Acacia arabicaAcacia arabica, showing leaves, flowers, and fruit
Aca′cia,a genus of plants, nat. ord. Leguminosæ, sub-order Mimoseæ, consisting of trees or shrubs with compound pinnate leaves and small leaflets, growing in Africa, Arabia, the East Indies, Australia, &c. The flowers, usually small, are arranged in spikes or globular heads at the axils of the leaves near the extremity of the branches. The corolla is bell- or funnel-shaped; stamens are numerous; the fruit is a dry unjointed pod. Several of the species yield gum-arabic and other gums; some having astringent barks and pods, used in tanning.A. Catechu, an Indian species, yields the valuable astringent called catechu;A. dealbāta, the wattle tree of Australia, from 15 to 30 feet in height, is the most beautiful and useful of the species found there. Its bark contains a large percentage of tannin, and is exported in large quantities. Some species yield valuable timber; some are cultivated for the beauty of their flowers.
Acad′emy,an association for the promotion of literature, science, or art; established sometimes by Government, sometimes by the voluntary union of private individuals. The name Academy was first applied to the philosophical school of Plato, from the place where he used to teach, a grove or garden at Athens which was said to have belonged originally to the hero Acadēmus. The home of Academies as associations of learned men (not institutes for instruction), was Hellenized Egypt and afterwards Italy of the Renaissance. The flourishing Academies at Florence, Naples, and Rome became the models of academies in other countries. Academies devote themselves either to the cultivation of science generally or to the promotion of a particular branch of study, as antiquities, language, and the fine arts. The most celebrated institutions bearing the name of academies, and designed for the encouragement of science, antiquities, and language respectively, are the French Académie des Sciences (founded by Colbert in 1666), Académie des Inscriptions (founded by Colbert in 1663), and Académie Française (founded by Richelieu in 1635), all of which are now merged in the National Institute. The most celebrated of the academies instituted for the improvement of language is the Italian Accademia della Crusca, or Furfuratorum (now the Florentine Academy), formed in 1582, and chiefly celebrated for the compilation of an excellent dictionary of the Italian language (Vocabulario della Crusca, Venice, 1612), and for the publication of several carefully-prepared editions of ancient Italian poets. The (Imperial) Academy of Science of St. Petersburg was projected by Peter the Great and established by Catherine I in 1725. The Academy of Science in Berlin was founded by Frederick I in 1700. It was opened in 1711 and had Leibnitz as its first president. In Britain the name of academy, in the more dignified sense of the term, is confined almost exclusively to certain institutions for the promotion of the fine arts, such as the Royal Academy of Arts and the Royal Scottish Academy. The Royal Academy of Arts (usually called simply the Royal Academy) was founded in London in 1768, "for the purpose of cultivating and improving the arts of painting, sculpture, and architecture". The number of academicians is now limited to forty-two, among whom are two engravers. There are also thirty associates, from whom the academicians are elected. Of the associates five are engravers. Any person who is possessed ofsufficient proficiency may be admitted as a student and receive instruction gratis, and prizes are annually bestowed on meritorious students. The annual exhibition of the Academy is open to all artists whose works show sufficient merit. The Royal Scottish Academy of Painting, Sculpture, and Architecture was founded in 1826 and incorporated in 1838. It consists of thirty academicians and twenty associates. The Royal Hibernian Academy at Dublin was incorporated in 1823 and reorganized in 1861. It consists of thirty members and ten associates. A British Academy for the Promotion of Historical, Philosophical, and Philological Studies was incorporated in 1902. (SeeBritish Academy.) In the United States, the American Academy of Arts and Sciences at Boston was founded in 1780, and since then various other societies of similar character and name have been instituted, as the New York Academy of Sciences, the Chicago Academy of Science, &c.
Aca′dia(Fr.Acadie), the name formerly given to Nova Scotia. It received its first colonists from France in 1604, being then a possession of that country, but it passed to Britain, by the Peace of Utrecht, in 1713. In 1756, 18,000 of the French inhabitants were forcibly removed from their homes on account of their hostility to the British, an incident on which is based Longfellow'sEvangeline. Many Acadians afterwards wandered back to their old homes, and their descendants are at present supposed to number 270,000, 100,000 of them living in French Canada.
Acale′pha(Gr.akalēphē, a nettle, from their stinging properties), a term formerly used to denote the Medusæ, or jelly-fishes, and allied species.
Acantha′ceæ,orAcanthads,a nat. ord. of dicotyledonous herbaceous plants or shrubs, with opposite leaves and monopetalous corolla, mostly tropical; species about 1400. SeeAcanthus.
Spines of Acanthopterygiia,b,c, Spines of the dorsal, anal, and ventral fins of Acanthopterygii
Acanthop′teri,Acanthopterygii(Gr.akantha, a spine,pterygion, a fin), a group of fishes, distinguished by the fact that at least the first rays in each fin exist in the form of stiff spines; it includes the perch, mullet, mackerel, gurnard, wrasse, &c.
Acanthus in architectureAcanthus. Examples of Greek and Roman decorative treatment
Acanth′us,a genus of herbaceous plants or shrubs, order Acanthaceæ, mostly tropical, two species of which,A. mollisandA. spinōsus(the bear's-breech or brankursine), are characterized by large white flowers and deeply-indented shining leaves. They are favourite ornamental plants in British gardens.—In architecture the name is given to a kind of foliage decoration said to have been suggested by this plant, and much employed in Greek, Roman, and later styles.
