Practical Encyclopaedia | Source of Science and Culture.

Adrenal Gland

2009-06-25T09:59:00.000-07:00

Adrenal Gland one of two small ductless glands located at the top of each kidney. The adrenal gland is functionally and histologically divided into two parts. The outher part, or cortex, produces an endocrine principle that is necessary for life. Cortical disease produces the syndrome of Addison's disease, which is fatal without treatment. The inner part, or the medulla, secretes the hormone epinephrine ( adrenalin ), which raises the blood pressure by stimulating the heart and contracting blood vessels. As part of the endocrine systemi the adrenal glands may exert their influence indirectly upon structures and functions for the most part controlled by other endocrine glands. The secretion of the adrenal medulla seems to have a protective or defensive function.

Abdomen

2009-02-10T02:35:00.000-08:00

Abdomen in man and other vertebrates the region of the body that lies between the thorax and the pelvis is called the abdomen. The abdominal cavity is separated from the thoracic cavity by the diaphragm and contains the viscera. It is lined by a serous membrane , the peritoneum. For convenience in locating ortangs and symptoms of disease , the abdomen is divided into mine regions : The upper regions are caşşed şeft hypochondriac , epigastric , and right hypochondriac ; the middle regions , left lumbar , umbilical , and right lumbar , and the lower , left inguinal , hypogastric , and right inguinal.

Abdominal pain is a symptom of many disorders and may originate outside as well as within the abdomen. Extra - abdominal causes of pain include disease of the chest , spine , or genitalia , poisoning , allergy , emotional upset , and disease of nerves. Within the abdomen pain my result from obstruction , inflammation , infection , disturbed function , or rupture. The treatment of abdominal pain varies with the cause.

In insects and other arthropoda , the abdomen is the posterior region of the body and is usually segmented.

Argus

2008-10-19T11:19:00.001-07:00

in Greek mythology, a fabulous creature with 100 eyes, of which only two slept at any one time. Hera placed him as guard over Io after she had been turned into a heifer. Hermes slew him after charming him to sleep with his music. Hera then changed him into a peacock with his eyes in the tail. In zoology, a genus of birds of the family Phasianidae and the subfamily Phasianinae. It contains the argus, or argus pheasant, Argusianus giganteus. The male measures between five and six feet from the tip of the bill to the extremity of the tail and is an eminently beautiful bird, the quill feathers of the wings, which often exceed three feet in length, being ornamented all along by a series of ocellated spots. The name Shetland argus is given to a starfish, Astrophylon scutatum. It is called also the basket urchin, or sea basket.

Argos

2008-10-19T11:16:00.000-07:00

Argos, a town in southern Argos and Corin-thia prefecture, northeastern Peloponnesus, Greece. Reputed to be the oldest city in Greece, it figured in Greek legends and in the 8th and 7th centuries B.C. dominated much of the Peloponnesus. It contains numerous ancient ruins. It was a center of worship of Hera.

Aneroid Barometer

2008-10-09T10:18:00.000-07:00

Aneroid Barometer, a barometer not containing a liquid and constructed on a totally different principle from that of the mercury barometer. Various forms of the instrument exist; one of these consists of a cylindrical metal box exhausted of air and having a lid of thin corrugated metal with a spring on the inside. An increase in atmospheric pressure forces the highly elastic lid inward; a decrease in pressure forces it outward. Delicate multiplying levers transmit these motions to an index, which moves on a scale and is graduated empirically by a mercurial barometer. The aneroid, being extremely delicate, is apt to get out of order, particularly when it has been exposed to great variations of pressure. When it is properly graduated , it is often used for determining the heights of mountains.

Anemone

2008-10-08T10:18:00.000-07:00

Anemone, a genus of plants belonging to the family Ranunculaceae (buttercups). It comprises approximately 120 species, most of which are perennial, are native to temperate and cold climates of the northern hemisphere, and bloom in early spring. Anemone coronaria, with tuberous roots, divided leaves, and large poppy-like blossoms of scarlet, blue, or white, is the well-known poppy anemone. Of about twenty species native to the U.S. and Canada, the most important are the wood anemone (Anemone quinquefolia), Anemone canadensis, Anemone hortensis, the garden anemone, and Anemone japonica, Japanese anemone. Anemones thrive in a well-drained, rich, loamy soil. Slight shade at midday and cool temperatures assure best growth.

Anemometer

2008-10-07T10:17:00.000-07:00

Anemometer, an instrument designed to measure the velocity of the wind. The first such instrument was invented by Wolfins in 1709. Three types of anemometers have been developed: those in which a windmill twists string around an axle against pressure, those in which a surface of definite dimensions is pressed against a spring, and those in which water or some other liquid is made to stand at a higher level in one leg of an inverted siphon than in the other. The anemometer most in use is of the first type, which was also the earliest type of the instrument. It has four light metallic hemispheres, called Robinson's cups (after Thomas Robinson who first employed them), which revolve like a vane or weathercock at the rate of exactly one-third the velocity of the wind. The result is recorded by a self-registering apparatus.

Analytical Chemistry

2008-10-06T09:54:00.000-07:00

Analytical Chemistry is an application of the principles of theoretical chemistry to the study of methods used for determining qualitatively the elements and compounds present in a substance of unknown composition and for determining quantitatively the percentage of each component in the unknown.

Analysis, a word meaning "separation into constituent parts," was first used in relation to chemical experiments by Robert Boyle (1627-1691). He distinguished between an element, a substance not decomposable by chemical means, and a compound. Although the analytical balance was not then available for precise mathematical treatment, he also performed quantitative experiments, searching for the amount of B and the amount of A in the unknown substance AB.

Qualitative analysis involves a preliminary examination using observation and simple tests followed by a schematic separation and the identification of the components. Following this analysis, a quantitative determination of the percentage of each component is performed by either chemical or physical methods. Chemical methods, both gravimetric and volumetric (titrimetric), are based on the mathematical relationship of reactants and products in a chemical reaction. These classical methods are supplemented but not replaced by the newer physical methods, which are based on the interaction of mass with energy. Among these methods are colorimetry, spectrophotometry, turbidimetry, nephelometry, fluorometry, x-ray spectrography, mass spectrography, x-ray diffraction, and polarography.
In academic and industrial laboratories the approach to an analytical problem is the same and is separated into these four steps: choice of method, sampling and preparation of unknown, determination, and evaluation of results. The trained analyst, in addition to a theoretical background in mathematics and chemistry, must have manual skill in laboratory techniques and familiarity with equipment.

Anaheim

2008-10-05T09:53:00.000-07:00

Anaheim, city, Orange Co., southern California, on a coastal plain, 23 miles southeast of Los Angeles. It lies in the heart of a rich fruit-growing valley, and its leading industries are the canning, packing, and processing of fruits and walnuts. Other manufactures are canning equipment, wire, and chemicals. Anaheim is near Disneyland, which is a 160-acre project conceived by Walt Disney. Disneyland includes an amusement center, a museum of Americana, and other facilities. Anaheim was founded in 1857 by German settlers as a cooperative community.

Anemias

2008-10-04T10:16:00.000-07:00

Anemia due to the faulty construction of red blood cells may occur in infections, chronic diseases (such as of the kidneys), and disorders of the spleen. Mechanical interference with the bone marrow results in anemia in such diseases as leukemia. Failure of blood formation may also be brought on by poisoning or irradiation injury.
The hemolytic anemias cover a wide variety of conditions in which the red blood cells are destroyed, a dramatic example being transfusion reactions from the use of incompatible blood. Chemical agents, including certain drugs; infections, such as malaria; vegetable and animal poisons, for example, snake venom; and various diseases, for example, Hodgkin's disease, are other important causes. Also in this category are congenital anemias in which the defect in the red blood cell is an inherited trait: congenital hemolytic jaundice, sickle-cell anemia, and Mediterranean anemia. Congenital hemolytic jaundice is successfully treated by splenectomy. For sickle-cellanemia and Mediterranean anemia, there is no known effective treatment.
The occurence of anemia secondary to acute blood loss is usually corrected by the transfusion of whole blood. The correction of anemia from chronic blood loss ultimately depends on correction of the underlying defect.

Anagram

2008-10-04T09:53:00.001-07:00

Anagram, a word or phrase formed by transposing and writing over again the letters of some other word or phrase. Strict anagrammatists do not admit a substitution or change in the letters to be transposed, but some famous anagrams do have these changes. Among the many famous anagrams are: "Honor est a Nilo" for Horatio Nelson and "I require love in a subject" for Queen Victoria's Jubilee Year. There are also interchangeable words, such as amor and Roma, Eros and rose, and evil and live. This old practice of anagrams is the foundation for a variety of games played by several persons.

Anacreon

2008-10-04T09:45:00.000-07:00

Anacreon , a renowned lyric poet of Greece, born at Teos in Ionia in the 6th century B.C. He enjoyed the patronage of Polycrates, tyrant of Sanios, and of Hipparchus at Athens. While at court, he composed most of the odes in praise of wine and women, which won for him pre-eminence among singers. A few of his authentic compositions have been preserved. More than 60 poems have been attributed to him, but they are probably imitations and the authorship is doubtful.

