Chapter XIII: Part 13

EQUATION OF PAYMENTS, an arithmetical rule for the purpose of ascertaining at what time it is equitable that a person should make payment of a whole debt which is due in different parts, payable at different times.

EQUATION OF THE CENTRE, the difference between the actual heliocentric longitude of a planet revolving in an elliptic orbit and that which it would have at the same instant if it revolved in a circular orbit. It is zero at perihelion and aphelion.

EQUATION OF TIME, the difference between mean and apparent time, or the difference of time as given by a clock and as given by a sun-dial, arising chiefly from the varying velocity of the earth in its orbit and the eccentricity of the orbit. The sun and the clock agree four times in the year; the greatest difference between them at the beginning of November is fully sixteen minutes. See _Day_.

EQUA'TOR, that great circle of our globe every point of which is 90deg from the poles. All places which are on it have invariably equal days and nights. Our earth is divided by it into the northern and southern hemispheres. From this circle is reckoned the latitude of places both north and south. There is also a corresponding celestial equator in the plane of the terrestrial, an imaginary great circle in the heavens the plane of which is perpendicular to the axis of the earth. It is everywhere 90deg distant from the celestial poles, which coincide with the extremities of the earth's axis, supposed to be produced to meet the heavens. During his apparent yearly course the sun is twice in the celestial, that is, vertically over the terrestrial equator, on 21st March and 23rd September. Then the day and night are equal all over the earth, whence the name _equinox_.--The _magnetic equator_ is a line at every point of which the vertical component of the earth's magnetic force is zero; that is to say, a dipping needle carried along the magnetic equator remains horizontal. It is hence also called the _aclinic line_. It has a slightly devious course, but upon the whole keeps fairly near the geographical equator.

EQUATO'RIAL, an astronomical instrument contrived for the purpose of directing a telescope upon any celestial object, and of keeping the object in view for any length of time, notwithstanding the diurnal motion of the earth. For these purposes a principal axis resting on firm supports is mounted exactly parallel to the axis of the earth's rotation, and consequently pointing to the poles of the heavens, being fixed so as to turn on pivots at its extremities. To this there is attached a telescope moving on an axis of its own in such a way that it may either be exactly parallel to the other axis, or at any angle to it; when at right angles it points to the celestial equator. The two axes carry graduated circles, with the help of which, even during the day, the telescope can be pointed to any star whose declination and right ascension are known. By means of clockwork the instrument is given such a motion round its principal axis that the star is kept stationary in the field of view.

EQ'UERRY, in Britain, the name of certain officers of the royal household, in the department of the Master of the Horse, whose duties consist in attendance when the sovereign rides abroad. Equerries also form part of the establishments of the members of the royal family.

EQUESTRIAN ORDER, the order of 'Knights' in ancient Rome. The _equites_ or knights originally formed the cavalry of the army. They are said by Livy to have been instituted by Romulus, who selected 300 of them from the three principal tribes. About the time of the Gracchi (123 B.C.) the equites became a distinct order in the state, and the judges and the farmers of the revenue were selected from their ranks. They held their position in virtue of a certain property qualification, and towards the end of the Republic they possessed much influence in the state. They had particular seats assigned to them in the circus and theatre, and the insignia of their rank, in addition to a horse, were a gold ring and a robe with a narrow purple border (the _clavus angustus_). Under the later emperors the order grew less influential, and finally disappeared.

EQ'UIDAE, the horse family, a division of the odd-toed (perissodactyle) Ungulates or hoofed mammals. There is but one existing genus, Equus, distinguished by the possession of a mane; hard pads (callosities) on the inner side of each fore-limb (and sometimes of the hind-limb); a single functional digit (the third or middle one) terminating in a large curved hoof; a simple stomach; 44 teeth, including 12 incisors with pitted crowns, 4 canines (tushes) reduced in the female, and 28 grinding teeth with broad crowns, except the first (wolf tooth), which is rudimentary. The forms included are horses, asses, and zebras; the first being distinguished from the others by the presence of callosities ('chestnuts') on the hind-limbs as well as the fore. The domesticated horse (_E. caballus_) has a large flat tail abundantly hair-clad, and is not known with certainty in the wild state, though possibly the tarpan of South Russia (Tartary) may represent the original stock. Another candidate for this honour is the small wild species (_E. przewalskii_) native to the deserts of Central Asia. The domestic ass (_E. asinus_) is related to a number of wild species, such as the onager (_E. onager_) of South Asia, the kiang (_E. hemionus_) of Tibet, and two African species (_E. africanus_ and _E. somalicus_). The striped zebras are purely African, and four species are generally recognized--the common or mountain zebra (_E. zebra_), Burchell's zebra (_E. burchelli_), Grevy's zebra (_E. grevyi_), and the quagga (_E. quagga_). The geological record enables us to derive horses from a small plantigrade five-toed form (Phenacodus), by gradual increase in size, complication of teeth, loss of digits, and elongation of limbs, to the unguligrade condition.

EQUILIB'RIUM, in statics, the condition when a body is acted on by two or more forces which balance one another. The body may be either at rest or moving with uniform speed in a straight line. In the first case, when the body, being slightly moved out of any position, always tends to return to its position, that position is said to be one of _stable equilibrium_; when the body, after a slight displacement, tends to move away from its previous position, the body is in _unstable equilibrium_. If, after displacement, the body tends to remain at rest, its state is one of _neutral equilibrium_.

EQUINOC'TIAL, in astronomy, the circle in the heavens otherwise known as the celestial equator. When the sun is on the equator, there is equal length of day and night over all the earth: hence the name _equinoctial_.--_Equinoctial gales_, storms which have been supposed to take place about the time of the sun's crossing the equator, that is, at the vernal and autumnal equinoxes, in March and September.--_Equinoctial points_ are the two points wherein the celestial equator and ecliptic intersect each other; the one, the first point of Aries, is called the _vernal_ point; and the other, in Libra, the _autumnal_ point. These points move backward or westward at the rate of 50" of arc in a year. This is called the precession of the equinoxes.