Acapul′co,a seaport of Mexico, on the Pacific, with a capacious, well-sheltered harbour; a coaling station for steamers, but with no great trade. Pop. 5950.
Acar′ida,a division of the Arachnida, including the mites, ticks, and water-mites. SeeMite.
Acarna′nia,the most westerly portion of Northern Greece, together with Ætolia now forming a nomarchy with a pop. of 188,597. The Acarnanians of ancient times were behind the other Greeks in civilization, living by robbery and piracy.
Ac′arus,the genus to which the mite belongs.
Acca′dians(Akkad), the primitive inhabitants of Northern Babylonia (Akkad), who had descended from the mountainous region of Elam on the east, and to whom the Assyrians ascribed the origin of Chaldean civilization and writing. This race is believed to have belonged to the Turanian family, or to have been at any rate non-Semitic. What is known of them has been learned from the cuneiform inscriptions. SeeBabyloniaandSummerians.
Accelera′tionis the rate of change of the velocity of a body under the action of a force. A body falling from a height is one of the most common instances of acceleration.—Acceleration of the Moon, the increase of the moon's mean angular velocity about the earth, the moon now moving rather faster than in ancient times. This phenomenon has not been fully explained, but it is known to be partly owing to the slow process of diminution which the eccentricity of the earth's orbit is undergoing, and from which there results a slight diminution of the sun's influence on the moon's motions.—Diurnal acceleration of the fixed stars, the apparent greater diurnal motionof the stars than of the sun, arising from the fact that the sun's apparent yearly motion takes place in a direction contrary to that of his apparent daily motion. The stars thus seem each day to anticipate the sun by nearly 3 minutes 56 seconds of mean time.
Ac′cent,a term used in several senses. In English it commonly denotes superior stress or force of voice upon certain syllables of words, which distinguishes them from the other syllables. Many English words, asas′pi-ra″tion, have two accents, a secondary and primary, the latter being the fuller or stronger. Some words, asin-com′pre-hen′si-bil″i-ty, have two secondary or subordinate accents. When the full accent falls on a vowel, that vowel has its long sound, as invo′cal; but when it falls on a consonant, the preceding vowel is short, as inhab′it. This kind of accent alone regulates English verse, as contrasted with Latin or Greek verse, in which the metre depended onquantityor length of syllables. In books on elocution three marks or accents are generally made use of, the first oracute(´) showing when the voice is to be raised, the second orgrave(`), when it is to be depressed, and the third orcircumflex(ˆ) when the vowel is to be uttered with an undulating sound. In some languages there is no such distinct accent as in English (or German), and this seems to be now the case with French.—In music, accent is the stress or emphasis laid upon certain notes of a bar. The first note of a bar has the strongest accent, but weaker accents are given to the first notes of subordinate parts of the bars, as to the third, fifth, and seventh in a bar of eight quavers.
Accen′tor(Accentor modulāris), orHedge Accentor,a British bird of the warbler family. SeeHedge Warbler.
Accep′tance,in law, the act by which a person binds himself to pay a bill of exchange drawn upon him. (SeeBill.) No acceptance is valid unless made in writing on the bill, but an acceptance may be either absolute or conditional, that is, stipulating some alteration in the amount or date of payment, or some condition to be fulfilled previous to payment.
Ac′cessary,orAc′cessory,in law, a person guilty of an offence by connivance or participation, either before or after the act committed, as by command, advice, concealment, &c. An accessarybefore the factis one who procures or counsels another to commit a crime, and is not present at its commission; an accessaryafter the factis one who, knowing a felony to have been committed, gives assistance of any kind to the felon so as to hinder him from being apprehended, tried, or suffering punishment. An accessary before the fact may be tried and punished in all respects as if he were the principal. In high treason, all who participate are regarded as principals.
Acciden′tals,notes introduced in the course of a piece of music in a different key from that in which the passage where they occur is principally written. They are represented by the sign of a sharp, flat, or natural immediately before the note which is to be raised or lowered.
Accipitres(ak-sip′i-trēz), the name given by Linnæus and Cuvier to the rapacious birds now usually called Raptores (q.v.).
Acclimatiza′tion,the process of accustoming plants or animals to live and propagate in a climate different from that to which they are indigenous, or the change which the constitution of an animal or plant undergoes under new climatic conditions, in the direction of adaptation to those conditions. The systematic study of acclimatization has only been entered upon in very recent times, and the little progress that has been made in it has been more in the direction of formulating anticipative, if not arbitrary hypotheses, than of actual discovery and acquisition of facts. The best-known society founded, for the purpose of naturalizing animals and plants, is the Société d'Acclimatation in Paris. It opened the Jardin d'Acclimatation in 1860. SeeTropical Hygiene. The term is sometimes applied to the case of animals or plants taking readily to a new country with a climate and other circumstances similar to what they have left, such as European animals and plants in America and New Zealand: but this is more properlynaturalizationthan acclimatization.—In agriculture the word is used with reference to stock, principally sheep, 'acclimatized' to a particular area, a special allowance being made by the landlord on transference of the farm and stock in respect of the acclimatization of the sheep. The value assigned to the advantages resulting from acclimatization of stocks varies considerably. In Argyllshire, for instance, Dumbartonshire, and the western portion of Perthshire the rates are high, while in the south of Scotland and the north of England they are much lower.