The Alamo

2008-10-02T05:57:00.000-07:00

a Franciscan mission in San Antonio, Tex., and the site of a gallant defense during the Texas war for independence. It was built about 1722 and consisted of a chapel, convent yard, convent and hospital building, and a plaza, all surrounded by a stout wall. After the disappearance of the Indians from the locality, the mission was abandoned, although after 1793 it was used occasionally as a fort. In 1836 it was occupied by a force of 150 Texans, commanded by Colonels William B. Travis and James Bowie. David Crockett fought here. Hoping for reinforcements, the garrison remained in the fort, despite the approach of the Mexican general Santa Ana and an army of over 4,000. When the Alamo was surrounded and hope of relief had faded, Travis and his men were faced with three alternatives: to surrender, make an attempt at an almost impossible escape, or resist.

Lucas Alaman

2008-10-01T05:51:00.000-07:00

Mexican historian and statesman, born in Guanajuato in 1792. When only 27 years of age he was sent as a delegate to the Spanish Cortes to plead the cause of Mexican independence. Under the Republic he served two terms as foreign minister and founded the Archivo General and the National Museum. His most important historical works were: Disertaciones sobre la historia de la Republica Mejicana, (5 vols., 1844) and Historia de Mejico desde la epoca colonial hasta nuestros dias, (5 vols., 1849-52). He died in 1853.

Alain Fournier

2008-09-29T05:48:00.000-07:00

Alain-Fournier,pseudonym of Henri Alain Fournier, a French author, born in La Chapelle-dAngillon, in 1886. He studied for the merchant marine, served for a short time in the army before World War I, and worked as a journalist. In 1913 he published The Wanderer, his only completed novel, and achieved widespread fame for this realistic study of adolescence. Fragments of the unfinished Colomhe Blanchet (1922) and Miracles (1924), stories and poems, were published after he was killed in action in 1914.

Alagoas

2008-09-28T05:34:00.000-07:00

Alagoas, a maritime state of northeastern Brazil bordering Pernambuco (north) and Sergipe (south). The chief products are sugar cane, cotton, manioc, corn, and rice; also timber and dyewoods.

El Alamein

2008-09-27T05:57:00.001-07:00

on the borders of Egypt and Cyrenaica, 60 miles west of Alexandria, was the site of the battle fought between German and Italian forces under Erwin Rommel and the British Eighth Army under Bernard Montgomery (Oct. 23-Nov. 4, 1942). Opposing forces were dug in on a front of 40 miles running from the sea at El Alamein south to the Qattara Depression. After a heavy artillery barrage, British infantry supported by armor attacked in the center and on the coast. On November 2 the enemy's defenses were smashed, and the triumphant advance to Tripoli began. The battle marked a turning point in World War II.

Alameda

2008-09-27T05:56:00.001-07:00

an island and city in San Francisco Bay, Alameda Co., California, 12 miles east of San Francisco. The city is connected with Oakland by several bridges and by a tunnel, called Posey Tube, completed in 1928. The major industries are shipyards and canneries. A naval air station, a Coast Guard base, and a maritime school are located here.

Alain de Lille

2008-09-27T05:48:00.001-07:00

Alain de Lille, in Latin Alanus ab Insulis, noted French scholastic philosopher, born in Lille about 1128. His aim was to combine rationalism with mysticism, and his basic principle was that, although reason can know the universe, a knowledge of God can be attained only by faith. He was the author of De planctu naturae and Anti-claudianus, and his great learning was admired by his contemporaries. He died in 1202.

Aladdin

2008-09-27T05:23:00.000-07:00

Aladdin in the story of "Aladdin and the Wonderful Lamp" in The Arabian Nights' Entertainment, the son of a poor widow. He possesses a magic lamp and ring, which enable him to command two powerful jinn. When he accidentally rubs the lamp, a jinni appears and builds him a palace and gives him riches and the princess of Cathay in marriage. His contest with the original owner of the lamp, a wicked magician, is told in the story.

Ague

2008-09-23T01:14:00.001-07:00

Ague an old name for malarial fever or any recurrent and severe symptom caused by malarial infection. It was also used to describe chills caused by other disease conditions

Aguascalientes

2008-09-23T01:14:00.000-07:00

Aguascalientes capital of the Mexican state of Aguascalientes, about 110 miles northeast of Guadalajara. The city maintains important Mexican railway shops. Its industries are chiefly processing industries but also include the production of sarapes and artistic leatherwork. Aguascalientes, founded in 1575, owes its name to its abundant thermal springs

Aguascalientes

2008-09-22T01:13:00.000-07:00

Aguascalientes small state in central Mexico, situated on the central plateau at about 6,000 feet. It is predominantly an agricultural region irrigated by the San Pedro, or Aguascalientes, River. Corn and chick peas are leading crops. There are large forested sections. The city of Aguascalientes is the capital. Area, 2,118 square miles.

Aguadilla

2008-09-21T01:13:00.000-07:00

Aguadilla, a seaport town of Puerto Rico, the largest community in the northwest corner of the island. It is situated on the Mona Passage, which connects the Atlantic Ocean with the Caribbean Sea. There is a small bay in which some fishing is done. The town has many well-paved roads and is on the main line of the coastal railroad. The Bor-inquen airfield is located 5 miles north of the town. The municipality of which Aguadilla is the administrative center is a fertile agricultural region furnishing coffee, tobacco, sugar, and fruit for export. The town has several large sugar refineries. Tradition has it that Christopher Columbus stopped in Aguadilla in 1493 to fill his water casks from the fountain that still flows in the town.

Agronomy

2008-09-20T01:12:00.000-07:00

Agronomy the science of soils and crops and their improvement. It has to do with crop rotation, field planning, and varieties of plants; insect, disease, and weed control; and planting, cultivation and harvest. The agronomist, in contrast with the animal husbandman, works with plant life. He seeks to produce better and more abundant forage and feed crops for livestock and improved strains of food and fiber plants and to develop better methods of soil treatment, tillage, and culture.

Agrippina the Elder

2008-09-19T01:11:00.000-07:00

Agrippina the Elder , daughter of Marcus Vipsanius Agrippa and granddaughter of Augustus, was the wife of Germanicus. She accompanied her husband on his military expeditions and was with him at Antioch, in Syria, when he died by poisoning a.d. 19. Returning to Rome she accused Piso, governor of Syria, of the crime, who, to avoid disgrace, committed suicide. Of her children the two best known were Agrippina the Younger and Gaius Caesar, later emperor Caligula. Tiberius, fearing that she might wish the throne for one of her children, banished her to an island near Naples, where she died a.d, 33.

Marcus Vipsanius Agrippa

2008-09-18T01:11:00.000-07:00

Roman general and statesman, commander of the fleet at Actium, born 63 b.c. A fellow-student with Augustus at Apollonia, he became one of his closest friends and most trusted counselors. He married first the niece and later the daughter of Augustus. By the emperor's niece Marcella, he had a daughter, Vipsania, who became the first wife of the emperor Tiberius. By Augustus' daughter Julia he had two daughters, of whom the one, Agrippina, became the wife of Germanicus. Agrippa's naval victories, especially that over Antony at Actium in 31 b.c, established Augustus as sole ruler of the empire. Agrippa commanded troops in Gaul, Spain, and Syria. In the course of his civil career, which included the consulship (27 B.C.), he directed the erection of the Pantheon and the construction of aqueducts, baths, and other public buildings. He died at Campania in 12 B.C.

Agrimony

2008-09-17T01:10:00.000-07:00

Agrimony, a genus of the rose family, common in thickets and open woods, growing in little clumps 1% to 3 feet high and producing spikes or stiff upright clusters of yellow flowers all summer. The leaves of the plant are made up of five to nine pointed, coarsely toothed leaflets, often having intermixed with them other very tiny leaflets. The flower spikes are borne at the ends of leafy stems. The flowers are small, and each has five yellow petals. The seeds are enclosed in a little bur covered with hooked spines, which readily catch onto the coats of animals, thus assuring the seeds of a wide distribution. The common agrimony, Agri-monia eupatoria, is a native of Europe, where it is often planted in gardens.

Topography of Afghanistan

2008-09-17T01:07:00.000-07:00

Afghanistan consists chiefly of a high tableland, some 4,000 feet in altitude, which is traversed by two lofty mountain ranges that form a rough letter V, with the apex in the mountains in the east. Fertile and well-watered valleys and plains occupy about one-fifth of the country only, the remainder being rocky and mountainous. The largest river is the Helmand, which rises in the mountains just northwest of Kabul and flows in a southwesterly direction through the center of the country to the great salt marsh-lake of Seistan, some 700 miles distant.
Climate and Productions. The climate is in general pleasant and healthful and is marked by seasonal and diurnal changes in temperature

Afghanistan

2008-09-16T01:06:00.000-07:00

Afghanistan, an independent kingdom of central Asia, lying between 29° and 38° N latitude and 61° and 75° E longitude. It is bounded on the south and southeast by West Pakistan, on the west by Iran, and on the north by the U.S.S.R. A northeastern extension, the Wakhan panhandle, touches China and Jammu and Kashmir. The quadrangular bulk of the country measures about 560 miles from east to west and is about 450 miles broad. Small sections of the borders with Pakistan and Iran are not well defined. The country has an area of about 250,000 square miles

Affirmation

2008-09-15T01:04:00.000-07:00

The act of affirming, in the sense of solemnly declaring in a court of law that certain testimony about to be given is true. Also, it is the statement made. First, the Quakers and Moravians, who objected on conscientious grounds to taking oaths, were allowed to make solemn affirmations instead. Now everyone objecting to take an oath has the same privilege, but false affirmations, no less than false oaths, are liable to the penalties of perjury.

