scale insect, common name for members of a highly modified group of insects belonging to several families of the superfamily Coccoidea. Scales possess antennae and are characterized by reduced legs. Only the males have wings; females are always wingless. Scales are popularly subdivided into three groups; the armored scales, the unarmored scales, and the mealybugs. The armored scales secrete a wax covering, the shape of which is characteristic for any given species. Under this coat, the insects develop and feed, sucking the sap of plants with their thin tubular mouthparts. The females never leave the protection of the scale after once forming it, but the adult males, which do not feed, develop a single pair of wings, leave the scale, and seek out the females, fertilizing them after the females are under the shell. Among the important armored scale pests of citrus, other fruits, and ornamentals are the San Jose scale, the oyster scale, the purple scale, and the California and Florida red scales. The unarmored scales (or soft scales) are similar to the armored scales except that only a small amount of wax is secreted, which adheres to the insect. Unarmored scale pests of citrus fruits include the black scale and citricola scale. Mealybugs appear as white cottony clusters on citrus, ornamentals, and greenhouse plants. Like other scale insects, newly hatched nymphs, called crawlers, have legs and actively seek out food. When they find a suitable spot, they settle down to feed. Some scales secrete a resinous covering, which is used in the commercial production of shellac, varnish, and paints (see lac). Control of scale insects has been largely by use of natural enemies, especially ladybird beetles and small parasitic wasps, which are natural predators of these pests. Scale insects have proved difficult to control by chemical means. Scale insects are classified in the phylum Arthropoda, class Insecta, order Homoptera, superfamily Coccoidea.

scale, in cartography, the ratio of the distance between two points on a map to the real distance between the two corresponding points portrayed. The scale may be expressed in three ways: numerically, as a ratio or a fraction, e.g., 1:100,000 or 1/100,000; verbally, e.g., "one inch to one mile" (not "one inch equals one mile"); and graphically, by marking distances on a sample line. The last method has the advantage that the scale remains true even if the map is enlarged or reduced mechanically. The first method is particularly useful since any unit of measurement may be used; e.g., if one uses metric units, a scale of 1:100,000 would mean that one centimeter on the map represents one kilometer on the earth's surface (since 100,000 centimeters equals one kilometer). The more the size of features on the map approaches the features' actual size on the earth's surface, the larger the scale of the map is said to be. A large-scale map usually shows more detail than does a small-scale map, but covers a smaller area than does a small-scale map of the same size.

scale, in music, any series of tones arranged in a step-by-step rising or falling order of pitch. A scale defines the interval relationship of each tone to the others upon which the composition depends. Scales further serve to classify and catalog the tonal material used in composition.

A great variety of scales have been used in the past and in different cultures; no single interval is common to all of them. In the 6th cent. B.C., Pythagoras defined the mathematical relationship of the perfect intervals (the octave, fourth, and fifth) and of the intervals between them (an interval being the difference in pitch between two tones). The Greek system was taken up by the Christian church, which adapted its note series to a number of modes used in medieval music, especially in plainsong.

The church modes, under the impact of the composition of polyphonic vocal music, became reduced in due course to the two characteristic scales of later Western music, the major and the minor. The major scale, called diatonic, has five whole tones (t) and two semitones (s) arranged thus: ttsttts (as in the white notes on the piano keyboard taken from one C to the next C); this scale, with certain modifications, became the basis of Western musical tonality until the end of the 19th cent. The dissemination and influence of the diatonic scale was therefore very great. The minor scale is based on tsttstt. This arrangement produces the lower third, sixth, and seventh degrees that are characteristic of the minor mode; the higher seventh degree, a semitone rather than a whole tone below the main note, or "tonic," is often borrowed from the major mode for use at cadences.

Akin to the modes, the concept of key was developed, whereby a home tone, or tonic, is the principal focus of a composition, and the various other tones assume importance according to their relationship to the tonic. The increasing complexity of instruments demanded more refined tuning systems. By J. S. Bach's time equal temperament had become established. The resulting scale, called chromatic, consisted of 12 notes divided by semitone intervals (the white and black notes of the keyboard). Although the diatonic scale is basically heptatonic (seven-noted), music that is in a major or minor tonality usually employs the remaining five tones of the chromatic scale as auxiliary or ornamental tones. Music that employs them freely is said to be highly chromatic, while music that employs them sparingly is said to be diatonic.