Accolade(ak-o-lād′; Fr., from Lat.ad, to,collum, the neck), the ceremony used in conferring knighthood, anciently consisting either in the embrace given by the person who conferred the honour of knighthood or in a light blow on the neck or the cheek, latterly consisting in the ceremony of striking the candidate with a naked sword.
Accol′ti,Benedetto, an Italian lawyer, born at Arezzo in Tuscany in 1415, died at Florence in 1466. He was secretary to the Florentine republic, 1459, and author of a work on the Crusades which is said to have furnished Tasso with matter for hisJerusalem Delivered.
Accommoda′tion Bill,a bill of exchange drawn and accepted to raise money on, and not given, like a genuine bill of exchange, in payment of a debt, but merely intended to accommodate the drawer: colloquially called awind billand akite.
Accommoda′tion Ladder,a light ladder hung over the side of a ship at the gangway to facilitate ascending from, or descending to, boats.
Accom′paniment,in music, is that part of music which serves for the support of the principal melody.
Accor′dion,a keyed musical wind-instrument similar to the concertina, being in the form of a small box, containing a number of metallic reeds fixed at one of their extremities, the sides of the box forming a folding apparatus which acts as a bellows to supply the wind, and thus set the reeds in vibration, and produce the notes both of melody and harmony. The accordion was invented by Damian of Vienna in 1829.
Accountant,a person whose chief business is with accounts and the drawing up of financial statements and balance-sheets. An accountant is an important official in banks, railways, and certain other institutions, and many persons carry on the business of accountant as a distinct profession, auditing the books of merchants, joint-stock companies, &c. There are several bodies of accountants in the United Kingdom incorporated by royal charter, and hence specially distinguished as 'chartered accountants' (C.A.). Since 1919 women are admitted as members of the Society of Incorporated Accountants.—Bibliography: L. R. Dicksee,Advanced Accounting; G. Lisle,Encyclopædia of Accounting(8 vols.).
Ac′cra,a British settlement in Africa, in a swampy situation, capital of Gold Coast, about 75 miles east of Cape Coast Castle. Exports gold-dust, ivory, gums, palm-oil; imports cottons, cutlery, &c. Pop. 20,000.
Ac′crington,a municipal borough of England, Lancashire, 5 miles east of Blackburn, with large cotton factories, print-works and bleaching-greens, and coal-mines. Pop. 43,610. Accrington was created a parliamentary borough in 1918.
Accu′mulator,a name applied to a kind of electric battery by means of which electric energy can be stored and rendered portable. In the usual form each battery forms a cylindrical leaden vessel, containing alternate sheets of metallic lead and minium wrapped in felt and rolled into a spiral wetted with acidulated water. On being charged with electricity the energy may be preserved till required for use.
Accu′sative Case,in Latin and some other languages, the term applied to the case which designates the object to which the action of any verb is immediately directed, corresponding, generally speaking, to theobjectivein English.
Ace,in aviation the name 'ace' is given to a flying-man who has distinguished himself by bringing down a large number (sometimes given as ten) of enemy machines. The word is used colloquially, and was borrowed from the French Air Force during the European War.
Aceph′ala,in zoology, the headless Mollusca or those which want a distinct head, corresponding to those that have bivalve shells and are also calledLamellibranchiata.
A′cer,the genus of plants (nat. ord. Aceraceæ) to which belongs the maple.
Acerra(a˙-cher′a˙), a town in South Italy, 9 miles north-east of Naples, the see of a bishop, in a fertile but unhealthy region. Pop. 17,878.
Acetab′ulum,an anatomical term applied to any cup-like cavity, as that of a bone to receive the protuberant end of another bone, the cavity, for instance, that receives the end of the thigh-bone.
Acetates(as′e-tāts), salts of acetic acid. The acetates of most commercial or manufacturing importance are those of aluminium and iron, which are used in calico-printing; of copper, which as verdigris is used as a colour; and of lead, best known as sugar of lead. The acetates of potassium, sodium, and ammonium, of iron, zinc, and lead, and the acetate of morphia, are employed in medicine.
Acet′ic Acid,an acid produced by the oxidation of common alcohol, and of many other organic substances. Pure acetic acid has a very sour taste and pungent smell, burns the skin, and is poisonous. From freezing at ordinary temperatures (58° or 59°) it is known asglacial acetic acid. Vinegar is simply dilute acetic acid. Acetic acid is largely used in the arts, in medicine, and for domestic purposes. SeeVinegar.
Acet′ic Ethers,orAcetic Esters,acetates of alcohol radicals. The common ester—ethyl acetate—is a volatile colourless liquid, manufactured by distilling a mixture of alcohol, oil of vitriol, and acetic acid, and used for flavouring purposes.
Acetone(as′), a constituent of ordinary wood spirit, a colourless volatile liquid used as a solvent, the simplest of theketones.
