PART 2

EBERT to ESTREMADURA

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PLATES

Page

ELECTRICAL MACHINERY 200 ENTOMOLOGY (_coloured_) 267

MAPS IN COLOUR

ENGLAND AND WALES 242

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KEY TO PRONUNCIATION

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The method of marking pronunciations here employed is either (1) by marking the syllable on which the accent falls, or (2) by a simple system of transliteration, to which the following is the Key:--

VOWELS

[=a], as in f_a_te, or in b_a_re.

[:a], as in _a_lms, Fr. _[^a]_me, Ger. B_a_hn = ['a] of Indian names.

[.a], the same sound short or medium, as in Fr. b_a_l, Ger. M_a_nn.

a, as in f_a_t.

[a:], as in f_a_ll.

_a_, obscure, as in rur_a_l, similar to _u_ in b_u_t, [.e] in h_e_r: common in Indian names.

[=e], as in m_e_ = _i_ in mach_i_ne.

e, as in m_e_t.

[.e], as in h_e_r.

[=i], as in p_i_ne, or as _ei_ in Ger. m_ei_n.

i, as in p_i_n, also used for the short sound corresponding to [=e], as in French and Italian words.

_eu_, a long sound as in Fr. j_e[^u]_ne = Ger. long _[:o]_, as in S_[:o]_hne, G_[:o]_the (Goethe).

eu, corresponding sound short or medium, as in Fr. p_eu_ = Ger. _[:o]_ short.

[=o], as in n_o_te, m_oa_n.

o, as in n_o_t, s_o_ft--that is, short or medium.

[:o], as in m_o_ve, tw_o_.

[=u] as in t_u_be.

u, as in t_u_b: similar to [.e] and also to a.

[u:], as in b_u_ll.

[:u], as in Sc. ab_u_ne = Fr. _[^u]_ as in d_[^u]_, Ger. _[:u]_ long as in gr_[:u]_n, B_[:u]_hne.

[.u], the corresponding short or medium sound, as in Fr. b_u_t, Ger. M_[:u]_ller.

oi, as in _oi_l.

ou, as in p_ou_nd; or as _au_ in Ger. H_au_s.

CONSONANTS

Of the _consonants_, B, D, F, H, J, K, L, M, N, NG, P, SH, T, V, Z, always have their common English sounds, when used to transliterate foreign words. The letter C is not used by itself in re-writing for pronunciation, S or K being used instead. The only consonantal symbols, therefore, that require explanation are the following:--

ch is always as in ri_ch_.

_d_, nearly as _th_ in _th_is = Sp. _d_ in Ma_d_ri_d_, &c.

g is always hard, as in _g_o.

_h_ represents the guttural in Scotch lo_ch_, Ger. na_ch_, also other similar gutturals.

[n.], Fr. nasal _n_ as in bo_n_.

r represents both English _r_, and _r_ in foreign words, which is generally much more strongly trilled.

s, always as in _s_o.

th, as _th_ in _th_in.

_th_, as _th_ in _th_is.

w always consonantal, as in _w_e.

x = ks, which are used instead.

y always consonantal, as in _y_ea (Fr. _ligne_ would be re-written l[=e]ny).

zh, as _s_ in plea_s_ure = Fr. _j_.

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EBERT, Fritz, first President of the new German Republic, born at Heidelberg in 1870, the son of a tailor. Having received an elementary education in his youth, he first worked in his father's shop, and was then apprenticed to a saddler. He spent his spare time in reading and acquiring knowledge, entered journalism, and in 1892 became editor of the _Bremer B[:u]rgerzeitung_. In 1908 he was elected to the Reichstag, and in 1916 became president of the Socialist group of this Assembly. He appealed for peace in the Reichstag in Sept., 1918, and having thus become rather prominent, he succeeded Prince Max of Baden as Chancellor of the Empire. The office was suppressed a few days later, and Ebert became Provisional President of Germany. He crushed the efforts made by the Spartacus group to prevent the elections for the National Assembly, and altogether showed tact and energy in those critical days. The National Assembly met at Weimar, and elected Ebert as first President of the Reich on 11th Feb., 1919.

E'BIONITES (Heb. _ebyonim_, poor), a sect of the first century, so called from their leader, Ebion. Irenaeus described them as Jewish Christians. They held several dogmas in common with the Nazarenes, united the ceremonies of the Mosaic institution with the precepts of the gospel, and observed both the Jewish Sabbath and Christian Sunday. They denied the divinity of Christ and rejected many parts of the New Testament.

EBLIS, or IBLIS, in Mohammedan mythology, the chief of the evil spirits; also the name given to the prince of darkness, or Satan.

EB'OLI, a city of Campania, Southern Italy, a few miles from the Gulf of Salerno. Pop. 12,741.

EB'ONY, the popular name of various plants of different genera, agreeing in having wood of a dark colour. The best-known ebony is derived from plants of the genus Diospyros, nat. ord. Ebenaceae. The most valuable is the heart-wood of _D. Eb[)e]num_, which grows in great abundance in the flat parts of Ceylon, and is of such size that logs of its heart-wood 2 feet in diameter and from 10 to 15 feet long are easily procured. Other varieties of valuable ebony are obtained from _D. melanoxylon_ of Coromandel, _D. tesseleria_ of Mauritius, and other species. Ebony is hard, heavy, and durable, and admits of a fine polish or gloss. The most usual colour is black, red, or green. The best is jet black, free from veins, very heavy, astringent, and of an acrid pungent taste. On burning coals it yields an agreeable perfume, and when green it readily takes fire from its abundance of fat. It is wrought into toys, and used for mosaic and inlaid work.

EBONY LORE. In ancient times ebony was a sacred wood. The Indians carved from it images of gods and drinking-cups. It was first used by the ancient Egyptians, who called it _heben_, and imported it from 'God-land' (Punt). The Hebrew name is _hobn[=i]m_, the Greek _ebenos_, the Hindi _[=a]ban[=u]sa_. Ezekiel (xxvii, 15) connects ebony with Tyre. The ebony displayed in Rome by Pompey in his triumph over Mithridates came, according to Solinus, from India. The Chinese call it _Wu-men_ ('black-streaked wood'), and anciently imported it from India and Indo-China.

E'BRO (Lat. _Ib[=e]rus_), one of the largest rivers in Spain, which has its source in the province of Santander, about 25 miles S. of the Bay of Biscay, and after a south-easterly course of about 500 miles enters the Mediterranean. Its navigation is much interrupted by rapids and shoals, to avoid which a canal about 100 miles long has been constructed nearly parallel to its course. Saragossa is the principal town on the river.

['E]CART['E] ([=a]-k[:a]r't[=a]), a card-game for two players, is played with thirty-two cards, the smaller ones, from two to six inclusive, not being used. The remaining cards rank as follows: king (highest), queen, knave, ace, ten, &c. In the English mode of playing, the players cut for the deal, which is decided by the lowest card. The dealer gives five cards to either player, three and two at a time, and turns up the eleventh card for trump. If he turns up a king he scores one; and if a king occurs in the hand of either player, the holder may score one by announcing it before the first trick. The non-dealer leads; trumps take all other suits, but the players must follow suit if they can. Three tricks count one point, five tricks two points; five points make game. Before play begins, the non-dealer may claim to discard (['e]carter) any of the cards in his hand, and to replace them by fresh ones from the pack. This claim the dealer may or may not allow. Should he allow it, he can himself discard as many cards as he pleases. Sometimes only one discard is allowed, sometimes more. Cf. Cavendish, _The Laws of ['E]cart['e] adopted by the Turf Club_.

ECBAT'ANA, the chief city or ancient metropolis of Media, the summer residence of the Median and Persian and afterwards of the Parthian kings. It was a place of great splendour at an early period. Its site can no longer be fixed with certainty, though many explorers agree in identifying it with the modern Hamadan.

ECCE HOMO (ek's[=e]; Lat., 'Behold the man!'), a name often given to crucifixes and pictures which represent Christ bound and crowned with thorns. The most celebrated of these paintings are by Sodoma, Correggio (in the National Gallery), Titian, Tintoretto, Guido Reni, and Murillo. The expression is derived from the words spoken by Pilate when he showed Christ to the multitude before he was led forth to Crucifixion (_John_, xix, 5).

[Illustration: Eccentric and Rod

P, Pulley. M, Strap. N, Rod. O, Centre of shaft. E, Centre of eccentric. O, E, Is the throw or radius of the eccentric.]

ECCEN'TRIC, a term in mechanics applied to contrivances for converting circular into reciprocating (backwards and forwards) rectilinear motion, consisting of circular discs attached to a revolving shaft, not centrally, i.e. eccentrically.

ECCHYMOSIS is extravasation of blood into the tissues underlying the skin. It is most frequently produced as the result of a bruise from injury, but may be due to some pathological condition.

ECCLEFECHAN (ek-l-fe_h_'an), a Scottish village in Dumfriesshire, near the Caledonian Railway main line, noteworthy as the birth-place and burial-place of Thomas Carlyle. Pop. 670.

ECCLES, a town of England, in Lancashire, 4 miles from Manchester, of which it may be considered a suburb. The town, engaged in textile industries, is famous for its cakes. Since 1918 it returns one member to Parliament. Pop. 41,946.

ECCLESIAS'TES (-t[=e]z), the title by which the _Septuagint_ translators rendered the Hebrew _Koheleth_ ('the gatherer of the people'), a symbolic name explained by the design of the book and the dramatic position occupied by Solomon in it, one of the canonical books of the Old Testament. The book consists of 12 chapters, being a series of discourses on the vanity of earthly things, and the tone, which is sceptical, is such as is found in Omar Khayy['a]m. According to Jewish tradition, it was written by Solomon; but the best modern criticism has decided that its style and language, no less than its thought, belong to a much later date.

ECCLESIASTICAL COMMISSIONERS, in England, a body corporate, constituted in 1836, with extensive powers in regard to the organization of the Church, the distribution of episcopal duties, and the formation of parishes. It consists of all the bishops of England and Wales, five cabinet ministers, four judges, and twelve others. Their decisions are ratified by orders in council, and acquire the force of Acts of Parliament. The Commissioners deal with an annual income of about 2 million pounds.

ECCLESIASTICAL COURTS, courts in which the canon law is administered and which deal with ecclesiastical cases, affecting benefices and the like. In England they are the _Archdeacon's Court_, _the Consistory Courts_, _the Court of Arches_, _the Court of Peculiars_, _the Prerogative Courts of the two archbishops_, _the Faculty Court_, and _the Privy Council_, which is the court of appeal, though its jurisdiction may by Order in Council be transferred to the new Court of Appeal. No separate ecclesiastical courts existed in England before the Norman Conquest, but by a charter of William I a distinction was made between courts civil and courts ecclesiastical. In Scotland the ecclesiastical courts are the _Kirk-session_, _Presbytery_, _Synod_, _General Assembly_ (which is the supreme tribunal as regards doctrine and discipline), and the _Teind Court_, consisting of the judges of the Court of Session, which has jurisdiction in all matters affecting the teinds of a parish. In the Isle of Man ecclesiastical courts still have, as formerly in England, jurisdiction in probate and matrimonial cases.

ECCLESIASTICAL LAW may, in the broad sense of the term, be taken to include the regulations existing in any Church or sect, however small, for the formation of its own polity and for the control of its members. It is, however, more generally applied to those legal bonds which exist between Established Churches and the State. The Roman Catholic Church claims to be the one and only true Church, regards her laws as being of universal application, and herself as an equal with the State; nevertheless she has, in non-Catholic countries, no higher legal standing than any small and obscure dissenting congregation, and is in this respect a 'free' Church. Protestant ecclesiastical law claims no such sovereign power, and in no way interferes with the State law. In England the Convocations of York and Canterbury have no authority to change the law, their power being limited to the making of recommendations. All changes in Church law are made by Parliament. Laymen can be, and often are, officials of the ecclesiastical courts. The civil law is subject to the canon law, above which is the common law, with, yet higher, statute law. Over all is the nominal supremacy of the Crown. Ecclesiastical law deals with such affairs and property of the Church of England as ecclesiastical parishes, churches, and matters matrimonial; but only so far as these are not controlled by common or statute law. It has long ceased to have any practical control of the laity. In Ireland, ecclesiastical law disappeared with the disestablishment of the Church.

ECCLESIAS'TICUS, a book placed by Protestants and Jews among the apocryphal scriptures. The author calls himself Jesus the son of Sirach, Originally written in Hebrew, it was translated into Greek by the author's grandson in the second century B.C. In 1896 fragments of four MSS. in the Hebrew original were discovered in the _Geniza_, or hiding-place for worn out copies of biblical books, in the synagogue at Cairo. Another fragment was discovered in Palestine by Mrs. Agnes Lewis.--Cf. Schechter and Taylor, _The Wisdom of Ben Sira: Portions of the Book Ecclesiasticus_.

['E]CHELLES, LES (l[=a]-z[=a]-sh[=a]l; 'the Ladders'), a village, France, department of Savoie, 12 miles south-west of Chamb['e]ry, in a valley from which egress at one end was formerly by means of ladders, but now by a tunnel. Pop. 798.

['E]CHELON (esh'e-lon), a formation of successive and parallel units facing in the same direction, each on a flank and to the rear of the unit in front of it.

ECHENEIS, the type genus of a small family (Echeneididae) of aberrant spiny-finned fishes, in which the first dorsal fin is modified into a transversely ridged suctorial disc. See _Remora_.

ECHEVERIA (ech-e-v[=e]'ri-a), a genus of succulent plants, ord. Crassulaceae (house-leek), chiefly natives of Mexico, but now cultivated in European and other gardens and greenhouses, some for their flowers, others for their foliage.

ECHIDNA ([=e]-kid'na), a genus of Australian toothless mammals, in size and general appearance resembling a large hedgehog, excepting that the spines are longer and the muzzle is protracted and slender, with a small aperture at the extremity for the protraction of a long flexible tongue. The habits of the Echidna are nocturnal; it burrows, having short strong legs with five toes, and feeds on insects, which it catches by protruding its long sticky tongue. It is nearly allied to the Ornithorhynchus, the two forming a peculiar class of animals, having in their structure some peculiarities at once of mammals, birds, and reptiles. In 1884 it was found that, as Geoffrey St. Hilaire had suspected, the Echidna, the closely related Proechidna of New Guinea, and the Ornithorhynchus constitute the lowest sub-class of mammals, the Prototheria or Monotremata, which present many reptilian characters. They possess a cloaca into which the intestine and urinogenital ducts open and are oviparous. During the breeding season a temporary pouch is formed, and into this the milk-glands open, but there are no teats. The egg when laid is put into the pouch by the mother, and is there hatched in a very immature state. It feeds by licking up the milk in the pouch. Later on, the mother digs a burrow, where she leaves the young at night, returning during the day to suckle it. One species (_E. hystrix_), from its appearance is popularly known as the _porcupine ant-eater_.

ECHINOCACTUS (e-k[=i]'-), a genus of cactaceous plants inhabiting Mexico and South America, and remarkable for their peculiar forms, being globular, oblong, or cylindrical, and without leaves, fluted and ribbed, with stiff spines clustered on woolly cushions. Some of them are very bulky. The flowers are large and showy. See _Cactus_.

ECHINOCOCCUS, the very large compound cyst which forms the bladder-worm stage in the life-history of a small tapeworm (_Taenia echinococcus_) living in the intestine of the dog. The cysts are found in various abdominal organs of herbivorous animals, and sometimes infest human beings, especially in Iceland.

ECHINODERMATA (e-k[=i]-n[=o]-d[.e]r'ma-ta), a phylum or sub-kingdom of invertebrate animals characterized by having a tough integument in which lime is deposited in scattered plates (sea-cucumber), flexibly articulated plates (star-fishes), or so as to form a rigid test or shell like that of the sea-urchin; and by the radial arrangement of many of the parts of the adult. Movable spines are commonly present. There is a system of tubes into which seawater is admitted (ambulacral system), and commonly tube-feet, that are put into use by being distended with fluid. Some of them, as the encrinites or sea-lilies, are permanently fixed by a stalk when adult. Their development is accompanied by metamorphosis, and the embryo shows a distinctly bilateral aspect, though the radiate arrangement prevails in the adult. By some they are classed with the Scolecida in the sub-kingdom Annuloida. The phylum is divided into nine classes: Asteroidea (star-fishes); Ophiuroidea (brittle-stars), Echinoidea (sea-urchins), Holothuroidea (sea-cucumbers), Crinoidea (sea-lilies, feather-stars, the latter free-moving), Thecoidea or Edrioasteroidea (extinct, stalkless but fixed), Carpoidea (extinct, stalked), Cystoidea (extinct, stalked), Blastoidea (extinct, stalked). All are marine.

ECHINOMYS, or SPINY RAT, a genus of South American rodent mammals distinguished by the presence of spines among the coarse fur. The long tail is covered by scales and hair intermixed, the ears are large, and all the extremities possess five digits.

ECHINUS (e-k[=i]'nus), SEA-URCHIN, or SEA-EGG, a genus of marine animals, the type of an order (Echinoidea) of the phylum Echinodermata (see above). In this type the body is spheroidal and invested in a test or shell composed of regularly arranged plates closely united together. It is covered with movable spines articulated by ball-and-socket joints. The mouth is situated in the centre of the under surface, and there is a complicated masticatory apparatus (Aristotle's lantern) consisting of five chisel-ended teeth supported by an elaborate framework. The anus is similarly placed on the upper side, and is surrounded by a circlet of ten plates (apical disc), one of which bears a furrowed tubercle (madreporite) perforated by small holes through which water enters the water-vascular system. Locomotion is effected by meridional rows of tube-feet, aided by the spines. _E. esculentus_ and some other species are edible. See _Sea-urchin_.

[Illustration: Echinus]

ECHINUS (e-k[=i]'nus), in architecture, the _ovolo_ or quarter-round convex moulding, seen in capitals of the Doric order. It is especially frequently found carved with the egg-and-dart ornament.

ECHO (ek'[=o]), the repetition of a sound caused by the reflection of sound-waves from some surface, as the wall of a building. The echo may, however, be very distinct when the reflecting surface is very irregular, and it is probable that the resonance of the obstacles and the masses of air which they enclose contribute in producing the echo. The waves of sound on meeting the surface are turned back in their course according to the same laws that hold for reflection of light. In order that the echo may return to the place from which the sound proceeds, the reflection must be direct, and not at an angle to the line of transmission, otherwise the echo may be heard by others but not by the transmitter of the sound. This may be effected either by a reflecting surface at right angles to the line of transmission, or by several reflecting surfaces which in the end bring the sound back to the point of issue. Sound travels about 1125 feet in a second; consequently, an observer standing at half that distance from the reflecting object would hear the echo a second later than the sound. Such an echo would repeat as many words and syllables as could be heard in a second. As the distance decreases, the echo repeats fewer syllables till it becomes mono-syllabic. The most practised ear cannot distinguish in a second more than from nine to twelve successive sounds, so that a distance of not less than 60 feet is needed to enable an average ear to distinguish between the echo and the original sounds. At a near distance the echo only clouds the original sounds, and this often interferes with the hearing in churches and other large buildings. Woods, rocks, and mountains produce natural echoes in every variety, for which particular localities have become famous.

ECHO, in Greek mythology, a mountain nymph (one of the Oreads). Legend relates that by her talking she detained Hera, when the latter sought to surprise Zeus among the mountain nymphs. To punish her the goddess deprived her of speech, unless first spoken to. She subsequently fell in love with Narcissus, and because he did not reciprocate her affection she pined away until nothing was left but her voice.

ECHUCA (e-ch[:o]'ka), an Australian town, colony of Victoria, on the Murray, over which is an iron railway and roadway bridge, connecting it with Moama in New South Wales; trade (partly by the river) in timber and wool. Pop. 4137.

['E]CIJA ([=a]-th[=e]-_h_[.a]), an ancient town of Southern Spain, province of Seville, on the Genil, with manufactures of textile fabrics and a good trade. It is one of the hottest places in Spain. Pop. 23,217.

ECK, Johann Maier von, the celebrated opponent of Luther, born in 1486, died in 1543. Having obtained a reputation for learning and skill in disputation, he was made doctor of theology, canon in Eichst[:a]dt, and pro-chancellor of the University of Ingolstadt. He went to Rome in 1520, and returned with a Papal bull against Luther, in attempting to publish which he met with violent popular opposition. In 1530, while at the Diet of Augsburg, he made the remarkable admission that he could confute the Augsburg Confession by the fathers but not by the Scriptures. Eck was present also at the Diets of Worms (1540) and Ratisbon (1541).

ECK'ERMANN, Johann Peter, German writer, born in 1792, died in 1854. In 1813 he served in the army against the French, and was afterwards appointed to a small governmental post. He finally settled in Weimar, where he became private secretary to Goethe. After Goethe's death he published his _Conversations with Goethe_, a book which has been translated into all European languages.

ECKM[:U]HL (ek'm[:u]l), a village of Bavaria, circle of Lower Bavaria, on the Gross Laber, 13 miles S.S.E. of Ratisbon, the scene of a sanguinary battle between the French and Austrians on 22nd April, 1809, in which the latter were defeated.

ECLAMP'SIA, a medical term applied to convulsions that seem to be of an epileptic character, but differ from true epilepsy as being due to some special poison. The use of the term is now practically restricted to puerperal eclampsia, convulsions occurring in pregnant women, generally those suffering from kidney disease.

ECLEC'TICS (Gr. _eklektikos_, select) is a name given to all those philosophers who do not follow one system entirely, but select what they think the best parts of all systems. The system is called _eclecticism_. In ancient philosophy Cicero was the most conspicuous representative of eclecticism, and in modern times the eclectic method found a notable supporter in the French philosopher Victor Cousin.

ECLIPSE (ek-lips'; Gr. _ekleipsis_, a failing, _ekleip[=o]_, I fail), an interception or obscuration of the light of the sun, moon, or other heavenly body by the intervention of another and non-luminous body. A star or planet may be hidden by the moon; in this case the phenomenon is called an occultation.

[Illustration: Diagrams illustrating the Theory of Eclipses]

_An Eclipse of the Moon_ is an obscuration of the light of the moon occasioned by an interposition of the earth between the sun and the moon; consequently, all eclipses of the moon happen at full moon. Further, the moon's direction from the earth must make only a very small angle with the axis of the earth's shadow, or line joining centres of sun and earth produced. But as the moon's orbit makes an angle of more than 5deg with the plane of the ecliptic, it frequently happens that though the moon is in opposition it does not come within the shadow of the earth. The theory of lunar eclipses will be understood from fig. 1, where S represents the sun, E the earth, and M the moon. If the sun were a point of light, there would be a sharp outlined shadow or _umbra_ only, but since the luminous surface is so large there is always a region in which the light of the sun is only partially cut off by the earth, which region is known as the _penumbra_ (P P). Hence during a lunar eclipse the moon first enters the penumbra, then is totally or partially immersed in the umbra, then emerges through the penumbra again.

_An Eclipse of the Sun_ is an obscuration of the whole or part of the face of the sun, occasioned by an interposition of the moon between the earth and the sun; thus all eclipses of the sun happen at the time of new moon. Fig. 2 is a diagram showing the cause of a solar eclipse. The dark or central part of the moon's shadow, where the sun's rays are wholly intercepted, is here the _umbra_, and the light part, where they are only partially intercepted, is the _penumbra_; and it is evident that if a spectator be situated on that part of the earth where the umbra falls, there will be a total eclipse of the sun at that place; in the penumbra there will be a partial eclipse, and beyond the penumbra there will be no eclipse. As the moon is not always at the same distance from the earth, and as the moon is a comparatively small body, if an eclipse should happen when the moon is so far from the earth that her shadow falls short of the earth, a spectator situated on the earth in a direct line with the centres of the sun and moon would see a ring of light round the dark body of the moon. Such an eclipse is called _annular_, as shown in fig. 3; when this happens, there can be no total eclipse anywhere. An eclipse can never be annular longer than 12 minutes 24 seconds, nor total longer than 7 minutes 58 seconds. The longest possible entire duration of an eclipse of the sun is a little over 4 hours.

An eclipse of the sun begins on the western side of his disc and ends on the eastern; and an eclipse of the moon begins on the eastern side of her disc and ends on the western. The largest possible number of eclipses in a year is seven, four of the sun and three of the moon, or five of the sun and two of the moon. The smallest is two, both of the sun. But a solar eclipse affects only a limited area of the earth, while a lunar eclipse is visible from more than a terrestrial hemisphere, as the earth rotates during its progress. Therefore at any given place eclipses of the moon are more frequently visible than those of the sun.--BIBLIOGRAPHY: R. Buchanan, _The Theory of Eclipses_; W. T. Lynn, _Remarkable Eclipses_.