EQ'UINOX, one of the equinoctial points. The term is also applied to the dates at which the sun passes through them, viz. 21st March and 23rd September, when day and night are of equal length all over the world. See _Day_; _Earth_; _Equinoctial_; _Seasons_.

EQUISETALES, a group of Pteridophytes, represented at the present day only by the genus Equisetum (q.v.). It was much more prominent in the Carboniferous flora, in which large woody horse-tails (Calamites) played an important part.

EQUISE'TUM, a genus of vascular cryptogamous plants with hollow jointed stems, type of the group Equisetales, growing in wet places, and popularly called _horse-tails_.

EQ'UITY (Lat. _aequus_, fair, equal), in English law, the system of supplemental law administered in certain courts, founded upon defined rules, recorded precedents, and established principles, the judges, however, liberally expounding and developing them to meet new exigencies. While it aims at assisting the defects of the common law, by extending relief to those rights of property which the strict law does not recognize, and by giving more ample and distributive redress than the ordinary tribunals afford, equity by no means either controls, mitigates, or supersedes the common law, but rather guides itself by its analogies, and does not assume any power to subvert its doctrines. The Court of Chancery was formerly in England the especial court of equity, but large powers were by the Judicature Act of 1873 given to all the divisions of the Supreme Court to administer equity, although many matters of equitable jurisdiction are still left to the chancery division in the first instance.--BIBLIOGRAPHY: F. T. White and O. O. Tudor, _Leading Cases in Equity_; C. Thwaites, _Student's Guide to Equity_.

EQUITY OF REDEMPTION, in law, the advantage allowed to a mortgager of a reasonable time to redeem an estate mortgaged, when it is of greater value than the sum for which it is mortgaged.

EQUIV'ALENT, in chemistry, the number of parts by weight of an element which will combine with or displace 8 parts by weight of oxygen or 1.008 parts by weight of hydrogen.

ERANTHIS. See _Winter Aconite_.

['E]RARD, S['e]bastien, a celebrated musical-instrument maker, born at Strasbourg in 1752, died 1831. He went to Paris at the age of eighteen, and in concert with his brother, Jean Baptiste, produced pianofortes superior to any that had previously been made in France. He afterwards established a manufactory in London, and made considerable improvements in the mechanism of the harp.

ERASIS'TRATUS, an ancient Greek physician and anatomist, said to have been a grandson of Aristotle. He lived in the third century before the Christian era, and was court physician of Seleucus Nicator, King of Syria. He was the first who systematically dissected the human body, and his description of the brain and nerves is much more exact than any given by his predecessors. He classified the nerves into nerves of sensation and of locomotion, and, it is said, almost stumbled upon the discovery of the circulation of the blood. Of his works only the titles and some fragments remain.

ERAS'MUS, Desiderius, a Dutch scholar, one of the greatest of the Renaissance and Reformation period, born at Rotterdam in 1467, died in 1536. His original name was Gerard, but this he changed according to a fashion of the time. After the death of his parents, whom he lost in his fourteenth year, his guardians compelled him to enter a monastery; and at the age of seventeen he assumed the monastic habit. The Bishop of Cambrai delivered him from this constraint. In 1492 he travelled to Paris to perfect himself in theology and literature. He became the instructor of several rich Englishmen (from one of whom--Lord Mountjoy--he received a pension for life), and accompanied them to England in 1497, where he was graciously received by the king. Returning soon after to the Continent, he took his doctor's degree, was relieved from his monastic vows by dispensation from the Pope, and published several of his works. In 1510 he returned to England, wrote his _Praise of Folly_ while residing with Sir Thomas More, and was appointed Lady Margaret professor of divinity and Greek lecturer at Cambridge. In 1514 he returned to the Continent and lived chiefly at Basel, where he died. To extensive learning Erasmus joined a refined taste and a delicate wit, and rendered great and lasting service to the cause of reviving scholarship. Although Erasmus took no direct part in the Reformation, and was reproached by Luther for lukewarmness, he attacked the disorders of monasticism and superstition, and everywhere promoted the cause of truth. A humanist rather than a reformer or a theologian, he waged war upon ignorance and superstition. He edited various classics, the first edition of the Greek Testament from MSS. (with Latin translation), &c., but his best-known books are the _Encomium Moriae_ (Praise of Folly) and his _Colloquies_. His letters are very valuable in reference to the history of that period.--BIBLIOGRAPHY: S. Knight, _Life of Erasmus_; C. Butler, _Life of Erasmus_; E. F. H. Capey, _Life of Erasmus_; P. S. Allen, _The Age of Erasmus_.

ERAS'TUS (Gr. _erastos_, lovely, translation of Ger. _Lieber_), the learned name of Thomas Lieber, a Swiss physician, who maintained the opinions from which the well-known epithet of _Erastian_, as now used, is derived. He was born at Baden in 1523, and died at Basel 1584. He was successively professor of medicine at Heidelberg, and of ethics at Basel. In his writings he maintained the complete subordination of the ecclesiastical to the secular power; and denied to the Church the right to exclude any one from Church ordinances, or to inflict excommunication.

ER'ATO, in Greek mythology, one of the nine Muses, whose name signifies loving or lovely. She presided over lyric and especially amatory poetry, and is generally represented crowned with roses and myrtle, and with the lyre in the left hand and the plectrum in the right in the act of playing.

ERATOS'THENES, an ancient Greek astronomer, born at Cyrene, in Africa, 276 B.C., died about 194 B.C. He was librarian at Alexandria, and gained his greatest renown by his investigations of the size of the earth. He rendered much service to the science of astronomy, and first observed the obliquity of the ecliptic. Of the writings attributed to him one only remains complete--_Katasterismoi_--which treats of the constellations.

ER'BIUM, a rare metal found along with yttrium, terbium, and other rare elements in some rare minerals. Its properties are but little known. It was discovered by Mosander in 1843.

ERCILLA Y ZUNIGA (er-thil'y[.a] [=e] th[:o]-ny[=e]'g[.a]), Don Alonso de, Spanish soldier and poet, born 1533, died 1595. He became page to the Infant Don Philip, accompanied him on his travels, and in 1554 went with him to England, on the occasion of his marriage with Queen Mary. After this he fought against the Araucanians of South America (Chile), and his epic _La Araucana_ is based on the events of this war. It is written in excellent Spanish, and occupies an honourable position in the national literature. The first fifteen cantos were published in 1569, and the continuations, thirty-seven cantos, appeared in 1578 and 1589.