Acet′ylene,C2H2, is a substance composed of two elements, carbon and hydrogen, and belonging to a class of compounds known as hydrocarbons. It is formed in the incomplete combustion of many hydrocarbons and also of coal-gas, and may be produced in a variety of ways, but is now made almost entirely from calcium carbide. Acetylene has been known for a long time, but only since 1870 has it been produced in any quantity. After the development of the electric furnace it was found that calcium oxide,quicklime, heated with carbon to the high temperature possible in such a furnace, is transformed into calcium carbide, and this compound reacts with water, generating acetylene. A great deal of heat is developed on adding water to calcium carbide, so that care has to be taken in generating acetylene. Various devices are in use for bringing the two substances in contact slowly, and for keeping the temperature low. When carbon and hydrogen combine to form acetylene a large amount of heat is used up, so that much heat is evolved when acetylene decomposes again, and once decomposition starts sufficient heat is developed to decompose the whole volume of gas.
Acetylene is a colourless gas slightly soluble in water and very sparingly soluble in brine. When pure it has little or no odour, but as ordinarily prepared it has a strong unpleasant odour due to traces of impurities such as sulphuretted hydrogen, phosphine, &c. The gas can be liquefied easily, and in the liquid state is highly explosive. It burns with an exceedingly sooty flame, but if it is allowed to pass through a very small orifice the carbon liberated becomes incandescent and acetylene burns with an intense white flame. It is largely used as an illuminant and for the production of great heat. As an illuminant the gas is produced in specially-constructed generators. It is led through iron pipes and burned from an acetylene burner, or it may be used with special types of incandescent mantles. Acetylene readily combines with copper and with silver to form metallic acetylides which are very explosive, hence pipes through which acetylene is passing must not be made of brass or copper. Acetylene mixed with air and brought in contact with an ignited body explodes even more violently than a mixture of air and coal-gas.
Large quantities of acetylene are generated and stored for oxy-acetylene welding. Acetylene, burning in oxygen, gives an intensely hot flame (about 2000°-3000° C.), sufficiently hot to melt iron. Although liquid acetylene is unstable, and even the gas, under slight pressure, is also unstable, it may be transported safely if dissolved in acetone. Acetone dissolves a large volume of acetylene, and this solution is quite stable and may be stored in iron cylinders and used for various purposes. If it is to be stored it must be carefully purified from phosphine, which is apt to cause sudden decomposition. Recently, numerous patents have been taken out for the preparation of compounds such as acetaldehyde, acetic acid, acetic anhydride, &c., using acetylene as starting-point, so that many substances may be prepared from acetylene just as many substances may be prepared from benzene.
Achæans(a-kē′anz), one of the four races into which the ancient Greeks were divided. In early times they inhabited a part of Northern Greece and of the Peloponnesus. They are represented by Homer as a brave and warlike people, and so distinguished were they that he usually calls the Greeks in general Achæans. Afterwards they settled in the district of the Peloponnesus, called after them Achaia, and forming a narrow belt of coast on the south side of the Gulf of Corinth. From very early times a confederacy or league existed among the twelve towns of this region. After the death of Alexander the Great it was broken up, but was revived again, 280B.C., and from this time grew in power till it spread over the whole Peloponnesus. It was finally dissolved by the Romans, 147B.C., and after this the whole of Greece, except Thessaly, was called Achaia or Achæa. Achaia with Elis now forms a nomarchy of the kingdom of Greece. Pop. 254,728. Cf. Freeman,History of Federal Government in Greece and Italy, London, 1893.
Achæmenidæ(ak-ē-men′i-dē) a dynasty of ancient Persian kings, being that to which the great Cyrus belonged.
Achaia(a-kā′ya). SeeAchæans.
Achalzik. SeeAkhalzik.
Achard(a˙h′a˙rt), Franz Karl, a German chemist, born 1753, died 1821, principally known by his invention (1789-1800) of a process for manufacturing sugar from beetroot. In 1801 the first beet-sugar factory ever established was started by him in Silesia.
Achard(a˙-shär), Louis Amédée Eugène, born 1814, died 1875, French journalist, novelist, and playwright. He was best known as a novelist; wrote the novelsBelle Rose,La Chasse royale,Châteaux en Espagne,Robe de Nessus,Chaînes de fer, &c. HisLettres Parisienneswere published in 1838 under the pseudonym of Grimm.
Achates(a-kā′tēz), a companion of Æneas in his wanderings subsequent to his flight from Troy. He is always distinguished in Virgil'sÆneidby the epithetfidus, 'faithful', and has become typical of a faithful friend and companion.
Acheen,orAtchin(a˙-chēn′) (Du.Atjeh), a native State of Sumatra, with a capital of the same name, in the north-western extremity of the island, now nominally under Dutch administration. Though largely mountainous, it has also undulating tracts and low fertile plains. By treaty with Britain the Dutch were prevented from extending their territory in Sumatra by conquest; but this obstacle being removed, in 1871 they proceeded to occupy Acheen. It was not till 1879, however, after a great waste of blood and treasure, that they obtained a general recognition of their authority. But they have not been able to establish it firmly, and have hadto put down many determined risings, sometimes costing them losses both in men and guns. In the seventeenth century Acheen was a powerful State, and carried on hostilities successfully against the Portuguese, but its influence decreased with the increase of the Dutch power. The principal exports are rice and pepper. Area, 20,471 sq. miles; pop. 789,664.