ECLIP'TIC, the sun's path, the great circle of the celestial sphere, in which the sun appears to describe his annual course from west to east--really corresponding to the path which the earth describes. (See _Earth_.) The Greeks observed that eclipses of the sun and moon took place near this circle; whence they called it the _ecliptic_. The ecliptic has been divided into twelve equal parts, each of which contains 30deg, and which are occupied by the twelve celestial signs, viz.:

[Aries] Aries (the Ram), 21st March. [Taurus] Taurus (the Bull), 20th April. [Gemini] Gemini (the Twins), 21st May. [Cancer] Cancer (the Crab), 21st June. [Leo] Leo (the Lion), 23rd July. [Virgo] Virgo (the Virgin), 23rd Aug. [Libra] Libra (the Balance), 23rd Sept. [Scorpio] Scorpio (the Scorpion), 23rd Oct. [Sagittarius] Sagittarius (the Archer), 22nd Nov. [Capricornus] Capricornus (the Goat), 22nd Dec. [Aquarius] Aquarius (the Water-carrier), 20th Jan. [Pisces] Pisces (the Fishes), 19th Feb.

These are also called signs of the _zodiac_, the zodiac being a belt of the heavens extending 9deg on each side of the ecliptic. The days of the month annexed show when the sun, in its annual revolution, enters each of the signs of the zodiac. From the First Point of Aries, or the place of the sun at the vernal equinox, the degrees of the ecliptic are counted from west to east. The plane of the ecliptic is that by which the position of the planets and the latitude and longitude of the stars are reckoned. The axis of the earth is not fixed in direction in space, but performs a slow conical motion about the pole of the ecliptic in about 26,000 years. In consequence of this the points at which the equator intersects the ecliptic, viz. the First Point of Aries and First Point of Libra, recede westwards upon the ecliptic at the rate of about 50 seconds a year. The signs of the zodiac, therefore, do not now coincide, as they did some 2000 years ago, with the constellations of the same names, and the First Point of Aries has now regressed through the greater part of the constellation Pisces. The angle at which the ecliptic and equator are mutually inclined is also variable, and has been diminishing for about 4000 years at the rate of about 50 seconds in a century. Laplace gave a theory to show that this variation has certain fixed limits, and that after a certain time the angle will begin to increase again. See _Precession_ and _Nutation_.

ECLOGUE (ek'log), a term usually applied to what Theocritus called _idyls_--short, highly finished poems, principally of a descriptive or pastoral kind, and in which the loves of shepherds and shepherdesses are described. Eclogues flourished among the ancients (_Bucolics_ of Virgil), and, under the name of pastorals, were fashionable in the sixteenth century, Spenser's _Shepherds' Calendar_ being a good example. They were revived in the eighteenth century by Pope.

['E]COLE DES BEAUX ARTS ('School of Fine Arts'), the French Government school of fine arts at Paris, founded by Mazarin in 1648, and provided with an extensive staff of teachers. The competitions for the _grands prix de Rome_ take place at this school. All artists between the ages of fifteen and twenty-five, whether pupils of this school or not, may compete, after passing two preliminary examinations. The successful competitors receive an annual allowance from the State for three or four years, two of which must be passed at Rome. The Palais des Beaux Arts, the home of the ['E]cole, was begun in 1820 and finished in 1863.

['E]COLE NORMALE SUP['E]RIEURE ('Superior Normal School'), a school at Paris for the training of those teachers who have the charge of the secondary education in France, founded by decree of the Convention in 1794, reorganized by Napoleon in 1808, and again in 1830 by the Government of Louis-Philippe. By the decree of 1903 the school forms part of the University of Paris. It maintains a hundred students and has a course of three years' duration.

['E]COLE POLYTECHNIQUE ('Polytechnic School'), a school in Paris established with the purpose of giving instruction in matters connected with the various branches of the public service, such as mines, roads and bridges, engineering, the army and the navy, and Government manufactures. It was founded in 1794, and is under the direction of the Minister of War. Candidates are admitted only by competitive examination, and have to pay for their board 1000 francs a year. The pupils who pass satisfactory examinations at the end of their course are admitted to that branch of public service which they select.

ECOLOGY, or OECOLOGY, the study of the relations of plants to their surroundings, a branch of plant geography.--BIBLIOGRAPHY: Horwood, _British Wild-flowers_; Tansley, _Types of British Vegetation_; Warming, _Oecology_.

ECONOMICS is the name applied, in substitution for the older one of political economy, to the scientific study of men in relation to the production, exchange, distribution, and consumption of wealth. The origin of both names lies in the analogy between provision for the needs of a household and for those of a State. To the former the term 'economy' was originally applied, as in Xenophon's treatise on the subject. But it was soon adopted to describe that branch of the art of government which dealt with public revenue and expenditure, and a matter intimately connected therewith, the enrichment of the community as a whole.

This conception of economics inspired all economic writings until late in the eighteenth century, a typical example being Thomas Mun's _England's Treasure by Foreign Trade_ (1664), containing an exposition of the mercantile system which sought to increase natural wealth by regulation of the balance of trade. The treatment of economics as a science had its origin in the writings of the Physiocrats, a group of French philosophers of whom Quesnay (1694-1774) was the most prominent, and with whom Turgot (1727-81), the great minister of Louis XVI, held many doctrines in common. The Physiocrats argued that the wealth of the community was raised to the maximum, not by State regulation, but by entire freedom in the economic sphere. But the chief importance of the Physiocrats lay in their paving the way for Adam Smith (1723-90), who in 1776 published _The Wealth of Nations_, a book which has exercised profound and widespread influence on thought and action, and is still a leading authority on the subject. Adam Smith definitely retained the conception of economics as part of the art of government. "Political economy", he says, "proposes two distinct objects: first, to provide a plentiful revenue or subsistence for the people ... and secondly, to supply the State or Commonweal with a revenue sufficient for the public service. It proposes to enrich both the people and the sovereign." But the book is also largely occupied with an investigation of the production, distribution, and exchange of wealth when free from all regulation and restriction, together with a powerful indictment of such regulation. This doctrine of non-interference by the State came to be known as the _laissez-faire_ doctrine, from a phrase used by Gournay, one of the Physiocrats. Mainly through Adam Smith's influence, it became the orthodox view of the State's relation to trade and industry. This meant that the aims of economics, in its older sense, were best achieved without State action at all; and, consequently, economics came to mean simply the study of what are in fact men's activities in relation to wealth. This conception is clearly expressed in such writers as Ricardo (1772-1823), whose _Principles of Political Economy and Taxation_ enunciates the theory of rent which has formed the basis of all subsequent reasoning on the subject, and states a theory of wages which gave colour to Karl Marx's doctrine of the exploitation of wage-earners by capitalists. It is also evident in the work of Nassau Senior (1790-1864), in the important _Principles of Political Economy_ of John Stuart Mill (1806-73), and is most fully expressed by J. E. Cairnes (1823-78).

This conception has formed the basis of all modern economics, despite important differences in the method of treating material. The modern view of the matter is well stated by Dr. Alfred Marshall in his _Principles of Economics_, a most important contribution to the subject, which has exercised much influence. Economics he defines as "a study of mankind in the ordinary business of life; it examines that part of individual and social action which is most closely connected with the attainment and with the rise of material requisites of well-being". The separation between economics and the investigation of social phenomena in general is not so rigidly maintained to-day as in the past. It is realized that men's activities in relation to wealth are affected by other than purely economic considerations, and that political, moral, religious, and aesthetic forces must be taken into account. At the same time, the science deals only with what is, and not with what ought to be done; and is therefore distinct from _Ethics_, which is concerned with moral judgments. Of late years, interest in the application of ethical considerations to economic problems has increased considerably, using the conclusions of economic science as its material, mainly in connection with problems of distribution, especially wages. One of the most important of modern political movements, Socialism, makes a just distribution of wealth the keynote of its doctrines. In so far as man's conduct is studied in economics, the science is concerned with psychological considerations; but it is distinct from _psychology_, taking the principles thereof as data rather than establishing them as conclusions. The traditional arrangement of the subject matter of economics into the production, exchange, and distribution of wealth is still maintained; but in recent years consumption, the end of almost all man's productive activity, has received much attention, notably from W. S. Jevons (1835-82) and Marshall. Important conceptions in this connection are those of the _diminishing utility_ to an individual or group of individuals of each successive increment of any commodity received beyond a certain point; and of _consumer's surplus_, measured by the difference between the price a person pays for a thing and what he would pay rather than go without it. Any rigid distinction between the different branches of economics is, however, impossible. For example, all processes of exchange may be considered as part either of distribution or of production.

The central problem of economics is really that of how the exchange value of commodities and services is determined; since in this determination all the forces regulating production, distribution, and consumption are brought to a focus, and their action and interaction can be investigated. The study of value covers that of all forces affecting either the demand for or the supply of a commodity, including its cost of production. On the side of production, technical processes are not studied in detail, though some knowledge of them is indispensable; but matters common to all production are dealt with, such as the so-called _laws of increasing and diminishing_ return, which are statements of the relation between the amounts of labour, land, and capital used in production, and the amount of product. Other questions considered are transport, markets of all kinds, banking, currency, finance, and trusts and combinations. The study of distribution includes the methods by which wages, interest and profits, and rent are determined; and since each of these is payment for a service (of labour, capital, and land respectively) it is really an aspect of the study of value. Distribution also covers such subjects as trade unionism, co-operation, and labour disputes. Economics also deals with public finance (including taxation), treating of the effects of different methods of collecting and expending the State revenue. In considering the above-mentioned subjects, the method of economics is strictly that of a science, in that it aims partly at a descriptive analysis of material, and partly at a statement of cause and effect. The laws of economics are, like other scientific laws, statements of tendencies. They are not laws such as the commands or prohibitions of the State, though they are often loosely referred to in this way. That economics should be able to generalize and to predict about the action of men is due to its dealing not with individuals, but with large groups, so that individual peculiarities can be neglected and the general characteristics of the group ascertained. It is in this connection that considerable controversy has arisen. The older writers on economics were mainly deductive in method, i.e. they took a few general principles, such as that every man follows his own interest and knows where that interest lies, and made certain assumptions, such as the existence of free competition; and on this basis worked out a group of principles which were sometimes quite unrelated to actual facts. This method is undoubtedly a most powerful one, and of great value provided that the original assumptions are kept clearly in mind, and variations from them in a particular case allowed for in applying conclusions. But the unreality of some of its results produced a reaction, of which an early instance is the famous _Essay on the Principle of Population_ by T. R. Malthus, published in 1798. This book inaugurated the rise of a school of economists who treated their subject from an inductive and historical point of view. The historians, who have been especially prominent in Germany, and of whom representatives are Roscher (1817-94), de Laveleye (1822-92), and Cliffe Leslie (1825-82), hold that economics should in the main be descriptive, and not attempt to formulate laws. The inductive school, of whom J. S. Mill is an important member, base their work upon more extensive investigation than the older writers, and constantly test their conclusions by reference to facts. Another important reaction against the early economists arose from the identification of the latter with the doctrine of _laissez-faire_. Alexander Hamilton (1757-1804) and Friedrich List (1789-1840) argued in favour of an extension of State activity, especially for the purpose of protecting industry against foreign competition, and may be considered the fathers of modern protectionist doctrine. In most modern treatment of economics, the deductive and inductive methods are employed side by side. The study of economic history has developed as a separate branch, but economists recognize that it provides them with much valuable material. Important recent developments in method are the increased use of statistics, made possible by their more widespread and careful compilation, and the application of mathematical methods to economic data. It is recognized that, with due care, many conceptions which are with difficulty expressed in words can be treated on mathematical lines to yield results of great service. In this work the researches of Italian writers, such as Pantaleoni and Pareto, are of conspicuous importance.--BIBLIOGRAPHY: A. C. Pigou, _Wealth and Welfare_; _Preferential and Protective Import Duties_; E. Cannan, _Wealth_; J. N. Keynes, _Scope and Method of Political Economy_; G. Cassel, _Nature and Necessity of Interest_; W. Smart, _Distribution of Income_; C. R. Fay, _Co-operation_; A. Andreades, _History of the Bank of England_; H. Levy, _Monopoly and Competition_; C. F. Bastable, _Public Finance_.

['E]CRASEUR is a wire loop or chain for amputating a growth suitably situated for such an instrument. The chain is passed round the base or pedicle of the growth, and gradually tightened by a screw till the growth falls off. Its application in surgery is limited.

ECTOCARPACEAE, a family of Brown Algae, section Phaeosporeae. The typical genus is Ectocarpus, comprising small, branched, filamentous plants of salt or brackish water. According to the species, growth of the filaments may be apical, intercalary, or common to all cells, whereas among the more advanced members of the Brown Algae either apical or intercalary growth is characteristic of entire families. The gametes show every gradation from complete similarity (isogamy) to a condition like that of Cutleria.

ECUADOR (ek-w[.a]-d[=o]r') (_Republica Del Ecuador_), a republic of South America, situated under the equator, whence it takes its name, between Peru and Colombia. It is of triangular shape, its base resting on the Pacific, but the boundaries between it and its neighbours are not very definitely fixed; estimated area, about 116,000 sq. miles. The state has still a boundary dispute with Peru, that with Colombia having been settled by treaty in 1917. The country is divided into fifteen provinces, one territory--'El Oriente'--and the Archipelago of Galapagos, officially called 'Colon'. It falls, as regards the surface, into three sections: the comparatively narrow and low-lying coast regions, the mountain region, and the extensive plains on the east. The mountain region is formed by a double range of snow-clad mountains--several of them active volcanoes--which enclose a longitudinal valley or tableland, with a breadth of 20 to 40 miles, and varying in elevation from 8500 to 13,900 feet. The most elevated of these mountains are, in the western range, Chimborazo, Pichincha, and Cotacachi, Chimborazo being 20,703 feet high. In the eastern range are Cayambe, Antisana, and Cotopaxi (19,500 feet). The cultivated land and the population of Ecuador lie chiefly in this elevated region, which extends along between the summits of the Cordillera, and may be considered as divided by transverse ridges or dikes into the valleys of Quito, Hambato, and Cuenca. The chief towns here are Quito, the capital, with a pop. of 70,000, Riobamba, and Cuenca, all situated at a height of 9000 feet or more above the sea. The chief ports of Ecuador are Guayaquil and Esmeraldas. The most considerable rivers, the Tigre, Napo, Pastaza, &c., belong to the basin of the Amazon; and some of them, notably the Napo, are navigable for long distances. On the western slope of the Andes the chief rivers are the Esmeraldas and the Guayaquil. Ecuador is comparatively poor in Mammalia; although various kinds of deer as well as tapirs and peccaries are found in the forests. Parrots and humming-birds are also numerous, but perhaps the most remarkable of the birds in Ecuador is the condor, which dwells on the slopes of the Andes. Reptiles, including serpents, are numerous. The forests yield cinchona bark, caoutchouc, sarsaparilla, and vegetable ivory. The climate on the plains, both in the east and the west, is moist, hot, and unhealthy. In the higher regions the climate is rough and cold, but in great part the elevated valleys, as that of Quito, enjoy a delightful climate. Here the chief productions are potatoes, barley, wheat, and European fruits. In the lower regions are grown all the food-products of tropical climates, cocoa, coffee, and sugar. The foreign commerce is not large, the exports and imports being annually about L2,700,000 and L1,670,000 respectively. In 1919 the imports from Ecuador to the United Kingdom amounted to L1,257,350, and the exports to Ecuador to L373,346. Cocoa forms three-fourths (or more) of the whole export; the remainder is made up of tagua or ivory-nuts, rubber, straw hats, coffee, and gold. A little gold is mined, and Panama hats are made. The State recognizes no religion, but grants freedom of worship to all. A system of education was organized in 1897 and improved in 1912. There are three universities: the Central University, at Quito; the Guayas University, in Guayaquil; and the Azuay University, in Cuenca. There are schools for higher education and primary schools. The executive government is vested in a President elected for four years, who is assisted by a Council of State. The Congress is the legislative body, and consists of two Houses, one formed of Senators, two for each province, the other of Deputies, one for every 30,000 inhabitants, both elected by universal suffrage. The Congress has extensive privileges, and cannot be dissolved by the President. The seat of government is Quito. In 1920 both the revenue and expenditure amounted to nearly L2,000,000. The debt amounts to about L5,620,000. The monetary standard is gold, the gold _condor_ of ten _sucres_ being equivalent to a sovereign. The metric system of weights and measures is the legal one. Railways and telegraphs have made little progress.--Ecuador at the time of the conquest of Peru by the Spaniards formed part of the great empire of the Incas. As the Presidency of Quito it was long included in the Vice-Royalty of Peru. From 1710 it became part of the Presidency of New Granada (or Santa F['e] de Bogot['a]). In the revolutionary war against Spain, Ecuador, along with the neighbouring territories, secured its independence (1822), and was ultimately erected into a separate Republic in 1831. The present Constitution of the Republic was promulgated on 6th May, 1906. Of the present population, the aboriginal red race form more than half; the rest are negroes, mulattoes, mestizoes, a degenerate breed of mixed negro and Indian blood, and Spanish Creoles or whites. The last-named are the chief possessors of the land, but are deficient in energy. Pop. (estimated) 2,000,000.--BIBLIOGRAPHY: F. Garcia-Calderon, _Latin America: its Rise and Progress_; C. R. Enock, _Ecuador_; T. H. Stabler, _Travels in Ecuador_.

ECUMENICAL COUNCIL, a general ecclesiastical council regarded as representing the whole Christian world or the universal Church; specially applied to the general councils of the early Christian Church, beginning with that of Nicaea in 325, and later to those of the Roman Catholic Church, of which the most recent was the Vatican Council at Rome in 1870.

EC'ZEMA is a skin eruption marked by the appearance of papules or vesicles and accompanied by irritation of the affected part, frequently very severe. The characteristic watery discharge of the disease is produced by the bursting of the vesicles. There is difference of opinion among dermatologists as to whether or not it is primarily caused by germs. Various predisposing causes, like digestive disturbances, anaemia, and nervous disorders are important factors in determining the course of the disease. Eczema may affect practically any part of the skin, but is most frequently seen on the scalp, ears, face, hands, nipples, armpits, and the genital regions.

ED'AM, a town of North Holland, near the Zuider Zee, 12 miles N.N.E. of Amsterdam, noted for its cheese markets; but 'Edam cheese' is mostly made elsewhere. Pop. 6623.

EDDA (meaning 'great-grandmother'), the name given to two ancient collections of Icelandic literature, the one consisting of mythological poems, the other being mainly in prose. The first of these collections, called the _Elder_ or _Poetic Edda_, was compiled in the thirteenth century, and discovered in 1643 by Brynjulf Sveinsson, an Icelandic bishop. For a long time an earlier date was given, the compiler being erroneously believed to have been Saemund Sigfusson, a learned Icelandic clergyman, who lived from about 1056 to 1133. It consists of thirty-three pieces, written in alliterative verse, and comprising epic tales of the Scandinavian gods and goddesses, and narratives dealing with the Scandinavian heroes. These poems are now assigned to a period extending from the ninth to the eleventh century. The _Prose Edda_, or _Younger Edda_, presents a kind of prose synopsis of the Northern mythology; a treatise on the Scaldic poetry and versification, with rules and examples; and lastly a poem (with a commentary) in honour of Haco of Norway (died 1263). In its earliest forms this collection is ascribed to Snorri Sturlason, who was born in Iceland in 1178, and was assassinated there in 1241 on his return from Norway, where he had been scald or court poet. Cf. S. Bugge, _Home of the Eddic Poems_.

EDDY, Mary Baker, founder of Christian Science (q.v.), born at Bow, New Hampshire, United States, 16th July, 1821, died 3rd Dec., 1910. She was married three times, to Mr. Glover, Mr. Patterson, and Mr. Asa Gilbert Eddy, all of whom she survived. She began to teach her system of psychotherapeutics in 1866, and founded the first Christian Science Church in Boston in 1879. In 1881 she established the Metaphysical College at Massachusetts. Her works, besides _Science and Health with Key to the Scriptures_, include: _Unity of God_, _No and Yes_, _Pulpit and Press_, _The First Church of Christ_, _Christian Science versus Pantheism_.--Cf. G. Milmine, _Life of M. B. G. Eddy and the History of Christian Science_.

EDDYSTONE LIGHTHOUSE, a lighthouse in the English Channel, erected to mark a group of rocks lying in the fair-way from the Start to the Lizard. The rocks are covered only at the flood. The first lighthouse was of wood, and built by Henry Winstanley in 1696. It was carried away in the storm of 1703. Another lighthouse, also of wood, was built in 1709 by Rudyerd, but was burned down in 1755. It was succeeded by one built by Smeaton between 1757 and 1759, a circular tower 85 feet high; but, as the foundations on which it stood became much weakened, a new structure, designed by Sir J. N. Douglass, was built between 1879 and 1882 on the neighbouring reef. Its light is visible 17-1/2 miles.

EDELWEISS ([=a]-d[.e]l-v[=i]s; Ger., 'noble white'), _Leontopodium alp[=i]num_, a composite plant inhabiting the Alps, and often growing in the most inaccessible places. Its flower-heads are surrounded by a spreading foliaceous woolly involucre, and its foliage is also of the same woolly character. It is not difficult to cultivate, but is apt to lose its peculiar woolly appearance.

E'DEN (Heb. _eden_, delight), the original abode of the first human pair. It is said to have had a garden in the eastern part of it, and we are told that a river went out of Eden to water this garden, and from thence it was parted into four heads, which were called respectively Pison, Gihon, Hiddekel, and Euphrates (Phrat), but this does not enable us to identify the locality. It was not the whole of Eden that was assigned to man for his first habitation, but the part towards the east, to which the translators of the Authorized Version have given the name of the Garden of Eden, and which Milton, in _Paradise Lost_, calls Paradise, that word (originally Persian) having in its Greek form (_paradeisos_) been applied to the Garden of Eden by the translators of the _Septuagint_.

EDEN, a river in England, in Westmorland and Cumberland, falling into the Solway Firth after a course of 65 miles.--Also, a river in Fifeshire, Scotland.

EDENTA'TA ([=e]-), or TOOTHLESS ANIMALS, the name applied to a primitive order of mammals mostly native to the neotropical region, but also represented in South Africa and South Asia. The body is often covered by horny scales or bony plates, the digits are clawed, and the teeth either imperfect or absent altogether. I. New World forms.--(1) _Ant-eaters._ Toothless, with long narrow snout, and protrusible tongue. Covered with dense fur. The great ant-eater (_Myrmecoph[)a]ga jubata_) lives on the ground; the much smaller Tamandua and Cycloturus are arboreal. (2) _Sloths._ Toothed arboreal leaf-eaters, covered by coarse fur, and provided with very strong curved claws, by which they hang upside down from branches. The three-toed sloth (Bradypus) has three digits in the fore-limb, the two-toed sloth (Cholaepus) only two. (3) _Armadillos._ Burrowing forms protected by a strong carapace of bony plates, and possessing numerous imperfect teeth. (4) _Extinct types._ The so-called ground sloths were of large size, Megatherium being nearly as large as an elephant, and Mylodon not much smaller. Glossodon, allied to the latter, survived into the human period. Glyptodon resembled a gigantic armadillo. II. Old World forms.--(1) The _aard-vark_ (Orycteropus) is a burrowing African form about the size of a pig, covered with coarse hair; long ears and snout; 20 imperfect grinding teeth. (2) _Scaly ant-eaters_ or _pangolins_ (Manis), native to South Africa and South Asia, are toothless forms not unlike the American ant-eaters in build, but the body is covered dorsally and laterally by large overlapping scales.

EDES'SA, the name of two ancient cities.--1. The ancient capital of Macedonia, and the burial-place of its kings, now _Vodhena_. It is probably the same as the still more ancient Aegae. Philip II was murdered at Edessa in 336 B.C.--2. An important city in the north of Mesopotamia, which, subsequent to the establishment of Christianity, became celebrated for its theological schools. In 1098, in the first Crusade, Edessa came into the hands of Baldwin, but ultimately became part of the Turkish Empire. It is thought to be the modern Urfah or Orfa.

EDFU, or EDFOO' (ancient APOLLINOPOLIS), a village in Upper Egypt, province of Assouan, on the left bank of the Nile, with manufactures of cottons and pottery. Its ancient magnificence is attested by several remains, especially a temple, founded by Ptolemy Philopator (181-145 B.C.), the largest in Egypt after those of Karnak and Luxor. Pop. 12,594.

ED'GAR (_the Peaceful_), one of the most distinguished of the Saxon Kings of England, was the son of King Edmund I. He succeeded to the throne in 959, and managed the civil and military affairs of his kingdom with great vigour and success. In ecclesiastical affairs he was guided by Dunstan, Archbishop of Canterbury, and he was a great patron of the monks. He died in 975, and was succeeded by his son Edward the Martyr.

EDGAR ATHELING, grandson of Edmund Ironside and son of Edward the Outlaw, was born in Hungary, where his father had been conveyed in infancy to escape the designs of Canute. After the battle of Hastings, Edgar (who had been brought to England in 1057) was proclaimed King of England by the Saxons, but made peace with William and accepted the earldom of Oxford. Having been engaged in some conspiracy against the king, he was forced to seek refuge in Scotland, where his sister Margaret became the wife of Malcolm Canmore. Edgar subsequently was reconciled to William and was allowed to live at Rouen, where a pension was assigned to him. In 1097, with the sanction of William Rufus, he undertook an expedition to Scotland for the purpose of displacing the usurper Donald Bane, in favour of his nephew Edgar, son of Malcolm Canmore, and in this object he succeeded. He afterwards took part in Duke Robert's unsuccessful struggle with Henry I, but was allowed to spend the remainder of his life quietly in England.