ERCKMANN-CHATRIAN (sh[.a]t-ri-[:a][n.]), the joint name of two French-Alsatian writers of fiction. ['E]mile Erckmann, born at Pfalzburg 1822, studied law at Paris, and died in 1899. Alexandre Chatrian, born near Pfalzburg in 1826, died in 1890, was for some time teacher in the Pfalzburg College. They formed a literary partnership in 1847, but it was not till the appearance of _L'Illustre Docteur Math['e]us_ in 1859 that success attended them. Among their most popular books are: _L'Ami Fritz_, _Madame Th['e]r[`e]se_, _Histoire d'un Conscrit de 1813_, _L'Histoire d'un Paysan_, and _Waterloo_, most of which have been translated into English. Their drama _Le Juif Polonais_ was made famous by Sir Henry Irving under the name of _The Bells_.

ERDMANN, Johann Eduard, German philosopher, born 1805, died 1892. He studied theology at Dorpat and Berlin; in 1829 became a clergyman, but in 1832 returned to Berlin and took his degree in philosophy. In 1836 he became professor extraordinary of philosophy at Halle, being appointed ordinary professor in 1839. He wrote numerous philosophical works, mostly characterized by Hegelian tendencies, including: _Body and Soul_, _Nature and Creation_, _Outlines of Psychology_, _Outlines of Logic and Metaphysics_, _Psychological Letters_, and _Belief and Knowledge_. His greatest work is his _Outlines of the History of Philosophy_, which has been translated into English (3 vols., 1889).

ER'EBUS, in Greek mythology, the son of Chaos and Darkness, and father of Aether and Hemera (day). The name Erebus was also given to the infernal regions.

ER'EBUS, MOUNT, a volcano of the antarctic regions in S. Victoria Land; height, 12,400 feet; discovered by Ross, 1841.

ERECHTHEUS (e-rek'th[=u]s), in Greek mythology, a mythical king of Athens to whom a fine temple, the _Erechth[=e]um_, was built on the Acropolis. In some representations of him he is depicted as half snake, so that he was one of the autochthones, the earth-born ancestors of the Athenians.

ERECTION, LORDS OF, in Scots history, those private owners into whose hands the ecclesiastical estates belonging to the clergy had passed during the religious changes of the Reformation period.

ER'FURT (Lat. _Erfordia_, ford of Erpe, its legendary founder), an important town in the Prussian province of Saxony, on the River Gera, formerly a fortress with two citadels, now given up as such. It has a fine cathedral dating from the thirteenth century and several handsome Gothic churches. The university, founded in 1378 and suppressed in 1816, was long an important institution. There is still an academy of science and a library with 60,000 volumes. The monastery (now an orphanage) was the residence of Luther from 1501 to 1508. Erfurt is a busy industrial town and is in a very flourishing condition. The industries are varied, including clothing, machinery, leather, shoes, ironmongery, and chemicals. Flower-growing is extensively carried on in the neighbourhood, plants and seed being produced for sale in great quantities. Pop. 123,550.

1, Spanish ergot. 2, Russian ergot.]

ER'GOT, the altered grain of rye and other grasses caused by the attack of an ascomycetous fungus called _Claviceps purpurea_. The grain is replaced by a dense fungoid tissue (sclerotium) largely charged with an oily fluid. In its perfect state this germinates and produces the Claviceps fructification. When diseased rye of this kind is eaten in food for some time, it sometimes causes death by a kind of mortification called dry gangrene. Ergot is used in obstetric practice to promote the contraction of the uterus.

ERICA (e-r[=i]'ka), the heaths, a large genus of branched rigid shrubs, type of the nat. ord. Ericaceae, most of which are natives of South Africa, a few being found in Europe and Asia. The leaves are narrow and rigid; the flowers are globose or tubular, and four-lobed. Five species are found in Britain.

ERICACEAE, a nat. ord. of gamopetalous Dicotyledons. Representative genera: Calluna, Erica, Rhododendron.

ERICHSEN (er'ik-sen), Sir John Eric, surgeon, born 1818, died in 1890. He was the son of a Copenhagen merchant, but spent nearly all his life in England. He studied at University College, London, became a member of the Royal College of Surgeons in 1839, a fellow in 1845, and in 1850 professor of surgery and hospital surgeon at University College. In 1865 he succeeded Quain as professor of clinical surgery in the same college, but retired in 1875. Appointed president of University College in 1887, he also held that post till his death. He was chief surgeon extraordinary to Queen Victoria, and in 1895 was made a baronet. His most important work was his _Science and Art of Surgery_ (1853), which has gone through many editions, and has been translated into several languages. He also published a volume on _Concussion of the Spine_ (1875).

ER'ICSSON, John, engineer, born in Sweden 1803, died in 1889. He served for a time in the Swedish army; removed to London in 1826, and to New York in 1839. He is identified with numerous inventions and improvements in steam machinery and its applications. His chief inventions are his caloric engine, the screw propeller (1836), which has revolutionized navigation, and his turret-ships, the first of which, the _Monitor_, distinguished itself in the American Civil War, and inaugurated a new era in naval warfare. He afterwards devoted himself to studies of the earth's motion and the intensity of solar heat.

ERIDANUS, the River Eridanus (modern Po), one of the constellations of the ancient astronomy, in which Ptolemy catalogued thirty-four stars. Appropriately to its name, it covers a large expanse of the heavens, its northern portion, just to south-west of Orion, reaching the celestial equator. The part visible in our latitudes does not contain bright stars, but at the southern extremity is the first-magnitude Achernar, a conspicuous object to southern observers.