Achelous(ak-e-lō′us) (nowAspropotămo), the largest river of Greece, rising on Mount Pindus, separating Ætolia and Acarnania, and flowing into the Ionian Sea. In Greek legend, Achelōus, the son of Oceanus and Tethys, was the river-god.
Achenbach(a˙′hen-ba˙ch), Andreas, was a distinguished German landscape and marine painter, born in 1815, died in 1910.
Achenbach,Oswald, born 1827, died 1905, brother of above, was also a distinguished landscape painter. Both are of the Düsseldorf school, and pupils of the famous painter Schadow.
AcheneAchene of Buttercup (magnified)E, Embryo. En, Endosperm. T, Testa and pericarp.
E, Embryo. En, Endosperm. T, Testa and pericarp.
Achene,orAchenium(a-kēn′, a-kē′ni-um), in botany, a small, dry carpel containing a single seed, the pericarp of which is closely applied but separable, and which does not open when ripe. It is either solitary, or several achenia may be placed on a common receptacle as in the buttercup.
Achensee,a lake in Tyrol, 20 miles north-east of Innsbruck and 3018 feet above sea-level. On its shores are beautiful villas and hotels frequented as summer resorts.
Acheron(ak′e-ron) (modernFanarioticos), the ancient name of several rivers in Greece and Italy, all of which were connected by legend with the lower world. The principal was a river of Thesprotia in Epirus, which passes through Lake Acherusia and flows into the Ionian Sea. Homer speaks of Acheron as a river of the lower world, and late Greek writers use the name to designate the lower world.
Acheulian,a term applied by archæologists to the late stage of Chellean civilization in the Pleistocene Age. It is named after St. Acheul in the Somme valley, where relics of it were found. The geological horizon, according to Professor James Geikie, is late Second Interglacial and Third Glacial periods.
Ach′iar,orAt′char,an Indian condiment made of the young shoots of the bamboo pickled.
Achievement(a-chēv′ment), in heraldry, a term applied to the shield of armorial bearings generally, or to a hatchment (q.v.).
Achill(ak′il), the largest island on the Irish coast, separated from the mainland of Mayo by a narrow sound, now bridged over. The chief occupation is fishing. The island is mountainous, has fine scenery, and is visited by many tourists, there being now a railway terminus here, and many recent improvements. Pop. nearly 7000.
Achillæ′a,the milfoil genus of plants.
Achilleion,famous castle at Corfu, which used to belong to the Empress Elizabeth of Austria. It was acquired by the ex-Kaiser William II, who bought it from the Archduchess Giséla, wife of Prince Leopold of Bavaria.
Achilles(a-kil′ēz), a Greek legendary hero, the chief character in Homer'sIliad. His father was Peleus, ruler of Phthia in Thessaly, his mother the sea-goddess Thetis. When only six years of age he was able to overcome lions and bears. His guardian, Cheiron the Centaur, having declared that Troy could not be taken without his aid, his mother, fearing for his safety, disguised him as a girl, and introduced him among the daughters of Lycomedes of Scyros. Her desire for his safety made her also try to make him invulnerable when a child by anointing him with ambrosia, and again by dipping him in the River Styx, from which he came out proof against wounds, all but the heel, by which she held him. His place of concealment was discovered by Odysseus (Ulysses), and he promised his assistance to the Greeks against Troy. Accompanied by his close friend, Patroclus, he joined the expedition with a body of followers (Myrmidons) in fifty ships, and occupied nine years in raids upon the towns neighbouring to Troy, after which the siege proper commenced. On being deprived of his prize, the maiden Briseïs, by Agamemnon, he refused to take any further part in the war, and disaster attended the Greeks. Patroclus now persuaded Achilles to allow him to lead the Myrmidons to battle dressed in his armour, and he having been slain by Hector, Achilles vowed revenge on the Trojans, and forgot his anger against the Greeks. He attacked the Trojans and drove them back to their walls, slaying them in great numbers, chased Hector, who fled before him three times round the walls of Troy, slew him, and dragged his body at his chariot-wheels, but afterwards gave it up to Priam, who came in person to beg for it. He then performed the funeral rites of Patroclus, with which theIliadcloses. He was killed in a battle at the Scæan Gate of Troy by an arrow from the bow of Paris which struck his vulnerable heel. In discussions on the origin of the Homeric poems the termAchilleidis often applied to those books (i, viii, and xi-xxii) of theIliadin which Achilles is prominent, and which some suppose to have formed the original nucleus of the poem. SeeIphigenia.
Achilles' Tendon,orTendon of Achilles,the strong tendon which connects the muscles of the calf with the heel, and which may be easily felt with the hand. The origin of the name will be understood from the above article.
Achilles Tatius(a-kil′ēz tā′shi-us), a Greek romance writer of the fifth centuryA.D., belonging to Alexandria; wrote a love story in 8 books calledLeucippē and Cleitophon.
Achimenes(a-kim′e-nēz), a genus of tropical American plants, with scaly underground tubers, nat. ord. Gesneraceæ, now cultivated in European greenhouses on account of their white, blue, and red flowers.
Achlamydeous(ak-la-mid′i-us), in botany, wanting the floral envelopes, that is, having neither calyx nor corolla, as the willow.