EDGEHILL, a ridge in Warwickshire, England, 7 miles north-west of Banbury, where was fought a fierce but indecisive battle on 23rd Oct., 1642, between the Royalists under Charles I and the forces of the Parliament under the Earl of Essex.

EDGEWORTH, Maria, Irish novelist, born at Black Bourton, Oxfordshire, 1st Jan., 1767, died 22nd May, 1849, at Edgeworthstown. She was the daughter of Richard Lovell Edgeworth (1744-1817) of Edgeworthstown, County Longford, Ireland. Her first novel, _Castle Rackrent_, a tale of Irish life, published in 1800, immediately established her reputation. Her later works include: _Belinda_, _Moral Tales_, _Leonora_, _Popular Tales_, _Tales of Fashionable Life_, _Patronage_, _Harrington_, _Ormond_, and _Helen_, besides an _Essay on Irish Bulls_, and a work on _Practical Education_, largely based on Rousseau's _['E]mile_. Miss Edgeworth's characteristics are a simple and lucid style and considerable power of observation, but she was not a great creative artist.

ED'INBURGH, the metropolis of Scotland, and one of the finest as well as most ancient cities in the British Empire, lies within 2 miles of the south shore of the Firth of Forth. It is picturesquely situated, being built on three eminences which run in a direction from east to west, and surrounded on all sides by lofty hills except on the north, where the ground slopes gently towards the Firth of Forth. The central ridge, which constituted the site of the ancient city, is terminated by the castle on the west, situated on a high rock, and by Holyrood House on the east, not far from which rise the lofty elevations of Salisbury Crags, Arthur's Seat (822 feet high), and the Calton Hill overlooking the city. The valley to the north, once the North Loch, but now drained and traversed by the North British Railway, leads to the New Town on the rising ground beyond, a splendid assemblage of streets, squares, and gardens. The houses here, all built of a beautiful white freestone found in the neighbourhood, are comparatively modern and remarkably handsome. The principal streets of the New Town are Princes Street, George Street, and Queen Street. From Princes Street, which is lined by fine gardens adorned with Sir W. Scott's monument and other notable buildings, a magnificent view of the Old Town with its picturesque outline may be obtained. The principal street of the Old Town is that which occupies the crest of the ridge on which the latter is built, and which bears at different points the names of Canongate, High Street, Lawnmarket, and Castle Hill. This ancient and very remarkable street is upwards of one mile in length, rising gradually with a regular incline from a small plain at the east end of the town, on which stands the palace of Holyrood, and terminating in the huge rock on which the castle is built, 437 feet above sea-level. The houses are lofty and of antique appearance. Amongst the notable buildings are the ancient Parliament House, since the Union the seat of the supreme courts of Scotland; St. Giles' Church or Cathedral, an imposing edifice in the later Gothic style, dating from the fourteenth century and carefully restored between 1879 and 1883; the Tron Church; Victoria Hall (where the General Assembly of the Established Church meets), with a fine spire; and also John Knox's House, besides some of the old family houses of the Scottish nobility and other buildings of antiquarian interest. From this main street descend laterally in regular rows numerous narrow lanes called _closes_, many of them extremely steep, and very few at their entrances more than 6 feet wide; those which are broader, and admit of the passage of carriages, are called _wynds_. In these and the adjacent streets the houses are frequently more than 120 feet in height, and divided into from six to ten stories, or _flats_, the communication between which is maintained by broad stone stairs, winding from the lowest part of the building to the top. In the Old Town the most remarkable public building is the castle, an extensive mass, of which the oldest portion--and the oldest building in the city--is St. Margaret's Chapel, the private oratory of the Saxon princess Margaret, queen of Malcolm Canmore; another portion being a lofty range of old buildings, in a small apartment of which Queen Mary gave birth to James VI in 1566; while in an adjoining apartment are kept the ancient regalia of Scotland. Here is also the old Parliament Hall, restored during 1888 and 1889. The castle as a fortress contains accommodation for 2000 soldiers, and the armoury space for 30,000 stand of arms. An old piece of ordnance built of staves of malleable iron, cask fashion, and known as _Mons Meg_, stands conspicuous in an open area. The palace of Holyrood, or Holyrood House as it is more generally called, stands, as already mentioned, at the lower or eastern extremity of the street leading to the castle. No part of the present palace is older than the time of James V (1528), while the greater portion of it dates only from the time of Charles II. In the north-west angle of the building are the apartments which were occupied by Queen Mary, nearly in the same state in which they were left by that unfortunate princess. Adjoining the palace are the ruins of the chapel belonging to the Abbey of Holyrood, founded in 1128 by David I. On the south side of the Old Town, and separated from it also by a hollow crossed by two bridges (the South Bridge and George IV Bridge), stands the remaining portion of the city, which, with the exception of a few unimportant streets, is mostly modern. Besides the buildings already noticed, Edinburgh possesses a large number of important edifices and institutions, chief amongst which are the Royal Institution (accommodating the Royal Society and other bodies), a beautiful Grecian building; the National (Picture) Gallery, another fine building in the Greek style, the two buildings standing on a conspicuous site between East and West Princes Street Gardens; the National Portrait Gallery, a building due to private munificence and accommodating also the National Museum of Antiquities; the Museum of Science and Art; the Episcopal Cathedral of St. Mary's, one of the largest religious edifices of modern times; the university buildings, including those of the medical department, standing apart from the others; the infirmary buildings; the high school, register office, and others. Amongst the more prominent educational institutions are the university, the high school, the academy, the United Free Church New College, the Edinburgh School of Medicine (connected with the Royal College of Physicians and the Royal College of Surgeons), Medical College for Women, College of Agriculture, the Edinburgh Veterinary College, Fettes College, the Heriot-Watt College, normal schools, technical, commercial, and other institutions, and endowed secondary schools. The Advocates' Library, the largest in Scotland, contains upwards of 550,000 printed volumes and 3000 MSS.; the university library, 200,000; the library of Writers to the Signet, 100,000. There is also a rate-supported public library in a building erected at the expense of the late Andrew Carnegie. Printing, bookbinding, coach-building, type-founding, machine-making, the making of rubber goods, furniture-making, ale-brewing on a very large scale, and distilling are the principal industries. Edinburgh is the head-quarters of the book trade in Scotland, and the seat of the chief Government departments. It is a great resort of tourists and other travellers. On account of its picturesque and commanding situation and its literary fame, Edinburgh is often called the 'Modern Athens'. The origin of Edinburgh is uncertain. Its name is by many thought to be derived from Eadwinsburh, the Burgh of Edwin, a powerful Northumbrian king of the early seventh century, who absorbed the Lothians in his rule. The town was made a royal burgh in the time of David I; but it was not till the fifteenth century that it became the recognized capital of Scotland, and from that time it was the scene of many important events in Scottish history. The city is now governed by a council, which elects from its members a Lord Provost, a city treasurer, and seven bailies. It returns five members to Parliament, and within the municipal boundaries are included Portobello, Granton, Liberton, Duddingston, and since 1920 also the port of Leith. Pop. 420,281.--BIBLIOGRAPHY: J. B. Gillies, _Edinburgh, Past and Present_; M. O. Oliphant, _Royal Edinburgh, Her Saints, Kings, Prophets, and Poets_; W. H. O. Smeaton, _Edinburgh and its Story_; H. E. Maxwell, _Edinburgh: a Historical Study_.

EDINBURGH, COUNTY OF, or MIDLOTHIAN, is bounded north by the Firth of Forth, along which it extends 11 or 12 miles; and by the counties of Linlithgow, Haddington, Berwick, Lanark, Peebles, Selkirk, and Roxburgh; area, 234,926 acres, over half of which is arable or under permanent pasture. The south-south-east and south-west parts of the county are diversified with hills, of which the two principal ranges are the Pentlands and Moorfoots, the former stretching across the county to within 4 miles of Edinburgh. The principal rivers are the North and South Esks and the Water of Leith, all running into the Forth. The lowlands towards the Forth are the most fertile; the farms are of considerable size, and the most approved methods of agriculture are in use. The hilly parts are chiefly under pasturage and dairy farming. The chief crops are oats, barley, turnips, and potatoes. The manufactures are comparatively limited, but include ale, whisky, gunpowder, paper, and tiles. The fisheries are valuable. The chief towns are: Edinburgh, Dalkeith, and Musselburgh. Midlothian and Peebles return two members to Parliament. Pop. 506,378.

EDINBURGH, DUKE OF, H.R.H. Prince Alfred Ernest Albert, K.G., K.T., K.P., &c., Duke of Saxe-Coburg-Gotha, the second son of Queen Victoria, was born at Windsor Castle, 6th Aug., 1844, died in 1900. At the age of fourteen he joined the navy as naval cadet, and served on various foreign stations. In 1862 he declined the offer of the throne of Greece. On his majority he received L15,000 a year from Parliament, and was created Duke of Edinburgh, Earl of Kent, and Earl of Ulster. In 1867 he was appointed to the command of the frigate _Galatea_, in which he visited Australia, Japan, China, and India. In 1873 he received an additional annuity of L10,000, and next year he married the Grand-Duchess Marie, only daughter of the Emperor of Russia. In 1882 he was made a vice-admiral, and subsequently held important commands. In 1898 he succeeded his uncle as ruler of Saxe-Coburg-Gotha, and resigned L15,000 of his annuity and his other privileges as an English prince, but retained his rank of admiral. He had one son (who predeceased him) and four daughters. He was succeeded as Duke of Saxe-Coburg by his nephew, Leopold Charles, Duke of Albany.

EDINBURGH REVIEW, THE, a quarterly review established in 1802. It had an immediate and striking success, the brilliancy and vigour of its articles being much above the standard of the periodical literature of that time. In politics it was Whig, and did good service to the party. The _Review_ was founded by a knot of young men living in Edinburgh, the more prominent of whom were Brougham, Jeffrey, Sydney Smith, and Francis Horner. It was edited from 1803 to 1829 by Jeffrey, under whom it was very successful. In reply to his criticisms Byron wrote his _English Bards and Scotch Reviewers_. Among the famous contributors to the _Review_ were Lord Macaulay, Lord John Russell, and John Stuart Mill.

EDINBURGH UNIVERSITY, the latest of the Scottish universities, was founded in 1582 by a charter granted by James VI. The number of professors and other teachers is now over 240. The university is a corporation consisting of a chancellor, rector, principal, professors, registered graduates and alumni, and matriculated students. Its government is administered by the University Court, the Senatus Academicus, and the General Council, as in the other Scottish universities, in all of which new ordinances have been introduced under the Universities (Scotland) Act of 1889. The University Court, which is the supreme governing body of the university, consists of the rector, who is president, the principal, the Lord Provost of Edinburgh, and eleven assessors. The Senatus superintends the teaching and discipline of the university, and consists of the principal and professors. The General Council consists of the chancellor, who is president, the members of the University Court and Senatus, and the graduates of the university. It takes cognizance of matters generally affecting the well-being of the university. The chancellor is the official head of the university, and it is through him or his deputy, the vice-chancellor, that degrees are conferred. He is elected for life by the General Council. The principal is the resident head of the university and president of the Senatus, and is appointed for life (at Edinburgh by a body called the 'Curators', elsewhere by the Crown). The lord rector is elected for three years by the matriculated students. There are six faculties in the university, viz. arts, science, divinity, law, medicine, and music. Some of the professors are appointed by the Crown, others by special electors, and a considerable number by the curators, who represent the university court and the town council. The number of students in 1919-20 was over 4300. Candidates for degrees in the different faculties must now pass an entrance examination before attendance upon classes. Women are admitted to all courses and degrees, equally with men, except in the faculty of divinity. Those desirous of taking the degree of Master of Arts (M.A.) must attend classes and pass examinations in at least seven subjects, selected from four departments, viz. language and literature, mental philosophy, science, history and law, the course of study extending over three academic years at least. There is a considerable restriction in choice of subjects, since four of them must be (_a_) Latin or Greek; (_b_) English or a Modern Language; (_c_) Logic or Moral Philosophy; (_d_) Mathematics or Natural Philosophy; and the whole subjects must include both of (_a_) or both of (_c_), or two out of the three--mathematics, natural philosophy, and chemistry. Four medical degrees are conferred: Bachelor of Medicine (M.B.), Bachelor of Surgery (Ch.B.), Master of Surgery (Ch.M.), and Doctor of Medicine (M.D.). Before any of these degrees can be obtained the candidate must have been engaged in medical study for at least five years. The degrees in law are Bachelor of the Law (B.L.), Bachelor of Laws (LL.B.), and Doctor of Laws (LL.D.), the last being purely honorary. In divinity the degrees are Bachelor and Doctor of Divinity (B.D. and D.D.), the latter being honorary. In science the degrees are likewise Bachelor and Doctor (B.Sc. and D.Sc.), both conferred in the three departments of pure science, engineering, and public health. There is also a B.Sc. in agriculture. The degree of Doctor of Philosophy (D.Phil.) is conferred for proficiency in mental science, and that of Doctor of Letters (D.Litt.) for proficiency in literary, philological, and linguistic studies. The degrees of Bachelor and Doctor of Music (Mus.B. and Mus.D.) are also conferred. There is a joint board of examiners for the four Scottish universities, having the control and supervision of the preliminary examinations. The university has splendid laboratories and museums. The foundation stone of a new science laboratory was laid by King George on 6th July, 1920. The library contains 200,000 volumes. There are bursaries, scholarships, and fellowships, amounting annually to about L12,500. Since 1918 the University of Edinburgh unites with the other Scottish universities in returning three members to Parliament. The constituency consists of the General Council.--BIBLIOGRAPHY: J. Kerr, _Scottish Education, School and University, from Early Times to 1908_; _University Calendar_; Sir Alex. Grant, _The Story of the University of Edinburgh from Early Times to 1908_.

ED'ISON, Thomas Alva, an American inventor, born in Ohio in 1847. He was poorly educated, became a newsboy on the Grand Trunk Railway, and afterwards, having obtained some type, issued a small sheet of his own known as the _Grand Trunk Herald_, printing it in a freight car. He then set himself to learn telegraph work, and in a short time became an expert operator. In 1863, while at Indianopolis, he invented an automatic telegraph repeater. This was the first of a long series of improvements and inventions. He opened an extensive establishment at Newark for the manufacture of electrical, printing, automatic, and other apparatus. In 1876, his health breaking down, he gave up manufacturing and devoted himself to investigation and invention. Amongst his numerous inventions are the quadruplex and sextuplex telegraph, the carbon telephone transmitter, the 'Edison system' of lighting, the electric fire-alarm, the 'Edison electric railway', the phonograph, and the megaphone. His improvements in the cinematograph made it practicable, though he did not originate the idea of it.

ED'MONTON, an urban district and parliamentary borough in England, county of Middlesex, 7-1/2 miles north of London, with an extensive trade in timber, carried on by the Lea River navigation. The 'Bell at Edmonton' has become famous by association with the adventures of Cowper's _John Gilpin_. The borough returns one member to Parliament. Pop. 64,820.

EDMONTON, a town of North-Western Canada, on the North Saskatchewan (here navigable). Since 1905 it is the capital of the province of Alberta, and has grown considerably in recent years. It is an important station on the Canadian Pacific, Grand Trunk Pacific, and Canadian Northern railway systems, and is the distributing centre of an immense area, being also the centre of an excellent farming district. Easily-mined coal is worked here. Pop, 61,000.

ED'MUND, ST., King of the East Angles, began to reign in 855, died in 870. He was revered by his subjects for his justice and piety. In 870 his kingdom was invaded, and he himself slain, by the Danes. The Church made him a martyr, and a town (Bury St. Edmunds) grew up round the place where he was buried.

EDMUND I, King of England, an able and spirited prince, succeeded his brother Athelstan in 940. He conquered Cumbria, which he bestowed on Malcolm, King of Scotland, on condition of doing homage for it to himself. He was slain at a banquet 26th May, 946.

EDMUND II, surnamed _Ironside_, King of England, the eldest son of Ethelred II, was born in 989. He was chosen king in 1016, Canute having been already elected king by another party. He won several victories over Canute, but was defeated at Assandun in Essex, and forced to surrender the midland and northern counties to Canute. He died after a reign of only seven months.

EDOM, in the New Testament _Idumaea_, in ancient times a country lying to the south of Palestine. The Edomites are said in _Genesis_ to be the descendants of Esau, who was also called Edom (a word signifying 'red'), and who dwelt in Mount Seir, the mountain range now called _Jebel Shera_, stretching between the Dead Sea and the Gulf of Akabah. Edom is frequently mentioned in the Assyrian inscriptions. The Edomites were subdued by King David, and after the separation of the ten tribes remained subject to the Kingdom of Judah until the reign of Jehoram, when they revolted and secured their independence for a time. They were again subdued about half a century later by Amaziah, and again, in the reign of Ahaz, recovered their independence, which they maintained till the time of the invasion of Judea by Nebuchadnezzar. They fell under the rule of the Persians, and afterwards their fortunes were merged in those of Arabia. The chief city in this region was Petra, which now presents remarkable ruins, as well as several rock-cut temples.

EDRED, King of England, son of Edward the Elder, succeeded to the throne on the murder of his brother, Edmund I, in May, 946. He quelled a rebellion of the Northumbrian Danes, and died in 955.

[Illustration: Edriophthalmata

1, Fresh-water shrimp (_Gammarus pulex_). _a_, Single eye. 2, Head of Cymothoa. _b_, Clusters of simple eyes.]

EDRIOPHTHAL'MATA, one of the great divisions of the Crustacea, including all those genera which have their eyes sessile, or embedded in the head, and not fixed on a peduncle or stalk as in the crabs, lobsters, &c. It is divided into two orders. (1) Amphipoda, laterally flattened, as in the marine sandhopper (Talitrus), and the fresh-water shrimp (Gammarus). (2) Isopoda, flattened from above downwards. Sea-slaters or wood-lice (Ligia and Idothea); fish parasites (Cymothoa); fresh-water wood-lice (Asellus); land wood-lice (Oniscus, Porcellio, Armadillidium, which can roll up).

EDRI'SI, Abu-Abdallah Mohammed, a famous Arabian geographer, a descendant of the ancient princely family of the Edrisites, born about A.D. 1100, died about 1180. He studied at the Moorish university of Cordova, after which he travelled through various countries. At the request of King Roger II of Sicily he constructed a globe with a map of the earth, which represented all the geographical knowledge of the age. He accompanied this with a descriptive treatise completed about 1154, and still extant. The work was published at Rome in Arabic (1592), and in 1619 a Latin translation of it, under the title of _Geographia Nubiensis_, appeared in Paris.

EDUCATION is the name applied to the systematic instruction given by each succeeding generation to the young of the race to fit them for the work of life. The word itself is derived from the Latin verb _educare_, which means to rear, to nourish, to bring up, and also to educate. Long before the dawn of civilization men saw that the young had to be prepared for the battle of life; had to learn how to make and how to use the offensive and defensive weapons employed against their enemies; how to form or build shelters to protect themselves against the weather and against their foes; how to make traps or snares for the wild things on which they fed; how, in fact, to use their powers of mind and body in such a way as to secure for themselves the fullest and most satisfactory life possible under the circumstances in which they found themselves.

While education thus understood would be the story of man on the earth, an account of his more or less satisfactory, but always continuous, efforts to perfect the relations between his desires and his environment, it would have to embrace also an account of the conflict between the demands of communities and the rights of individuals. Education, however, as we understand it, is more limited in its scope. It is the instrument employed by the State for the training of its citizens.

The Greeks were the first Europeans to treat education as a science. The results they obtained were good, and have to a certain extent determined the course taken by European education ever since. Plato defined the aim of the education of which he gives us an account in the _Republic_, to be the "development in the body and in the soul of all the perfection which it is possible for them to attain". This was the Greek ideal of what education should aim at; a high ideal indeed; but one that omits an element of immense importance which we find introduced in Milton's definition of the 'end of learning', that is, the aim of education. Milton boldly declares this to be: "To repair the ruin of our first parents by regaining to know God aright, and out of that knowledge to love Him, as we may the nearest by possessing our souls of true virtue, which being united to the heavenly grace of faith makes up the highest perfection". Perfection is the end sought in both cases, and which seems the nobler it is unnecessary to say. This impression is deepened when he proceeds to declare that as "Our understanding cannot ... arrive so clearly to the knowledge of God and things invisible, as by orderly conning over the visible and inferior creatures, the same method is necessarily to be followed in all discreet teaching".

By Aristotle the order of education was: first, education of the body, the just and proportionate development of its powers. The instrument employed for this purpose was gymnastics; not the gymnastics employed in training professional athletes, but more moderate exercises; for, as the philosopher insists, too strenuous bodily exertion is apt to spoil the child, because body and mind must not be hard worked at the same time. Music, according to him, had various aims: education proper, the training of the affections, and the occupation of leisure. Drawing was taught as a branch of music for the purpose of developing the child's sense of beauty, mathematics were taught to cultivate his intellect, and dialectic (logic and philosophy) to prepare the pupil for a scientific training.

To the idealistic philosopher Plato, the whole life of man, at least the whole of what we may call the active life, was educative. Education was State-controlled, and at the end of the first six years, spent by the child in the seclusion of family life, the State took charge. The aim of the education proposed by Plato was to develop in the child the cardinal virtues--honour to parents, love of fellow-citizens, courage, truthfulness, and self-control. From the seventh to the tenth year the training was mainly in gymnastics; from the tenth to the thirteenth the child learned to read and to write; from the thirteenth to the sixteenth his affections and his sense of the beautiful were cultivated through learning poetry and studying music; from the seventeenth to the twentieth year he applied himself mainly to athletics, so that he might be qualified to take his share in the defence of the State. At twenty men were called upon to choose their occupation; to turn their minds to the study of the sciences; and to shape by practical military and other services to the State that character which it was the aim of education to form. From thirty to thirty-five Plato supposes the citizens of his ideal republic to devote themselves to the study of _Dialectics_, the method of purely intellectual knowledge, by which reason, using hypothesis, arrives at the first principles of things. From thirty-five to fifty the life of the citizen was to be given up to public service, that is, to the promotion in the position for which he was best fitted of the general well-being.

The training set forth by the Greek philosophers was the training thought necessary to fit a man to be a ruler. As the Greek city states were slave states, and most of the manual work was performed by slaves, that necessary part of the training of the youth of the community is ignored. This fact has had, undoubtedly, an enormous influence on the ideas of education put forward since. The preliminary training demanded by the Greeks included, besides gymnastics, grammar and music. At a later time these were understood to include the seven arts: Grammar, Rhetoric, Dialectic (_Trivium_), and Arithmetic, Music, Geometry, and Astronomy (_Quadrivium_). To the Greeks, myths were the instruments of the earliest education, the aim of which was the development of a character in the citizen which would lead him to give his best and most loyal services to the State.

The aim of Greek education was the formation of the philosophic thinker, the man fitted by nature and training to guide and direct the energies of the man of action. Roman education, on the other hand, directed its efforts mainly to the moulding of the man of action himself. The Romans adopted the form rather than the spirit of Greek education. The aim of Roman education was to make a man who could do things; a practical man, a man full of energy, who was ever ready to sacrifice himself in the interests of the State; a man who knew the laws and who regulated his conduct by them; who reverenced his father and his country's gods; and found his chief pleasure in the complete overthrow and utter destruction of his country's foes. He could discourse eloquently and not unphilosophically; and he spared neither himself nor others in his effort to maintain the freedom of his country, and to bring destruction on the enemies of Rome. Roman education began in the home, and during the earlier years was largely directed by the mother. Later the preparation of the boy for life was taken over by the father; but it is probable that, from very early times many, if not most, Romans boys were sent to school, where, under the _magister literarius_ (elementary teacher), the _grammaticus_ (advanced teacher), and the _rhetor_ (professor), they acquired the knowledge and accomplishments it was needful for them to obtain.

The Roman schools, elementary and secondary, seem to have been conducted in a verandah, and boys and girls seem to have been taught in the same school. The chief Roman writers on education are Cicero, Seneca, and Quintilian. Quintilian tells us that Cato also wrote a treatise on the subject, but that that work had been lost. The oratorical training of which Quintilian was the expositor seems to have been largely out of connection with real life; and, though he claims that the orator must be a widely cultured, wise, and honourable man, seems to have developed a tendency to the bombastic abuse of ornate and stilted speech. The practical effects, too, of the corruption of family education were far from satisfactory. Moral degradation followed, and humanity seems to have been rescued only by the introduction of a new ideal of life, which substituted for the pagan self-reliance, self-control, moderation, and proportion, self-denial, self-forgetfulness, and humility; which made the last, indeed, the chief virtue, and looked on pride and self-confidence as spiritual sins.

The introduction of Christianity was followed by the inroads into the Roman Empire of barbarous tribes from the north and east. Before these attacks the Western Roman Empire collapsed, and with it to a greater or less extent the educational system of the time.

It must be remembered that between three and four hundred years elapsed between the downfall of the Western Roman Empire and the beginnings of the Holy Roman Empire under Charlemagne. Classical or pagan culture, as profane learning, was at a discount, and the aim of the monasticism which grew out of the introduction of Christianity was mystic absorption in the contemplation of God.