The 12 scales, one for each note as the home tone, plus the 12 concomitant minor scales remained the basic organizing structure of Western music until the system was challenged by the dodecaphonic (twelve-tone scale) composers, in particular Arnold Schoenberg, who worked into the mid-20th cent. (see atonality; serial music). The whole-tone scale, which divides the octave into six equal whole tones (C, D, E, F sharp, G sharp, and A sharp, on the piano), gives a feeling of vagueness that made it adaptable to impressionism; its possibilities were thoroughly explored in the works of Debussy. The pentatonic scale (the black keys of the piano illustrate one form) has long been thought of as having an Asian character because of the prevalence of pentatonic scales in Chinese, Japanese, and Javanese music. The most complex scales known belong to Arabian music and Hindu music.

scale, in weights and measures, instruments for determining weight, generally for other than laboratory use. For the principles of operation of all weighing devices, see balance. Platform scales utilize a succession of multiplying levers that transmit the weight to a beam or other registration device. They are used where massive objects or large quantities are to be weighed. For example, a railway car or truck moves onto a platform scale before and after unloading or loading, in each case the difference between the weighings being the weight of its cargo. As the name implies, counter scales are used in commercial establishments where weighing can be most conveniently done on a counter. Cylinder, drum, or barrel scales show their calibrations on a rotatable chart. These find wide use because of the ease with which the cost of a given weight may be read from them through the juxtaposition of fixed and rotating charts. The same purpose is served by the fan-type scale, in which an indicator moves through an arc marked from zero to the maximum capacity of the scale. Both the indicator and the fan expanse are calibrated for automatic computation. A great variety of scales are specially constructed for industrial uses in which weighing of a continuous flow of material is required. The scale in such cases is part of the machinery that carries the weighed material to a succeeding operation. Many scales provide printed records of each reading, and some keep a cumulative registration of a succession of readings.

scale, in zoology, an outgrowth, either bony or horny, of the skin of an animal. The major component of the scales of fishes is bone, and they are formed directly in the skin membrane as the fish grows. The number of rows of scales, as well as the kind, figures in the identification of a species. The growth of the scales is marked by rings, which aid in determining the age of the fish. The placoid scales of sharks, which have a dentine base with a pulp cavity, are thought to be similar to the forms from which the teeth of the higher vertebrates evolved. Ganoid scales, found in primitive fishes such as the gar pike and the sturgeon, are heavy and platelike. Other fishes have either rough scales (ctenoid) with comblike edges or smooth scales (cycloid). The horny scales, or scutes, of most reptiles develop embryologically as outpushings of the epidermis. In some lizards the scales are modified to form tubercles or granules. Other lizards and snakes have overlapping scales, highly developed in the snakes as aids to locomotion. The crocodile has both horny and bony scales. Among turtles and their relatives scales are usually found on the head, neck, limbs, and tail; in most of the group horny scales also form a pattern of flat plates overlying the bony dermal skeleton of the back and belly. Birds have horny scales on the feet and sometimes on the legs. Some mammals, e.g., the mouse and the rat, have scales on the tail; the pangolin and the armadillo have a body covering of large horny scales.

chromatic scale, in music: see scale.

centigrade temperature scale: see Celsius temperature scale.

absolute temperature scale: see Kelvin temperature scale; temperature.

Wechsler Adult Intelligence Scale (WAIS): see psychological tests.

San Jose scale, common name for a scale insect, Aspidiotus perniciosus, introduced from China into San Jose, Calif., c.1870 on nursery stock. The insect has since spread throughout much of the United States and Canada. It is found in the commercial fruit-growing areas throughout the world and is a serious pest of apples, pears, peaches, plums, sweet cherries, gooseberries, and many other trees and shrubs. Only the winged males and young scales are mobile. The young nymphs, or crawlers, move about for a few hours in search of a good feeding spot; then they molt, lose their functional legs and antennae, and secrete a resinous waxy shell, or armor, under which they feed by sucking the sap of the host plant until they become adults. The sedentary female mates and gives birth to several hundred living young while still securely under the protection of the scale, which it never leaves. Two to six generations are produced per year, with an estimated 30 million progeny possible from a single female during one year. Infested trees show a decrease in vigor, take on a gray appearance from the low, conical, overlapping scales, and eventually die if the scale is not controlled. The pest is dispersed by being carried on the bodies of larger insects, on the feet and beaks of birds, by wind, and by shipment of infested nursery stock. The San Jose scale is classified in the phylum Arthropoda, class Insecta, order Homoptera, family Diaspididae.