Achor(ā′kor), a disease of infants, in which the head, the face, and often the neck and breast become incrusted with thin, yellowish or greenish scabs, arising from minute, whitish pustules, which discharge a viscid fluid.
Achromat′ic(Gr.a, priv., andchrōma, chrōmatos, colour), in optics, transmitting colourless light, that is, not decomposed into the primary colours, though having passed through a refracting medium. A single convex lens does not give an image free from the prismatic colours, because the rays of different colour making up white light are not equally refrangible, and thus do not all come to a focus together, the violet, for instance, being nearest the lens, the red farthest off. If such a lens of crown-glass, however, is combined with a concave lens of flint-glass—the curvatures of both being properly adjusted—as the two materials have somewhat different optical properties, the latter will neutralize the chromatic aberration of the former, and a satisfactory image will be produced. Telescopes, microscopes, &c., in which the glasses are thus composed are calledachromatic.
Acid(Lat.acidus, sour), a name applied to a number of compounds, having more or less the qualities of vinegar (itself a diluted form of acetic acid). Their general properties are sour taste, the power of changing vegetable blues into reds, of evolving hydrogen in presence of magnesium, of decomposing chalk with effervescence, and of being in various degrees neutralized by alkalies. An acid has been defined as a compound of hydrogen, the whole or a part of which is replaceable by a metal when this is presented in the form of a hydroxide; beingmonobasic,dibasic, ortribasic, according to the number of replaceable hydrogen atoms in a molecule. SeeChemistry.
Acierage(ā′sē-ėr-āj), (Fr.acier, steel), a process by which an engraved copper-plate or an electrotype from an engraved plate of steel or copper has a film of iron deposited over its surface by electricity in order to protect the engraving from wear in printing. By this means an electrotype of a fine engraving, which, if printed directly from the copper, would not yield 500 good impressions, can be made to yield 3000 or more; and when the film of iron becomes so worn as to reveal any part of the copper, it may be removed and a fresh coating deposited so that 20,000 good impressions may be got.
Acipenser(as-i-pen′sėr), the genus of cartilaginous ganoid fishes to which the sturgeon belongs.
Aci Reale(ä′chē rā-ä′lā), a seaport of Sicily, north-east of Catania, a well-built town, with a trade in corn, wine, fruit, &c. Pop. 35,587.
A′cis,according to Ovid, a beautiful shepherd of Sicily, loved by Galatea, and crushed to death by his rival the Cyclops Polyphemus. His blood, flowing from beneath the rock which crushed him, was changed into a river bearing his name, and renowned for the coldness of its water. It has been identified as the Fiume di Jaci.
Aclin′ic Line(Gr. priv.a, klinō, to incline), the magnetic equator, an irregular curve in the neighbourhood of the terrestrial equator, where the magnetic needle balances itself horizontally, having no dip. SeeMagnetism.
Acne(ak′nē), a skin disease, consisting of small hard pimples, usually on the face, caused by congestion of the follicles of the skin.
AcolyteAcolyte
Acolytes(ak′o-līts), in the ancient Latin and Greek Churches, persons of ecclesiastical rank next in order below the subdeacons, whose office it was to attend the officiating priest. The name is still retained in the Roman Church. Cf. Duchesne,Christian Worship, its Origin and Evolution.
Aconcagua(a˙-kon-kä′gwa˙), a province, a river, and a mountain of Chile. The peak ofAconcagua, whose summit is just within the Argentine Republic, rises to the height of 23,080 feet, and is probably the highest mountain of the western hemisphere. Area of province, 5406 sq. miles. Pop. (1919), 132,165.
Ac′onite(Aconītum), a genus of hardy herbaceous plants, nat. ord. Ranunculaceæ, represented by the well-known wolf's-bane or monk's-hood, and remarkable for their poisonous properties and medicinal qualities, being used internally as well as externally in rheumatism, gout, neuralgia, &c.
Acon′itine,an alkaloid extracted from monk's-hood and some other species of aconite; used medicinally, though a virulent poison.
Aconquija(a˙-kon-kē′ha˙), a range of mountains in the Argentine Republic; the name also of a single peak, 17,000 feet high.
A′corn,the fruit of the different kinds of oak. The acorn-cups of one species are brought from the Levant under the name ofvalonia, and used in tanning.
Acorn-shell. SeeBalanus.
Ac′orus,a genus of plants, including the sweet-flag. SeeSweet-flagandCalamus.
Acos′ta,Gabriel, afterwards Uriel, a Portuguese of Jewish descent, born at Oporto in 1590, died by his own hand 1640. Brought up a Christian, he afterwards embraced Judaism. Having gone to Amsterdam, where he attacked the practices of the Jews, and denied the divine mission of Moses, he suffered much persecution at the hands of the Jews. He left an autobiography, published in 1687, under the titleExemplar Humanæ Vitæ. He is the hero of a novel,Die Sadducäer von Amsterdam, and of a tragedy,Uriel Acosta, both by Gutzkow.
Acotyle′dons,plants not furnished with cotyledons or seed-lobes. They include ferns, mosses, seaweeds, &c., and are also called flowerless plants or cryptogams.
Acousimeter,orAcoumeter(Gr.akouein, to hear, andmetron, measure), an instrument used to determine the acuteness of hearing. It consists of a small bar which gives a uniform sound when struck by a hammer.