This interval was followed by the efforts of Charlemagne to revive Roman culture, and to establish schools throughout Western Europe. In this he was aided by Alcuin and other scholars from England, where in the comparative quiet that followed the conquest of Britain there had grown up a system of education. Throughout his dominions three classes of schools were established by Charlemagne, the Palace School, the Bishop's School, and the Monastery School. These were intended to take the place of the splendid system of public schools that had grown up under the Roman Empire. The course of studies established in these mediaeval schools, following the practice of Greece and Rome, was divided into two parts: the _Trivium_, including Grammar, Dialectic, Rhetoric; and the _Quadrivium_, which embraced Geometry, Arithmetic, Music, and Astronomy. Education in the palace or castle schools had a different aim. It sought to develop the bodily powers, and to awake in the pupils that respect for the weak which was shown in the worship of women, and that love of justice, and belief in its supremacy, which characterized the _chivalry_ of the Middle Ages.

The scholastic education of this time laid special stress on formal logic and metaphysics. Latin was taught, was, indeed, the universal language of the period. Questions about the nature of the unseen and the spiritual occupied much of men's minds; while their time was taken up in discussing the character of universals, the true realities which lay behind the individual manifestations of experience. As a rule, the physical world was ignored, and human intelligence disregarded; but there were notable exceptions, among which the teachings of Bishop Grosseteste (died 1253) and of Roger Bacon (1214 to 1294) take a prominent place.

It was during the period of scholasticism that universities, in imitation of the trade guilds of the time, sprung up in different parts of Europe, particularly in Spain, Italy, France, and England. To the famous schools both in England and on the Continent scholars flocked from all parts, and their instruction presented little difficulty, as Latin, the language in which the instruction was given, was the common language of scholars in Western Europe. The establishment of universities in different countries was a sign rather than a cause or result of that intellectual and spiritual awakening which, after nearly a thousand years of almost complete stagnation, manifested itself among the peoples of Europe.

It is usual to date the Renaissance from 1453, the fall of Constantinople; but it must not be forgotten that owing to the clash between East and West, the struggle between Christianity and Mohammedanism (the Crusades, as these religious wars were called), there had from the end of the eleventh century been a considerable change of outlook among the nations of Western Europe. This was specially the case in Italy, where city states, not unlike those of Greece in their character, had sprung up, and where, as in Greece in the time of Pericles, there had been the great outburst of literary activity which is associated with the names of Boccaccio, Dante, and Petrarch. In Northern and Western Europe the intelligence stimulated by the new learning was directed towards the improvement of the method of study. All study was linguistic. Latin was the instrument of common intercourse; Greek and Hebrew were sacred as the tongues in which the Scriptures had been conveyed; it was no wonder, therefore, that the humanistic education was almost entirely confined to the study of languages. Sturm (1507 to 1589) drew up a scheme of studies which had long a great influence on the school courses of instruction throughout Europe.

The reaction against authority which marked the Reformation period was specially noted for the reaction against the purely verbal education given to the young, whose education, as we learn from Locke, was calculated to teach them "not to believe, but to dispute", and to fit them "for the university, not for the world". On the Continent Rabelais (1483 to 1533) led this realistic movement, which was continued by Montaigne (1533 to 1592) in France, and under the influence of Bacon by Brinsley and Hoole in England, and Ratke and Comenius on the Continent. Up to this time the chief English writers on the subject of education had been Sir Thomas Elyot in his _Governour_, Roger Ascham in his _Scholemaster_, and Richard Mulcaster in his _Positions_.

The intellectual activity which marked in England the closing decades of the sixteenth and the first part of the seventeenth century saw the issue of Milton's _Tractate_, one of the most famous books on education ever produced. The _Tractate_ discusses only the kind of education that should be given to gentlemen's sons between the ages of twelve and twenty-one, so that it is strictly limited in its application, as it does not deal with the education of the people, nor with the education of women. The ideal which Milton put before him as the aim of "a complete and generous education" was "to fit a man to perform justly, skilfully, and magnanimously all the offices both private and public of peace and war". Milton in his _Tractate_ discusses studies, exercise, and diet, showing that he clearly understood that education was concerned with the body as well as the mind and spirit.

Towards the close of the seventeenth century Locke, an English physician and philosopher, published (1693) his _Thoughts concerning Education_, a book which influenced immensely the character and direction of future educational studies. As he informs his readers in his letter to Edward Clarke, he counsels everyone "after having well examined and distinguished what fancy, custom, or reason advises in the case ... to promote everywhere that way of training up youth ... which is the easiest, shortest, and likeliest to produce virtuous, useful, and able men in their distinct callings". He begins his essay with the statement, "A sound mind in a sound body is a short but full description of a happy state in this world", and the suggestions he makes as to the physical, moral, and intellectual training of the young are for the most part sound. He decried a too severe discipline, maintaining that "If the mind be curbed and humbled too much in children, ... they lose all their vigour and industry". On the other hand, he held that if you "Remove hope and fear, there is an end of all discipline"; and he held that, as far as possible, "Childish actions are to be left perfectly free and unrestrained". He applied the science of psychology to the study of child nature, and of the methods to be employed in training it; and so prepared the way for the modern methods of education. "Interest is the secret of Herbart", according to one of his devoted admirers. Locke seems to have anticipated this when he declares that "None of the things they are to learn should ever be made a burden to them, or imposed on them as a task".

Though his attitude towards the universe was utterly opposed to the attitude of Locke, Rousseau drew almost all that was practical in his scheme for the education of the young from the English writer. Rousseau's work, though largely inspired by Locke, was essentially of a revolutionary kind. It held that man is the great corrupter; that "Everything is good as it comes from the hands of the Creator; and that man's handling makes everything worse". In effect he said, leave the child as much as possible alone. An attempt constantly to direct him can only result in stupefying him. It is true we receive our education from nature, from men, and from things; but nature must be our guide in determining the use of the other two. As few restraints as possible must be imposed on the child, and the use of books should be prohibited. For the child there should be "no other book but the world", and "no other instruction but facts". The child's education he divides into four stages, infancy, childhood, boyhood, and youth. The first two stages last till the beginning of the thirteenth year, when the boy is supposed to be fit for instruction. From such instruction the teaching of words must disappear, and the teaching of things must take its place. The subjects most suitable for instruction were, Rousseau declared, measuring, drawing, geometry, speaking, and singing. Books, he declares, are useless, are, indeed, altogether harmful. The method he advocates is the method of self-teaching and the use of the senses, which Rousseau held would work to the profit of the intelligence. The child's knowledge should rest on his own observation, and not on belief in authority, and each child should be taught a manual trade.

At fifteen, according to Rousseau, real education begins; and it is the duty of the teacher to study the subject he has to act upon, in other words, to discover the nature of the pupil, which must in all cases determine the means and the method employed in his education. Two things must be taught. These are the true relations, racial and individual, that exist among men; and how to direct and control the emotions aroused by the environment so that the best results may arise. Here he finds occasion for the use of moral teaching and for instruction in religion. The facts of history must be placed before him; but he must be left to form his own judgment. He is now to be taught religion as a help to the regulation of the passions; but not the religion of any particular sect. His time is to be given up largely to reading and to the acquirement of taste; to the study of history and eloquence; and to attendance at the theatre.

The revolutionary doctrines preached by Rousseau in his _['E]mile_ and in his other educational works had an immense effect on the Continent, and particularly on the work of one of his most ardent admirers, the Swiss farmer and schoolmaster Pestalozzi, an eccentric, dubbed by his schoolfellows "Harry Oddity of Fools-town". Thinking the education demanded for ['E]mile by Rousseau vastly superior to that which he himself received, he very early became an ardent admirer of the system advocated by the French philosopher, and an eager reformer. _['E]mile_ and the _Contrat Social_ were condemned by the magistrates of Zurich, and Pestalozzi and some of his fellow-students were imprisoned for the _Memorial_ in which they defended these works. Later Pestalozzi determined to be a farmer. He was married at the age of twenty-three, and started growing madder and vegetables on some poor land near Zurich. On the land he built for himself a house, the _Neuhof_.

In the winter of 1774 he hit upon the expedient of taking into his house some twenty poor children of the neighbourhood, whom he treated as his own. They worked with him in summer in the fields, and in winter in the house. Improved health for the children, increased intelligence, and a manifest devotion to their benefactor were some of the results speedily displayed, and the experiment drew much attention to itself. Urged on by his love for the children, Pestalozzi took in a larger number, and in a very short time found himself bankrupt. In this period of seeming disaster Pestalozzi turned author. The books which he produced were greedily read on the Continent, and aroused the greatest interest. After some work at Stanz and at Burgdorf, Pestalozzi settled to work in the castle of Yverdun on Lake Neuch[^a]tel, which became in the early years of the nineteenth century a place of pilgrimage for European students and lovers of education. Forced to leave Yverdun in 1815, he continued his work at Clindy till 1824.

Friedrich Froebel spent the years 1807 to 1809 at Yverdun, and so fitted himself to carry on the work Pestalozzi had to some extent made popular. His name, however, is specially associated with the schools for very young children to which he gave the name of _Kindergarten_, that is, 'gardens of children', places where young children, like young plants, were properly watched and tended. For the children in these schools their employment was to be play, play from which and by which they acquired clear notions regarding themselves and their environment. "Education", he asserted, "should lead and guide man to clearness concerning himself and in himself, to peace with nature, and to unity with God." He held that powers were developed by exercise; that failure to use any part of the body or mind led to the shrinkage of the part, and sometimes even to its complete loss. He held that if we wish to develop the body we must exercise the body, and that, similarly, if we wish to develop the intellect or the emotions they must be exercised. He insists that teachers must be careful to interfere as little as possible; must remember at all times that the aim of teaching is "to bring ever more and more out of man rather than to put more and more into him". He based his system on action; agreed with Montaigne that "children's games were their most serious occupations"; and with Locke that "All the plays and diversions of children should be directed towards good and useful habits". Froebel was not the founder of infant schools. These were first established on the Continent and in Britain with the object of helping mothers. In Britain their establishment is associated with the names of the educational enthusiasts James Buchanan and Samuel Wilderspin.

Nearly ten years before Froebel's stay with Pestalozzi at Yverdun, Herbart, next to Kant and Hegel the most influential of German philosophers, visited the inspired educationist at Burgdorf, and found him employing methods based on the principles which he himself had worked out in his psychology. To both it was clear that there is a definite order in which subjects should be taught to the children, and that this order is determined, not merely by the relation of the subjects to each other, but by their power of satisfying the growing wants and capacities of the child. Pestalozzi had arrived intuitively at a method, and had practically applied it, which Herbart had scientifically worked out as applicable to the whole educational field. Three years later Herbart published pamphlets on Pestalozzi's best-known book, _How Gertrude teaches her Children_, and on _The A.B.C. of Sense-perception_, and in these showed what weight he attached to observation as an instrument of education. Two years later he published one of his most notable works on education, _The Aesthetic Revelation of the World_, and in 1806 _General Pedagogy_. In 1809 he was appointed professor of philosophy at K[:o]nigsberg, where he remained till 1833, and where his services to the cause of education, both by his writings and by his establishment of normal schools and experimental schools, cannot be exaggerated. He warns teachers not to educate too much; to be careful not to destroy the individuality of the child, such individuality being that which characterizes individuals of the same class. He lays the greatest stress on the importance to the teacher of child study, maintaining that he will be unable to teach unless he knows the child as he is. For Herbart the aim of education is summed up in morality, "the highest aim of humanity and consequently of education", itself. "I have no conception", he writes, "of education without instruction, just as I do not acknowledge any instruction that does not educate." "Instruction", he says elsewhere, "will form the circle of thought, and education the character; the last is nothing without the first." A great deal, according to Herbart, depends upon the pupil himself, who "grasps rightly what is natural to him", and who must be saved from the tendency to one-sidedness in which following his bent would result, by the cultivation in him of many-sidedness. This cultivation involves the control of the pupil's mental activity, and the instrument for this control is interest, which causes the pupil's complete absorption in its object. For the attainment of this Herbart proposes certain formal steps of instruction. These steps are usually set forth as (1) Preparation, (2) Presentation, (3) Comparison, (4) Generalization, (5) Application.

The nineteenth century was a period of continuously increasing interest in education, and of a generally growing belief in its utility. It was taken up by the Governments of the different countries, and ordered and regulated almost out of existence. Seven years before the death of Pestalozzi the first public grant for education was made by the British Parliament, and from that time up to the present the Government has continued to extend its power over the education of the country. For a long time the Government in Britain was satisfied to subsidize elementary education; but later it insisted on hard-and-fast lines of instruction. So thoroughly were these regulated in most countries that a French Minister of Education could boast he was able to say what work every child in France was engaged in at that particular moment.

In Britain it was only bit by bit, and with very considerable reluctance, that the Government took upon itself the responsibility for the education of the country. In Scotland a national system of general education, constituted in 1560, remained in force until reconstructed by the _Education Act_ of 1872. (See _Scotland_.) Compulsory education was introduced into England in 1870, together with what was described as payment by results; and, for some time, the aim which the teacher had to keep before him was the production at the annual examination of the largest number of pupils who could satisfy the tests in Reading, Writing, and Arithmetic, or, as they were called, the 'three R's', and so earn the Government grant. For between thirty and forty years this unnatural and mechanical system remained in force. From 1864 onwards Commission after Commission sought to reduce English secondary education to order. The most notable of these was The Bryce Commission of Enquiry into Secondary Education, 1894-5, whose recommendations have since been put into force by legislation. One of the results of the increasing interest in education throughout England was the founding, early in the latter half of last century, of great day schools, like the City of London, St. Paul's, and Merchant Taylors, in London and other large cities; and, after the passing of the Education Act of 1902, the establishment everywhere of Council Secondary Schools.

Of the immense number of works on education issued during the last half of the nineteenth century, perhaps the best known are those of Herbert Spencer and of Professor Bain. The former seeks to explain education from the Darwinian standpoint, and the latter to determine from psychology the intellectual value of the various subjects taught in school, and the average age at which they should be taught to children. Of practical English educators during the nineteenth century, the most outstanding names are undoubtedly those of Arnold of Rugby, Thring of Uppingham, and Abbott of the City of London School.

In recent times the advances made in the theoretical and practical studies of the sciences of anthropology, physiology, and psychology have exercised an enormous influence on educational theories and practices. Careful observations of young children by scientific observers like Darwin, Dearborn, and Preyer have added greatly to our knowledge of child-nature; and helped to suggest new methods of studying it and developing it. The result has been the promulgation within the present century of a number of educational methods, some of which, in contrast to the older practices, must seem almost revolutionary. Among these must be remembered the 'Heuristic Method' of teaching science put forward by Professor H. E. Armstrong. The object of the method is to put the student as completely as may be in the position of an original investigator; and it has been classed by writers on education as being, like so many other modern methods, a 'play method'. Froebel in his kindergarten was one of the first to introduce successfully the play method in education, and the 'gifts' by which the plan was carried through were of his own devising; but such cannot be said of Dr. Montessori, whose method of education engrosses so much attention at the present time. The Montessori apparatus was originally devised by Dr. Seguin for the instruction of mental defectives. Dr. Montessori used the apparatus first for the training of young children; but the cardinal feature of the Montessori system is the determined effort to make the child entirely responsible for his own education, and to interfere as little as possible with his development. The apparatus is so contrived that it can only be used in one way if the problem is to be solved; so the child is forced to attend to the differences in size and shape and carefully to compare the different pieces. In addition, the Montessori system attempts to cultivate the social virtues; teaches the children to live and to work and play with others, and so to learn to be well-mannered. The teacher in this system retires into the background, and the children are left to go their own way, to choose their own tasks, and to be their own critics. Great attention is also given to the physical development of the children.

Experimental education has been attempted both in Germany, where the need for it was first put forward by Kant, and in England; but it is in the United States of America that the chief advances in this direction have been made. There the Binet attempt to measure the intelligence of the child, to fix in fact a metric scale of intelligence, has been elaborated, and the Binet-Simon system of tests devised, and later modified by L. M. Terman. There, too, schools have been established which have tried the working out of what may be described as the non-interference with the pupil principle. Among these may be mentioned the 'George Junior Republic' and the Gary Schools. The latter, we are told by their founder, were "not instituted to turn out good workers for the steel company, but for the educational value of the work they involved". To this must be added the 'Dalton Laboratory Plan', tried lately as an experiment by Miss Helen Parkhurst in a public secondary day school in Dalton. By this plan, the time-table is abolished, the child undertakes to get up a certain amount of work each month in each particular subject, and is left free to distribute his time as he chooses, so that he can devote more time to those subjects in which he is backward. The school is divided into departments (laboratories) each under a specialist who gives the help needed, but leaves the pupil to himself as much as possible.--BIBLIOGRAPHY: Bartley, _The Schools for the People_; Norwood and Hope, _Higher Education of Boys in England_; Quick, _Essays on Educational Reformers_; Browning, _An Introduction to the History of Education Theories_; Sleight, _Educational Values and Methods_; Nunn, _Education: Its Data and First Principles_; Wilton, _What do we mean by Education?_ _The New Teaching_, edited by Adams; Kerr, _Scottish Education_; Morrison, _Education Authorities' Handbook_; Dewey, _Schools of To-morrow_; Rusk, _Introduction to Experimental Education_; Montessori, _The Montessori Method_ and _The Advanced Montessori Method_.

EDUCATION ACT, the name given to several Acts dealing with education in Great Britain. Among the principal Education Acts are: (1) that of 1870, which introduced compulsory education; (2) that of 1891, which reduced, or in some cases abolished, school fees; (3) that of 1902, which authorized the levying of an education rate; and (4) that of 1918, which raised the age for leaving school, and made education compulsory up to the age of eighteen by means of continuation schools. Pupils must attend these schools for 320 hours each year.

EDWARD, known as _the Elder_, King of England, son of Alfred the Great, born about 870, died in 925. He succeeded his father in 901, and his reign was distinguished by successes over the Danes. He fortified many inland towns, acquired dominion over Northumbria and East Anglia, and subdued several of the Welsh tribes.

EDWARD, surnamed _the Martyr_, King of England, succeeded his father, Edgar, at the age of fifteen, in 975. His reign of four years was chiefly distinguished by ecclesiastical disputes. He was treacherously slain in 979 by a servant of his stepmother, at her residence, Corfe Castle. The pity caused by his innocence and misfortune induced the people to regard him as a martyr.

EDWARD, King of England, surnamed _the Confessor_, was the son of Ethelred II, and was born at Islip, in Oxfordshire, about 1004. On the death of his maternal brother, Hardicanute the Dane, in 1041, he was called to the throne, and thus renewed the Saxon line. Edward was a weak and superstitious, but well-intentioned prince, who acquired the love of his subjects by his monkish sanctity and care in the administration of justice. His queen was the daughter of Godwin, Earl of Kent. He died in 1066, and was succeeded by Harold, the son of Godwin. Edward caused a body of laws to be compiled from those of Ethelbert, Ina, and Alfred, to which the nation was long fondly attached. He was canonized by Pope Alexander III in 1161.

EDWARD, Prince of Wales, surnamed _the Black Prince_, born 15th June, 1330, the eldest son of Edward III and Philippa of Hainault. In 1346 he commanded part of the forces at the battle of Cr['e]cy, and earned the praise of his warlike father. It was on this occasion that he adopted the motto _Ich dien_ (I serve), used by all succeeding Princes of Wales. In 1355 he commanded the army which invaded France from Gascony, and distinguished himself the following year at the great battle of Poitiers. By the Peace of Br['e]tigny the provinces of Poictou, Saintonge, P['e]rigord, and Limousin were annexed to Guienne and formed into a sovereignty for the prince under the title of the Principality of Aquitaine. A campaign in Castile, on behalf of Pedro the Cruel, and the heavy taxes laid on Aquitaine to meet the expenses, caused a rebellion, and ultimately involved him in a war with the French king. His own health did not allow him to take the field, and having seen his generals defeated he withdrew into England, and after lingering some time died (1376), leaving an only son, afterwards Richard II.

EDWARD I (of the Norman line), King of England, son of Henry III, was born at Winchester in 1239, died 7th July, 1307. The contests between his father and the barons called him early into active life, and he finally quelled all resistance to the royal authority by the decisive defeat of Leicester at the battle of Evesham, in 1265. He then proceeded to Palestine, where he showed signal proofs of valour, although no conquest of any importance was achieved. His father's death in 1272 gave him the crown. On his return home he showed great vigour as well as a degree of severity in his administration. He commenced a war with Llewellyn, Prince of Wales, which ended in the annexation of that Principality to the English Crown in 1283. Edward's ambition was to gain possession of Scotland, but the death of Margaret, the Maid of Norway, who was to have been married to Edward's son, for a time frustrated the king's designs. But on 26th Dec., 1292, John Baliol was induced to do homage for his crown to Edward at Newcastle. Baliol was forced by the indignation of the Scottish people into war with England. Edward entered Scotland in 1296, devastated it with fire and sword, and placed the administration of the country in the hands of officers of his own. Next summer a new rising took place under William Wallace. Wallace's successes recalled Edward to Scotland with an army of 100,000 men. Wallace was at length betrayed into his hands and executed as a traitor. All Edward's efforts, however, to reduce the country to obedience were unavailing, and with the flight of Robert Bruce, Earl of Carrick, to Scotland, the banner of Scottish independence was again unfurled. Edward assembled another army and marched against Bruce, but only lived to reach Burgh-on-Sands, a village near Carlisle, where he died. Edward I was wise in council and vigorous in action. During his reign great progress was made in the establishment of law and order throughout the land.

EDWARD II, King of England, born at Carnarvon Castle in 1284, and the first English Prince of Wales, succeeded his father, Edward I, in 1307. He was of an agreeable figure and mild disposition, but indolent and fond of pleasure. After marching as far as Cumnock, in Ayrshire, with the army collected by his father, he returned, dismissed his troops, and abandoned himself entirely to amusements. His weakness for a clever but dissolute young Gascon, Piers Gaveston, on whom he heaped honours without limit, roused the nobles to rebellion. Gaveston was captured in Scarborough Castle, and executed as a public enemy on 19th June, 1312. Two years after this, Edward assembled an immense army to check the progress of Robert Bruce, but was completely defeated at Bannockburn. In 1322 he made another expedition against Scotland, but without achieving anything important. The king's fondness for another favourite, Hugh le Despenser, had made a number of malcontents, and Queen Isabella, making a visit to France, entered into a correspondence with the exiles there, and formed an association of all hostile to the king. Aided by a force from the Count of Hainault, she landed in Suffolk in 1326. Her army was completely successful. The Despensers, father and son, were captured and executed, and the king was taken prisoner and confined in Kenilworth, and ultimately in Berkeley Castle, where he was murdered 21st Sept., 1327.

EDWARD III, King of England, son of Edward II by Isabella of France, was born in 1312, died 21st June, 1377. On his father's deposition in 1327 he was proclaimed king under a council of regency, while his mother's lover, Mortimer, really possessed the principal power in the State. The pride and oppression of Mortimer led to a general confederacy against him, and to his seizure and execution (10th Oct., 1330). Edward now turned his attention to Scotland, and, having levied a well-appointed army, defeated the regent, Douglas, at Halidon Hill, in July, 1333. This victory produced the restoration of Edward Baliol, who was, however, again expelled, and again restored, until the ambition of the English king was diverted by the prospect of succeeding to the throne of France. Collecting an army and accompanied by the Black Prince, he crossed over to France. The memorable battle of Cr['e]cy followed, 25th Aug., 1346, which was succeeded by the siege of Calais. In the meantime David II, having recovered the throne of Scotland, invaded England with a large army, but was defeated and taken prisoner by a much inferior force under Lord Percy. In 1348 a truce was concluded with France; but on the death of King Philip, in 1350, Edward again invaded France, plundering and devastating. Recalled home by a Scottish inroad, he retaliated by carrying fire and sword from Berwick to Edinburgh. In the meantime the Black Prince had penetrated from Guienne to the heart of France, fought the famous battle of Poitiers, and taken King John prisoner. A truce was then made, at the expiration of which (1359) Edward again crossed over to France and laid waste the provinces of Picardy and Champagne, but at length consented to a peace. This confirmed him in the possession of several provinces and districts of France which were entrusted to the Prince of Wales (the Black Prince), but gradually all the English possessions in France, with the exception of Bordeaux, Bayonne, and Calais, were lost.

EDWARD IV, King of England, was born in 1442, died in April, 1483. His father, Richard, Duke of York, was grandson of Edmund, Earl of Cambridge and Duke of York, fourth son of Edward III, while the rival line of Lancaster descended from John of Gaunt, the third son. The York line had intermarried with the female descendants of Lionel, the second son, which gave it the preferable right to the Crown. Edward, on the defeat and death of his father at the battle of Wakefield, assumed his title, and, having entered London after his splendid victory over the troops of Henry VI and Queen Margaret at Mortimer's Cross, in Feb. 1461, was declared king by acclamation. The victory of Towton, soon after his accession, confirmed his title, and three years after this, on 4th May, 1464, the battle of Hexham completely overthrew the party of Henry VI. The king now made an imprudent marriage with Elizabeth, widow of Sir John Grey, at the very time when he had dispatched the Earl of Warwick to negotiate a marriage for him with the sister of the French king. He thus alienated powerful friends, and Warwick, passing over to the Lancastrian cause, gathered a large army, and compelled Edward to fly (in Sept. 1470). Henry's title was once more recognized by Parliament. But in 1471 Edward, at the head of a small force given him by the Duke of Burgundy, landed at Ravenspur in Yorkshire, and his army, being quickly increased by partisans, marched swiftly on London and took the unfortunate Henry prisoner. Warwick now advanced with an army to Barnet, where a battle was fought, 4th April, 1471, which ended in the death of Warwick and a decisive victory for Edward. Shortly afterwards Edward also met and defeated a Lancastrian army, headed by Queen Margaret and her son Edward, at Tewkesbury. The prince was murdered, and the queen was thrown into the Tower, where Henry VI soon after died. Edward was preparing for an expedition against France when he died.