Affidavit

2008-09-14T04:04:00.000-07:00

Affidavit , a statement of facts or declaration reduced to writing and sworn or affirmed to before some officer who has authority to administer an oath. The word is derived from the old Latin form of a declaration on oath, which commenced "Affidavit M. N.," or "M. N. has sworn." The use of affidavits is generally confined to litigation but is sometimes employed to lend force to a public statement, for a person who knowingly and advisedly swears falsely to an affidavit is guilty of perjury. In judicial proceedings the affidavit is used in place of oral evidence. It differs from a deposition in that, in the latter, the opposite party has an opportunity to cross-examine the witness, whereas an affidavit is always taken ex parte.

Agrippina the Younger

2008-09-14T01:12:00.001-07:00

daughter of Agrippina the Elder and mother of Nero; born about a.d. 16. The sister of the emperor Caligula, she became the wife of another emperor when she married her uncle Claudius. She induced him to name Nero, the son of her first marriage, as his successor instead of his own son Britannicus. Later, to secure the throne for Nero, she poisoned the emperor. Nero, however, refused to be dominated by his mother, whom he assassinated a.d. 59 when she threatened to support the claims of Britannicus.

Afghan Hound

2008-09-14T01:05:00.001-07:00

Originally from Afghanistan, where it has served as a guard and hunting dog for centuries. It is like the greyhound in build, but its long shaggy coat, which covers its hindquarters, flanks, legs, and shoulders, makes it appear heavier. It has straight, well-boned legs, ears carried close to its head, and a ringed tail having a curl at its tip. It is an intelligent hardy outdoor dog and should not be kept in small houses

Aetolia

2008-09-14T00:59:00.000-07:00

Aetolia , a district of ancient Greece, lying on the north shore of the Gulf of Patras. It was divided from Acarnania by the river Achelous and on the north touched Thessaly. In later times, these boundaries were considerably extended to the north and east. The country had few cities and was, except on the coast, generally wild and barren. Here, according to the legend, Meleager slew the Calydonian boar. The Aetolians made a great figure in the heroic age of Greece, but at the time of the Peloponnesian War they were rude and barbarous. The Aetolian Confederacy, first called into existence about 323 B.C., became an important rival to the Achaean League. Its assembly was called the Panaetolicon. It sided with the Romans against the Achaean League but afterward aided Antiochus III against the Romans and was subjugated by the Romans in 189, B.C. It was not formally included in a Roman province till 146 B.C. Along with Acarnania, Aetolia now forms a prefecture of the modern kingdom of Greece, with a united area of 2,137 square miles. The mountains in the northeast are offsets of the Pindus chain and slope steeply on the southwest down to the central plains. The chief towns are Missolonghi and Naupaktos.

Aggressio

2008-09-13T07:47:00.000-07:00

Aggressio , in psychology, the type of behavior that aims at injury or destruction and that is associated with feelings of anger and hate. Continued frustration is recognized as the cause of aggression, and the strength of the aggressive behavior is directly related to the intensity of the frustration. Aggression may be turned against society in the form of psychopathic behavior, against minority groups, or against the persons actually responsible for the frustration.

Ageratum

2008-09-12T07:46:00.000-07:00

Ageratum, a group of tropical American herbs, family Compositae, sometimes called floss flower. It is an annual plant grown in gardens and as a house plant, for its soft, fuzzy, gray-blue, bluish-lavender, or white flowers. These are borne in hairy flat-topped clusters made up of many little feathery heads, each head composed of 50 to 60 tiny flowers. The plant grows from 6 inches to 2 feet in height and is rather hairy all over. Its foliage is dense, with small heart-shaped or oval leaves, hardly seen when the plant is in full bloom because of the abundance of flowers, which sometimes form almost a carpet of color. The plant blooms all summer.

Agesilaus 2

2008-09-11T07:46:00.000-07:00

king of Sparta from about 400 to 360 b.c, whose succession to the throne was due to the influence of Lysander. In 396 Agesilaus sailed to Asia Minor to lead a Spartan army against Persia, for the Persians were attacking the Ionian Greeks in retaliation for Greek participation in the expedition of Cyrus the Younger. After a successful campaign in Phrygia, however, Agesilaus was compelled to return to Greece to lead his forces against a coalition of Thebes, Athens, and other Greek states. Marching south from Thrace he met the allies at Coronea and defeated them. Some years later war between Sparta and Thebes broke out again. This time the Thebans defeated the Spartans in a decisive battle at Leuctra, in 371, which ended the Spartan supremacy. Almost ten years later the Thebans under Epaminondas again defeated the Spartans at Mantinea in 362, but Agesilaus succeeded in defending his country. The following year he sailed to Egypt to aid in a war against Persia and died on the homeward passage in 360.

Age of Organisms

2008-09-10T07:37:00.000-07:00

The average duration of existence enjoyed by individuals of various species of animals and plants. Each species, from the simplest to the most complex, has its particular life span, which the individual members of the species tend to attain in the absence of accidents. With certain exceptions, in the latter part of this period the vital forces of the organism are gradually withdrawn, the metabolism is reduced (or in the case of plants, the ability to build new tissue diminishes), and the individual then dies, either through a general decay not partaking of the nature of illness or else, and more commonly, as a result of diseases that the enfeebled structures of the body are unable to combat. Among human beings the cases in which death occurs from mere senescence uncomplicated by specific ailments are exceedingly rare; while among wild animals natural death from old age is almost unknown, the weakened animal either falling prey to predatory animals or else dying as a result of an accident, probably long before it would perish of sheer agedness in a place of safety. Domestic animals that might die of old age are often killed as an act of mercy.

All but the simplest forms of animal life are subject to the unvarying rule of birth, growth, maturity, senescence, and death. But certain unicellular organisms, such as the amoeba, reproduce by the division of the parent cell into two equal parts, thus achieving a kind of immortality. In the plant world, too, a natural life span is frequently to be observed, though immortality, or at least extreme longevity, is comparatively common. Annual plants in the temperate regions sprout, reproduce, and die all within a single growing season, though they may survive for a somewhat longer period in warm climates. Biennials normally grow one year and bloom and die the next. Even perennials tend to exhaust themselves and die sooner or later. Many plants are immortal, however, in that they can propagate vegetarively, that is, by non-sexual methods. Reproduction by means of tubers, runners, bulblets, and the like is of the vegetative sort and allows a true survival of the individual specimen, even though all portions of its tissues of some earlier time may have perished. The life plan of plants is such that some species, at any rate, appear capable of living and growing indefinitely. The oldest known living things are the gigantic sequoia trees of the Pacific Coast. The annual growth rings in some specimens that have been cut down indicate that they lived for more than 3,000 years.

The Biblical statement of human life expectancy of "three score years and ten" has long expressed truly the limit beyond which relatively few survive. Some of the extreme ages of biblical personages, such as the 969 years of Methuselah, the 950 years of Noah, and the 930 of Adam, are generally considered instances of the heroic scale on which the histories and characteristics of demigods of various mythologies are dealt with. According to another explanation, the time units mentioned in the Bible should not have been translated as "years," since they referred to some much briefer period. The most famous English cases of longevity, those of Henry Jenkins (169), "that old old very old man, Thomas Parr" (152), and the countess of Desmond (140), all occurred so long ago that reputable evidence is difficult to find. There was no proof of Jenkins' age except his own statement for it, Parr's age was based on hearsay, and investigation has suggested that the countess of Desmond's years should be attributed not to one but to three successive ladies of the same name. Furthermore, for most cases of persons claiming to be over 100 years old there are no birth records available. It should also be remembered diat the memory and reliability of elderly persons often fail, while the distinction that extreme age confers often leads to exaggerations.

Race, sex, climate, nutrition, genetic stock, and other hereditary and environmental factors all influence human longevity. Persons whose parents and grandparents lived beyond the normal age have a much better than average life expectancy.
The average length of human life in most civilized countries has undergone a very significant increase in the last century, the greatest increase having come since 1900. This is largely the result of improved public health measures, coupled with the conquest of certain infectious diseases. The general technological advance through which more adequate nutrition and comfort are available for the general population is another significant factor. There are now more elderly people than in the past, an increase that has created social security and medical problems. The special study of the diseases of old people is called geriatrics.