Saffir-Simpson scale, standard scale for rating the severity of hurricanes as a measure of the damage they cause; it is based on observations of numerous North Atlantic Basin hurricanes. First developed in the late 1960s by Herbert Saffir, a structural engineer, to quantity potential damage from hurricane winds, the scale was expanded in the early 1970s by Robert Simpson, then the Director of the National Hurricane Center. In its present form there are two definitive scales: the Saffir-Simpson Hurricane Scale and the Saffir-Simpson Hurricane Damage Intensity Scale. The Saffir-Simpson Hurricane Scale rates hurricanes from category 1 through category 5 in order of increasing intensity. Each intensity category specifies the range of conditions of four criteria: barometric (central) pressure, wind speed, storm surge, and damage potential. The Saffir-Simpson Hurricane Damage Intensity Scale, in addition to the wind speed, outlines the damage potentially possible with an associated categorized hurricane.

As popularly employed, the Saffir-Simpson scale is used to give an estimate of the potential property damage and flooding expected along the coast from a hurricane landfall. Wind speed is the determining factor in the scale, as storm surge values are highly dependent on the slope of the continental shelf in the landfall region. A category 1, or "minimal," hurricane has winds of 74-95 mph (119-153 kph), has a storm surge of 3-5 ft (1.0-1.7 m), and will cause some damage to shrubbery, trees, and unanchored mobile homes and some flooding of low-lying coastal roads. A category 2, or "moderate," hurricane has winds of 96-110 mph (154-177 kph), has a storm surge of 6-8 ft (1.8-2.6 m), and will cause considerable damage to shrubbery with some trees being blown down, extensive damage to mobile homes, and inundation by rising water of coast roads and low-lying escape routes. A category 3, or "extensive," hurricane has winds of 111-130 mph (178-209 kph); has a storm surge of 9-12 ft (2.7-3.8 m); will cause large trees to be blown down, some structural damage to small buildings, destruction of mobile homes, and flooding of sea-level coastland 8 mi (13 km) or more inland; and requires evacuation of low-lying residences near the shoreline. A category 4, or "extreme," hurricane has winds of 131-155 mph (210-249 kph), has a storm surge of 13-18 ft (3.9-5.6 m), and will cause severe damage to roofing materials, windows, and doors, complete destruction of mobile homes, flooding of low-lying areas as much as 6 mi (10 km) inland, and major damage to structures near shore due to battering by waves and floating debris. A category 5, or "catastrophic," hurricane has winds greater than 155 mph (249 kph), has a storm surge higher than 18 ft (5.6 m), and will cause complete failure of roofs on residences and industrial buildings, the overturning or sweeping away of small buildings, and major damage to structures less than 15 ft (4.6 m) above sea level within 1,500 ft (457 m) of shore. A category 5 storm requires evacution of all residential areas on low-lying ground within 5-10 mi (8-16 km) of shore.

Réaumur temperature scale: see temperature.

Richter scale, measure of the magnitude of seismic waves from an earthquake, devised in 1935 by the American seismologist Charles F. Richter (1900-1985). The scale is logarithmic; that is, the amplitude of the waves increases by powers of 10 in relation to the Richter magnitude numbers. The energy released in an earthquake can easily be approximated by an equation that includes this magnitude and the distance from the seismograph to the earthquake's epicenter. Numbers for the Richter scale range from 0 to 9, though no real upper limit exists. An earthquake whose magnitude is greater than 4.5 on this scale can cause damage to buildings and other structures; severe earthquakes have magnitudes greater than 7. The famous San Francisco earthquake of 1906 was 7.8 on the Richter scale; the Alaskan earthquake of 1964 was 8.4; the Kobe, Japan, quake of 1995 was 6.9; and the Izmit, Turkey, earthquake of 1999 was 7.4. Like ripples formed when a pebble is dropped into water, earthquake waves travel outward in all directions, gradually losing energy, with the intensity of earth movement and ground damage generally decreasing at greater distances from the earthquake focus. In addition, the nature of the underlying rock or soil affects ground movements. In order to give a rating to the effects of an earthquake in a particular place, the Mercalli scale, developed by the Italian seismologist Giuseppe Mercalli, is often used. It measures the severity of an earthquake in terms of its effects on the inhabitants of an area, e.g., how much damage it causes to buildings.