EDWARD V, King of England, the eldest son of Edward IV, was in his thirteenth year when he succeeded his father in 1483. His uncle, the Duke of Gloucester, soon made himself king as Richard III, and caused the young king and his brother to be sent to the Tower, where he had them smothered by ruffians.

EDWARD VI, King of England, son of Henry VIII by Jane Seymour, was born in 1537, died in July, 1553. At his father's death he was only nine years of age. His education was entrusted to men of the first character for learning, under whose training he made great progress, and grew up with a rooted zeal for the doctrines of the Reformation. His reign was, on the whole, tumultuous and unsettled. In Oct., 1551, the Protector Somerset, who had hitherto governed the kingdom with energy and ability, was deposed by the intrigues of Dudley, Duke of Northumberland, who became all-powerful. He induced the dying Edward to set aside the succession of his sisters, Mary and Elizabeth, and settle the crown upon Lady Jane Grey, to whom he had married his son Lord Guildford Dudley. Edward VI restored many of the grammar schools suppressed by Henry VIII, and these schools are still known as King Edward's schools.

EDWARD VII, King of Great Britain and Ireland and Emperor of India, eldest son of Queen Victoria and the Prince Consort, was born at Buckingham Palace on 9th Nov., 1841, died 6th May, 1910. In Dec., 1841, he was created Prince of Wales. He was educated under private tutors and at Edinburgh, Oxford, and Cambridge; visited Canada and the United States in 1860; and underwent military training at the Curragh camp in 1861. Promoted to the rank of general in 1862, he visited Palestine and the East, and next year took his seat in the House of Lords. On 10th March, 1863, he was married in St. George's Chapel, Windsor Castle, to Princess Alexandra, eldest daughter of Christian IX of Denmark, and from this time onwards he discharged many public ceremonial functions. Attacked by typhoid fever in the winter of 1871, his life was for a time despaired of, but he recovered early in 1872, his recovery being made the occasion of a thanksgiving service in St. Paul's Cathedral. During 1875 and 1876 he visited India. He was a member of the Poor Law Commission of 1893. He promoted the establishment of the Imperial Institute as a memorial of Queen Victoria's jubilee (1887), and he commemorated her diamond jubilee (1897) by founding the Prince of Wales's (now King's) Hospital Fund for the better financial support of the London hospitals. On the death of Queen Victoria on 22nd Jan., 1901, he succeeded to the throne, and was crowned on 9th Aug., 1902. King Edward did much to promote friendly relations with foreign powers, especially with France and the United States. It was through his personal influence that the Entente Cordiale with France was brought about. To him and Queen Alexandra were born: Albert Victor Christian Edward, Duke of Clarence and Avondale, born 1864, died 1892; George Frederick Ernest Albert, who succeeded his father as George V, born 1865, married 1893, to Princess Victoria Mary of Teck; Princess Louise, now Princess Royal, born 1867, married 1889, to the Duke of Fife, who died 29th Jan., 1912; Princess Victoria, born 1868; and Princess Maud, born 1869, married 1896, to Prince Charles of Denmark, now King of Norway as Haakon VII.--BIBLIOGRAPHY: _Life of the King_, by 'One of His Majesty's Servants'; Holt-White, _The People's King_; E. Legge, _King Edward in his true Colours_; J. P. Brodhurst, _The Life and Times of Edward VII_; W. H. Wilkins, _Edward the Peacemaker_.

EDWARD, Thomas, a Scottish naturalist, born 1814, died 1886. The son of poor parents, he was apprenticed to a shoemaker and worked at his trade till nearly the end of his life, but succeeded in acquiring much knowledge of natural history and some fame as a naturalist. An interesting biography of Edward (_Life of a Scottish Naturalist_), written by Samuel Smiles, appeared in 1876, and a pension of L50 a year was shortly afterwards conferred on him by Queen Victoria.

EDWARDS, Amelia Blandford, English novelist and Egyptologist, born in London in 1831, died in 1892. She gave early evidence of great literary ability by her contributions to periodicals, and attracted attention by her novel _My Brother's Wife_ (1855). Among her best-known novels are: _Hand and Glove_ (1859), _Barbara's History_ (1864), _Half a Million of Money_ (1865), _Debenham's Vow_ (1870), and _Lord Brackenbury_ (1880). Miss Edwards wrote also ballads and books of travel, and in 1882 founded the Egypt Exploration Fund and devoted herself to Egyptology, leaving funds to found a chair of Egyptology in University College, London.

EDWARDS, Bryan, English writer, born in Wiltshire in 1743, died in 1800. He inherited a large fortune from an uncle in Jamaica, where he long resided. His _History, Civil and Commercial, of the British Colonies in the West Indies_ appeared in 1793.

EDWARDS, John Passmore, British philanthropist and journalist, born at Blackwater, Cornwall, in March, 1823, died on 22nd April, 1911. Trained as a journalist, he became representative of the paper _The Sentinel_, and was opposed to the Corn Laws. In 1862 he bought _The Building News_, and in 1876 the London _Echo_, of which he was director for twenty years. Although somewhat unpopular on account of his opposition to the Boer War, he is remembered as a public benefactor, having founded numerous Passmore Edwards institutions, public libraries, and settlements, and contributed largely to hospitals. He was a delegate to the peace congresses at Brussels, Paris, and Frankfort (1848-50), and twice refused a knighthood.

EDWARDS, Jonathan, American theologian and metaphysician, born 5th Oct., 1703, died 22nd March, 1758. He entered Yale College in 1716, and studied till 1722, when he received a licence as preacher. In 1723 he was elected a tutor in Yale College, but resigned in 1726 to be ordained as minister at Northampton (Mass.). After more than twenty-three years of zealous service here, he was dismissed by the congregation owing to the severity with which he sought to exercise church discipline. He then went as a missionary among the Indians at Stockbridge, in Massachusetts. Here he composed his famous work on the _Freedom of the Will_, which appeared in 1754. In 1757 he was chosen president of the college at Princeton, New Jersey, but died shortly afterwards.

EDWY, King of England, son of Edmund I, succeeded his uncle Edred in 955. Taking part with the secular clergy against the monks, he incurred the confirmed enmity of the latter. The Papal party, headed by Dunstan, was strong enough to excite a rebellion, by which Edwy was driven from the throne to make way for his brother Edgar. He died in 959, being probably not more than eighteen or nineteen years old.

EECLOO ([=a]k-l[=o]'), a town, Belgium, province of East Flanders, 11 miles north-west of Ghent, the seat of textile manufactures. Pop. 13,536.

[Illustration: Eel-bucks on the Thames]

EEL, the popular name of fishes belonging to the teleostean sub-order Apodes. The common eel (_Anguilla vulgaris_) is the type of a special family (Anguillidae) and has a very wide distribution in the fresh waters of the globe. It is snake-shaped, devoid of ventral fins, and the minute scales are embedded in the slimy skin. When five or six years old it migrates to the deep sea for spawning, after which it probably dies. Curious flattened larvae (Leptocephalus) hatch out from the floating eggs, and undergo a metamorphosis to become young eels or elvers, which when a year old ascend rivers in vast numbers as 'eel fare'. Eels are esteemed as an article of food, and even elvers are compressed into a sort of cake. In England river eels are caught in great numbers by means of eel-bucks or eelpots, traps consisting of a kind of basket with a funnel-shaped entrance composed of willow rods converging towards a point, so that the eels can easily force their way in but cannot return. A stocking or tube of coarse cloth hanging from an aperture of a box down into the interior is also used. In England a kind of trident called an _eel-spear_ is used also for taking them. A fisherman wades to the shallows, and, as he strikes his spear in the mud in every direction around him, the eels reposing on the bottom are caught between the prongs. They are also taken by hooks and lines and in other ways. See _Conger-eel_; _Muraena_. Electric eels belong to another group. See _Electrical Fishes_.

EFFEN'DI, a Turkish title which signifies lord or master. It is particularly applied to the civil, as _aga_ is to the military officers of the Sultan. Thus the Sultan's first physician is called _Hakim effendi_, and the priest in the seraglio _Imam effendi_.

EFFERVES'CENCE, the rapid escape of a gas from a liquid, producing a turbulent motion in it, and causing it to boil up. It, is produced by the actual formation of a gas in the liquid, as in fermentation, or by the liberation of a gas which has been forced into it, as in aerated beverages.

EFFICIENCY, in mechanics and engineering, the ratio of the useful energy given out by a machine to the energy supplied to it. Energy cannot be created or destroyed, but it may assume various forms, and, within limits, can be changed from any one of these forms to any other. A machine or engine is an apparatus for converting energy in some given form into energy in another assigned form. In practice it is found impossible to convert the whole of the given energy into the form wanted, there being always a residue which is not of the right kind, and is, therefore, counted as useless. The smaller the residue, the more efficient is the machine. In the machines of elementary mechanics, such as the lever or the screw, the energy supplied is work done by the power or effort, and the energy wanted is work done on the load. If E is the effort, and W the load, then if there were no friction we would have E = Wr, where r is the velocity ratio, or ratio of the velocities of the points of application of load and effort. The relation found by experiment, however, is usually of the type E = Wr + C, where C is a constant. The efficiency is the fraction Wr/E or 1 - C/E, so that it increases with the load. In _heat engines_, energy in the form of heat is converted into mechanical energy. Heat is taken in at the source, part of it is changed into mechanical energy, and the remainder is rejected to the condenser. According to the second law of thermodynamics, the efficiency of such an engine has a definite upper limit which it cannot exceed, this being the ratio of the difference of the temperatures of the source and the condenser to the temperature of the source, these temperatures being measured on the absolute scale, that is, from -273deg C. reckoned as the zero. The efficiency of a steam-engine is usually compared with that of an ideal engine working between the same temperatures, and going through a definite periodic set of operations called the Rankine cycle. If the thermal efficiency of an actual engine is 27 per cent, and that of an ideal engine working on the Rankine cycle is 30 per cent, obviously the important figure is the ratio of 27 to 30, or 90 per cent.

The performance of a steam-engine depends, not only on its _thermal efficiency_, but also on its _boiler efficiency_ and its _mechanical efficiency_. The boiler efficiency is the percentage of the heat obtainable from the fuel consumed which is actually used in the engine; in a good boiler it may be 75 per cent. The mechanical efficiency is the ratio of the work given out at the crank-shaft to the work done on the piston; in other words, it is the ratio of brake horse-power to indicated horse-power. It may perhaps be 80 per cent. To arrive at the over-all efficiency, the various partial or component efficiencies must be multiplied together. In comparing one type of engine with another, what is important is obviously this over-all efficiency, or ratio of energy output to the theoretical energy value of the fuel employed. Thus, to take the case of marine engines, the Diesel oil-engine is inferior to the turbine and to the reciprocator in point both of thermal and of mechanical efficiency. But when the efficiency of the boilers is taken into account, the Diesel comes out very decidedly ahead of the others. Taking coal at 10,000 British thermal units per pound, and Diesel oil at 18,000 British thermal units per pound, Mr. T. R. Wollaston has given the following figures for the number of British thermal units consumed per brake horse-power hour: steam-engine 19,000; steam turbine 21,000; gas-engine 15,000; Diesel engine 9000. Electrical plant in general reaches a high standard of efficiency. Some figures are: transmission lines 85 to 95 per cent; motors and generators at full load 70 to 80 per cent from 1 to 5 h.p., 80 to 90 per cent from 5 to 50 h.p., and 95 per cent for large sizes. Electrical transformers are the most efficient of all machines. Their efficiency ranges from about 90 per cent in small sizes, up to perhaps 98.5 per cent for large machines at full load. See _Energy_; _Internal-combustion Engines_; _Steam-engines_; _Thermodynamics_.

EFFLORES'CENCE, the property which certain hydrated salts have of losing water when exposed to air. Thus washing-soda, Na_2CO_3, 10H_2O, if left in air becomes opaque, loses its crystalline appearance, and finally falls to a powder by loss of water. The term is also applied in botany to the process of flowering.

EFFLUENTS, a general term applying to liquids, on being discharged, after undergoing some form of treatment. The term is more particularly applied to the purified liquid discharged into rivers and streams from sewage-works, the crude sewage having been freed of the grosser solids, and rendered clear and innocuous to animal and vegetable life.

EFFODIEN'TIA, the name proposed for a new order of mammals to include pangolins and aard-varks. See _Edentata_.

['E]GALIT['E], Philippe. See _Orleans, Louis Philippe Joseph_.

EGBERT, considered the first king of all England, was of the royal family of Wessex. He succeeded Brihtric in 802 as King of Wessex. He reduced the other kingdoms and rendered them dependent on him in 829, thus becoming their overlord. He died in 839.

EGEDE, Hans ([=a]'ge-d[=a]), the apostle of Greenland, born in 1686 in Norway, died in 1758. In 1721 Egede set sail for Greenland with the intention of converting the natives to Christianity, and for fifteen years performed the most arduous duties as missionary, winning by his persevering kindness the confidence of the natives. In 1736 he returned to Copenhagen, where he was made a bishop and director of the Greenland Missions.

EGER ([=a]'g[.e]r), a town of Bohemia, Czecho-Slovakia, on a rocky eminence above the Eger, 91 miles west of Prague; once an important fortress, though now quite dismantled. It has manufactures of woollens, cottons, leather, and soap. Wallenstein was assassinated there (1634). Pop. 26,620.

EGE'RIA, a nymph who received divine honours among the Romans. Numa is said to have received from her the laws which he gave to the Romans.

EGERSUND ([=a]'g[.e]r-s[u:]nd), a seaport on the south-west coast of Norway, some distance south of Stavanger, and connected with it by railway, has a large pottery-work, fishing and shipping trade. Pop. 3500.

EGERTON, Francis. See _Bridgewater, Duke of_.

[Illustration: Section of Hen's Egg

A, White or albumen. B, Vitelline membrane. C, Chalaza. D, White yolk. E, Germinal disc. F, Shell. G, Air space. H, Shell membrane. K, Yellow yolk.]

EGG, (1) in the narrower sense, the female reproductive or germ-cell, which after impregnation or fertilization by a male germ-cell (spermatozoon or sperm) develops into an embryo. (See _Ovum_.) (2) The term is applied, more broadly, to a more complicated reproductive body that consists of an ovum together with supplementary parts. The egg of a bird, for example, includes the fertilized and developing ovum (yolk), nutritive white (albumen), and protective double egg membrane covered by a porous calcareous shell. The eggs of animals lower than the birds have usually only three parts, viz. the germinal spot or dot, the germinal vesicle, and the vitellus or yolk; the first being contained in the vesicle, and that again in the yolk. The common domestic fowl, the turkey, the pea-hen, and the common duck produce the eggs which are commonest in the market. The eggs of the green plover (_Vanellus cristatus_) are esteemed as a delicacy. The hard roes of fishes are the ovaries, containing innumerable eggs (over nine millions in the cod). The salted hard roes of the sturgeon are known as caviare. A hen's egg of good size weighs about 1000 grams, of which the white constitutes 600, the yolk 300, and the shell 100. When the white of an egg is warmed it coagulates to a firm opaque mass. Eggs form an important article in British commerce; the number imported in 1919 amounted to the value of L8,613,000, mainly from Russia, Denmark, Austria, France, and Italy.

EGG, an island of Scotland. See _Eigg_.

EGGA, a town of N. Nigeria, on the right bank of the Niger, about 70 miles above the junction of the Binue. Pop. 10,000.

EGGAR, or EGGER, a name given to moths of the family Lasiocampidae. _Lasiocampa trifolii_, a well-known British moth, is called the grass-egger, and the _L. quercus_ the oak-egger, from the food of their caterpillars.

EGG-BIRD, or SOOTY TERN (_Sterna fuliginosa_), a bird of considerable commercial importance in the West Indies, as its eggs, in common with those of two other species of tern, form an object of profitable adventure to the crews of numerous small vessels.

EGGLESTON, Edward, American novelist and miscellaneous writer, born in 1837, died in 1902. He entered the ministry of the Methodist Church, was engaged in pastoral work for some years, afterwards as pastor of an independent church founded by himself. He wrote and edited much, among his books being: _The Hoosier Schoolmaster_ (1871), which first appeared in _Hearth and Home_; _The End of the World_: _A Love Story_; _Roxy_, a highly popular novel (1878); _The Hoosier Schoolboy_; _The Graysons_; _Household History of the United States_; _The Faith Doctor_. His novels are marked by abundance of incident, skilful handling of dialect, and realistic portraiture.

EGG-PLANT, or BRINJAL (_Sol[=a]num melong[)e]na_), nat. ord. Solanaceae, an herbaceous plant, from 1 foot to 18 inches high, with large white or purplish flowers. The fruit is about the size of a goose's egg, and generally yellow, white, or violet, and when boiled or stewed is used as an article of food. It is cultivated in India, the United States, &c., and in European hothouses. There are several other species of egg-plants, as _S. indicum_ and _S. sodomeum_.

EGHAM, an urban district of England, county of Surrey, on the Thames opposite Staines, about 21 miles from London, with the Royal Holloway College for women, and the Holloway Sanatorium. Near it is Runnymede, where King John signed Magna Charta.

EGIL SKALLAGRIM, an Icelandic bard or poet of the tenth century, who distinguished himself by his warlike exploits in predatory invasions of Scotland and Northumberland. Having fallen into the hands of a hostile Norwegian prince, he procured his freedom by the composition and recitation of a poem called _Egil's Ransom_, which is still extant.

EGINHARD, or EINHARD, friend and biographer of Charles the Great (Charlemagne), born in Maingau (East Franconia) about 770, died in 840. He was educated in the monastery at Fulda, and his capacity attracted the attention of Charles, who made him superintendent of public buildings, and of whom he became the constant companion. He also enjoyed the favour of his son Louis the Pious. His later years were passed at M[:u]hlheim-on-the-Main, where he founded a monastery. His _Vita Caroli Magni_ is a work of great value, and his letters are also important.

EG'LANTINE, one of the names of the sweetbrier (_Rosa rubiginosa_), a kind of wild rose. The name has sometimes been erroneously used for other species of the rose and for the honeysuckle.

EG'MONT, Lamoral, Count, Prince of Gavre, was born in 1522, of an illustrious family of Holland. He adopted a military career, accompanied Charles V in his African expeditions, and distinguished himself under Philip II in the battles of St. Quentin (1557) and Gravelines (1558). Philip having gone to Spain, Egmont soon became involved in the political and religious disputes which arose between the Netherlands and their Spanish rulers. He tried to adjust the difficulties between both parties, and in 1565 went to Spain to arrange matters with Philip. He was well received, sent back with honour, but quite deceived as to the king's real intentions. In 1567 the Duke of Alva was sent with an army to the Netherlands to reduce the insurgents. One of his first measures was to seize Count Egmont and Count Horn. After a trial before a tribunal instituted by Alva himself they were executed at Brussels 5th June, 1568. A well-known drama of Goethe's is founded on the story of Egmont.

E'GOISM, as a philosophical doctrine, the view that the elements of all knowledge and the reality of the things known are dependent on the personal existence of the knower. This theory is also called Subjective Idealism or Solipsism. It maintains that his individual ego is the only being that a man can logically assert to exist. As an ethical theory (practical egoism) it is the opposite of altruism. It maintains that the governing principle of conduct for the individual is his own good on the whole, and that self-interest is the basis of morality. Egoism is to be distinguished from egotism, which denotes the practice of putting forward or dwelling upon oneself, of thinking, talking, or writing about oneself.

EGREMONT, a town of England, in Cumberland, in the valley of the Ehen, 3 miles from the sea, giving name to a parliamentary division. It has ruins of an ancient (twelfth century) castle associated with a legend that served Wordsworth as the subject of a poem. Iron-ore and limestone are worked. Pop. 6300.

[Illustration: Little Egret (_Ard[)e]a garzetta_)]

EG'RET, a name given to those species of white herons which have the feathers of the lower part of the back elongated and their webs disunited, reaching to the tail or beyond it at certain seasons of the year. Their forms are more graceful than those of common herons. The American egret (_Ard[)e]a egretta_) is about 37 inches long to the end of the tail; plumage soft and blended; head not crested; wings moderate; the tail short, of twelve weak feathers. The European egret (_A. alba_) is about 40 inches long, of a pure white plumage; the bill is black or dark brown, yellow at the base and about the nostrils, and the legs are almost black. The little egret (_A. garzetta_) is about 22 inches long from bill to end of tail, the plumage is white. The term egret is used in the feather trade for a bunch of the loose plumes, valued as an ornament.

[Illustration: Diagrammatic Section across Egypt from Farafra Oasis to Sinai]

EGYPT (from Gr. _Aiguptos_) is, as Herodotus has said, "the gift of the Nile". This great river, about 4000 miles in length, rises as the White Nile, three degrees south of the equator, drawing its waters from the Central African lakes. To the south of Khartoum, and 1350 miles from the sea, it is joined by the Blue Nile, which rises in the mountains of Abyssinia, and about 140 miles farther on it is fed by the Atbara, its last tributary. On the tableland of Nubian sandstone between Khartoum and Elephantine the river forms two great loops, and is intercepted by shallows or cataracts, of which there are six in all. The 'first cataract'--the last on the journey northward--is at Assouan, where a ridge of intercepting granite crops up. At Edfu, about 68 miles farther north, the limestone formation is entered, and the Nile then flows uninterrupted between flanking hills that here and there attain the height of 1000 feet. Egypt proper extends from Assouan to the Mediterranean. At a distance of about 100 miles from the sea the Nile divides into the branches forming the Delta. To the south of Cairo it sends out the Bahr Yusuf, a branch about 200 miles long, which flows into the fertile Fayum. The narrow valley, the average breadth of which is 10 miles, is 'the land of Egypt'. Its cultivable area is not so large as Belgium, being under 10,000 sq. miles in extent. Rain falls to the north of Cairo, but in Upper Egypt there are showers only once in every three or four years. The fertility of the country is due to the Nile. Each year the great river rises in flood when the equatorial lakes are suddenly swollen by heavy tropical rains and the snow melts in the Abyssinian mountains. The mean summer heat is 83deg F. in the Delta and 122deg F. in the valley. It is a dry heat, not so oppressive as that of India, and malaria is practically unknown. The most trying part of the year is during the period of 'Low Nile'. Before the surplus waters were stored in the Assouan Dam, the river shrank so low that its flow seemed uncertain. For about two months the hot and blistering 'hanseen' (or 'sand-wind') keeps blowing. A new season is ushered in by the cool north wind--the Etesian wind of the Greeks--which clears the accumulated dust from vegetation. It is lauded in ancient texts by priestly poets and Pharaohs. About the same time the conspicuous star Sirius makes its appearance. It was anciently regarded as a form of the Mother Goddess. On the 'Night of the Drop', in June, a fertilizing tear was supposed to fall from this star, and thereafter the 'new Nile' was born. For about four days (before the Assouan Dam was constructed) the rising river flowed green, the slimy matter on the marshes of Upper Egypt being pushed forward by the 'new water'. This was the 'Green Nile'. Then the Nile turned blood-red with Abyssinian clay. This was the 'Red Nile'. As soon as the fertilizing 'new water' touched the parched sands, Egypt awoke to new life. Countless insects appeared, new grass and flowers sprang up, and trees and shrubs broke into brilliant blossoms that filled the air with sweet perfume. Bursting over its banks, the steadily rising river flooded the valley generously and refreshingly. According to the Coptic Calendar, the inundation season lasted from June till September, the seed-time from October till January, and the harvest began in February.

[Illustration: Part of the Hieroglyphic Legend of Heru-Behutet and the Winged Disk, cut on the Walls of the Temple of Edf[^u] in Upper Egypt

Translation: In the three hundred and sixty-third year of R[=a]-Heru-Khuti, who liveth for ever and for ever, His Majesty was in TA-KENS, and his soldiers were with him; (the enemy) did not conspire (auu) against their lord, and the land (is called) UAUATET unto this day. And R[=a] set out on an expedition in his boat, and his followers were with him, and he arrived at UTHES-HERU, (which lay to) the west of this nome, and to the east of the canal PAKHENNU, which is called ( ... to this day). And Heru-Behutet was in the boat of R[=a], and he said unto his father R[=a]-Heru-Khuti (i.e. R[=a]-Harmachis), "I see that the enemies are conspiring against their lord; let thy fiery serpent gain the mastery ... over them."--Reproduced by permission from Vol. XXXII of _Books on Egypt and Chaldaea_, by Sir E. A. Wallis Budge.]