There is little correlation between the sizes of species and their spans of life. Horses, with a life expectancy of 30-50 years, live much longer than insects, some of which survive only a few days, but a shorter time than the small sea anemone, which has been known to live more than 60 years in captivity. Again, the 17-year locust outlives many mammals much larger than itself. Nor is there any general correlation between activeness and length of life, since many birds, with a great output of energy and a high metabolic rate, live to an extreme old age just as does the cold-blooded and sluggish tortoise.

Lack of adequate records makes it difficult to set up any reliable averages of the life spans of animal species. Estimates vary, but the following list gives a rough approximation for some common species:

Species Life Span in Years
Mouse ....................... 4—6
Rabbit ....................... 10
Sheep ........................10-15
Dog .........................10-20
Goat......................... 6-15
Cat .......................... 10
Cow .........................15-20
Chicken ...................... 15

Species Life Span in Years
Mouse ....................... 4—6
Rabbit ....................... 10
Sheep ........................10-15
Dog .........................10-20
Goat......................... 6-15
Cat .......................... 10
Cow .........................15-20
Chicken ...................... 15

Agency

2008-09-09T07:33:00.000-07:00

Agency a branch of the law dealing with tlie liability of a principal for the acts of his agent. Although the idea of vicarious liability is of ancient origin and is referred to in canon law, the modern law of agency has been developed through court decisions within the last 300 years. In general, under the principle of respondeat superior (let the principal answer), an employer must pay damages resulting from wrongs committed by an employee in the course of his employment. The principal is also bound on contracts made by an agent within the scope of his actual or apparent authority.

Agen

2008-09-08T07:29:00.001-07:00

Agen ,capital of the department of Lot-et-Garonne, France, on the Garonne River, 75 miles southeast of Bordeaux. It is an important railroad junction between Bordeaux and Toulouse and serves as a market for the surrounding fruit-growing region. Woolen fabrics are manufactured. Before being taken by the Romans, Agen was the capital of the Nitiobriges, a Gallic tribe, and was later the capital of the Frankish county of Agenais.

Age

2008-09-08T07:28:00.001-07:00

in law, the number of years a person must have lived before he is deemed capable of exercising the rights and privileges and assuming the duties of citizenship. In the United States full age is reached at 21; however, women are of legal age in some states at 18. Voting age, generally 21, is 18 in Georgia for both sexes. For certain purposes, such as capability of consent to marriage, legal age is generally lower and varies among the states. Legal ages necessary to hold certain United States political offices are as follows: Congressional representative, 25; senator, 30; president, 35.

Agawam

2008-09-03T03:00:00.000-07:00

a town located in Hampden Co., southwestern Massachusetts, on the Connecticut and Westfield rivers. It lies 3 miles southwest of Springfield. The principal manufactures of Agawam are woolen goods and metal products. There is some truck farming. The town was settled in 1635 and was incorporated in 1855

Agate

2008-09-02T02:59:00.000-07:00

Agate , a mineral classed by Dana as one of the cryptocrystalline varieties of quartz, chalcedony, some of the other minerals falling under the same category being carnelian, onyx, hornstone, and jasper. Phillips and the earlier school of mineralogists had made quartz and chalcedony different minerals and placed agate under the latter species. The classifications differ but little, for Dana defines agate as a variegated chalcedony. He subdivides agates by their colors into those which are banded, those in clouds, and ties. Under the first category is reckoned the eye agate, and under the third, the moss agate, or mocha stone, and the dendritic agate. Other terms sometimes used are ribbon agate, brecciated agate, and fortification agate. Of these the most familiar is the fortification agate, or Scotch pebble, found in amygdaloid and with layers and markings not unlike a fortification. Moss agate does not, as the name would lead one to infer, contain moss, the appearance of that form of vegetation being produced, in most cases at least, by an infiltration of mineral matter. Agates can be stained and highly polished and are thus made into semiprecious gems. Idar-Oberstein in Germany is among the chief centers of the agate-polishing and staining industry. The stones themselves are found principally in Brazil, Uruguay, and in the United States in Oregon and Wyoming. They are also found in many parts of Scotland, especially at the Hill of Kinnoull, near Perth.

Agassiz Lake

2008-09-02T02:52:00.000-07:00

Name given to the basin of a large sheet of water that in the glacial period covered a considerable area in the Red River Valley of Minnesota, North Dakota and Manitoba. Larger than all of the Great Lakes combined, Lake Agassiz at one time measured 700 miles long and 250 miles wide. It is believed that the lake discharged through a channel 50 miles long into the Minnesota River. The lake bed, now covered by a fertilizing silt, produces rich grain.

Alimony

2008-09-01T03:13:00.000-07:00

Alimony, in law, the allowance, awarded out of her husband's estate, to which a wife is entitled on separation or divorce. Jurisdiction in this matter in England rested with the ecclesiastical court until 1857, when it was conferred upon a court of divorce. In the United States it is vested in the courts of equity. Alimony may be granted by the court during litigation, in which case it is known as pendente lite (during the suit), or at the conclusion of the suit, when it is called permanent. The former enables the wife to pursue the litigation, whether proceedings have been brought by or against her. The amount granted lies within the discretion of the court. Permanent alimony is a periodical allowance awarded to the wife if the termination of the suit is favorable to her. By a writ of ne exeat (let him not depart), the court can prevent the husband from leaving the state if he has not provided sufficient security to cover the payments awarded to his wife. Under certain circumstances alimony may be granted to the husband from the wife's estate.

Alkyne

2008-08-29T13:54:00.000-07:00

Alkyne ,an unsaturated hydrocarbon containing a triple bond in the carbon skeleton and having the general formula CnH2n_2- The most important alkyne is acetylene, C2H2, the first member of the alkyne series. Al-kynes are highly reactive. Like alkenes, they are subject to electrophilic additions. But, unlike alkenes, they also accept nucleophilic additions. Hydrogen cyanide and water are capable of adding to acetylene but not to ethylene. The triple bond is sufficiently more reactive than the double bond that selective hydrogenation is feasible for compounds containing both a double and a triple bond. Alkynes have slightly acid properties. They can be prepared from vic-dihalides by treatment with alkali and by alkylation of acetylene. Acetylene is often prepared from calcium carbide and water. Industrial cracking processes are also used in preparing acetylene and other alkynes.

Aliphatic Compound

2008-08-29T03:12:00.000-07:00

Aliphatic Compound is composed of an open-chain carbon skeleton. These compounds comprise one of the four major groups of organic compounds. Their non-cyclic structure differentiates them from the aromatic, alicyclic, and heterocyclic groups composed of a cyclic structure. Aliphatics include the simplest of organic compounds, the hydrocarbons, composed solely of carbon and hydrogen atoms. Systematic nomenclature begins with the hydrocarbons and names the more complex compounds as hydrocarbon derivatives.

Alkaloid

2008-08-28T13:52:00.000-07:00

Alkaloid, a substance resembling an alkali in properties. Alkaloids are natural organic bases containing nitrogen, hydrogen, carbon, and usually oxygen. They occur in many plants and in some animal tissues; atropine, nicotine, and coniine are typical examples; some have been synthesized. They are substitution compounds of ammonia; most are tertiary amines. The alkaloids form salts with acids and double salts with platinic chloride. They are generally crystalline bodies, soluble in hot alcohol, sparingly soluble in water. They have mostly a bitter taste and act powerfully on the animal system; many are used in medicine, such as quinine, morphine, and strychnine; they are often very poisonous.

Alien Property

2008-08-28T03:11:00.000-07:00

property in the United States belonging to enemy nationals or to nationals of enemy-occupied countries, including aliens interned in the United States. The Office of the Alien Property Custodian controls all alien property except cash, bank deposits, and investments, which are under the jurisdiction of the Treasury. The Alien Property Custodian has the authority to manage, supervise, or take title to business enterprises, estates and trusts, real estate, patents and patent applications, copyrights, ships, and the like. This property has either been liquidated or put to work for the benefit of the United States. In business enterprises taken over by the custodian, enemy nationals were replaced by loyal Americans. Patents in which loyal Americans have no interest have been licensed to American industry on a royalty-free basis.

Final disposition of alien property, or money received for it, is not a function of the Alien Property Custodian but comes within the general settlement of postwar problems.

Alienation

2008-08-27T03:08:00.000-07:00

Alienation in real-estate law, the voluntary transfer of land or other real property from one person to another with no right, interest, or possession remaining to the person giving up the property. Alienation may be accomplished by deed or by public act such as a legislative grant. Under canon law, church property can be alienated only for good cause, after two appraisals, and with the consent of the proper superior.

Alienation of affections is the civil wrong of depriving a married person of the assistance and society of his or her spouse. For damages to be awarded by the court, it must be shown that the aggrieved spouse has lost the conjugal fellowship of husband or wife. Alienation of affections, as such, is considered an aggravation of this.
In medical law, alienation refers to the different kinds of mental derangement.