ERIE ([=e]'ri), one of the great chain of North American lakes, between Lakes Huron and Ontario, about 265 miles long, 63-1/2 miles broad at its centre, from 40 to 60 fathoms deep at the deepest part; area, 6900 sq. miles. The whole of its southern shore is within the territory of the United States, and its northern within that of Canada. It receives the waters of the upper lakes by Detroit River at its south-western extremity, and discharges its waters into Lake Ontario by the Niagara River at its north-east end. The Welland Canal enables vessels to pass from it to Lake Ontario. It is shallow compared with the other lakes of the series, and is subject to violent storms. The principal harbours are those on the United States side--Buffalo, Erie, and Cleveland.

ERIE, a city, Pennsylvania, United States, an important railway and commercial centre on the southern shore of Lake Erie. There are numerous ironworks (including foundries, rolling-mills, and blast-furnaces), petroleum refineries, breweries, tanneries, and wood-working factories. The harbour is one of the best on the lake. Pop. 76,600.

ERIE CANAL, the largest in the United States, serving to connect the great lakes with the sea. It begins at Buffalo on Lake Erie, and extends to the Hudson at Albany. It is 363 miles long; has in all 72 locks; a surface width 70 feet, bottom width 42 feet, and depth 7 feet. It is carried over several large streams on stone aqueducts; cost nearly L2,000,000, and was opened in 1825. The navigation is free.

ERIGENA (e-rij'e-na), Joannes Scotus (_Scotus_, Scot, and _Erigena_, Irish-born), an eminent mediaeval scholar and metaphysician, probably born of Scotch parentage in Ireland about 800-810, died in France about 875. He spent a great part of his life at the court of Charles the Bald of France, and was placed at the head of the school of the palace. The king further imposed upon him the double task of translating into Latin the Greek works of the pseudo Dionysius the Areopagite, and of composing a treatise against Godeschale on _Predestination and Free-will_. This treatise, and another, _De Divisione Naturae_, contained many views in opposition to the teachings of the Church. They were condemned by the Councils of Valencia in 855 and of Langres in 859, and Pope Nicholas I demanded the immediate disgrace of the culprit. His subsequent history is not known.--Cf. Gardner, _Studies in John the Scot_.

ERIN'NA, a Greek poetess who lived about 600 B.C. She is said to have been an intimate friend of Sappho, and died at the age of eighteen. She acquired a high reputation for poetry, and her chief work was called _Elakat[=e]_ (The Distaff), of which nothing has come down to us. An epitaph or two which are still extant, and believed by some to be hers, are by others deemed spurious.

ERIODEN'DRON, the wool tree, a genus of plants, nat. ord. Malvaceae (mallows). There are eight species natives of America, but one belongs to Asia and Africa. The species are noble plants, growing from 50 to 100 feet high, having palmate leaves, and red or white flowers. The woolly coat of the seeds of some of the species is used in different countries for stuffing cushions and similar purposes.

ERIS, in Greek mythology, the goddess of discord, the sister of Ares, and, according to Hesiod, daughter of Nyx (night). Not being invited to the marriage of Peleus, she revenged herself by means of the _apple of discord_.

ER'ITH, a town of England, in Kent, on the Thames, about 14 miles east of London, a pleasant summer resort. Pop. 27,755.

ERITRE'A, or ERYTHRAE'A (from Gr. _erythros_, red, referring to the Red Sea), the official name of an Italian colonial possession stretching along the African shore of the Red Sea, and between it and Abyssinia, from the Egyptian coast territory to the French territory of Obok, at the Strait of Bab-el-Mandeb. The coast-line is about 670 miles in length, the area of the colony about 45,800 sq. miles. Pop., largely nomadic, about 450,000. The chief town is Massowah.

ER'IVAN, a fortified city in Armenia, formerly the capital of a Russian government of the same name in Transcaucasia, on the Sanga, north of Mount Ararat. It has a citadel, barracks, a cannon foundry, and some manufactures. The Armenian Republic of Erivan was constituted in May, 1918. Pop. 34,000. The former Russian government of Erivan had an area of 10,725 sq. miles, and a pop. of 970,000.

ERLANG'EN, a town of Bavaria, 10 miles N.N.W. of N[:u]rnberg. The Protestant university, founded in 1743, is the chief institution. The industries include cotton spinning and weaving, mirrors, hosiery, gloves, and combs. Pop. 24,874.

ERLAU, or EGER, a town, Hungary, on the Eger, 65 miles E.N.E. of Budapest. It has sundry manufactures; and the red wines of the district, esteemed the best in Hungary, are largely exported. Pop. 28,050.

ERL-KING, the English form of the name given in German and Scandinavian poetical mythology to a personified natural power which devises and works mischief, especially to children. Goethe's celebrated poem _Der Erlk[:o]nig_ (literally 'elf-king') has rendered this malicious spirit universally known.

ER'MINE, the stoat (_Putorius ermineus_), a mammal of the weasel family widely distributed through the northern parts of both hemispheres, with a considerable range to the south. It is not generally known that the ermine and stoat are the same. In winter, in cold countries or severe seasons, the fur changes from a reddish-brown to a yellowish-white, or almost pure white, under which shade the animal is recognised as the ermine. In both states the tip of the tail is black. Its fur is short, soft, and silky, the best skins being brought from Russia, Sweden, and Norway. It is in great request, and was formerly one of the insignia of royalty, and is still used by judges. When used as linings of cloaks the black tuft from the tail is sewed to the skin at irregular distances. Stoats are among the enemies of the poultry-keeper, but by keeping down small rodents they benefit agriculture to a considerable extent.--In heraldry, ermine is one of the furs, represented with its peculiar spots black on a white ground.

ERNE ([.e]rn), the name often given to all the eagles of the genus Haliaetus, but more specifically to the white-tailed sea-eagle.

ERNE, LOUGH, a lake, Ireland, County Fermanagh, consisting of a north or lower, and a south or upper lake (with the town of Enniskillen between), connected by a narrow winding channel, and properly forming only expansions of the River Erne. Its entire length is about 40 miles; average breadth, 6 miles. It contains numerous small islands, and is well stocked with fish.--The River Erne rises in Lough Gowna, in the county of Longford, flows through Loughs Oughter and Erne, and falls into Donegal Bay below Ballyshannon. Length, 72 miles.