_Early Religion and Civilization._--In its earliest phases the religion of ancient Egypt reflected the natural phenomena of the Nile Valley in their relation to the needs, experiences, and achievements of mankind. The flood was an annual 'miracle of mercy', and the early people tried to account for it. They concluded it was a gift of the gods. It ensured the food-supply; it brought health and relief from the oppressive heat endured when the sand-wind prevailed and the river was low. The new water was 'the water of life'; it fertilized the parched soil and caused barley and millet (which grew wild in the Delta) to spring up, trees to yield fruit, and curative herbs to appear on the river banks. In the prehistoric period the Nile was identified with Osiris, who, according to the traditions of the Delta people, once reigned as their king, and introduced the agricultural mode of life which made it possible for large and growing communities to dwell in the narrow valley. In the Pyramid Texts (_c._ 2700 B.C.) Osiris is the controller of the Nile, the principle of life in the Nile, and the Nile itself. In one of his phases the god is the 'Green One'--the Green Nile. A Pyramid Text reads: "Horus comes! He beholds his father in thee, Green One, in thy name of Water of Greenness". The soul-substance (literally 'the seed') of Osiris was the vital principle in the green or new water. Osiris was the serpent-soul in the water, and the serpent (leviathan) of the ocean which 'encircled the netherworld'. The god is addressed in a Pyramid Text: "Thou art great, thou art green in thy name of Great Green" (Mediterranean Sea). Osiris was slain by Set, and his life-blood was the Red Nile, which entered the soil and vegetation. Osiris was not regarded as the Green One because vegetation is green; the ancient Egyptians appear to have attributed the greenness of vegetation to the Green Nile, the soul-substance of Osiris. The sap of shrubs and trees was 'Blood'--the blood of the god. Osiris continued to live after death. On earth he was in barley, fruit, &c., and in the fertilized soil. He was in the other world Judge and King of the Dead. In his underworld Paradise the souls of the dead grew corn and cultivated fruit-trees--the 'food of life'. The Osirian cult had origin in the Delta of Lower Egypt. In Upper Egypt a solar cult exalted Horus, the falcon god, as chief deity. Their heaven was beyond the sky 'to the east'. In the Pyramid Texts there is clear evidence that the solar cult believed the souls of the dead went eastward, while the Osirian cult believed they went westward. Osiris was called 'First of the Westerners'. The 'Easterners' of the south (Upper Egypt) conquered the 'Westerners' of the north (Lower Egypt), and Egypt was united into a single kingdom by the traditional King Mena, with whom begins the dynastic history of Egypt. This conquest appears to have been due to the introduction of copper weapons.

The idea that the Horites were invaders from Arabia or Mesopotamia has been abandoned. Copper was anciently found in the wadis of Upper Egypt and on the shores of the Red Sea. After boat-building and navigation were well advanced copper was mined in Sinai. According to Egyptian evidence, Edfu was the centre of the early copper industry and of the Horus cult. As Egyptian copper is naturally hard, it required no amalgam. Egypt, therefore, never had a Bronze Age, nor had it a Neolithic Age. The copper artifacts were imitations of Palaeolithic forms of the Solutrian type. After the conquest there occurred fusions of religious cults. Local pantheons reflected local politics. But although the sun-cult of Heliopolis exalted Ra [Illustration: Painted inner wooden coffin of Pen-Amen-Neb-Nest-Taui, a prophet of the God Amen and of the Goddess Bast at Thebes.] [Illustration: Types of Columns from Egyptian Temples.] (or Re) as King of the Gods, the belief that all that existed originated in water persisted till the end. The water-mother was Hathor, who gave birth to Osiris. As the Nile was supposed to come from heaven, she was the sky-goddess; her animal was the primeval cow of a pre-dynastic cult, and she was the shell-spirit of water as well--the Egyptian Aphrodite. The shell, pearl, cow, sky, sun, moon, and stars were connected with Hathor as Nut. Ra, the sun-god, was, like Osiris, regarded as her son. Her attributes were in time absorbed by Isis. At the dawn of the Dynastic Age the religious beliefs of the Egyptian peoples were already well developed, the agricultural mode of life was established in the Nile Valley and in the Delta area, the calendar had been introduced, while copper weapons and implements were in use. The subsequent history of the official religion has a political aspect. Local cults rose into prominence as a city-state or ruling family achieved political ascendancy. Memphite theology and the Memphite god Ptah (the god of artisans) assumed importance when the city of Memphis became the capital of the united kingdom. Heliopolis ('the city of the sun') was the northern centre of the solar cult, which, during the fourth and fifth dynasties (_c._ 2900-2625 B.C.), became influential enough to impose its theology on the court. The popular Osirian faith was absorbed. Pharaohs were 'Sons of Ra', the sun-god, and Ra supplanted the southern sun-god Horus. Before the Pyramid Age the Osirian and Horite cults had been blended, and Horus became the son of Osiris. Although the living Pharaoh, however, was the son of Ra, he was also a Horus; after death he became an Osiris. The culture-blending process introduced many complexities. During the twelfth dynasty (2000-1788 B.C.) the name of the Theban god Amon entered into royal names. But the permanent political ascendancy of Amon of Thebes really followed upon the expulsion of the Hyksos military aristocracy about 1580 B.C. By this time the northern sun cult's influence had become sufficiently strong to have Ra blended with the Theban deity who was subsequently known as Amon-Ra. Before the close of the eighteenth dynasty (_c._ 1350 B.C.) a royal sun cult, promoted by Pharaoh Akhenaton (Amenhotep IV), exalted Aton, the sun-disc, as sole god of Egypt and the rest of the world. The Amon-Ra cult regained its political ascendancy with the rise of the nineteenth dynasty. In later times the chief gods of the reigning families were blended forms of Amon, Ra, Ptah, and Osiris. Not only the gods, but the rival Paradises, were blended. Osiris's under-world Paradise was transferred to the mythical other world beyond the horizon, and the sun-barque of the sun-god, which carried the soul of the Pharaoh, was supposed to touch at 'the port of Paradise'. It went westward and passed through the under-world, and emerged again next morning at dawn in the east. The contradictions in the Egyptian religious texts are believed to be mainly due to the blending of beliefs regarding the fate of man which were originally fundamentally different. Local deities were embraced in the official theology, but at their centres remained prominent and influential. But these, too, were in time so strongly influenced by the solar and Osirian faiths that they suffered in no small degree loss of identity except in name. The religious beliefs of Egypt as a whole were never completely systematized. There were no heresies because there were no orthodox beliefs. Any religious cult was tolerated, so long as it acknowledged the supremacy of the god or pantheon of the ruling family. In the later period the cult of Serapis (Asar Hapi), the bull form of Osiris, was popular.

[Illustration: Egyptian Pottery-making

From a wall-painting in the tombs of Beni-Hassan.]

_Arts and Crafts._--Art developed in ancient Egypt under religious patronage. The earliest use made of Nubian gold was in manufacturing imitation luck-shells worn by the pre-dynastic peoples. Gold thus acquired a religious significance; at an early period it was associated with the sun-deity--the mother-goddess in her solar aspect was called 'Golden Hathor'. The hieroglyph for gold (_nub_) is a collar of beads. Exquisite gold ornaments in symbolic shapes were produced during the early dynasties. No finer gold ornaments have ever been produced anywhere than those of the twelfth dynasty (_c._ 2000 B.C.). These include chased gold pectoral ornaments and coronets and crowns inlaid with stones. When copper was first introduced it was used like gold. After implements were made of copper, vases of alabaster, diorite, &c., were worked with increasing skill and taste. The hardest stone was hewn and dressed for building purposes. No people have ever shown greater skill than the Egyptians in their stonework. The sculptors set themselves, when constructing temples, to imitate in stone the lashed palm-sticks, reeds, and papyrus stems used in the earliest shrines to stiffen the mud walls. Massive temple pillars were decorated with lotus petals, rose petals, &c. The early artists, who carved ivory, began to work in stone after copper implements were invented, and produced low reliefs in temples and tomb-chapels. Statuary in limestone, wood, and copper in the early dynastic period was vigorous and realistic. The sculptors were using the hardest material by the time of the Pyramid Age (_c._ 2700 B.C.). A great tomb-statue of Pharaoh-Khafra, in diorite, preserved in the Cairo Museum, is one of the triumphs of Egyptian sculpture. The Empire-period sculpture reached a high level of excellence. It was to provide 'soul-bodies' for dead Pharaohs that these great works of art were produced. A great advance in the manufacture of pottery was achieved during the Pyramid Age, when the potter's wheel was invented. To Egypt the ancient world owed this notable contrivance. It was introduced in time into Babylonia, Iran, India, China, Crete, Greece, and Western Europe. Shipbuilding is another Egyptian industry which promoted progress. Cretan and Phoenician vessels were of Egyptian design. In all histories of shipping and navigation the ancient Egyptians are credited with being the pioneers of maritime enterprise. The custom of mummification arose in Egypt, and promoted the study of anatomy. Surgery had its origin in mummification, as astronomy had in astrology, and chemistry had in alchemy. Connected with each temple were architects, artists and sculptors, metal-workers and dyers. Ships were constructed to obtain wood for temples and to import pearls, precious stones, herbs, incense-bearing shrubs and trees, &c., for religious purposes. In the history of early civilization the Egyptian priests play a prominent part as patrons of the arts and crafts.

[Illustration: Nefert, a royal princess of the Old Kingdom period

From a limestone statue in the Cairo Museum.]

_History._--In the hot, dry sands of Upper Egypt, which preserve the dead from decay, have been found the bodies of large numbers of pre-dynastic Egyptians. They were of the type known as the 'Mediterranean race'. The contents of their stomachs have yielded husks of barley and millet and fragments of mammalian and fish bones. Circumcision was practised, and some men shaved. These people used malachite as an eyelid paint. When they discovered that copper could be extracted from malachite, it was used at first like gold, as has been stated. The production of copper implements and weapons was followed by the conquest of Lower Egypt by the copper-using Upper Egyptians. After the latter moved north, they found that the bodies of their dead decayed, and the practice of mummification was introduced. Before 3000 B.C. the broad-headed, long-bearded Armenoid type began to filter into Lower Egypt. The blending of Armenoids and Arabians in Syria produced 'the hybrid race of Semites'. In Egypt the ethnic fusion was most marked at the commercial capital, Memphis, and especially during the time of the pyramid builders (_c._ 2900-2750 B.C.). The spread of 'copper culture', and the importation into Egypt of timber from Lebanon, apparently brought the ancient races into close contact. Withal, shipbuilding and the art of navigation had advanced by leaps and bounds. Before the Pyramid Age there were sea-traders on the Mediterranean, and the Egyptians imported copper from Sinai across the Red Sea. The legendary Pharaoh who united Upper and Lower Egypt was Mena or Menes. From his time (_c._ 3400 B.C.) till the close of the sixth dynasty (_c._ 2475 B.C.) the capital was Memphis. This period is known as that of the 'Old Kingdom'. Among its outstanding monarchs were Khufu, Khafra, and Menkure of the fourth dynasty, the builders of the largest pyramids. Herodotus refers to them as _Cheops_, _Chephren_, and _Mykerinos_. The 'Middle Kingdom' begins with the rise of Thebes in Upper Egypt as the centre of political power. During this period the nobility became so influential that the Pharaohs had to recognize their rights and privileges. In the period of the famous twelfth dynasty (_c._ 2000-1788 B.C.) the Theban monarchs established a uniform control of Egypt. The later kings of this dynasty were unable, however, to withstand the inroads of Asiatics, and the Middle Kingdom came to an end with the Hyksos invasion. Of the Hyksos, the so-called 'Shepherd Kings', little is known. They were civilized Asiatics, and during their overlordship of Egypt, which embraced the thirteenth till the seventeenth dynasties (_c._ 1800-1575 B.C.), the horse and chariot were introduced into Egypt. A Theban royal house rose into prominence during the latter part of their sway, and the Hyksos were finally expelled by Pharaoh Aahmes, who founded the eighteenth dynasty. The Empire period was then inaugurated. Egypt's greatest emperor, Thothmes III (1515-1461 B.C.), extended his conquests to the borders of Asia Minor, and received tribute from the Hittites, and even from Cyprus and Crete. During the reign of Akhenaton, the Hittites and their allies, the Amorites, seized the Egyptian sphere of influence in Syria and Northern Palestine.

In the nineteenth dynasty (1350-1205 B.C.) much of the lost territory was recovered. Rameses II (1325-1258 B.C.) fought his Waterloo at Kadesh, but found it necessary about 1300 B.C. to conclude a treaty of peace with the Hittites, the Assyrian Power at the time becoming very powerful and aggressive. Rameses III of the twentieth dynasty was the last great Pharaoh of the Empire period. He successfully resisted the threatened invasions of naval and military peoples from Greece and Anatolia in 1200 B.C. It is believed that the Trojan War (1194-1184 B.C.) was waged by the same confederacy which had attempted to invade the Delta region. No fewer than nine Pharaohs named Rameses ruled in Egypt after Rameses III. Most of these were priest-kings. A Libyan dynasty held sway for about two centuries (950-750 B.C.). One of its Pharaoh-Sheshhonks was the 'Shishak' who was an ally of Solomon; after the death of that monarch he invaded Palestine. The Ethiopians of Nubia (Sudan) subsequently overran Egypt. One of its Pharaohs, Shabaka, was the ally of King Hosea of Israel against Assyria; he was defeated at Raphia by Sargon in 720 B.C. The last Ethiopian Pharaoh, Taharka, was in 662 B.C. overcome by the invading army of the Assyrian Emperor, Ashur-banipal. The northern royal family of Sais then came into power, and the twenty-sixth dynasty, which lasted for about 130 years (662-525 B.C.), was inaugurated by Psamtik I. Pharaoh-Necho, referred to in the Bible, was the second ruler. It was during Necho's reign that his Phoenician mariners circumnavigated Africa. Egyptian culture was at the time spreading far and wide along sea and land routes. Trade was flourishing. The greatest world-power at the time, however, was Persia, and in 525 B.C. Egypt was conquered by Cambyses and became a Persian province, with short interruptions of weak native dynasties (the twenty-eighth to thirtieth), until in 332 B.C. Alexander the Great seized it and founded Alexandria. The Ptolemaic dynasty afterwards held sway for about three centuries. During this period learning and the arts flourished. Alexandria was not only a commercial town, but a centre of culture and the capital of Egypt. Osiris was worshipped there in the form of Serapis. During the latter part of the dynasty the native Egyptians were using Greek and Graecized names, and the whole country was more or less Hellenized. The fifteenth Ptolemy was the younger brother of the famous Cleopatra, the seventh of her name. He vanished, and was succeeded by Cleopatra's son, Caesarion--Ptolemy XVI--whose father was Julius Caesar. Both Cleopatra and her son perished when Egypt became a Roman province in 30 B.C. A daughter of Cleopatra and Antony became the wife of Juba, King of Morocco.

[Illustration: Queen Ahmes (wife of Thothmes I)

From a relief on the wall of the temple at Der-el-Bahari. The face is of Mediterranean type. She represents the royal line which soon afterwards fused with a foreign strain, so that the facial type changed.]

[Illustration: Head of Rameses II

From the mummy]

The Romans drew vast quantities of gold from the mines of Nubia (_nub_ means 'gold') and made Egypt their 'granary'. Egyptian religious beliefs and customs were perpetuated by the Roman emperors. Tiberius and Vespasian restored ancient Nilotic temples. The worship of Isis spread to Rome. Hadrian had to give a decision in a dispute between Memphis and Heliopolis regarding the sacred bull. But Egyptian native learning was decaying, and the knowledge of hieroglyphic writing was dying out. Christianity was introduced during the Roman period, and the Coptic Church established. In A.D. 642 the Romans finally abandoned Egypt, which, till 868, became a province of the successive Mohammedan caliphates of Medina, of Damascus, and Baghdad. The Turkish soldiery dominated Egypt for a period. The Shia heretics afterwards became powerful, and the Christians were well treated. In 1250 the Mamelukes (descendants of slaves) came into power. Their pomp-loving sultans and emirs lived in great splendour. They came under Turkish sway early in the sixteenth century, but when Napoleon conquered Egypt in the eighteenth century they were again semi-independent. The British drove the French out of Egypt. Mehemet Ali, an Albanian officer in a Turko-Albanian force, had himself declared Sultan of Egypt, but when he overran Syria and threatened to march to Constantinople, Russia intervened. Britain and France afterwards prevailed on Mehemet Ali to rule Egypt as the viceroy of the Sultan of Turkey. His successor and grandson, Abbas I, built the first railway in Egypt. The next viceroy, Said Pasha, son of Mehemet Ali, granted to a French company the right to construct the Suez Canal. Egypt became bankrupt under his successor, Ismail Pasha, the first Khedive (Prince), during whose reign the Suez Canal was opened. He was deposed when the British and French took over the control of Egyptian finance. During the term of his successor, Tewfik Pasha, the Arabi Pasha rebellion took place. The military occupation of Egypt by British troops was followed by peace and good government. But trouble broke out in the Sudan. Mohammed Ahmed declared himself the Mahdi (Messiah) of the Mohammedans, and conquered a great part of the Sudan. In Nov., 1883, General Hicks ('Hicks Pasha') led an army of 10,000 Egyptians against the false prophet, but while marching across the driest part of the Sudan, misled by spies who acted as guides, his thirst-stricken army was entirely destroyed by the Mahdi's force. This victory gave the false prophet great prestige. In Jan., 1884, General Gordon was sent to Khartoum as Governor-General of the Sudan, but was completely isolated there. Khartoum was captured and the gallant general slain on 26th Jan., 1885, before a relieving force could reach him. The Mahdi died in June, 1885, and was succeeded by Abdullah the Khalifa. After a period of reorganization and preparation in Egypt, the reconquest of the Sudan was begun. Lord (then Sir Herbert) Kitchener was Sirdar, or Commander-in-Chief of the Egyptian army, and his expeditionary force was strengthened by British regiments. In April, 1898, the Khalifa's army was defeated on the banks of the Atbara, and on 2nd Sept. Kitchener won a great victory near Omdurman. The Khalifa escaped, but was rounded up by Sir Reginald Wingate's force, and slain with his emirs at Umme Dubraykat on 24th Nov., 1899. Thereafter the Sudan came under the control of a British-Egyptian _condominium_, which appointed a Governor-General.

[Illustration: The Great Pyramids of Giza and the Sphinx

Built by Cheops (Khufu) and Cephron (Khafra) as their future tombs, in order to secure immortality by the preservation of the mummy.]

At the time of the outbreak of the Great War, in the autumn of 1914, the Khedive of Egypt was in Constantinople. He sided with the Central Powers. He was consequently deposed by Britain, and Prince Hussein Kamil was declared Sultan of Egypt; the suzerainty of Turkey terminated at the same time. The new ruler of Egypt was the uncle of the deposed Khedive, Abbas Pasha Hilmi (second son of the first Khedive, Ismail Pasha, and brother of Tewfik Pasha, the second Khedive). Hussein Kamil died in 1917 and was succeeded by Ahmed Fuad Pasha. Under the Peace Treaty, Egypt is recognized as an independent kingdom protected by Great Britain. The capital of modern Egypt is Cairo, situated near the site of ancient Memphis. Thebes is represented by Luxor and Karnak.--BIBLIOGRAPHY: (Religion) Breasted, _Development of Religion and Thought in Ancient Egypt_; Renouf, _Book of the Dead_; Budge, _Gods of the Egyptians_; Wiedemann, _Religion of the Ancient Egyptians_; Sayce, _Religion of Ancient Egypt and Babylonia_; G. Elliot Smith, _The Migrations of Early Culture_; (History)--G. Elliot Smith, _The Ancient Egyptians_; Breasted, _A History of Egypt_; Flinders Petrie, _A History of Egypt_; King and Hall, _Egypt and Western Asia in the Light of Recent Discoveries_; H. R. Hall, _The Ancient History of the Near East_; Sir A. Colvin, _The Making of Modern Egypt_; Lord Cromer, _Modern Egypt_.

EGYPTIAN BLUE, a brilliant and very permanent pigment used by the Romans in the early centuries of the Christian era. It has been found in ancient frescoes in the Vatican, and also at Pompeii. The chemist Fouqu['e] proved by analysis that it is a double silicate of calcium and copper.

EGYPTIAN VULTURE (_Neophron perenopt[)e]rus_), a bird that frequents both shores of the Mediterranean, but rarely passes farther north, though it has been found in the British islands. It is one of the smaller vultures, about the size of a raven. The general colour is white, the quill feathers of the wing being dark brown. It frequents the streets of Eastern towns, where it is protected on account of its services as a scavenger. This vulture is sometimes known as Pharaoh's Hen, on account of its frequent representation in Egyptian hieroglyphics. In Spain it is called the _quebranta-huesos_ (bone-smasher) in reference to its supposed habit of breaking up bones left by other vultures.

EHRENBERG ([=a]'r[.e]n-ber_h_), Christian Gottfried, a German scientist, born in 1795, died in 1876. After studying theology, medicine, and natural history, he joined in 1820 an expedition to Palestine, Egypt, and Abyssinia, returning to Berlin in 1825. In 1829 he accompanied Humboldt to the Ural and Altai ranges and to Central Siberia. His great work on Infusoria appeared in 1838, and was at once recognized as the highest authority on the subject. It was followed in 1854 by his _Microgeology_.

EHRENBREITSTEIN ([=a]'ren-br[=i]t-st[=i]n), a dismantled Prussian fortress formerly of great strength and situated opposite the confluence of the Moselle with the Rhine, on a precipitous rock 387 feet above the river, and inaccessible on three sides. It is connected with Coblentz on the opposite shore by a bridge of boats. The fortifications, which were erected between 1816 and 1820 at a cost of L1,200,000, could accommodate a garrison of 14,000 men, and possessed room for stores to last an army of 60,000 for a year.

EHRLICH, Paul, German physician, born in Silesia in 1854, died in 1915. Educated at Breslau, Strasburg, and Leipzig, he became _privat-dozent_ at the University of Berlin in 1889, and in 1896 was appointed director of the Royal Institute for Serum Research at Steglitz, which was transferred to Frankfurt in 1899, and became the Royal Institute for Experimental Therapeutics. His studies in the histology of blood are very important, but his claim to fame is based upon his discovery of _salvarsan_ (606) and of _neosalvarsan_ (614), arsenic compounds which are very efficacious in the treatment of syphilis. He delivered the Croonian lectures in 1900 and the Harben lectures in 1907, received honorary degrees from the universities of Oxford and Chicago, and in 1908 shared the Nobel prize for medicine with Metchnikoff of the Institut Pasteur in Paris. His works include: _Beitr[:a]ge zu Histologie und Klinik des Blutes_, _Anaemie_, _Abhandlungen [:u]ber Salvarsan_, &c.

EIBENSTOCK ([=i]'ben-stok), a town in the south-east of Saxony, with important manufactures of lace. Pop. 9528.

EICHHORN ([=i]_h_'horn), Johann Gottfried, German Orientalist, historian, &c., born in 1752, died in 1827. He became professor of Oriental languages at Jena, and then at G[:o]ttingen. Amongst his works are: _The Hebrew Prophets_, _History of Literature_, _History of the Last Three Centuries_, _Introductions to the Old and New Testaments and to the Apocrypha_.

EICHST[:A]TT ([=i]_h_'stet), an old town, Bavaria, in a deep valley of the Altm[:u]hl, 67 miles N.N.W. of Munich. Its principal edifice is a fine Gothic cathedral, founded in 1259. Pop. 8029.

EIDER ([=i]'d[.e]r), a river of Schleswig-Holstein, rises 8 miles S. of Kiel, and after a winding course falls into the North Sea at T[:o]nning; length, 112 miles. By means of a canal it long gave communication between the North Sea and Baltic, but the new ship canal here has superseded this route.

[Illustration: Eider Duck (_Somateria molliss[)i]ma_), female]

EIDER DUCK (_Somateria molliss[)i]ma_), a species of duck found from 45deg north to the highest latitudes yet visited, both in Europe and America. Its favourite haunts are solitary rocky shores and islands. In Greenland and Iceland they occur in great numbers, and also breed on the western islands of Scotland. The eider duck is about twice the size of the common duck, being about 2 feet 3 inches in length, 3 feet in breadth of wing, and from 6 to 7 lb. in weight. The male is black, head and back white, with a black crown. The female is reddish drab spotted with black, and with two white bands on the wings. They feed largely on shell-fish and crustaceans. Their nests are usually formed of drift grass or dry seaweed, lined with a large quantity of down, which the female plucks from her own breast. In this soft bed she lays five eggs, which she covers over with a layer of down. If this, with the eggs, is removed, the bird repeats the process. One female generally furnishes about 1/2 lb. of down, but the quantity is reduced by cleaning. This down, from its superior warmth, lightness, and elasticity, is in great demand for beds and coverlets; and the districts in Norway and Iceland where these birds abound are guarded with the greatest vigilance as a most valuable property. As found in commerce this down is in balls of the size of a man's fist, and weighing from 3 to 4 lb. It is so fine and elastic that 5 lb. of the best quality is sufficient for a whole bed. The down from dead birds is little esteemed, having lost its elasticity. The king eider duck (_Somateria spectab['i]lis_) is another species resembling the preceding and inhabiting the same coasts.--Cf. J. G. Millais, _British Diving Ducks_.