Alkene

2008-08-26T13:53:00.002-07:00

Alkene, an unsaturated hydrocarbon having the general formula CnH2n. Alkenes have fewer hydrogen atoms than alkanes with equal carbon content. The carbon skeleton of an alkene contains at least one double bond. Alkenes with two double bonds are sometimes called dienes. The cyclic alkene benzene has three double bonds. Alkenes are more reactive than alkanes. They are termed olefins (oil-forming substances) because they form oily addition products with halogens. The names of alkenes are similar to those of alkanes, but the ending -ene (often followed by a number indicating the position of the double bond) is substituted for -ane. Preparation of alkenes is by dehydration of alcohols, from alkyl halides, or by thermal cracking of alkanes.

Alkane

2008-08-26T13:53:00.001-07:00

a saturated hydrocarbon having the general formula CnH2n+2- The alkanes form a homologous series, of which the initial members are: methane, CH4; ethane, C2H6; propane, C:{H8; butane, C4H10; and pentane, C5H12. The Kekule formulas of these compounds may be found by drawing a skeleton of carbon atoms connected by single bonds and attaching hydrogen atoms to all the remaining bonds (each carbon atom is capable of four bonds). Kekule formulas will show the possibility of two isomers for butane, three for pentane, and more for the higher members of the series. Alkanes, or paraffinic hydrocarbons, are fairly inert. They may be prepared from alkyl halides by the Wurtz reaction or the Grignard reaction and from carboxylic acids by decar-boxylation or the Kolbe synthesis. Petroleum contains many alkanes.

Alkaline Earth Metal

2008-08-26T13:52:00.001-07:00

an element of the group II A of the periodic system. This group includes, in order of increasing atomic weight: beryllium, Be; magnesium, Mg; calcium, Ca; strontium, Sr; barium, Ba; and radium, Ra. These metals have two electrons in the outer energy level. They tend to form bivalent anions with an ease that increases in the order of the atomic weights. Beryllium does not react with water at ordinary temperatures, but the other alkaline earth metals react with water in a manner similar to the alkali metals. In general this group is somewhat less reactive than are the alkali metals.

Alkali Metal

2008-08-26T13:31:00.000-07:00

an element of the group I A of the periodic system. This group includes, in order of increasing atomic weight, lithium, Li; sodium, Na; potassium, K; rubidium, Rb; cesium, Cs; and francium, Fr. These metals have only one electron in the outer energy level. They tend to form uni-valent anions with an ease that increases in the order of the atomic weights. Alkali metals react readily with all electronegative elements. They react with water to form metal ions, hydroxyl ions, and free hydrogen gas. The hydroxides of alkali metals are called alkali. They are strong bases that are readily soluble in water. In commerce the name alkali usually refers to caustic soda, NaOH; soda, Na.,COj; caustic potash, KOH; or potash, K2CO:J. the alkali metals are the most reactive group of metals. They have many economic uses.

Alien and Sedition Acts

2008-08-26T03:04:00.000-07:00

Legislation passed by Congress in the summer of 1798, when publication of the XYZ Correspondence increased resentment against France. The acts regarding aliens increased the residence period for naturalization from five to fourteen years, empowered the president to deport dangerous aliens, and made legal the apprehension or deportation of resident aliens when war was declared against the United States. The Sedition Act made it a felony to print false, scandalous, or malicious writings to bring the government, Congress, or the president into contempt or disrepute or to encourage hostile designs against the United States. The severity of the act was mitigated by making truth a good defense, making juries the judges of fact, and limiting its operation till Mar. 4, 1801. The acts were pushed through by Federalists who feared that the Republicans had reached an understanding with the French radicals and intended to overthrow the government and the constitution. They were bitterly resented by the Republicans as invading state rights and trial by jury. They were important chiefly as the cause of the Kentucky and Virginia Resolutions, the first formal statement of a spirit of state resistance to national power. The acts proved generally unpopular and contributed to the downfall of the Federalists.

Alien

2008-08-25T03:03:00.000-07:00

a person residing in a country of which he is not a citizen or subject. Aliens must obey the laws of their resident country; their specific rights and privileges are determined by local law, which must conform to treaty obligations and to the requirements of international law.
After the year 1930, with the increasing regimentation of life and with the growing fear of espionage in the tense international situation, the practice has been to impose rigid restrictions on aliens, affecting their movement and choice of occupation.

The civil rights usually granted to aliens include security of person and property, liberty of conscience and worship, liberty to carry on commerce and trade, although subject to many restrictions, and instruction in the public schools. Since the ownership of real property has traditionally been considered a privilege associated with political allegiance, this right has been refused in many countries. Political rights, such as the franchise and the holding of public office, are not granted, except in unusual cases; some of the American states, however, have extended these rights to aliens, especially to those who have taken out first papers. In the United States all children born of alien parents automatically become American citizens.
Enemy aliens are citizens of the enemy state in time of war. Under international law they may be interned or otherwise restricted but may not be treated as prisoners of war; their property may be restricted or even confiscated.

Under the Alien Registration Act of 1940 nearly 3,000,000 persons were registered. A new law, passed in 1952, retains the provisions of the old law and further requires the registration of aliens remaining in the United States 30 days or longer. Those 14 years of age or older must be fingerprinted. Every three months aliens in temporary residence must report their addresses.

Alicyclic Compound

2008-08-24T03:03:00.000-07:00

Alicyclic compounds are one of the four major groups of organic compounds. The structure is a ring or closed chain, in contrast with the open chain of the aliphatic structure. The ring is composed solely of carbon atoms, in contrast with the heterocyclic ring composed of more than one kind of atom. The carbon atoms on the ring are linked by low-stability bonds, in contrast with carbon atoms on the aromatic ring linked by high-stability bonds. Systemic nomenclature follows that used for aliphatic compounds preceded by the prefix cyclo.

Alice

2008-08-23T03:02:00.000-07:00

city, seat of Jim Wells Co., southern Texas, about 40 miles west of Corpus Christi. It is the main trade center for a rich agricultural area that produces cattle, grain, cotton, vegetables, fruits, and dairy products. Alice is also a railroad division point from which cattle are shipped. Its chief industries include oil refining, cotton ginning, cottonseed-oil milling, and the manufacture of cheese, beverages, oilfield machinery, and clay products.
Alice has a natural-gas recycling plant, and there are sulfur mines in the vicinity.
Alice was founded in 1886 and was named for Alice Kleberg, a member of the Texas family that now owns the famous King Ranch. It was incorporated as a city in 1910.

Alicante

2008-08-22T03:01:00.000-07:00

a seaport in the southeastern portion of Spain; capital of the province of Alicante; the ancient Lucentum. It is situated at the foot of a cliff 850 feet high, which is crowned by the Fort of Santa Barbara. It has one of the best harbors on the Mediterranean and carries on a considerable trade,

Alibi

2008-08-21T03:01:00.001-07:00

in procedure under criminal law, the presentation of evidence that the person accused of a crime was in some location other than that of the crime when it was committed and therefore could not be guilty. It is customary for the accused to state that he was elsewhere and for him to produce witnesses to verify the alibi.

Ali Baba

2008-08-21T02:56:00.000-07:00

Ali Baba the hero of the story "Ali Baba and the Forty Thieves" in The Arabian Nights' Entertainments, who sees a band of robbers enter a cavern by means of the magic password "Open Sesame." When they have gone away he enters the cave, loads his ass with treasure, and returns home. The 40 thieves discover that Ali Baba has learned their secret and resolve to kill him, but the slave girl Morgiana finally outwits them.

Antigua

2008-08-20T23:52:00.000-07:00

island of the British West Indies, the most important of the Leeward group; about 13 miles long and 10 wide; area, 108 square miles. It was discovered by Columbus in 1493. The surface is varied and fertile. St. Johns is the principal town. The chief exports are sugar and sea-island cotton.

Antifreeze

2008-08-19T23:51:00.000-07:00

Antifreeze , a liquid or substance that is added to the cooling system of an engine to keep the coolant from freezing during cold-weather conditions. Salt-base antifreezes have proved too corrosive. The most widely used bases are alcohols, such as meth-anol, ethanol, and isopropanol, and glycols such as ethylene and propylene. An antifreeze should have a low freezing point, good circulating ability, little or no evaporation, and no corrosive action. Antifreezes usually contain chemicals to stop leaks, foaming, and seepage.

Antigonish

2008-08-18T23:52:00.000-07:00

Town and capital of Antigonish county, northeast Nova Scotia, Canada, about 110 miles northeast of Halifax, at the head of Antigonish Bay. The major industries are lumbering, fishing, dairying, and woolen milling. It has a university and a cathedral. Antigonish is the seat of a bishop.

Antietam Creek

2008-08-17T23:50:00.000-07:00

Rises in southern Pennsylvania, flows 40 miles south to join the Potomac River near Harper's Ferry, W.Va. On Sept. 17, 1862, a battle was fought on its banks near Sharpsburg between a Union army of about 70,000 men under General McClellan and a Confederate army of less than 40,000 men under General Lee. The indecisive battle was costly for both sides.