Acoustics(a-kou′stiks), the science of sound. It deals with the production of sound, its propagation and velocity in various media; the reflection, refraction, and interference of sound waves; the properties of musical notes; and the general phenomena of such vibrations of elastic bodies as affect the organ of hearing.
In order that a sound may be heard, it is necessary that an uninterrupted series of particles of elastic matter should extend from the sounding body to our ear. Sound is propagated by a longitudinal wave-motion in the medium (gaseous, liquid, or solid), that is, the particles oscillate along the line in which the wave is travelling, giving rise to regular series of condensations and rarefactions.
The velocity of sound varies directly as the square root of the elasticity, and inversely as the square root of the density, of the medium in which it is propagated. The velocity of sound in air at 0° C. is 330.6 metres per second, or 1085 feet per second; in water 1.49 kilometres per second, or 0.926 mile per second; in copper 5.01 kilometres per second, or 3.12 miles per second.
The intensity of sound varies inversely as the square of the distance from the sounding body. Recently sound-ranging instruments have been produced by means of which the position of a gun can be determined.
A note produced by a musical instrument consists of afundamentalof a certain frequency, together with a number ofovertonesof various higher frequencies and much smaller amplitude. Thetimbreof a note depends on the overtones present, theloudnessdepends on the amplitude of the vibrations, and thepitchdepends on the frequency. The musical scale consists of eight notes, C D E F G A B C, whose frequencies are in the proportion of the numbers 24, 27, 30, 32, 36, 40, 45 and 48. The interval between two notes is the ratio of the frequency of the higher note to the frequency of the lower note. In order that the intervals may be the same in all keys, a tempered scale is used in music. (See Table, p. 25.)
Bibliography: Lord Rayleigh,Theory of Sound; H. Smith,The Making of Sound in the Organ and Orchestra; J. W. Capstick,Sound(Cambridge Natural Science Manuals); E. H. Barton,Text-book of Sound.
Acqui(a˙k′wē), a town of Northern Italy, 18 milesS.S.W.of Alessandria, a bishop's see. It has warm sulphurous baths, which were known to the Romans, and which still attract a great many visitors. Pop. 16,500.
Acre,a standard British measure of land, also used in the colonies and the United States. The imperial statute acre consists of 4840 sq. yards, divided into 4 roods. The old Scotch acre contains 6146.8 sq. yards, the old Irish acre 7840 sq. yards.
Acre(ā′kėr) (ancientAcchoandPtolemais), a seaport of Syria, in Northern Palestine, on the Bay of Acre, early a place of great strength and importance. Taken from the Saracens under Saladin in 1191 by Richard I of England and Philip of France; bravely defended by the Turks, assisted by Sir Sidney Smith, in 1799 against Napoleon; in 1832, taken by Ibrahim Pasha; in 1840, bombarded by a British, Austrian, and Turkish fleet, and restored to the Sultan of Turkey. The town was occupied by British troops under General Allenby in September, 1918. Pop. 10,000.
MUSICAL INTERVALS.—SeeAcoustics
NOTES OF PERFECT DIATONIC SCALE (with their Frequencies)
PERFECT DIATONIC SCALES (Transition to Key of Dominant)
Example—Key of C to Key of G
Acri(ā′krē), a town of S. Italy, province of Cosenza. Pop. 4000.
Ac′rita(Gr.akritos, undistinguishable, doubtful), a name sometimes given to the animals otherwise called Protozoa.
Acroceph′ali,tribes of men distinguished by pyramidal or high skulls.
Acrocerau′nia(thunder-smitten peaks) (nowCape GlossaorLinguetta), a promontory of Western Greece, in Epirus, running into the Adriatic.
Acrocorin′thus,a steep rock in Greece, nearly 1900 feet high, overhanging ancient Corinth, and on which stood the acropolis or citadel, the sacred fountain of Pirēnē being also here. This natural fortress has proved itself of importance in the modern history of Greece.
Ac′rogens(-jenz), lit. summit-growers, a term applied to the ferns, mosses, and lichens (cryptogams), as growing by extension upwards, in contradistinction to endogens and exogens.
Ac′rolith,an early form of Greek statuary in which the head, hands, and feet only were of stone, the trunk of the figure being of wood draped or gilded.
Acrop′olis(Gr.akros, high, andpolis, a city), the citadel or chief place of a Grecian city, usually on an eminence commanding the town. That of Athens contained some of the finest buildings in the world, such as the Parthenon, Erechthēum, &c.
Acros′tic,a poem of which the first or last, or certain other, letters of the line, taken in order, form some name, motto, or sentence. A poem of which both first and last letters are thus arranged is called a double acrostic. In Hebrew poetry, the term is given to a poem of which the initial letters of the lines or stanzas were made to run over the letters of the alphabet in their order, as inPsalmcxix.—Acrostics have been much used in complimentary verses, the initial letters giving the name of the person eulogized. They were very popular among French poets of the sixteenth and seventeenth centuries. In modern times Edgar Allen Poe has written quite remarkable acrostic verses.
