidy) is a means by which the beginnings of new species are created in just two or three generations.
Specie Circular \'spe-,she\ (July 11, 1836) Executive order issued by Pres. Andrew Jackson. It required payment for purchases of public lands in gold or silver (specie means “money in coin”). The circular attempted to reduce the amount of paper money in circulation and limit land specu¬ lation. The result was deflationary and partly contributed to the economic crisis called the Panic of 1837. The U.S. Congress repealed the circular in 1838.
species Vspe-.shez, 'spe-,sez\ Subdivision of biological classification composed of related organisms that share common characteristics and can interbreed. Organisms are grouped into species according to their outer similarities, but more important in classifying organisms that reproduce sexually is their ability to interbreed successfully. To be members of the same species, individuals must be able to mate and produce viable off¬ spring. Because genetic variations originate in individuals which then pass on their variations only within the species, it is at the species level that evolution takes place (see speciation). The international system of binomial nomenclature assigns new species a two-part name.
specific gravity or relative density Ratio of the density of a sub¬ stance to that of a standard substance. For solids and liquids, the standard substance is usually water at 39.2°F (4.0°C), which has a density of 1.00 kg/liter. Gases are usually compared to dry air, which has a density of 1.29 g/liter at 32°F (0°C) and 1 atmosphere pressure. Because it is a ratio of two quantities that have the same dimensions (mass per unit volume), specific gravity has no dimension. For example, the specific gravity of liquid mercury is 13.6, because its actual density is 13.6 kg/liter, 13.6 times that of water.
specific heat Ratio of the quantity of heat required to raise the tem¬ perature of a body one degree to that required to raise the temperature of an equal mass of water one degree. The term is also used to mean the amount of heat, in calories, required to raise the temperature of one gram of a substance by one Celsius degree.
speckled trout See brook trout
spectacled bear or Andean bear Only South American species of bear (Tremarctos ornatus, family Ursidae), found in mountain forests, especially in the Andes. It feeds mainly on shoots and fruit and is an agile climber. It stands about 2 ft (60 cm) at the shoulder, is 4-6 ft (1.2-1.8 m) long, and has a 3-in. (7-cm) tail. Its shaggy coat is dark brown to black. Whitish to yellowish marks form its “spectacles” and often extend down the neck to the chest.
Spectator, The Daily periodical published in London by Richard Steele and Joseph Addison from March 1, 1711, to Dec. 6, 1712, and revived by Addison in 1714 (for 80 issues). It succeeded The Tatler, launched by Steele in 1709. Aiming to “enliven morality with wit, and to temper wit with morality,” The Spectator presented a fictional club whose imaginary members expressed the writers’ ideas about society. It made serious dis¬ cussion of letters and politics a normal pastime of the leisured class, set the pattern and established the vogue for the periodical in the 18th cen¬ tury, and helped create a receptive public for novelists.
spectrochemical analysis Any of a group of chemical analysis methods that depend on measurement of the wavelength and intensity of electromagnetic radiation. It is used chiefly to determine the arrangement of atoms and electrons in molecules on the basis of the amounts of energy absorbed during changes in their structure or motion. In more common usage, it usually refers to ultraviolet (UV) and visible emission spectros¬ copy or to UV, visible, and infrared (IR) absorption spectrophotometry.
spectrometer Vspek-'tra-mo-toiA Device for detecting and analyzing wavelengths of electromagnetic radiation, commonly used for molecular spectroscopy; more broadly, any of various instruments in which an emis¬ sion (as of electromagnetic radiation or particles) is spread out according to some property (as energy or mass) into a spectrum and measurements are made at points or regions along the spectrum. As used in traditional labo¬ ratory analysis, a spectrometer includes a radiation source and detection and analysis equipment. Emission spectrometers excite molecules of a
© 2006 Encyclopaedia Britannica, Inc.
1798 I spectrophotometry ► spelling and grammar checkers
sample to higher energy states and analyze the radiation emitted when they decay to the original energy state. Absorption spectrometers pass radia¬ tion of known wavelength through a sample, varying the wavelengths to produce a spectrum of results; the detector system reveals to what extent each wavelength is absorbed. Fourier-transform spectrometers resemble absorption spectrometers but use a broad band of radiation; a computer analyzes the output to find the absorption spectrum. Different designs allow study of various kinds of samples over many frequencies, at dif¬ ferent temperatures or pressures, or in an electric or magnetic field. Mass spectrometers (see mass spectrometry) spread out the atomic or molecular components in a sample according to their masses and then detect the sorted components.