Anticyclone

2008-08-16T23:50:00.000-07:00

Anticyclone, in meteorology, a somewhat circular area of relatively high pressure in the atmosphere. The anticyclone is the controlling center of an airmass and is shown on a weather map by closed isobars. The pressure gradient is directed outward from the center so that winds blow spirally outward in a clockwise direction in the Northern Hemisphere and counterclockwise in the Southern. Anticyclones, or highs, average about 1,000 miles in diameter. The anticyclone was first plotted and named in 1861 by Francis Galton. It is important in weather forecasting.

Anticosti Island

2008-08-15T23:49:00.000-07:00

Anticosti Island , in the Gulf of St. Lawrence, off the Quebec coast and west of Newfoundland, 140 miles long and 30 miles wide. It is of low relief, with hills rising some 600 feet along the north coast. Fur and lumbering are the chief industries. It has been owned by various governments and was sold to Canadian paper interests in 1926.

Anti-Comintern Pact

2008-08-14T23:47:00.000-07:00

Anti-Comintern Pact,an agreement signed on Nov. 25, 1936, by Germany and Japan on mutual defense against Communist subversive activities and the Communist International (Comintern). On Nov. 6, 1937, Italy announced that she had joined. Hungary and Spain joined in 1939. The Western democracies believed that the pact was a thinly disguised aggressive alliance that was using the Comintern simply as an excuse. In 1939 a military alliance between Italy and Germany was signed. In August, 1939, Germany and the Soviet Union signed the Non-Aggression Pact, which abrogated the Anti-Comintern Pact. In 1943 the Comintern was dissolved by the U.S.S.R.

Anatomy

2008-08-14T08:53:00.000-07:00

Anatomy, strictly, the art of dissection. It implies generally the science that treats of the structure of living beings, it being reserved for the related science of physiology to study the functions of living beings. The term "living beings" includes both plants and animals. Thus there are vegetable anatomy, or phytotomy, having to do with the structure of plants, and the anatomy of animals, or zootomy, a special branch of which is human anatomy, or anthropotomy. Comparative anatomy discusses the resemblances and differences among the structure of the bodies of the various animals and man, a comparison that is a great aid to exact knowledge; while special anatomy is concerned only with the structure of single types. By minute anatomy, or histology, is meant the study of the elements of which a tissue or organ is built up, a study conducted by means of highly magnifying microscopes and aided by the use of chemical reagents and dyeing materials, which, by attacking the various elements of a tissue in different ways, render them easily distinguishable from one to another. The tracing of the development of form and structure from the earliest stage of an organism to its most complete form belongs to developmental anatomy. Morbid, or pathological, anatomy treats of the changes of structure due to or accompanying disease or congenital malformations, and physiological anatomy treats of structure with reference to the functions of parts. There are also regional anatomy, or the anatomy dealing with regions of the body, and surgical anatomy, dealing with body regions in relation to diagnosis and treatment of surgical disease.

Anaxagoras

2008-08-13T03:03:00.000-07:00

Anaxagoras,a famous Greek philosopher of the Ionic school, born at Clazomenae, about 500 B.C. He explained eclipses and advanced physical science. In philosophy, he taught that the universe is regulated by an eternal self-existent and infinitely power¬ful principle, called by him mind; matter he seems to have asserted to be eternal, what is called generation and destruction being merely the temporary union and separation of ever-existing elements; he disproved the doctrine that things may have arisen by chance. Fragments of his Treatise on Nature are still in existence. He died in 428 B.C.

Anaximander

2008-08-12T07:11:00.000-07:00

A Greek mathematician and philosopher, successor of Thales as head of the physical school of philosophy, was born at Miletus, in 611 B.C. He is said to have discovered the obliquity of the ecliptic, and he certainly taught it. He appears to have applied the gnomon, or style set on a horizontal plane, to determine the solstices and equinoxes. The invention of geographical maps is also ascribed to him. As a philosopher, he speculated on the origin (arche) of the phenomenal world, and this principle he held to be the infinite or indeterminate (to apeiron). From it he conceived all op-posites, such as hot and cold, dry and moist, to proceed through a perpetual motion and to return to it again. Of the manner in which he imagined these opposites to be formed, and of his hypothesis concerning the formation of the heavenly bodies from them we have no sufficient information. Some of his particular opinions were that the sun is in the highest region of the heavens and is in circumference 28 times greater than the earth, and resembles a cylinder from which flow continual streams of fire; also that the earth is of the form of a cylinder, that it floats in the midst of the universe and that it was formed by the drying up of moisture by the sun. He died in 547 B.C.

African Methodist Episcopal

2008-08-11T11:57:00.000-07:00

A term applicable to two Methodist Episcopal churches founded by Negroes at the end of the 18th century because of the discrimination they suffered in that era.
The larger of these churches traces its origins to 1787, when a group of Negroes withdrew from the Methodist Episcopal Church in Philadelphia and established a church that excluded Caucasians from every office except that of preacher or public speaker. This denomination, the African Methodist Episcopal church, was formally organized in 1816, and its first bishop was consecrated the same year. After the Civil War it grew rapidly in the South. In 1961 it had 1,166,301 members in 5,878 churches.
Negroes founded still another Methodist Episcopal church in 1796. This church was nationally organized in 1821, and after 1848 it was known as the African Methodist Episcopal Zion church. This denomination in 1961 had 780,000 members in 3,090 churches.

Anophylaxis

2008-08-10T12:25:00.000-07:00

Anophylaxis the acute reaction produced by the intravenous injection of a foreign substance, usually a protein, into an animal made susceptible by previous injection with the same substance. It was first recognized in the course of blood-serum experimentation on laboratory animals. The injection of a foreign protein (antigen) into an animal or individual elicits a response that consists of the production of neutralizing substances (antibodies) in the blood and in the tissue cells. This constitutes sensitization. Subsequent intravenous injection of the same antigen causes anaphylaxis, an intense reaction between the antigen and the antibodies established by the first or sensitizing injection. A guinea pig that has been injected for the first time with horse serum, for example, shows no ill effects; after an interval of about ten days, however, a second injection of horse serum usually causes convulsions and death. Many other species of animals are similarly subject to lethal reactions from serum injections. The severity of the reaction is determined by the degree of sensitization, the amount of antigen injected, the nature of the antigen, and numerous other factors. Fatal reactions are usually the result of an abrupt fall in blood pressure.
The term "anaphylaxis," or lack of protection, was first applied to these phenomena in 1902 by the French physiologist Charles Richet. It was he who demonstrated through experiments on dogs that an incubation period was necessary before a second injection would cause an anaphylactic reaction. Following his researches the subject has been widely investigated and has provided a basis for study and scientific treatment of the related phenomena of allergy.
Anaphylaxis occasionally occurs following the administration of serum for the prevention and treatment of various infectious diseases, when the individual has become sensitized by a previous injection of serum prepared from the same animal species, although not necessarily for the same disease. Prompt injection of adrenalin often prevents an otherwise fatal drop in blood pressure in these instances.

Almagest

2008-08-09T12:34:00.001-07:00

The name applied to book on geometry , and astronomy written , about A.D 140 , by Claudius Ptolemy of Alexandria. The book originally appeared with Grek title Megale Syntaxis ( great system ), which was later changed by the admirers of Ptolemy to Megista (greatest ). The arabians , in A.D 827 , translated this work as Al-majisti , and from the Arabic title was derived the word almagest , which , in the Middle Ages , was a term applied to all Works on astonomy.

Anniston

2008-08-08T06:57:00.000-07:00

City in Calhoun Co. , Alabama on the Louisville and Nashville and the Southern railroads , and U.S. hihgways 78 and 431 ; 55 miles east of Birmingham. It is situated inn the foothills of the Blue Ridge Mountains and is the sixth largest city in the state. It makes cast-iron soil pipe , iron and steel products , cotton goods , cordage , and chemicals. Fort McClellan , a pernabebt Arny oıst i şs bear by. Cheaha State Park , highest point in Alabama , is located southeast of Anniston. The city is near Oxford Lake , which has swimming and boating facilities. It was founded in 1872.

Amur River

2008-08-06T03:59:00.000-07:00

In northeastern Asia formed by the junction of the Shilka and the Argun , which both come from the southwest. From the junction , the river flows first southeast and then northeast , and after a total course of 1.767 miles , empties into the Sea of Okhotsk , opposite the island of Sakhalin. Its main tributaries are the Sungari and the Ussuri , both from the south. The Amur forms the boundary between Russian Siberia and Manchuria.

Amadis of Gaul

2008-08-04T00:31:00.001-07:00

The name of a famous romance of chivalry. The earliest extant text , by Garcia Rodriguez de Montalvo , was pulished in 1508 in four volumes. Three of these were based on an earlier version , believed to have been written by a Portuguese author named Vasco de Lobeira in about 1403 , although the story was mentioned as early as the 13th century. The hero of the romance is a model of every knightly virtue and is seccussful in all his adventures. The tale of his exploits attained great popularity and was widely imitated. In Don Qıixote Cervantes satirized the tradition and chivalric romances represented by Amadis of Gaul.

Everyone Needs Friends...