ERNEST AUGUSTUS, King of Hanover and Duke of Cumberland, the fifth son of George III, born 1771, died 1851. In 1799 he was created Duke of Cumberland, in England, and became a field-marshal in the British army. On the death of William IV in 1837 he ascended the throne of Hanover, in consequence of the succession to the sovereignty of that country being limited to heirs male. He was succeeded by his son, George V, the last of the Hanoverian kings.

EROS, an asteroid discovered in Aug., 1898. It completes its orbit in 642 days, and has a mean distance from the sun of 135-1/2 million miles, or 6 million less than that of Mars, and was the first to be discovered of the class of minor planets which come within the orbit of Mars. It can approach at times to 13-1/2 million miles from the earth. It is supposed to have a diameter of 20 miles or less.

EROSION THEORY, in geology, the theory, now held by all geologists, that valleys are, in the great majority of cases, due to the wearing influences of subaerial agents, such as rivers and glaciers, as opposed to the theory which regards them as the result of fissures in the earth's crusts produced by strains during its upheaval.

EROT'IC (from the Gr. _er[=o]s_, love), relating to love.--_Erotic poetry_, amatory poetry.--The name of _erotic_ writers has been applied, in Greek literature, particularly to a class of romance writers, and to the writers of the _Milesian Tales_.

ERRAT'ICS, OR ERRATIC BLOCKS, in geology, boulders or large masses of angular rock which have been transported to a distance from their original positions by the action of ice during a glacial period. Thus on the slopes of the Jura Mountains immense blocks of granite are found which have travelled 60 miles from their original situation. Similarly, masses of Scottish and Lake-district granites and of Welsh rocks (some of which weigh several tons) occur not uncommonly in the surface soil of the Midland counties of England.

ERROMAN'GO, OR ERROMAN'GA, one of the more important of the New Hebrides Islands, with an area of about 400 sq. miles, hilly and not very fertile, but with spots well cultivated. Several missionaries have been murdered by the natives--including the missionary John Williams--but perhaps half of the 2500 natives are now Christians.

ERRORS OF OBSERVATION. In scientific measurements, objects and instruments alike are so constituted that numerical results can only be approximate. We have to find the value of some quantity, not exactly, but to so many significant figures. Even so, when a number of measurements are made of the same quantity, it regularly happens that different values are obtained, the difference between a value as obtained and the true value being called an _error of observation_. It remains to combine the various measurements in such a way as to obtain the best result which they are capable of yielding.

The usual method is to take the arithmetic mean of the values obtained as the correct value. It is also customary in careful work to state the average deviation of the observed values from the mean. For example, various experimenters found the following numbers for the charge on an electron: 4.67, 4.77, 4.65, 4.79, 4.69. Here the _mean_ is 4.71, and the average _deviation_ from the mean, taken without regard to algebraic sign, is .05. The final result is stated as 4.71 +/- .05. The ambiguous term +/- .05 is sometimes called the probable error. The smaller the probable error, the more reliable is the mean result.

A case of much practical importance occurs when the results obtained by two distinct methods differ by greater amounts than can be accounted for by the uncertainty of either result. In this case there must be a _constant error_ present in at least one of the sets of measurements. Recognition of a constant error has occasionally led to an important discovery; for instance, the hint which led to the detection of argon in the atmosphere came from the observed discrepancy in the densities of atmospheric nitrogen and nitrogen from ammonia.

In many measurements what is sought is not the value of a single quantity, but the relation between the values of two variable quantities. In such cases graphical methods are of great service. Corresponding values of the two variables are found and plotted; and a smooth curve, or it may be a straight line, is drawn to lie as evenly as possible among the plotted points. Where great accuracy is wanted, analytical methods are also available. See _Squares, Method of Least; Probability_.

ERSCH (ersh), John Samuel, German bibliographer, born 1766, died 1828. He was principal librarian and professor of geography and statistics at Halle. Among his publications are: a _Dictionary of French Writers_; a _Manual of German Literature_; and, in connection with Gruber, the _Universal Encyclopaedia of Arts and Sciences_.

ERS'KINE, Ebenezer, the founder of the Secession Church in Scotland, born 1680, died 1754. He studied at Edinburgh, and was ordained minister of Portmoak, in Fife, in 1703, in which situation he continued for twenty-eight years, when he removed to Stirling. His attitude towards patronage and other abuses in the Church led to his being deposed, when, in conjunction with his brother and others, he founded the Secession Church. Erskine was the leader of the Burghers (q.v.). He is the author of several volumes of sermons.

ERSKINE, The Hon. Henry, Scottish barrister, was the third son of Henry David, tenth Earl of Buchan: born at Edinburgh 1746, died 1817. After studying at the Universities of St. Andrews, Edinburgh, and Glasgow, he adopted the legal profession, and in 1768 was called to the Bar. He twice held the office of Lord-Advocate, was for long the leader of the Scottish Bar, and held a high reputation as a wit.

ERSKINE, John, of Carnock, afterwards of Cardross, Scottish jurist, born 1695, died 1768. He was called to the Scottish Bar in 1719, and was author of _Principles of the Law of Scotland_, and the _Institutes of the Law of Scotland_, both works of authority.

ERSKINE, Ralph, brother of Ebenezer Erskine, born 1685, died 1752. He was ordained to the parish of Dunfermline in 1711, and in 1737 joined his brother, who had seceded from the Established Church. His _Gospel Sonnets_ and other religious works were once very popular.

ERSKINE, Thomas, Lord Erskine, Scottish lawyer, the youngest son of the tenth Earl of Buchan, was born in 1750, and died in 1823. He was educated partly at the High School of Edinburgh, and partly at the University of St. Andrews. After serving four years in the navy and seven in the army, he commenced the study of law, and in 1778 both took his degree at Cambridge and was called to the Bar. His success was immediate. In May, 1783, he took silk, and the same year was elected member of Parliament for Portsmouth, a seat he held (except from 1784-90, when he had no seat) till 1806, when he was raised to the peerage. The rights of juries he firmly maintained on all occasions, but particularly in the celebrated trial of the Dean of St. Asaph for libel. In 1789 he defended Stockdale, a bookseller, for publishing what was charged as a libellous pamphlet in favour of Warren Hastings. In 1792, being employed to defend Thomas Paine, when prosecuted for the second part of his work _The Rights of Man_, he declared that, waiving all personal convictions, he deemed it right, as an English advocate, to obey the call: by the maintenance of which principle he lost his office of Attorney-General to the Prince of Wales. In the trials of Hardy, Tooke, and others for high treason in 1794, which lasted for several weeks, the ability displayed by Erskine was acknowledged by all parties. He was a warm partisan of Fox, and a strenuous opposer of the war with France. In 1802 the Prince of Wales not only restored him to his office of Attorney-General, but made him Keeper of Seals for the Duchy of Cornwall. On the death of Pitt, in 1806, Erskine was created a peer, and raised to the dignity of Lord Chancellor. During his short tenure of office the Bill for the abolition of slavery was passed. After he retired with the usual pension, he took little part in politics.