Rankine temperature scale, temperature scale having an absolute zero, below which temperatures do not exist, and using a degree of the same size as that used by the Fahrenheit temperature scale. Absolute zero, or 0°R;, is the temperature at which molecular energy is a minimum, and it corresponds to a temperature of -459.67°F;. Because the Rankine degree is the same size as the Fahrenheit degree, the freezing point of water (32°F;) and the boiling point of water (212°F;) correspond to 491.67°R; and 671.67°R;, respectively. The temperature scale is named after the Scottish engineer and physicist William John Macquorn Rankine, who proposed it in 1859. Another absolute temperature scale, the Kelvin temperature scale, is more commonly used for scientific measurements. See also Celsius temperature scale.

Mercalli scale: see Richter scale.

Kelvin temperature scale, a temperature scale having an absolute zero below which temperatures do not exist. Absolute zero, or 0°K;, is the temperature at which molecular energy is a minimum, and it corresponds to a temperature of -273.15° on the Celsius temperature scale. The Kelvin degree is the same size as the Celsius degree; hence the two reference temperatures for Celsius, the freezing point of water (0°C;), and the boiling point of water (100°C;), correspond to 273.15°K; and 373.15°K;, respectively. When writing temperatures in the Kelvin scale, it is the convention to omit the degree symbol and merely use the letter K. The temperature scale is named after the British mathematician and physicist William Thomson Kelvin, who proposed it in 1848. Another absolute temperature scale, the Rankine temperature scale, is used by some engineers. See also Fahrenheit temperature scale.

Fujita scale or F-Scale, standard scale for rating the severity of tornadoes as a measure of the damage they cause, devised in 1951 by the Japanese-American meteorologist Tetsuya (Ted) Fujita (1920-98). It classifies tornadoes on a hierarchy beginning with category F0, or "light" (winds of 40-72 mph; some damage to chimneys, TV antennas, roof shingles, trees, signs, and windows), which accounts for about 28% of all tornadoes. Category F1, or "moderate" (winds of 73-112 mph; automobiles overturned, carports destroyed, and trees uprooted), accounts for about 39% of all tornadoes. Category F2, or "significant" (winds of 113-157 mph; roofs blown off homes, sheds and outbuildings demolished, and mobile homes overturned), accounts for about 24% of all tornadoes. Category F3, or "severe" (winds of 158-206 mph; exterior walls and roofs blown off homes, metal buildings collapsed or severely damaged, and forests and farmland flattened), accounts for about 6% of all tornadoes. Category F4, or "devastating" (winds of 207-260 mph; few walls, if any, left standing in well-built homes and large steel and concrete missiles thrown great distances) accounts for about 2% of all tornadoes. Category F5, or "incredible" (winds of 261-318 mph; homes leveled or carried great distances and schools, motels, and other larger structures have considerable damage with exterior walls and roofs gone), accounts for less than 1% of all tornadoes.

In 2007 the National Weather Service adopted the Enhanced Fujita scale or EF-Scale, developed by the Texas Tech Univ. Wind Science and Engineering Research Center in conjunction with other wind engineers and meteorologists. Incorporating improved knowledge of wind speeds and the resulting damage, as well as including more damage indicators (and thus allowing for a more accurate assessment of a tornado based on the destruction it caused), the scale retained the categories used by the Fujita scale but revised the associated wind speeds. Category EF0 has estimated winds of 65-85 mph; EF1, 86-110 mph; EF2, 111-135 mph; EF3, 136-165 mph; EF4, 166-200 mph; and EF5, over 200 mph.

Fahrenheit temperature scale, temperature scale in which the temperature difference between two reference temperatures, the melting and boiling points of water, is divided into 180 equal intervals called degrees. The freezing point is taken as 32°F; and the boiling point as 212°F;. The scale was established by the German-Dutch physicist Gabriel Daniel Fahrenheit in 1724. William John Macquorn Rankine used it as the basis of his absolute temperature scale, now called the Rankine temperature scale, in 1859. Although the Fahrenheit scale was formerly used widely in English-speaking countries, many of these countries began changing to the more convenient Celsius temperature scale in the late 1960s and early 1970s; a notable exception is the United States, where the Fahrenheit scale is still in common use together with other English units of measurement. Temperatures on the Fahrenheit scale can be converted to equivalent temperatures on the Celsius scale by first subtracting 32° from the Fahrenheit temperature, then multiplying the result by 5/9, according to the formula (F-32)5/9=C.