2008-08-01T06:47:00.000-07:00

Everyone needs friends,but how many?Psychologists say it's god to have a lot of different friends,not just one best friend.Each friend gives you something different.So what differnt types friends are there?
First,there's your 'school friend;This friend is hard-working and helpful.When you have difficulties with your homework,your school friend helps you.He or she is cherful and you feel happy to see this friend every day.
Another type of friend is your 'weekend friend;You and this friend are interested in the same things.You have the same hobbies;football,shopping or the cinema.You always have fun with this friend.
Your 'anytime friend' is the third type of friend.This friend always listes to u.He or she understands you and is never jealous.You laugh or cry with this friend and you knw your anytime friend is always your friend.
People need all types of friends, but anytime friends are the most important.

Visit Egypt

2008-07-31T15:54:00.000-07:00

There are a lot of things to do in Egypt.Visit the pyramids,swim in the sea,ride a jetski ,or learn to windsurf ! Go to the fantastic cafes and eat great food ,or go shopping in the markets and buy fantastic presents for your friends.You can also learn about the River Nile.
Why not visit the desert?The desert is a big and exciting place.It's got a lot of snakes and other interesting animals.You can go on a day trip,or you can go for a week and sleep under the stars.You can travel in a jeeo or on a camel.Camesl are a fantastic from of transport in the desert .But be careful!Camels are strong and they aren't easy to control
Visit Egypt for a great holiday!

How a Reactor Works

2008-07-31T12:03:00.000-07:00

Inside a nuclear reactor there are four vital materials : the fuel rods , the modreator , the coolant fluid and the control rods. All four are to be found in every part of the reactor. The fuel is uranium. When a U-235 nucleus is split inside a nuclear reactor , it produces two or three fast neutrons. The idea is to get one of these neutrons to split another U-235 to keep the chain reaction going. These fast neutrons are slowed down as they pass throug the modreator because slow neutrons are better at splitting U-235. The control rods stop the other neutrons before they can split a nucleus , otherwise the chain reaction would multiply out of hand. The energy of the neutrons heats the reactor up , and the coolant fluid carries the heat away to the boilers to make steam for the turbines.

The Mysteries of Easter Island

2008-07-30T07:25:00.001-07:00

If you go to Easter Island,you'll see some of the most amazing sights in the world.You'll also discover that the island has a very mysterious history.

In 1722,a Dutch explorer arrived on Easier Island.He was the first European to go there.People were already living on the island,but there was no written history of their lives.European explorers began to ask quesitons.The island is 2,000 miles away from the nearest land.So how did the first people arrive there?Did they come from South America ,in the east,or from Polneysia,in the north and west?It's a very long voyage to Easter Island from any direction.So how did the first people travel so far?

The most popular idea is that a small group of Polynesians travelled there in about 400 AD.An island myth decribes how,1,500 years ago,a Polynesian chief named Hotu Matu 'a sailed ther with his wife and family .Maybe he was loking for a new alnd for his people ,or maybe he was escaping from a war.

There is another great mystery on the island .If you walk around the island,you 'll see nearly 900 amazing stone satues.These statues are nearly are nearly five metres high.Ehy did the islanders build them?A lot of people belive they were statues of important people from that time.Many of the status are near the coast,with their backs to the sea.But some of them are still in the hilss,and are unfinished .How did the islanders move them?theyonly had stone,wood,rope and human power to help them.Perhaps this is why they didn't complete thier huge task.

Ther are many unanswered questions about Easter Island.Archaeologists and visitors continue to search for the answers.But unless we find new evidence,we'll probably never know truth

Geothermal Energy

2008-07-30T05:53:00.000-07:00

One alternative source of energy to fossil fuel has been use for thousands of yeras : geothermal heat. Deep down , the earth is very hot , owing to the naturel radioactivity in the rock. This provides a source of energy as the heat leaks slowly to the surface. In some parts of the world, mostly in volcanically active regions , hot springs and geysers have been tapped to provide district heating. In princible it should be possible to drill holes in suitable hot rock formations and extract endless free energy for heating and even for electricity generation. Unfortunately, the amount of energy leaking to the Earth's surface is generally negligible. It is useful only in a few locations where variations in the Earth's crust have allowed the heat to build up near the surface.

Geothermal energy is neither clean nor renewable , but it will continue to be a valuable energy source in places like Iceland and New Zealand for the foreseeable future. And it does not add to the Greenhouse effect. To find a buried fuel which will not increase carbon dioxide in the atmosphere , and yet produce enough convenient energy where we want it , we must turn to uranium.

Abbeville

2008-07-29T00:15:00.000-07:00

A town of France , on the Somme , 12 miles from the English Channel. It has some trade in woolens and carpets. A place of settlement from Paleolithic times , Abbeville became the chief town of Ponthieu and in the 9th century A.D. belonged to the abbey of St. Riquier. For a time it was ruled by England. Abbeville has a number of fine medieval and Renaissance buildings. It was a British base during World War 1. In World War 2 it was occupied by German armored column , which cut of the Allies in Flanders. It was liberated in 1944 by the british .

Abencerrages

2008-07-27T10:26:00.001-07:00

The name given by Spanish chroniclers to a noble family in the Moorish kingdom of Granada, several of whom distinguished themselves immediately before the fall of the Mohammedan empire in Spain. Their struggles with the family of the Zegris and their tragic destruction in the royal palace of the Alhambra , in Granada , seem to be destitute of historical foundation.

Achilles

2008-07-27T02:05:00.000-07:00

A hero in Greek legend and a leadmg figure in Homer's Iliad. He was the son of Peleus , king of the Myrmidons , and Thetis , Thetis dipped him into the River Styx when he was an infant and rendered him invulnerable except for the heel by which she held him. Odysseus persuaded him to join the expedition against Troy , where he distinguished himself by his valor and strength. In the tenth year of the war he quarelled with the commander , Agamemnon , over a slave girl , Briseis . Achilles withdrew from the war , and the Trojans were victious over the Greek armies for a time. When his friend Patroclus was slain by Hector, Achilles returned to the conflict to kill Hector. He was himself killed by Paris , who wounded him in his vulnerable heel.

Accordion

2008-07-26T11:56:00.000-07:00

A portable musical instrument played by means of a keyboard and a bellows. The keyboard , which may have as many as 50 keys , is played with the right hand , while the left hand operates the belvide various chords.Each key operates two different reeds , one when the bellows is expanded and the other when it is compressed. The accordion was invented either by Buschmann of Berlin ,in 1822 or by Damian of Vienna in 1829.

Fosil Fuels

2008-07-25T13:54:00.001-07:00

Coal, oil and natural gas are the buried remains of vegatation and other organisms that flourished on the Earth in ancient geological periods of the Earth’s development.The energy in these ‘’fosil fuels’’ comes from the accumulated sunshine collected by prehistoric plants while they were growing.Gradually the slow processes of rock formation have squeezed and transformed the organic substances in these plants into the coal, oil and natural gas that we now take for granted.The fosil fuels took many millions of years to form., but we are now squandering them sof ast that future supplies are already in danger.If we continue to burn them as we have in the past, all the most valuable reserves will be consumed during the next few generations of the human race.If this happens, our descendansts will surely accuse us of irresponsibility.

Fosil fuels (and uranium) are used throughout the world in the power stations that generate electricity.The huge stations the provide most of our electricity all work on the same principle.They burn the fuel to make heat, which is used to boil water into steam.The pressure of the steam turns the shaft of the electric generator.Now the whole idea of a power station is to extract the energy from the fuel and send that energy out into the public electricity network.Unfortunately, the process of making electricity from a hot fuel is very inefficient.Only about a third of the energy leaves the power station as electricity.The other two-thirds end up in the cooling system of the power station, and are entirely wasted.In fact, the system is carrefully designed to get rid of this waste heat immeiately, as the turbines will not work properly if surplus heat is allowed to build up.Power stations are often built near the coast so that they can use sea water to carry away the waste heat.Inland stations use a river or enormous cooling towers in which the waste heat is carried upwards in a stream of warm, moist air.

Amethyst

2008-07-25T00:58:00.000-07:00

The most valuable of the semiprecious quartzes , is usually purple or violet in color. Many supertions have been built around this Stone ; it has been claimed that it is , among other things , a love charm , a protection against or cure for drunkenness , and protection against burglars. The oriental amethyst is really neither amethyst nor quartz , but a rare and very hard mixture of corundum and other minerals. Brazil , Czechoslovakia , the Ural Mountains and Mexico are principal sources of amethyst and some is also found in the United States.

Oakes Ames

2008-07-24T07:09:00.000-07:00

Oakes Ames

American capitalist , born in Easton , Mass. 1806 ; amassed a fortune manufacturing shovels. He became a national figure in railroad building upon the discovery of gold in California and was the chief promoter of the Union Pacific. In 1872 he was removed from his seat in Congress because of Massachusetts passed a resolution vindicating Ames. He had , however , died on May 8 , 1873. The city of Ames Iova , was named for him

Solar Energy

2008-07-21T07:37:00.000-07:00

As most of our energy comes originally from the sun , it makes sense to capture it right away , rather than wait for nature to precess it into fossil fuels. The simplest method is the flat - plate collector on the roof of a house.