EIFFEL ([=a]-fel), Alexandre Gustave, French engineer, born in 1832; attended, from 1852 to 1855, the ['E]cole Centrale des Arts et Manufactures at Paris, and devoted himself chiefly to the designing of large structures in iron, especially bridges and viaducts, the great bridge over the Douro being one of his works. His name is best known, however, from the lofty iron tower erected by him in connection with the Paris Exhibition of 1889, rising to the height of 985 feet on the Champ de Mars. He was condemned in 1893 to two years' imprisonment and a fine of 20,000 francs for misappropriation of funds belonging to the Panama Canal Company, but the judgment was set aside on technical grounds. In 1913 he published a work entitled _Resistance of the Air_. See next article.

EIFFEL TOWER, a structure named after the originator, one of the sights of Paris, is by far the loftiest structure in existence, surpassing the Washington Obelisk, the next highest (555 feet), by 430 feet. It cost about L260,000, and was erected partly at the cost of the State, partly by funds provided by Eiffel himself, who formed a company for the purpose. The company derived its profits from the fees which visitors had to pay, but the tower became the property of the State in 1909. The top may be reached by stairs and lifts. The first stage or platform is at the height of 189 feet, and forms a quadrilateral 213 feet square, fitted up as a restaurant. The next platform is at the height of about 380 feet, and is 98 feet square. The third platform is at the height of 906 feet, and is large enough to accommodate a good number of persons, affording a magnificent view. The lantern higher up is supplied with powerful electric searchlights, and on the very summit is a small area utilized chiefly for scientific observations. The tower has been utilized in experiments connected with the fall of bodies, vibration of the pendulum, and pressure of the air. In recent years the tower has become an important wireless telegraphy station.

EIGG (eg), an island on the west coast of Scotland, county of Inverness, about 10 miles from the mainland, and 5 miles long by about 3 broad. It has bold, rocky shores, and terminates to the south in a lofty promontory called the Scuir of Eigg, with a peak of columnar pitchstone porphyry 1339 feet above the sea, and on one side perpendicular as a wall. It is the scene of the massacre, towards the end of the sixteenth century, of 200 Macdonalds by the Macleods of Skye, who suffocated them in a cave where they had taken refuge. Pop. 211.

EIGHT-HOUR DAY. The eight-hour day was proposed in England as early as 1833, and in 1869 the Trade Union Congress of Birmingham formulated the demand that this ideal working day should be adopted throughout the United Kingdom. The Trade Unions and the Socialists sought to secure the establishment of the eight-hour day through legislation, and it gradually came into force not only in coal-mining, but in various trades and industries. The agitation in favour of an eight-hour day became very strong in Europe towards the end of the nineteenth and at the beginning of the twentieth centuries, and in England it was granted to miners in 1908, and to railway employees in 1919. Since the European War the movement has made great headway, and it now forms part of the programme of the Labour parties in almost all European countries.--BIBLIOGRAPHY: Hedfield and Gibbins, _A Shorter Working Day_; Robertson, _The Eight Hour Question_.

EIGHTY CLUB, THE, a club formed in 1879 by a number of prominent English Liberals with a view to the promotion of the success of Liberalism at the general election of 1880, whence its name. The members lecture on political subjects and address Liberal associations throughout the country. Women were first admitted to membership in 1920.

EIKON BASILIK[=E] ([=i]'kon ba-sil'i-k[=e]; Gr., 'the royal image'), the name of a book published shortly after the execution of Charles I in Jan., 1649, and supposed by some to have been written by the king himself. At the Restoration Gauden, afterwards Bishop of Worcester, laid claim to the authorship, and a memorandum in the copy of the Earl of Anglesea, Lord Privy Seal under Charles II, affirms his claim with the authority of Charles II and the Duke of York. The Royalist Clarendon, author of the _History of the Rebellion_, accepted this statement, but others refused to credit Gauden with the authorship. Within a year of its publication, 48,000 copies of the book were sold, and the republicans put forward Milton to answer it, his _Eikonoklastes_ (that is 'image-breaker') appearing the same year, by order of Parliament. The _Eikon Basilik[=e]_ professes to be a sort of private journal of the king, written in an affectedly dignified strain, and containing numerous assertions of love for his misguided and ungrateful people.--Cf. Almack, _Bibliography of the King's Book, or Eikon Basilik[=e]_.

EILDON HILLS ([=e]l'don), a picturesque hill-mass with three summits, south of Melrose, Roxburghshire, Scotland, reaching a height of nearly 1400 feet, fabled to have been cleft in three by Michael Scott.

EILEITHYIA ([=i]-l[=i]-th[=i]'ya), the Greek name of the ancient Egyptian city Nekheb (the modern El-Kab), on the Nile, some distance above Esneh. Important remains have been obtained from rock-tombs in the neighbourhood, and there are several ruined temples.

EILENBURG ([=i]'l[.e]n-b[u:]r_h_), a town, Prussian Saxony, 26 miles N.N.E. of Merseburg, on an island of the Mulde. It has manufactures of calico. Pop. 17,400.

EIMBECK ([=i]m'bek), or EINBECK, a town of Prussia, province of Hanover, 40 miles south of Hanover, once famous for its beer (_Eimbecker Bier_, whence _Bock_). Pop. 9430.

EINSIEDELN ([=i]n'z[=e]-d[.e]ln), a village and district, Switzerland, in the canton and 9 miles north by east of Schwyz, 3000 feet above the sea, celebrated for its Benedictine abbey. An image of the Virgin, alleged to possess miraculous powers, annually attracts immense numbers of pilgrims. Pop. 8438.

EINSTEIN, Albert (1879- ), physicist, was born at Ulm, W[:u]rtemberg, Germany, of German-Jewish parents. He was educated at the Gymnasium in Munich, and, on leaving school in his sixteenth year, accompanied his parents to Milan. Six months later, he enrolled at the Technical High School in Zurich, where he studied from 1896 to 1900. He held a post in the Swiss Patent Office from 1902 to 1909, then various professorships in Zurich till 1914, when he received a call to the Prussian Academy of Science, Berlin, as successor to van't Hoff. Einstein has been twice married. He has become famous as the author of the Theory of Relativity (q.v.). The 'special theory', which deals chiefly with electrodynamics and optics, was published in 1905, and the 'general theory' or theory of gravitation, about ten years later. His name became popularly known in 1919, after observations made during the solar eclipse of that year had verified his prediction of the bending of rays of light coming from a star and passing close to the sun. He has made other valuable contributions to Theoretical Physics, among these being a theory of the Brownian movements and various important applications of the modern quantum theory of energy. In 1921 he visited the United States and Britain, and delivered many lectures on Relativity.

EISENACH ([=i]'z[.e]n-[=a]_h_), a town of Germany, in the former grand-duchy of Saxe-Weimar, near the mountains of Thuringia, at the junction of the Nesse and H[:o]rsel. It is an attractive town, and contains a palace erected in 1742. It has manufactures of pottery, leather, woollen yarn, &c. Sebastian Bach was born there in 1685. Near it lies the Wartburg, where Luther was kept for safety during 1521 and 1522. Pop. 38,362.

EISENBERG ([=i]'z[.e]n-ber_h_), a town of Germany, former duchy of Saxe-Altenburg, with a palace and various manufactures. Pop. 10,750.

EISLEBEN ([=i]s'l[=a]-b[.e]n), a town, Prussian Saxony, 25 miles north-west of Merseburg, celebrated as the place where Luther was born and where he died. There are many memorials of Luther, and also a bronze statue of the reformer erected in 1883. Copper is extensively worked in the neighbourhood. Pop. 24,630.

EISNER, Kurt, Bavarian revolutionary leader, born in 1867 at Berlin, of a Jewish family. He studied at the University of Marburg, and early acquired a vast erudition. Entering journalism, he contributed to the _Frankfurter Zeitung_, where he published an article attacking the Kaiser. For this he was condemned to nine months' imprisonment. He then wrote for the Socialist press and eventually became editor-in-chief of the _Vorw[:a]rts_. In 1907 he published a work entitled _The Fall of the Empire_ which attracted much attention, and in 1910 he attacked Prussian ascendancy in the _Munich Post_. Eisner took an active part in the Revolution of 1918, and was appointed Prime Minister of Bavaria. A revolutionary and a Socialist, he was, however, opposed to Bolshevism, which he did not hesitate to criticize violently. But his policy of separation, his aim of liberating the South German States, and his constant attacks upon the Kaiser and the whole military caste of Germany, brought him many enemies. Whilst on his way from his house to the Foreign Office he was shot at and killed by Count Arco Valley on 21st Feb., 1919.

EISTEDDFOD ([=i]-steth'v[=o]d; W. _eistedd_, to sit, and _bod_, to be; pl. _eisteddfodau_), an ancient assembly of Welsh bards for the purpose of musical and poetical contests, the judges being originally appointed by commissions from the native princes, and after the conquest from the English kings. There are two kinds of eisteddfodau, the national or general, and the provincial gatherings which take place in many parts of Wales. The last commission was issued by Queen Elizabeth in 1568, but the eisteddfod fell into abeyance during the seventeenth century. In 1798 the ancient custom was revived by the Gwynnedigion Society, and on a more elaborate scale by the Cambrian Society, which grew out of the Gwynnedigion. Eisteddfodau are now held annually in North and South Wales alternately, and are attended by many thousands of people. The festivals of 1919 and 1920 were held at Corwen and at Barry, Glamorgan, respectively.--Cf. Rhys and Brynmor Jones, _The Welsh People_.

EJECT'MENT, in law, an action wherein the title to lands and tenements may be tried and the possession recovered. It is commenced by a writ addressed to the tenant in possession and all entitled to defend the possession, bearing that the plaintiff lays claim to the property in question, and calling upon all interested to appear within a certain time to defend their rights. In its older form the action was remarkable for the curious fictions on which procedure was based. The names of John Doe, an imaginary plaintiff, and of Richard Roe, an imaginary defendant, were familiar in cases of this kind in the English courts until 1852, when the Common Law Procedure Act abolished these fictitious suitors.

EJECTOR, in mechanical engineering, an appliance for ejecting gases, vapours, or liquids from closed spaces by the use of another gas, vapour, or liquid at a higher pressure. For instance, the air may be extracted from a condenser by an ejector. A jet of steam is directed along a short specially-shaped pipe leading from the condenser to the outside atmosphere. The velocity of the steam when it leaves the jet in the pipe is very high, and it blows out into the atmosphere in spite of the atmospheric pressure against it. In blowing out into the atmosphere it sucks the air in the condenser along with it, and after it has been in operation some time practically the whole of the air is sucked out of the condenser. The appliance works on the principle of momentum. The active jet mixes with the material to be ejected and imparts a common momentum to the mixture, which is sufficient to enable it to pass outside the vessel from which the ejection is taking place. The same principle is used in the mercury air-pump (see _Air-pump_).--BIBLIOGRAPHY: W. E. Dalby, _Steam Power_; _Modern Mechanical Engineering_ (The Gresham Publishing Company).

EKAT'ERINBURG, a town, Russia, in the government and 170 miles S.E. of Perm, founded in 1723 by Peter the Great. It is the mining and metallurgy centre of the Ural regions; and gem-cutting, the making of machinery, cloth, and candles are industries. Pop. 70,000.

EKAT'ERINODAR, a town of Russia in the Caucasus, chief town of the Kuban territory, on the River Kuban, a poorly-built place with a considerable trade. Pop. 107,360.

EKAT'ERINOSLAV, a town of the Ukraine, capital of a government of the same name, on the right bank of the Dnieper, 250 miles N.E. of Odessa. Founded in 1787, it is a manufacturing centre, producing iron, machinery, tobacco, and beer. Pop. 220,100.--The government, which is intersected by the Dnieper and reaches the Sea of Azov, has great mineral wealth, especially in coal (Donetz basin), iron, manganese, and rock-salt; and its fertile black-earth soil produces abundant crops of wheat and other grains. Area, 24,478 sq. miles; pop. 3,537,300.

ELAEAGNA'CEAE, the oleaster family of plants, a small nat. ord. of apetalous dicotyledons scattered over the northern regions. The only British member is the sea-buckthorn (_Hippophae rhamnoides_).

ELA'IN, the oily principle of fat obtained by submitting fat to the action of boiling alcohol, allowing the stearin to crystallize, and then evaporating the alcoholic solution. It is not unlike vegetable oil in its appearance and its properties, and forms soaps with alkalies.

E'LAM, the ancient name of a country on the eastern border of Babylonia. Its civilization dates back beyond 3000 B.C. Before 2000 B.C. it was strong enough to subdue part of Babylonia. Its power was finally broken by the last Assyrian monarchs. The capital was Susa, which became prominent again after the rise of Cyrus. Its splendour during the Persian period is reflected in the _Book of Esther_, in which it is referred to as 'Shushan'.

[Illustration: Eland (_Oreas canna_)]

E'LAND, _Oreas_ (_Orias_) _canna_, a species of antelope inhabiting Africa, the largest of all its kind, being about the size of an ox. Its flesh, especially that of the thighs, which are dried and used in this state, is highly prized. It is now almost extinct south of the Limpopo, but it is plentiful in the Kalahari. The colour is a light or greyish brown, and it possesses a short mane. The horns, which are about 18 inches long and nearly straight, are spirally keeled.

EL'ANUS, the name of certain species of raptorial birds of the genus El[=a]nus, belonging to the kites. The type species is the black-winged kite (_E. caeruleus_) of Africa and South Asia, which strays to South-West Europe. A very similar form (_E. leucurus_) is native to tropical and subtropical America, and other species (_E. scriptus_ and _E. axillaris_) are Australian.

ELAPHOMYCES, a genus of Ascomycetous fungi, section Plectascineae, with closed, subterranean ascus-fruits resembling those of the genuine truffles (Tuberineae), but not closely allied to that family. _E. cervinus_ (Hart's truffle) is not infrequent in Britain; it forms 'mycorhiza' with roots of oak, beech, and various conifers.

E'LAPS, a genus of poisonous American snakes, the type of the family Elapidae, to which belongs the cobra de capello.

EL-ARISH, Egyptian city on the Mediterranean, on the Wadi el-Arish, and chief city of the territory bearing the same name. It was taken by the French under Kl['e]ber in 1799, but abandoned the same year. Pop. about 5000.

ELASMOBRANCHII (-brang'ki-i), a sub-class of fishes, including sharks, dog-fishes, rays (skates); and also Chimaera (q.v.) and its allies. They are predaceous forms, in which the mouth is a transverse slit on the under side of the head, the numerous simple teeth are in several rows (except in chimaeroids), the short intestine possesses a spiral valve and opens into a cloaca. The tail is asymmetrical (heterocercal), and numerous placoid scales (dermal denticles) are embedded in the skin. The skeleton is cartilaginous; the heart possesses a muscular conus arteriosus with numerous rows of pocket-valves; and there are five (sometimes six or seven) pairs of gill-pouches opening by slits to the exterior, these not being covered by an external flap (operculum) except in chimaeroids. Fertilization is internal, and the male is provided with a pair of copulatory organs (claspers) projecting backwards from the pelvic fins. The eggs sometimes develop within the body of the mother, but are usually laid in horny pouches (mermaids' purses). The group is of great antiquity, and many extinct fossil types are known.

ELASMOTHE'RIUM, an extinct genus of Mammalia, found in the post-Pliocene strata of Europe, comprising animals of great size allied to the rhinoceros, and having probably one large horn and a smaller nasal horn.

ELASTIC BITUMEN, ELATERITE, or MINERAL CAOUTCHOUC, an elastic mineral bitumen of a blackish-brown colour, and subtranslucent. It has been found at Castleton, in Derbyshire.

ELASTICITY, the property in virtue of which bodies resist change of volume or of shape, and tend to regain their original bulk or shape when the deforming forces are removed. Solids possess elasticity of volume and of shape. Liquids and gases have elasticity of volume; they resist compression, but offer only a transient resistance to change of shape (see _Viscosity_). The elasticity of a gas is measured by the pressure to which the gas is subjected, if there is no change of temperature. When a gas is compressed suddenly, it has a greater elasticity on account of the rise of temperature which takes place. Liquids are less compressible than gases; water is compressed by about 1 part in 20,000 when the pressure on it is increased by one atmosphere. A knowledge of the elastic properties of solids is of importance in all branches of applied mechanics. Homogeneous solids offer definite resistance to compression, twisting, stretching, and bending, and this resistance is expressed by a number called a modulus. Let the deforming force be reckoned per unit of area, e.g. a pressure in tons per square inch; this is called the stress. The unital deformation produced by the stress is called the strain, for example, compression per unit of volume. The modulus is obtained by dividing the stress by the strain; if this is done with the above example, the ratio will give the bulk modulus. When the applied forces cause change of shape without change of volume, the ratio of stress to strain is called the shape modulus or the rigidity of the material. This property is brought into play when mechanical power is transmitted by means of shafting. Young's modulus is employed in the cases of stretching and bending. It is given by the ratio stretching force per unit area to stretch per unit length. In 1678 Hooke stated the law that stress is proportional to the strain which it causes. This law is found in practice to be true for metals within a certain range of stress which lies below the elastic limit. If the stress is increased beyond this limit, the material begins to give way, and permanent change of shape or volume takes place. In the processes of riveting and wire-drawing, the material is purposely strained beyond the elastic limit, whilst the correct working of a spring balance requires that the spring should never be overstrained. When metals are subjected to frequently repeated stresses, they undergo a weakening and are said to become fatigued, and are liable to give way under a smaller stress than would otherwise cause fracture. The speed with which sound waves are transmitted through a material depends on the elasticity of the material; such compressional waves in water have been employed by the Roumanian engineer, Constantinescu, to transmit power by means of water-pipes.

_Mathematical Theory._--Consider an elastic body at rest and free from strain. Let the body be subjected to forces, fulfilling the ordinary statical conditions of equilibrium, and therefore not tending to give the body any motion of translation or rotation as a whole. The particles of the body will move very slightly relative to each other; in other words, a system of strain will be set up in the body. To maintain this strain a definite system of stress is necessary. The problem for the mathematical theory is to determine the state of strain and stress at every point of the body when the applied forces are given. These applied forces may either be body forces (of which practically the only example is weight), or surface forces; the latter are pressures or tractions, and are defined by their directions and amounts per unit area. It is first of all necessary to show how strain and stress can be specified mathematically.

_Strains._--If x, y, z are the co-ordinates of a point in the unstrained body, and if this point is displaced to (x + u, y + v, z + w) when the straining forces are applied, then u, v, w, which are supposed to be very small, are called the component displacements at (x, y, z). It is clear that if u, v, w were constant, the body would simply be displaced without strain. The state of strain can in fact be shown to depend on the first derivatives of u, v, w with respect to x, y, z. The strain round any given point consists simply of three stretches parallel to a certain set of three mutually perpendicular directions. These directions vary from point to point, so that this specification of the strain is inconvenient for calculations. A suitable method depends on the fact that the strain is known round a point when we know the values of the six quantities

du/dx, dv/dy, dw/dz, dw/dy + dv/dz, du/dz + dw/dx, dv/dx + du/dy,

at the point. These are called the components of strain at (x, y, z). The first three are _stretches_ parallel to the axes, the other three are _shearing_ strains. We may get an idea of the nature of these strains from two simple typical cases. 1. Let u = ex, v = 0, w = 0. This makes du/dx = e, and the other five strains zero. But we see that the displacement of every particle is perpendicular to the yz plane, and proportional to its distance from that plane. Every line parallel to the axis of x is therefore elongated by a definite fraction of its original length, the value of this fraction being e, which is du/dx. The strains du/dx, dv/dy, dw/dz are therefore _stretches_ parallel to the axes. 2. Let u = 0, v = cz, w = 0. This gives dv/dz + du/dy = c, and the other five strains zero. The displacement of every particle is parallel to the axis of y, and proportional to its distance from the plane xy. The strain is therefore a slide, or _shear_ of planes parallel to xy in the direction of the axis of y.

_Stresses._--To specify the stress round a point (x, y, z), consider a small plane area through the point. The material on one side of this acts on the material on the other side with a certain force whose components parallel to the axes are F, G, H, say, per unit area. If we know F, G, H for every orientation of the small plane area, the state of stress round (x, y, z) is defined. But it is easy to show, as below, that we can find F, G, H for every area if we know them for areas parallel to the co-ordinate planes. We are thus led to the specification of the stress round (x, y, z) by the six _components of stress_, [=xx], [=yy], [=zz], [=xy], [=xz], [=yz]; where [=xy], for example, means the force per unit area _parallel_ to Ox exerted on a plane _perpendicular_ to Oy by the material on the positive side of that plane on the material on its negative side. Thus e.g. the components of the force per unit area exerted across the yz plane through (x, y, z) by the material on the positive side of that plane are [=xx], [=xy], [=xz]. It is important to note that [=xy] = [=yx]. This is easily proved by considering the equilibrium of a small rectangular volume of the material round (x, y, z) as centre, with its edges parallel to the axes; if [=xy] were not equal to [=yx], there would be a residual couple in the plane xy.

_Relations between the Strains and the Stresses._--When the strains are known, the stresses can be found from a generalized Hooke's law, which can be deduced from the principle of energy, combined with consideration of symmetry. If the solid is isotropic, i.e. is symmetrical in its elastic properties in all directions round a point, the relations between stress and strain are of the form

[=xx] = [lambda](du/dx + dv/dy + dw/dz) + 2[mu]du/dx,

[=yz] = [mu](dw/dy + dv/dz);

the values of the other four components of strain can be written down from symmetry. Here [lambda] and [mu] are constants, each being a _modulus_ of elasticity. In particular [mu] is the _shape modulus_ or the _rigidity_, already referred to. The Young's modulus and the bulk modulus can easily be found in terms of [lambda] and [mu].

_Equations of Equilibrium in Terms of the Stresses._--A rectangular element dx, dy, dz, of the body is held in equilibrium by the body force, and the tractions on its faces arising from the stress. The tractions per unit area, parallel to the axis of x, on the six faces, are: on the plane x, -[=xx]; on the plane x + dx, [=xx] + (d/dx [=xx])dx; on the plane y, -[=xy]; on the plane y + dy, [=xy] + (d/dy [=xy])dy; and similarly for the plane z. Let the force acting on the mass of the body, such as its weight, be (X, Y, Z) per unit mass, and let [rho] be the density. By equating the sum of the x components of all the forces to zero, we get

d[=xx]/dx + d[=xy]/dy + d[=xz]/dz + [rho]X = 0;

Similarly d[=xy]/dx + d[=yy]/dy + d[=yz]/dz + [rho]Y = 0,

and d[=xz]/dx + d[=yz]/dy + d[=zz]/dz + [rho]Z = 0.

_The Surface Tractions in Terms of the Stresses._--Draw a small tetrahedron round (x, y, z) with its faces perpendicular to the axes and to the direction (l, m, n), and consider the equilibrium of this small body. Let F, G, H be the components per unit area of the force on the plane whose direction cosines, _drawn outwards_, are l, m, n. If A be the area of the face perpendicular to (l, m, n), we get, by resolving parallel to Ox,

F.A = [=xx].lA + [=xy].mA + [=xz].nA.

Hence F = l[=xx] + m[=xy] + n[=xz],

and similarly G = l[=xy] + m[=yy] + n[=yz],

H = l[=xz] + m[=yz] + n[=zz].

If (x, y, z) is a point at the surface of the body, and l, m, n are the direction cosines of the outward normal at that point, these values of F, G, H are the component of the force that must be applied from outside to the surface at (x, y, z) to maintain the state of stress.

_The Equations connecting the Displacements and the Applied Forces._--By using, in the equations of equilibrium, the values of the stresses in terms of the strains, we find the body equations of equilibrium in terms of displacements,

[mu](d^2u/dx^2 + d^2u/dy^2 + d^2u/dz^2) + ([lambda] + [mu])d/dx(du/dx + dv/dy + dw/dz) + X[rho] = 0,

with two similar equations.

The surface equations of equilibrium can also be written down at once by substituting the values of stresses in terms of strains in the expressions for F, G, H given above.

_The Problem of Equilibrium._--To find the strain under given forces we have to solve the body and surface equations of equilibrium, when X, Y, Z and F, G, H are given. This problem has not been completely solved except in a few cases. It was solved by Lam['e] and Lord Kelvin for a solid or hollow sphere; it has also been solved for an infinite solid bounded by two parallel planes, or by a circular cylinder. Many particular solutions, however, are known for bodies of other shapes. Some of these solutions are of great practical value, e.g. St. Venant's solutions for the torsion and flexure of prisms. For bodies in which one or two dimensions are small, i.e. for thin plates and shells, and for thin rods, approximate theories have been given, which are partly deduced from the above exact equations, and partly from plausible hypotheses, a complete treatment based on the exact equations being in most cases impracticable.