ERUPTIVE ROCKS, in geology, those which, as lavas, have broken through other rocks while in a molten state, and become eruptive at the surface.

ERVUM. See _Lentil_.

ERYNGIUM, a genus of plants belonging to the nat. ord. Umbelliferae. There are upwards of 100 species found in temperate and sub-tropical climates, but chiefly in South America. _E. marit[)i]mum_, also called sea-holly, is the only truly native British species. It frequents sandy shores, and is distinguished by its rigid, spiny, glaucous, veined leaves, and its dense heads of blue flowers. The roots are sometimes candied, and are reputed to be stimulating and restorative, as well as to have aphrodisiac properties. It is mentioned by Shakespeare, _Merry Wives_, v. 5, 23, as an aphrodisiac.

ERYSIP'ELAS, ROSE, or ST. ANTHONY'S FIRE, is a contagious disease of the skin due to infection by a germ, the Streptococcus, and accompanied by severe general disturbance. Cold, damp weather favours its appearance. It rarely affects those under fifteen years, and is commoner in women than men. The disease is characterized by sudden onset, with shivering, headache, vomiting, and occasionally sore throat, followed by the appearance of the typical erysipelatous flush on the skin of the affected part, most usually the face. This part becomes deep red, and is much swollen, with a glossy, tender surface. It is definitely raised, and has a spreading edge merging into the normal parts around. In extreme cases there is marked disfigurement. Local treatment to allay pain and prevent spreading is by the application of lotions and ointments, and general treatment in the form of stimulating foods is given to maintain strength. Serum treatment has been used, but so far there have been very conflicting results. The disease is not so common nor so fatal as previously.

ERYSIPHA'LES, an important family of ascomycetous Fungi, distinguished by the presence of typical sexual organs and closed ascus-fruits (_cleistocarps_) which bear characteristic appendages concerned with dispersal; also by the fact that each segment of the septate mycelium contains a single nucleus. They are all parasites, appearing on leaves, stems, or fruits as white patches of mycelium ('mildew'). During summer innumerable conidia are produced, which spread the disease rapidly; in autumn the black ascus-fruits develop and carry the fungus through the winter. Erysiphales are responsible for many important plant-diseases, e.g. the mildew of hops (_Sphaerotheca Castagnei_), vine (_Uncinula spiralis_), wheat (_Erysiphe communis_), and the American gooseberry mildew (_Sphaerotheca Mors-uvae_), a 'notifiable' disease in Britain.

ERYTHE'MA is redness of the skin, and in this sense is applied to a number of general conditions which bring about redness of the skin, e.g. abscess, oedema, scarlet fever, &c. Of late, in medicine, its use has been more restricted, and refers only to an inflammation of part of the skin. This disease is characterized by redness and tenderness, and may become sufficiently severe to lead to the production of bullae in the centre of the affected part. Dermatologists recognize various types of erythema.

ERYTHRAE'AN SEA, in ancient geography, a name given to what is now called the Indian Ocean, but including the Persian and Arabian Gulfs. The name was eventually restricted to the Arabian Gulf.

ERYTHRI'NA. See _Coral Tree_.

ERYTHRO'NIUM. See _Dog's Tooth Violet_.

ERYTHROPHLOE'UM, a genus of tropical trees, nat. ord. Leguminosae, containing three species, two found in Africa and the third in Australia. The _E. guineense_ of Guinea has a poisonous juice, which is used by the natives as a test of innocence and guilt, hence the name 'ordeal tree'.

ERYX, an ancient city and a mountain in the west of Sicily, about 2 miles from the sea-coast. The mountain, now Monte San Giuliano, rises direct from the plain to a height of 2184 feet. On the summit anciently stood a celebrated temple of Venus. All traces of the ancient town of Eryx have now disappeared, and its site is occupied by the modern town of San Giuliano.

ERZBERGER, Matthias, German politician, born at Buttenhausen in 1875. Educated at Freiburg, where he studied political economy, he took an interest in 1897 in the Christian Socialist movement, and entered the Reichstag as a member of the Centre or Catholic party. He became prominent in 1917, when he accused the German Government of misrepresenting the military situation, and urged for a statement of Germany's peace aims. Secretary of State in 1918, he became Minister of Finance in 1919 in Bauer's Cabinet, but was compelled to resign in 1920. He was murdered on 26th Aug., 1921, by two young men of the militarist party.

ERZERUM, ERZEROUM, or ERZEROOM (er'ze-r[:o]m), a city of Armenia, formerly the capital of a Turkish vilayet with an area of 27,000 sq. miles, and a pop. of 582,745. The town is about 6000 feet above sea-level, and forms an important strategical centre. It is irregularly built, its narrow dirty streets, flanked by mean houses, being crowded together in the small space enclosed by its lofty walls. The Moslem element prevails largely over the Christian, although it is the metropolis of the Armenian Church in union with Rome. In addition to important manufactures, especially in copper and iron, it carries on an extensive trade, and is a chief halting-place for Persian pilgrims on their way to Mecca. The town was captured by the Russians in Feb., 1916, and recaptured by the Turks in March, 1918. Pop. (before the European War), about 80,000.

ERZGEBIRGE (erts'ge-bir-ge; 'Ore Mountains'), a chain of European mountains forming a natural boundary between Saxony and Bohemia, nearly 120 miles in length and 25 miles broad. The highest summits, which are on the side of Saxony, rise to 3800 or 3900 feet. The mountains are rich in silver, iron, copper, lead, cobalt, and arsenic.