Act,in special senses: (1) In dramatic poetry, one of the principal divisions of a drama, in which a definite and coherent portion of the plot is represented; generally subdivided into smaller portions calledscenes. The Greek dramas were not divided into acts. The dictum that a drama should consist of five acts was first formally laid down by Horace, and is generally adhered to by modern dramatists in tragedy. In comedy, especially since the time of Molière, more freedom is allowed, and a division into two or three acts is common.—(2) Something formally done by a legislative or judicial body; a statute or law passed.—(3) In universities, a thesis maintained in public by a candidate for a degree. SeeAct of God,of Parliament,of Settlement.
Acta Diur′na(Lat., proceedings of the day), a daily Roman newspaper which appeared under both the republic and the empire.
Actæ′a.SeeBaneberry.
Actæ′on,in Greek mythology, a great hunter, turned into a stag by Artĕmis (Diana) for looking on her when she was bathing, and torn to pieces by his own dogs.
Acta Erudito′rum(Lat., acts of the learned), the first literary journal that appeared in Germany (1682-1782). It was started by Otto Mencke, after the model of theJournal des Savants. Among the contributors, the most distinguished was Leibnitz.
Acta Sanctorum(Lat., acts of the saints), a name applied to all collections of accounts of ancient martyrs and saints, both of the Greek and Roman Churches, more particularly to the valuable collection begun by John Bolland, a Jesuit of Antwerp, in 1643, and which, being continued by other divines of the same order (Bollandists), now extends to sixty volumes, the lives following each other in the order of the calendar.
Actin′ia,the genus of animals to which the typical sea-anemones belong. SeeSea-anemone.
Ac′tinism,the property of those rays of light which produce chemical changes, as in photography, in contradistinction to the light rays and heat rays. The actinic property or force begins among the green rays, is strongest in the violet rays, and extends a long way beyond the visible spectrum.
Actinium,an element or elementary substance obtained in minute quantities in connection with the study of radioactivity. It was discovered by Debierne in 1899. In 1902 Giesel discovered another substance which he calledemanium, and which was considered to be identical withactinium. Marckwald, however, came to the conclusion that these two substances are not identical but closely related to each other. SeeRadium,Chemistry.
Actin′olite,a mineral nearly allied to hornblende.
Actinom′eter,an instrument for measuring the intensity of the sun's actinic rays. SeeActinism.
Actinozo′a(lit. ray-animals), a class of animals belonging to the sub-kingdom Cœlenterata, and including sea-anemones, corals, &c., all having rayed tentacles round the mouth.
Action,the mode of seeking redress at law for any wrong, injury, or deprivation. Actions are divided into civil and criminal, the former again being divided into real, personal, and mixed.
Ac′tium(nowLa Punta), a promontory onthe western coast of Northern Greece, not far from the entrance of the Ambracian Gulf (Gulf of Arta), memorable on account of the naval victory gained here by Octavianus (afterwards the Emperor Augustus) over Antony and Cleopatra, 2nd Sept., 31B.C., in sight of their armies encamped on the opposite shores of the Ambracian Gulf. Soon after the beginning of the battle Cleopatra escaped with sixty Egyptian ships, and Antony basely followed her, and fled with her to Egypt. The deserted fleet was not overcome without making a brave resistance. Antony's land forces soon went over to the enemy, and the Roman world fell to Octavianus. In 1538 a victory was gained at Actium by the Turks over the Spanish and Venetian fleets.
Act of God,a legal term defined as "a direct, violent, sudden, and irresistible act of nature, which could not, by any reasonable cause, have been foreseen or resisted". No one can be legally called upon to make good loss so arising.
Act of Parliament,a law or statute proceeding from the Parliament of the United Kingdom passed in both houses, and having received the royal assent. Before it is passed it is aBilland not an Act. Acts are either public or private, the former affecting the whole community, the latter only special persons and private concerns. The whole body of public Acts constitutes thestatute law. An Act of Parliament can only be altered or repealed by the authority of Parliament. Acts are usually cited in this way, "13 and 14 Vict. c. (or chap.) 21", which means the 21st Act in succession passed in year 13th-14th of the queen's reign (that is, 1850). Short titles, such as "the Merchant Shipping Act, 1854", are also used. Up to the time of Edward I Acts of Parliament were in Latin; then French was introduced, and for some time was exclusively employed. It was not till Henry VII's reign that all Acts were in English.
Act of Settlement,an Act passed by the English Parliament in 1700, by which the succession to the throne of the three kingdoms, in the event of King William and Princess (afterwards Queen) Anne dying without issue, was settled on the Princess Sophia, electress of Hanover, and the heirs of her body, being Protestants. The Princess Sophia was the youngest daughter of Elizabeth, Queen of Bohemia, daughter of James I. By this act George I, son of the Princess Sophia, succeeded to the crown on the death of Queen Anne.—Another Act of Settlement was that by which, under Cromwell's government, a new allotment was made of almost all landed property in Ireland, in 1652.
Act of Toleration,an Act of Parliament Passed in 1689, by which Protestant dissenters from the Church of England, on condition of their taking the oaths of supremacy and allegiance, and repudiating the doctrine of transubstantiation, were relieved from the restrictions under which they had formerly lain with regard to the exercise of their religion according to their own forms.
Act of Uniformity,an English Act passed in 1662, enjoining upon all ministers to use theBook of Common Prayeron pain of forfeiture of their livings. SeeNonconformity.