Celsius temperature scale, temperature scale according to which the temperature difference between the reference temperatures of the freezing and boiling points of water is divided into 100 degrees. The freezing point is taken as 0 degrees Celsius and the boiling point as 100 degrees Celsius. The Celsius scale is widely known as the centigrade scale because it is divided into 100 degrees. It is named for the Swedish astronomer Anders Celsius, who established the scale in 1742. William Thomson Kelvin used it as the basis of his absolute temperature scale, now known as the Kelvin temperature scale, in 1848 (see also absolute zero). Temperatures on the Celsius scale can be converted to equivalent temperatures on the Fahrenheit temperature scale by multiplying the Celsius temperature by 9/5 and adding 32° to the result, according to the formula 9C/5+32=F.

Beaufort scale, a scale of wind velocity devised (c.1805) by Admiral Sir Francis Beaufort of the British navy. An adaptation of Beaufort's scale is used by the U.S. National Weather Service; it employs a scale from 0 to 12, representing calm, light air, light breeze, gentle breeze, moderate breeze, fresh breeze, strong breeze, moderate gale, fresh gale, strong gale, whole gale, storm, hurricane. Zero (calm) is a wind velocity of less than 1 mi (1.6 km) per hr, and 12 (hurricane) represents a velocity of more than 74 mi (119 km) per hr.

Beaufort's original scale was later correlated to wind speed in two different ways. The U.S. and British scale is for winds measured at a 36-ft elevation, while the international scale requires only a 20-ft elevation. The Beaufort scale is the oldest method of judging wind force. Separate scales for tornadoes and hurricanes did not come until the 1970s. The Fujita scale for tornadoes was proposed in 1971 by Tetsuya (Ted) Fujita; in 2007 the Enhanced Fujita scale, incorporating improved knowledge of wind destruction, as was adopted. Soon after the development of the Fujita scale the Saffir-Simpson scale for hurricanes was formulated by Herbert Saffir and Robert Simpson.

Any member of several families of sap-sucking insects (order Homoptera) whose bodies are covered by a waxy shell (the scale). The eggs are protected by the female's body or scale or a waxy filamentous mass. Scale insects may attack any part of a plant, but each species is host-specific. Many species are serious plant pests; others have commercial value. The lac insect is used in a red dye and in shellac. Cochineal, a red dyestuff, consists of the dried, pulverized bodies of females of the species Dactylopius coccus. Seealso cottony-cushion scale, San Jose scale.

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In music, primary pitches of a key or mode arranged within an octave. Scales are distinguished by the pattern of the intervals between adjacent notes. A scale can be seen as an abstraction from melody—that is, the pitches of a melody arranged in stepwise order.

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Interval of time occupied by the Earth's geologic history, extending from circa 3.9 billion years ago (corresponding to the age of the oldest known rocks) to the present day. It is, in effect, the part of the Earth's history that is recorded in rock strata. The geologic time scale is classified in nested intervals distinguished by characteristic geologic and biologic features. From longest to shortest duration, the intervals are eon, era, period, and epoch.

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Scale insect (Icerya purchasi, order Homoptera) that is a pest especially of California citrus trees. The adult lays bright red eggs in a distinctive large white mass that juts out from a twig. Distributed worldwide, cottony-cushion scale is found on many other plants, including acacia, pittosporum, and willow. Australian ladybird beetles (see ladybug), a natural enemy, have been imported to keep it from destroying the California citrus industry.

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Species (Aspidiotus perniciosus) of scale insect first discovered in North America at San Jose, Cal., in 1880 but probably a native of China. A waxy gray secretion (the scale) covers the yellow females, which are about 0.06 in. (1.5 mm) in diameter. The scale is elevated in the center and is surrounded by a yellow ring. The female produces several generations of living young each year. San Jose scales can completely cover tree branches and may eventually kill the tree.

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Widely used measure of the magnitude of an earthquake, introduced in 1935 by U.S. seismologists Beno Gutenberg (1889–1960) and Charles F. Richter (1900–1985). The scale is logarithmic, so that each increase of one unit represents a 10-fold increase in magnitude (amplitude of seismic waves). The magnitude is then translated into energy released. Earthquakes that are fainter than the ones originally chosen to define magnitude zero are accommodated by using negative numbers. Though the scale has no theoretical upper limit, the most severe earthquakes have not exceeded a scale value of 9. The moment magnitude scale, in use since 1993, is more accurate for large earthquakes; it takes into account the amount of fault slippage, the size of the area ruptured, and the nature of the materials that faulted.

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