ESARHAD'DON (Assyr. _Asur-akhi-iddina_, Asur has given a brother), the son of Sennacherib, and one of the most powerful of all the Assyrian monarchs. He extended the empire on all sides, and is the only Assyrian monarch who actually reigned at Babylon. He died about 667 B.C.

E'SAU, the eldest son of Isaac, and twin-brother of Jacob. His name (which signifies rough, hairy) was due to his singular appearance at birth, being "red, and all over like an hairy garment". The story of his losing the paternal blessing through the craft of Rebekah and Jacob, with other facts, is told in _Genesis_, xxvii. He was the progenitor of the Edomites.

ESBJERG, a Danish seaport in South-West Jutland, opposite the Island of Fan[:o]. Pop. 18,000.

ESCALLONIA, a genus of saxifragaceous shrubs and trees, natives chiefly of the Andes. _E. rubra_ is a handsome evergreen shrub, with shiny, resinous, aromatic leaves, and fine pink flowers; it is hardy in many parts of Britain, and makes an excellent hedge, especially near the sea, where it bears the salt-laden winds without damage.

2, Recoil escapement. The pallets are not concentric to the axis _a_, and therefore a slight recoil of the wheel takes place after the escape of a tooth (whence the name escapement). When the pallets leave a tooth, the teeth slide along their surfaces, giving an impulse to the pendulum. Lettering for 1 and 2: The anchor H L K is made to oscillate on the axis _a_ by the pendulum. The teeth of the escapement-wheel A come alternately against the outer surface of the pallet K and the inner surface of the pallet H.

3, Chronometer escapement. As the balance rotates in the direction of the arrow, the tooth V presses the spring against the lever, thus pressing aside the lever and removing the detent from the tooth of the wheel. As the balance returns, V presses aside and passes the spring without moving the lever, which then rests against the stop E.]

ESCAPE'MENT, the general contrivance in a timepiece by which the pressure of the wheels (which move always in one direction) and the vibratory motion of the pendulum or balance-wheel are accommodated the one to the other. By this contrivance the wheelwork is made to communicate an impulse to the regulating power (which in a clock is the pendulum and in a watch the balance-wheel), so as to restore to it the small portion of force which it loses in every vibration, in consequence of friction and the resistance of the air. The leading requisite of a good escapement is that the impulse communicated to the pendulum or balance-wheel shall be invariable, notwithstanding any irregularity or foulness in the train of wheels. Various kinds of escapements have been contrived, some of which are shown in the accompanying figure. See _Clock_; _Watch_.

ES'CAR, or ESKER, a geological formation in the superficial drift, generally consisting of a long linear ridge of sand and gravel, sometimes including blocks of considerable size. The materials are derived from the waste of till or boulder-clay, and their arrangement took place probably in water flowing in channels beneath ice-sheets, the escar becoming exposed as the ice finally melted away. In Sweden escars have been formed, season by season, at the mouths of glacier-tunnels as the ice shrank back, the ice-front opening on a lake. See _Kames_.

ESCHAR (es'k[.a]r), a slough or portion of dead or disorganized tissue. The name is commonly applied to the crust or scab occasioned on the skin by burns or caustic applications.

ESCHATOL'OGY (es-ka-; Gr. _eschatos_, last, and _logia_, account), in theology, the 'doctrine respecting the last things', which treats of the millennium, the second advent of Christ, the resurrection, judgment, conflagration of the world, and the final state of the dead.

ESCHEAT (es-ch[=e]t'), in law, a species of reversion arising from default of heirs. Lands, if freehold, escheat to the king or other lord of the manor; if copyhold, to the lord of the manor. By modern legislation there can be no escheat on failure of the whole blood wherever there are persons of the half-blood capable of inheriting.

ESCHENBACH (esh'en-b[.a]_h_), Wolfram von, German mediaeval poet or minnesinger, flourished in the first half of the thirteenth century. The most esteemed of his numerous works are: _The Parzival_ (printed 1477); _The Titurel_, or _The Guardian of the Graal_ (printed 1477); and _The Willehalm_, a poem on the deeds of William of Orange, a contemporary of Charlemagne.

ESCHSCHOLTZIA (esh-sholt'si-a), a small genus of glabrous whitish plants, of the poppy order, natives of California and the neighbouring regions. They have divided leaves, and yellow peduncled flowers. The sepals cohere and fall off as the flower opens in the form of a cap. They are now common in the gardens of Great Britain.

ESCHWEGE (esh'v[=a]-ge), a town of Prussia, province of Hesse-Nassau, on the Werra, 26 miles E.S.E. of Cassel. Pop. 12,540.

ESCHWEILER (esh'v[=i]-l[.e]r), a town of Prussia, in the province of Rheinland, 9 miles E.N.E. of Aix-la-Chapelle, on the Inde. It is the seat of large and varied manufacturing industries, especially in iron, copper, and zinc, and has coal-mines. Pop. 24,718.

ESCOBAR Y MENDOZA (es-ko-b[:a]r' [=e] men-_d_o'-th[.a]), Antonio, a Spanish casuist and Jesuit, born 1589, died 1669. His principal works are: _Summula Casuum Conscientiae_, and several scriptural commentaries. His casuistry was severely criticized by Pascal in his _Lettres Provinciales_, and the extreme laxity of his moral principles was ridiculed by Boileau, Moli[`e]re, and La Fontaine.

ESCROW', a legal writing delivered to a third person to be delivered by him to the person whom it purports to benefit, when some condition is performed. Upon the performance of this condition it becomes an absolute deed, but if the condition be not performed, it remains an _escrow_ or scroll.