Pipes on the plate carry water to and from the domestic hot water tank. Sunshine warms the plate , and heat is picked up by the water as it passes. A sheet of glass allows by preventing the escape of infra-red radiation - this is a delibrate form of greenhouse effect.

The water will only warm up once the sun is high enough in the sky. On cloudy days and in winter a flat-plate collector may not provide quite enough energy for a full tank of hot water , but it can still help to reduce the bill for gas or electricity.

Naturally , solar collectors are popular in sunny countries. In Israel , an interesting development is the solar pond , which is certainly not suitable for swimming. To begin with , it is partly filled with very salty water indeed , and then a layer of fresh water is carefully poured on top. The sun shines through the water and heats a black absorbing layer at the bottom of the pond , which makes the deep water warm.Normally this warm water would rise to the top , but in the solar pond the saltiest , and therefore the densest , water is at the bottom , and no amount of heating will make it rise. In fact it would reach boiling point if the heat were not piped off to a heat engine to generate electricity.

Andhra Pradesh

2008-07-20T02:20:00.001-07:00

Andhra Pradesh, a state of southeastern India; area 110,250 sq.mi.It fronts on the Bay of Bengal and extends westward across the Easthern Ghats and into the Deccan Plateau.It is bordered on the North by Orissa, Madhya Pradesh, and Maharashtra on the west by Mysore, and on the South by Madras.The capital is Hyderabad.The state produces over 80 per cent of India’s tobacco.Other crops ar erice, cotton, sugar cane, hemp, and peanuts.Hyderabad is the chief industrial city, and Vizagapatnam is India’s shipbuilding center.The state was created in 1953 from the Telugu-speakin region of Madras state.In 1956 the Telugu-speaking area of Hyderabad was added to it.

Robert Anderson

2008-07-20T02:19:00.001-07:00

Robert Anderson, an American army officer born in 1805 near Louisville, Ky.He was graduated from West Point in 1825, where he instructed from 1835 to 1837.He served under General Scott in the Mexican War.Commissioned major, he was appointed to command the forts in Charleston Harbor in 1860.Fearing attack, he removed his garrison from Fort Moultrie to Fort Sumter.On Apr.14, 1861, the Confederate forces began the Civil War by shelling Sumter.After a 34-hour bombardment, Anderson was compelled to surrender.Later, he was promoted brigadier general and assigned to command the department of Kentucky.In 1863 he was retired, and he died in 1871.

Maxwell Anderson

2008-07-20T02:18:00.002-07:00

Maxwell Anderson, American dramtist, born in 1888 in Atlantic, Pa. Educated at the University of North Dakota and Stanford, he taught English and wrote for numerous U.S. newspapers before the success of his play What Price Glory?(1924) , written with Laurence Stallings.Many of his plays are historical tragedies.Anderson early adopted verse, and he became a successful American experimenter in poetic drama.Among his best plays were Saturday’s Children (1927), Elizabeth the Queen (1930), Night Over Taos (1932), Both Your Houses (1933), Mary of Scotland (1933), Valley Forge (1934), Winterset (1935), The Wingless Victory (1936), High Tor (1936), The Masque of Kings (1937), Key Largo (1939), The Eve of St.Mark (1942), Joan of Lorraine (1946), Anne of The Thousand Days (1948), Barefoot in Athens (1951), and The Bad Seed (1954).He collaborated with Kurt Weill in Knickerbocker Holiday (1938) and Lost in the Stars (1949).

With other playwrights Anderson formed the Playwrights’ Company in 1938 to produce the plays of its members.He received many awards, including a Pulitzer prize and two New York Drama Critics awards.He died Feb. 27, 1959

Amsterdam

2008-07-20T02:18:00.001-07:00

Amsterdam

Amsterdam, the chief city of the Netherlands, a great commercial center, officially the capital, although The Hague is the seat of government.It is located on the Ijsselmeer and connected with the ocean by the North Sea Canal.The city is divided by many canals into a hundred small islands connected by more than 500 bridges.

The chief industrial establishments are sugar refineries, engineering Works, mills for polishing diamonds and other gems, dockyards, breweries, distilleries, and manufactories of sails, ropes, tobacco, jewelry, clothing, foofstuffs, and chemicals.There are banking, insurance, and export houses.

The former Raadhuis (City Hall), converted in 1808 into a palace of King Louis Bonaparte, and stil retained by the reigning family, is a noble structure.The cruciform Nieuwe Kerk (New Church), a Gothic edifice of 1408-1414, is the finest ecclesiastical structure in the city, with a splendidly carved pulpit and the tombs of Admiral de Ruyter, the great Dutch poet Vondel, and various other worthies.The Old Church (Oude Kerk), built in the 14th century, is rich in stained glass, has a Grand organ, and contains several monuments of naval heroes.The city’s two universities are the Municipal University, founded in 1632, and the Free University of Amsterdam, founded in 1880.The Free University is the only Calvinist university in the world.Amsterdam also has academies of arts and sciences, museums and picture galleries, a palace of national industry, a botanical garden, and theaters.

Amsterdam was occupied by the Nazis in May, 1940.It was recovered by Allied forces 1945.

Anaconda

2008-07-19T16:38:00.000-07:00

Anaconda, a large serpent of the boa family, common in tropical America.The head is comparatively small, conical, very flat below, and truncated in front.The color is grayish-brown or olive above, with two rows of large black spots running down the back and tail.The sides are adorned with black rings on a yellow ground.The under surface is ocher-yellow with black spots.The anaconda is the largest of living snakes, sometimes reaching a lenght of over 30 feet.Brazil and Guiana form its chief habitat.It always lives in or in the neighborhood of water; lies in wait for it sprey in the water or stretched on the sand; seldom attacks man; and during the dry season buries itself and becomes torpid.

Photovoltaic Energy

2008-07-19T14:19:00.000-07:00

Perhaps the most exciting prospect for the future is electricity from solar cells. The complications of heat engines , turbines , generators , air pullution and radioactive waste could all be avoided , if only the price of solar cells could be brought down. A small electric voltage is produced when light shines on a solar cell. It does not have to be direct sunlight: cloudy daylight will work fine.

Solar cells are made from very pure silicon crystals. Silicon itself is cheap , as it is common in sand and rocks : the high cost lies in the processes of purifying and crystallising the silicon. It may eventually be possible to make cheaper solar cells froum amorphous silicon , which is not crystalline. Electricity forum solar cells could then compete with power forum fossil fuels. But as usual there is a snag, and it applies to all forms of solar power. It is that solar energy is available only during the day , and there is not much daylight in winter when more power is needed for heating and lighting.

One way round this problem is to find another source of renewable energy which will still work in the dark , and especially in winter. Fortunately , there is one readily available : the wind.

Amphitheater

2008-07-19T14:01:00.001-07:00

Amphitheater, a theater of oval shape, with rising tiers of seats located around a central arena.The amphitheater was largely developed by the Romans, who built them wherever they went.Among the spectacles exhibited were fights between wild beasts, combats between gladiators and fights between men and beats.The most splendid amphitheater ruins in existence are those of the Colosseum at Rome, which is said to have held about 50.000 people.

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Amino Acid

2008-07-19T12:18:00.000-07:00

Amino acid, in organic chemistry, a carboxylic acid that contains one or more amino groups.They are primarily amino acids, having the general Formula RCH (NH2) COOH, and are the building blocks of proteins by hydrolysis either through enzyme action or by boiling the protein with hydrochloric or sulfuric acid.There are known to be 27 amino acids of biological importance, determining the physiological activity of animals and plants.Ten of the known amino acids are necessary for growth in rats: arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalamine, threonine, tryptophan, and valine.

Several classes of amino acids are now known and identified.Among these, glycine, leucine, valine, alanine, and isoleucine are included in the group of monoaminocarboxylic acids.These acids are neutral compounds, soluble in water.The dicarboxylic-monoamino acids are acidic substances.Aspartic acid, glutamic acid, and hydroxyglutamic acid are such compounds.The diamino acids, which include lysine, arginine, and histidine, are basic substances.

Thyroxine is a neutral amino acid that is formed by the thyroid gland.It possesses a high iodine content.A lack of iodine in the diet often results in a deficiency of thyroxine production by the thyroid gland, causing goiter.Cystine, which is prepared by the hydrolysis of hair, is a bisulfide amino acid used as an essential ingredient in mediums for cultivating bacteria growth fort he commercial manufacture of diphtheric toxin.

The amino acids are crystalline substances anda re usually very souble in water.They decompose when heated above 200° C. And, therefore, have no definite melting points.They may be made to react with alcohols to form esters.

Emil Abderhalden

2008-07-19T07:54:00.000-07:00

Swiss biochemist and physiologist , born in Oberuzwil in 1877. He was educated at the University of Basel and taught physiology both there and at Halle University. In 1939 he was appointed president of German Academy of Scientist. He became noted for his research in the metabolism of foods , particularly proteins. His work in the chemistry of egg albumen , protective ferments of animal organisms , and synthesis of cellular materials in plants and animals is of great importance in biochemistry. Hi died in 1950.