ESCU'RIAL (Sp. _el Escorial_), a remarkable building in Spain, comprising at once a palace, a convent, a church, and a mausoleum. It is distant from Madrid about 24 miles in a north-westerly direction, and situated on the acclivity of the Sierra Guadarrama, the range of mountains which divides New from Old Castile. It was built by Philip II, and dedicated to St. Lawrence, in commemoration of the victory of St. Quentin, fought on the festival of the saint in 1557. It is popularly considered to be built on the plan of a gridiron, from the fact that St. Lawrence is said to have been broiled alive on a sort of large gridiron. The building is a rectangular parallelogram measuring 744 feet in length by 580 feet in breadth. The interior is divided into courts, formerly inhabited by monks and ecclesiastics, while a projection 460 feet in length (the handle of the gridiron) contains the royal palace. It was begun in 1563 and finished in 1584. It is of moderate height, and its innumerable windows (said to be 11,000) give it (apart from the church) somewhat the aspect of a large mill or barracks. The church is the finest portion of the whole building. The dome is 60 feet in diameter, and its height at the centre is about 320 feet. Under it is the Pantheon or family vault of the Spanish sovereigns. The library contains a valuable collection, including a rich store of Arabic MSS. The Escurial was partly burned in 1671, when many MSS. were destroyed, and was pillaged by the French in 1808 and 1813. It was restored by Ferdinand VII, but the monks, with their revenues which supported it, have long since disappeared. In 1872 it was fired by lightning, and suffered serious damage.--Cf. A. F. Calvert, _The Escorial_.

ESDRAE'LON, PLAIN OF, a fertile plain in Northern Palestine, between the Mediterranean and the Jordan, drained by the River Kishon, and now traversed by the railway from Haifa to Damascus. This plain is celebrated for four battles having been fought there. Sisera was defeated there; Gideon and his three hundred won a battle there; Saul and Jonathan fought there; and it was there that Josiah was killed, In the centre of the plain is Megiddo (q.v.), identified with Armageddon (_Rev._ XVI, 16). Allenby won a great victory here in Sept., 1918.

ESDRAS, BOOKS OF, two apocryphal books, which, in the _Vulgate_ and other editions, are incorporated with the canonical books of Scripture. In the _Vulgate_ the canonical books of _Ezra_ and _Nehemiah_ are called the first and second, and the apocryphal books the third and fourth books of _Esdras_. The _Geneva Bible_ (1560) first adopted the present nomenclature, calling the two apocryphal books first and second _Esdras_. The subject of the first book of Esdras is the same as that of _Ezra_ and _Nehemiah_, and in general it appears to be copied from the canonical Scriptures. The second book of _Esdras_ is supposed to have been either of much later date or to have been interpolated by Christian writers.

E'SERIN, or PHYSOSTIGMIN, a drug obtained from Calabar-bean, the active principle of this plant, used as a remedy in cases of tetanus (lockjaw). A solution of eserin dropped in the eye causes contraction of the pupil, and hence its use in some eye ailments, as, for instance, glaucoma.

ESHER, a village and parish of England, north-west Surrey. Here is Claremont, built by Sir John Vanbrugh, in 1816 settled upon Princess Charlotte and her husband, afterwards the residence of the Orleans family when expelled from France. The so-called 'Wolsey's Tower' is the gatehouse of a palace built by William Waynflete, Bishop of Winchester. Pop. 2609.

ESK (Celtic for water), the name of two small rivers in England--one in Cumberland and the other in Yorkshire; and of several in Scotland, the chief being the Esk in Dumfriesshire, the North Esk and South Esk in Forfarshire, and the North Esk and South Esk in Edinburghshire.

ESKI-JUMNA, a town of Bulgaria, on the northern slope of the Binar-Dagh. Pop. 10,000.

ESKILSTU'NA, a town of Sweden, on a river of the same name connecting Lake Maelar with Lake Hjelmar, with ironworks and manufactures of steel goods and weapons. It is named after St. Eskil, the English apostle of Christianity in S[:o]dermanland. Pop. 28,500.

ES'KIMOS. See _Esquimaux_.

ESKI-SAGRA, or STARA-ZAGORA, a town of Bulgaria, on the south slope of the Balkans, 50 miles N.E. of Philippopolis. In its vicinity are extensive rose-gardens, orchards, and mineral springs. Pop. 28,480.

ESKI-SHEHR, a town of Asia Minor, 90 miles S.E. of the Sea of Marmora, with warm baths and manufactures of meerschaum pipes. Fighting took place near the town in 1921, between the Greeks and Turks. Pop. 20,000.

ESMARCH (es'm[:a]r_h_), Johannes Friedrich August von, German surgeon, born in 1823, died in 1908. He held high official positions during the Schleswig-Holstein and Franco-German Wars, and was a great authority on gunshot wounds. He also originated valuable improvements in barrack-hospitals and ambulances, introduced the antiseptic treatment into Germany, and was the author of several surgical works.

ES'NEH, a town of Upper Egypt, on the left bank of the Nile, 28 miles S.S.W. of Thebes, on the site of the ancient Latopolis, now easily reached by railway and river. Among the ruins there is a beautiful portico of twenty-four lofty and massive columns, belonging to a temple of Kneph (the only portion of the temple cleared out), and erected in the Ptolemaic and Roman period, with a zodiac on the ceiling. Esneh has a caravan trade, manufactures cottons and pottery, and is very healthy. There is an irrigation barrage here. Pop. 15,800.

ESOC'IDAE, the family of fishes to which the true pike (_Esox lucius_) belongs, as also the much larger maskinongy (_E. nobilior_) of America.

ESPAL'IER, in gardening, a sort of trelliswork on which the branches of fruit trees or bushes are extended horizontally, with the object of securing for the plant a freer circulation of air as well as a full exposure to the sun. Trees thus trained are not subjected to such marked nor so rapid variations of temperature as wall trees.

ESPARTERO (es-p[.a]r-t[=a]'r[=o]), Baldomero, Duke of Vittoria, a Spanish statesman, born 1792, died 1879. The son of a wheelwright, he was educated for the priesthood, but joined the army as a volunteer in 1808. He took a leading part in the conflict with the Carlists, and was one of the most prominent men in Spain during several decades of the nineteenth century. He was regent of the kingdom from 1841 to 1843, and again head of the Government from 1854 to 1856. He was exiled to England for several years (1843-7). In 1870 his name was vaguely put forward in the Cortes as a candidate for the throne, but the proposal was not supported with any enthusiasm, and the closing years of his life were spent in retirement.