_The Problem of Vibrations._--When a body is vibrating, the mass acceleration parallel to Ox of the particle at (x, y, z) is [rho] dx dy dz d^2u/dt^2. The equations of vibration are therefore found by writing - d^2u/dt^2 instead of X, in the first body equation of equilibrium, and similarly with the others. The surface conditions will usually be that F, G, H are zero. The problem has been completely solved by H. Lamb for a solid or hollow sphere. For the elastic solid theory of the luminiferous ether, see _Ether_; for some practical solutions of the general equations of equilibrium, see _Strength of Materials_.--BIBLIOGRAPHY: A. E. H. Love, _Mathematical Theory of Elasticity_; Lord Kelvin and Tait, _Natural Philosophy_; Todhunter and Pearson, _History of Elasticity and Strength of Materials_.

EL'ATERIDAE, the name of a family of beetles, remarkable for their ability to throw themselves to a considerable height in the air, when placed on their back, by a vigorous muscular movement. Hence their names of springing-beetles, click-beetles, skip-jacks, &c. When alarmed, the elater counterfeits death. Flowers, grass, and decaying wood are the habitations of these animals, which are almost always found singly. The larvae are often very injurious to vegetation, especially those which devour the roots of herbaceous plants (as in the genus Agri[=o]tes), and are known from then slenderness and hardness as wire-worms. The fireflies of America belong to the family. In these a pair of luminous organs is found on the thorax, while there is a third on the under side of the base of the abdomen. The _Pyroph[)o]rus noctil[=u]cus_, called _cucujos_ in Brazil, is used as a personal ornament by ladies. The largest species of the genus Elater, the _Elater flabellicornis_, is 2-1/2 inches in length.

ELATE'RIUM, a substance obtained from the fruit of the squirting or wild cucumber (_Ecballium agreste_). The juice of the unripe fruit, when expressed and allowed to stand, deposits elaterium as a green sediment with an acrid taste, a faint odour, and powerful cathartic properties. It is a violent purgative, and is poisonous, but its action is not constant. The active principle in it is called _elaterin_.

ELBA (Lat. _Ilva_), a small island in the Mediterranean, in the province of Livorno (Leghorn), Italy, separated from the mainland by the Strait of Piombino, about 6 miles wide. The island is 18 miles long and from 2-1/2 to 10-1/2 miles broad, and is traversed by mountains rising to a height of over 3000 feet. It is rich in iron, marble, granite, salt, &c.; and iron ore is exported. Excellent wine and fruits are produced. It has two seaports--Porto-Ferrajo (the capital) and Porto-Longone. The Treaty of Paris in 1814 erected Elba into a sovereignty for Napoleon, who resided in it from 4th May, 1814, to 26th Feb., 1815, when he escaped and landed at Cannes on 1st March. After Napoleon's departure the island was restored to Tuscany, which became part of Italy in 1860. Pop. 30,450.

ELBE (elb; Ger., pronounced el'be; Lat. _Albis_; Bohem. _Labe_), an important river in Central Europe. It rises on the south-west slopes of the Schneekoppe or Snowcap, one of the Riesengebirge, between Bohemia and Silesia. From this point it flows nearly due south into Bohemia for about 50 miles, when it turns to the west, and after about 40 miles takes a general north-north-west direction till it falls into the North Sea, intersecting Saxony and a considerable portion of Prussia. The finest scenery of its valley is in the Saxon Switzerland. Its length is 725 miles; drainage area, 56,865 sq. miles. The principal affluents are: on the right, the Iser, Schwarz-Elster, and Havel; on the left, the Alder, Moldau, Eger, Mulde, and Saale. In the lower part of its course the river divides into several arms, which unite again about 5 miles below Hamburg. It is more or less navigable for about 525 miles, but its estuary is much encumbered with sand-banks. In 1870 its navigation was declared free from Hamburg to Melnik in Bohemia. The North Sea and Baltic ship canal connects its estuary with Kiel Bay, and there are other important connected canals. It is well stocked with fish.

ELBERFELD (el'b[.e]r-felt), a town of Rhenish Prussia, in the government of and 15 miles east of D[:u]sseldorf, on both sides of the Wupper, enclosed by lofty hills. Taken with Barmen it stretches along the Wupper valley for about 7 miles. The old streets are narrow and irregular, but the newer quarters are well built. It is a great seat of manufacturing industry, among its leading products being cottons, woollens, silks, velvet, mixed textile goods, buttons, ribbons, lace, yarns, thread, carpets, aniline dyes, iron and steel, machinery, pianofortes, and paper. Calico-printing, dyeing, and bleaching are very extensively carried on. It has given its name to a system of poor relief, combining organized voluntary effort and individual treatment. Pop. 170,195.

ELBEUF (el-beuf), a town of France, department of Seine-Inf['e]rieure, 11 miles S.S.W. of Rouen, in a valley on the left bank of the Seine, connected by two bridges with St. Aubin on the opposite side of the river. It is an important centre for the production of woollen manufactures, chiefly of lighter cloths and fancy goods, and is also an entrep[^o]t for the finer and heavier cloths of Louviers and Sedan. It communicates by steamers with Paris, Rouen, and Havre. Pop. 19,240.

ELBING, a seaport town of West Prussia, on the Elbing, near its entrance into the Frische-Haff. It was once a flourishing Hanse town, and is still a place of considerable industry and trade, the manufactures including iron goods, machinery, brass and tinplate goods. It has also shipbuilding yards. Pop. 58,636.

ELBURZ, a lofty mountain range extending over Northern Persia, parallel with and overlooking the Caspian. Highest peak, Mt. Demavend, 19,400 feet; average height, 6000 to 8000 feet.

ELCESAITES (el-ses'a-[=i]ts), a sect of Gnostics which arose in the reign of Trajan about the beginning of the second century. They were a branch of the Essenes, and resembled the Ebionites. A Jew, named Elxai, or Elkesai, is their reputed founder.

ELCHE (el'ch[=a]), a town of Spain, in the province and 14 miles W.S.W. of Alicante, on the left bank of the Vinalopo, surrounded by palm trees. It contains various Roman remains, a fine church, and a town house of the fifteenth century. Chief industry, the culture of dates. Each summer, from the 13th to the 15th of August, an interesting f[^e]te is held at Elche, and a fourteenth century liturgical drama (_The Representation of the Assumption of Our Lady St. Mary_) is performed. Pop. 27,620.

ELCHINGEN (el'_h_ing-en), OBER and UNTER, two villages of Bavaria, on the left bank of the Danube, about 3 miles apart and 8 miles north-east of Ulm. In 1805 Marshal Ney defeated the Austrians at Ober Elchingen, and won for himself the title of Duke of Elchingen.

[Illustration: Common Elder: Foliage, Inflorescence, and Fruit]

ELDER, a name given to different species of the genus Samb[=u]cus, nat. ord. Caprifoliaceae. These are small trees or shrubs, with opposite and pinnated leaves, bearing small white flowers in large and conspicuous corymbs, small berries of a black or red colour, and bitter and nauseous leaves possessing purgative and emetic properties. The wood of the young shoots contains a very large proportion of pith. The common elder of Britain (_S. nigra_) is a wild shrub or small tree, distinguishable by its winged leaves, its clusters of small, cream-white flowers, and the small black berries by which these are succeeded, and from which a kind of wine is sometimes made. The dwarf elder or danewort (_S. Ebulus_) is also found in many parts of Britain, and was popularly supposed to have sprung from the blood of the Danes. Two species inhabit North America: _S. canadensis_, a common plant from the 49th to the 30th parallel of latitude, the berries of which are black and have a sweet taste; and _S. pubescens_, which bears red berries, and inhabits Canada, the northern parts of New England, and the Alleghany Mountains. Elder wood is yellow, and in old trees becomes so hard that it is often substituted for box-wood. Its toughness, also, is such that it is made into skewers and tops for fishing-rods. The light pith is utilized for balls for electric experiments, and various ointments, drinks, and medicinal decoctions are made from the bark, leaves, flowers, and berries.

ELDERS, persons who, on account of their age, experience, and wisdom, are selected for office, as, among the Jews, the seventy men associated with Moses in the government of the people. In the modern Presbyterian Churches elders are officers who, with the pastors or ministers, compose the consistories or kirk-sessions, with authority to inspect and regulate matters of religion and discipline in the congregation. As a member of the kirk-session the elder has an equal vote with his minister, and as a member of the higher Church courts, when delegated thereto, he has a right to discuss and vote on all matters under discussion in the same manner as the clergy themselves. In the Mormon Church the elder is an officer whose duty it is "to preach and baptize, to ordain other elders, to bless children, and to take the lead at all meetings". Among the Shakers there are four elders, two men and two women, in each congregation.

ELDON, John Scott, Earl of, Lord Chancellor of England, born in 1751 at Newcastle-on-Tyne, died in London, 13th Jan., 1838. His father was a coal-dealer and public-house keeper of means, and John was educated with his brother William (afterwards Lord Stowell) at Newcastle, and at Oxford, where he obtained a fellowship. He was called to the Bar in 1776, and in 1782 was made King's Counsel. Next year he entered Parliament, supported Pitt, and was made Solicitor-General, and knighted. In 1792 he purchased the estate of Eldon. In 1793 he became Attorney-General, and in 1799 was created Chief Justice of the Court of Common Pleas, and raised to the peerage and the House of Lords by the title of Baron Eldon. On the accession of the Addington ministry he became Lord Chancellor (1801), and retained this post under the subsequent administration of Pitt until the death of the latter in 1806. A year later, however, he resumed the chancellorship under Liverpool, and held it without break for twenty years. In 1821 he was created an earl by George IV. On the accession of the Canning ministry in 1827 he resigned the chancellorship, and never again held office. As a lawyer he was a master of English jurisprudence; as a politician he was opposed to reform, and by no means free from the charge of servility and intrigue.

EL DORA'DO, a country that Orellana, the lieutenant of Pizarro, pretended he had discovered in South America, between the Orinoco and Amazon Rivers; and which he named thus on account of the immense quantities of gold and precious metals which, he asserted, he had seen in Manoa, the capital of the country. The term El Dorado was first applied to a South American tribal king who was said to cover his body annually with gold-dust. It now designates any place abounding in gold, or offering opportunities for the acquisition of sudden wealth.

ELEANOR CROSSES (el'i-nor), memorial crosses erected on the spots where the bier of Eleanor, the wife of Edward I, rested on its way from Grantham to Westminster. Twelve were erected, but only three, those of Northampton, Geddington, and Waltham, remain.

ELEAT'IC SCHOOL, a Grecian philosophical sect, so called because it originated in Elea (Lat. _Velia_), a town of Magna Graecia (Southern Italy), of which also three of its most celebrated teachers, Parmenides, Zeno, and Leucippus, were natives. The founder was Xenophanes of Colophon, who came to Elea late in life, bringing with him the physical theories of the Ionian school, to which he added a metaphysic. The two schools soon drifted widely apart, especially in respect of method. In opposition to the physical philosophy of the Ionian school, and also the doctrine of Heraclitus, who taught that everything is flux, the Eleatic philosophers asserted that change and difference are only empty illusions, and that the only true reality is changeless being. Starting from the observation of external nature, the Ionians endeavoured to discover some elementary principle, as water, air, fire, or a combination of elements, by the action of which the phenomena they observed might be accounted for. The Eleans made the abstract idea of Being or God, deduced from the contemplation of the Universe as a whole, their starting-point. Their reasonings sometimes led them to deny the reality of external phenomena altogether.

ELECAMPANE (el-i-kam-p[=a]n'; _In[)u]la Hel[=e]nium_), a plant of the nat. ord. Compositae, found in Britain and other parts of Europe, and in Asia. It is 3 or 4 feet high; the radical leaves are often 2 feet and more in length; the flowers are large and yellow; the root, which is perennial, possesses a bitter camphor-like taste. It was formerly much used as a stimulant for all the secreting organs, and in tuberculosis on account of the germicidal action of the bitter principle (helenin) which it contains.

ELECTION, in theology, the doctrine that God has from the beginning elected a portion of mankind to eternal life, passing by the remainder. It is founded on the literal sense of certain passages of Scripture, and has been amplified by the labours of systematic theologians into a complete and logical system. It dates in ecclesiastical history from the time of Augustine; but Calvin has stated it so strongly and clearly in his _Institutes_ that it is generally associated with his name.

ELECTION, in politics, the selection by voting of a person or persons to occupy some post or office. The most important elections are those of the members of the legislative assemblies of the different countries, and as to the manner in which these are carried out strict laws are in force. In such elections voting by ballot is now general. The chief forms of election in Britain are parliamentary and municipal elections, in both of which the basis of the suffrage (or right of voting) is the payment of poor rates. Members of Parliament formerly required a property qualification in England and Ireland; but this restriction, which never existed in Scotland, has been abolished. In both parliamentary and municipal elections the ballot has been in operation since 1872. For the prevention of bribery and corrupt practices many Acts have been passed, of which that now in operation came into force in Oct., 1883, and has been annually renewed. By it persons convicted of treating, bribery, personation, and undue influence are liable to imprisonment with hard labour, and to disqualification in respect of the franchise and public offices. It also imposes many limitations with regard to the number of assistants and committee-rooms, and the use of conveyances. By the Reform Act of 1918, the maximum expenditure for campaign purposes during parliamentary elections is to be sevenpence per elector in county constituencies, and fivepence per elector in boroughs. By this Act the cost of registration is paid half out of local rates, and half by the State. At election times the returning officer's expenses are to be paid by the Treasury. Under the provisions of the Ballot Act the returning officer is required, in the case of a county election, to give notice of an election within two days after that on which he receives the writ; or in the case of a borough election, to give notice on the day on which he receives the writ, or at the latest on the day following. In county or district borough elections the nomination must take place within ten days of the receipt of the writ, at least three clear days, however, being allowed to elapse between the first public notice and the day of nomination. In ordinary borough elections the candidate must be nominated not earlier than the third day after public notice, and not later than the fourth day after that on which the writ is received. A candidate is nominated in writing, with the signatures of a proposer, seconder, and eight other electors, all registered in the constituency to be represented. In the event of there being more candidates than vacancies, the returning officer adjourns the election for the purpose of taking a poll. The polling must take place not less than two or more than six clear days after the day of nomination, if it be a county or district borough election; in the case of an ordinary borough, it must take place not more than three clear days after nomination, Sundays, Christmas Day, &c., not being counted as days. Where the votes for rival candidates are equal, the returning officer, if registered in the constituency, may give the casting-vote. If he decline to do so, a scrutiny is demanded, which usually results in certain deductions on the ground of spoiled papers, disqualified voters, &c., sufficient to give one candidate priority. In elections for the school boards the cumulative system of voting is employed (see _Cumulative Vote_).--Cf. C. Seymour and D. P. Frary, _How the World Votes_.

ELECTOR (Ger. _Kurf[:u]rst_, 'electoral prince'), the title of certain princes of the Holy Roman Empire, who had the right of electing the emperors. In the reign of Conrad I, King of Germany (912-918), the dukes and counts became gradually independent of the sovereign, and assumed the right of choosing future monarchs. In the thirteenth century the number of these electors was seven--the Archbishops of Mainz, Cologne, and Tr[`e]ves, the King of Bohemia, the Count Palatine, the Duke of Saxony, and the Margrave of Brandenburg. In 1648 an eighth electorate was created to make room for Bavaria, and Hanover was added as a ninth in 1692. The votes of the Palatinate and of Bavaria were merged in one in 1777. In 1802 the two ecclesiastical electors of Cologne and Tr[`e]ves were set aside, and Baden, W[:u]rtemberg, Hesse-Cassel, and Salzburg declared electorates; so that there were ten electors in 1806 when the old German Empire was dissolved.--Cf. Viscount Bryce, _The Holy Roman Empire_.

ELECTRICAL FISHES, a name given to fishes possessing the property of communicating an electric shock when touched with the hand or any electric conductor. One of the best known is the electric eel (_Gymn[=o]tus electricus_), a native of South America. It is of nearly equal thickness throughout; head and tail obtuse; ordinary length, 3-1/2 to 4 feet. The seat of the four electrical organs is along the under side of the tail, and they are said to possess the power of knocking down a man, and of painfully numbing the affected limb for several hours after the shock. After a few discharges, however, the faculty of producing a shock is impaired, and an interval of rest is required for a new storage of force. Similar but less-marked powers are possessed by an African cat-fish (_Malapterurus electricus_), in which the electric organ invests the entire body as a sort of jacket under the skin. Still feebler in this respect are the electric rays, of which the best known (species of Torpedo) are native to the Mediterranean, Red Sea, Atlantic, and Pacific Oceans. Here the electric organ consists of a large mass on each side of the front part of the body.

ELECTRICAL MEASURING INSTRUMENTS, the name given to instruments which measure electric power, energy, voltage, or current. The majority of such instruments are current-operated. Thus, with the exception of electrostatic voltmeters, all voltmeters are really current measuring instruments; but since this current is made to be proportional to the P.D. between the voltmeter terminals, the scale reading is proportional to the voltage being measured. One and the same instrument may be used as an ammeter or as a voltmeter, by providing it with shunts for use as an ammeter, and series resistances for use as a voltmeter. If the current to be measured is large, the _shunt_ will have a very _low_ resistance compared with that of the instrument, so that only a small fraction of the total current passes through the instrument. Similarly, when a large P.D. is being measured, the _series resistance_ will have a very _high_ value, so that the current through the instrument may not exceed that which gives full-scale reading. By using shunts or series resistances of different values, different ranges can be given to the instruments.

In addition to the types already described (see _Ammeter_), there is a class depending on the mutual action of current-carrying conductors placed near one another. This type is largely used in alternating-current work. It is also specially suitable for power measurements, and practically all _wattmeters_ work on this principle. The Siemens Dynamometer was the first instrument of this type.

The Kelvin Standard Balance is a special form of dynamometer, in which the mechanical turning-moment due to weights on a beam is balanced by the electrical turning-moment due to currents in fixed coils and in coils attached to the ends of the beam. The electrostatic voltmeter mentioned above is the only instrument which is operated by a P.D. instead of a current. In it a moving vane is attracted into a fixed pair of quadrants; or a set of vanes is attracted into a set of quadrant cells.

The majority of electricity meters are of the motor type, i.e. a disc is driven by motor action at a speed which is proportional to the power passing through the meter. The disc spindle engages with gearing which drives the pointers on a set of dials recording the energy units. There are also meters depending on electrolytic action (Wright meter); or on the difference in period between two pendulums, one of which is controlled by the load current (Aron meter).

ELECTRIC BATTERY, a group of primary or secondary cells, suitably arranged for the purpose of producing an electric current. Primary batteries consisting of a few cells are commonly used for intermittent work where a relatively small current is required, e.g. for electric bells. If a larger current is necessary, especially if it has to be maintained over a considerable period, a battery of secondary cells is used. Such batteries are commonly used for country house lighting. Very large batteries, used either alone or in conjunction with automatic reversible boosters, are frequently employed in public electric supply systems.

The name _electric battery_ was originally given to an arrangement of Leyden jars (see _Leyden Jar_), but is now applied only to cells, the Leyden-jar arrangement being called a Leyden-jar battery.

ELECTRICITY, the name given to the ultimate cause of electrical phenomena. The laws governing these phenomena are well known, but the actual nature of electricity has not yet been fully revealed, although much light has been thrown on the subject by recent researches. (See _Electron_.) Although the practical applications of electrical phenomena have all been developed within the last fifty years, the production of an electric charge by friction, as demonstrated by the power of rubbed amber to attract light bodies, was observed by a Greek philosopher as long ago as 600 B.C. The Greek name for amber, [Greek: elektron] (electron), is the root from which our word electricity is derived. Friction was the only artificial source of electricity known until Galvani, near the close of the eighteenth century, accidently obtained it by the contact of two metals with the limbs of a frog; and Volta, developing Galvani's discovery, invented the first galvanic or voltaic battery.

The discovery by Faraday in 1831 of the principle of the production of an electromotive force by the motion of a conductor in a magnetic field, laid the foundation for the development of the electric generator (q.v.), and thus of modern electric power supply.

The study of electrical phenomena is conveniently divided into two branches, one dealing with stationary charges of electricity (_electrostatics_), the other with electric currents (_current electricity_).

_Electrostatics._--If a pair of ebonite rods be electrified by friction with flannel, then by suspending the one rod and presenting the other to it, it is easily demonstrated that a mutual mechanical force of repulsion exists between them. If now a glass rod be electrified by friction with silk, it will be found that it attracts the suspended electrified ebonite rod. These experiments reveal the facts that electric charges may be of two opposite kinds, and that like charges repel one another, while unlike charges attract one another.

The charge produced on glass by friction with silk is called _positive_; that produced on ebonite by friction with flannel is called _negative_. The kind of charge produced depends not merely on the material rubbed, but also on the material of the rubber. Thus a warm dry glass rod becomes _negatively_ electrified when rubbed with fur. The rubber always becomes electrified with a charge of the _opposite_ kind to that produced on the material rubbed, and these two charges are _equal in amount_. All bodies may be electrified by friction, but those which allow a free movement of the charge over them (such bodies are called _conductors_, to distinguish them from _insulators_, which do not allow this free movement) must be held by an insulating handle, or else the charge will be removed as quickly as it is produced.

Coulomb proved that the magnitude of the mutual mechanical force exerted between two charged bodies depends on the amounts of the charges and the distance between them. Faraday called attention to the influence of the medium in which the charges are placed. Thus if two charges of q_1 and q_2 units respectively are placed d centimetres apart in a given medium, the mechanical force f in dynes exerted between them is given by the equation f = (q_1q_2)/(Kd^2), provided the dimensions of the bodies on which the charges are concentrated are small in comparison with d. The coefficient K is called the _dielectric constant_ of the medium, and its value is taken as unity for air.

In accordance with this relationship, _unit charge_ is defined as that charge which repels an equal and similar charge placed at a distance of 1 centimetre in air, with a force of 1 dyne.

If the medium surrounding a charged body be explored with a unit charge, a mechanical force varying in magnitude and direction from point to point will be found to act on the unit charge. In such a case, an _electric field_ is said to exist in the medium.

The _strength of the electric field_ at any point is defined as numerically equal to the mechanical force which would act on a unit charge placed in air (or more strictly in a vacuum) at that point. The _direction_ of the electric field at any point is defined to be the direction of the mechanical force acting on a unit _positive_ charge placed at that point.

It should be noted that the strength of the electric field and the mechanical force are numerically equal only when the dielectric constant of the medium is unity. Thus if F is the field strength, K the dielectric constant, and U the mechanical force acting on a unit charge, F = KU.

It is very convenient to represent an electric field by means of what are called _lines of electric force_. If lines are drawn, starting from a positive charge and ending on a negative charge, such that the tangent to the line at any point is the direction of the electric force at that point, these lines are called lines of electric force. They can be drawn in such a way that the strength of the electric field at any point is numerically equal to the number of lines of electric force passing through unit area surrounding that point (and taken at right angles to the direction of the force). The lines of electric force will thus completely represent the electric field.

Further, if the following properties are attributed to the lines of electric force, viz. (_a_) that a line of electric force tends to shorten itself as far as possible; (_b_) that lines of electric force mutually repel one another; then all the phenomena due to the presence of an electric field may be interpreted by the behaviour of the lines of electric force.

Figs. 1 and 2 show the lines of electric force in the space surrounding two charged spheres. Fig. 1 shows the case where the charges are opposite, fig. 2 the case where they are similar. In fig. 1 the attraction between the spheres may be thought of as due to the tendency of the lines of force to shorten themselves. Similarly, the mutual repulsion of the spheres in fig. 2 may be regarded as a consequence of the mutual repulsion of the lines of force.

[Illustration: Fig. 1]

[Illustration: Fig. 2]

The distribution of a charge upon an insulated conductor isolated in space depends upon the shape of the conductor. If the conductor is spherical, the charge is uniformly distributed. If the curvature varies from point to point, the quantity of charge per unit area, or the _electric surface density_, will vary from point to point. The sharper the curvature is, the greater the surface density will be. In fig. 3 the distance of the dotted lines from the surface of the conductors is proportional to the surface density. These lines, therefore, give a graphical representation of the distribution of charge. In sharply pointed conductors nearly the whole charge will be concentrated at the pointed end. Owing to the large charge per unit area at the pointed part, particles of dust, water-vapour, &c., will be powerfully attracted, will become charged by conduction, and will then be powerfully repelled. In this way the original charge will be rapidly dissipated. This effect may be shown by keeping a sharply pointed conductor powerfully charged by an electric machine. The streaming of the particles from the point produces a wind which is sufficient to blow out the flame of a candle.

[Illustration: Fig. 3]

Conductors which are intended to retain their charge for a long period must be smooth and polished, and the maximum curvature must be as small as possible. In lightning-conductors practical advantage is taken of this 'power of points' to dissipate a charge rapidly.

The distribution of the charge on a conductor is influenced by the presence of other conductors, whether charged or not. This is due to what is called _electrostatic induction_. If an uncharged insulated conductor B is brought near a charged conductor A, a charge of the _opposite_ kind is induced on the parts of B nearer to A, and a charge of the _same_ kind on the parts farther away from A. Since B was originally uncharged, these induced charges are equal in amount.

If B is now removed to a distance, the induced charges neutralize one another, and B returns to its original uncharged state.

While B is near A, let the induced charge of the _same_ kind as the charge on A be neutralized by touching B with an earth-connected conductor, say the finger. On removing B to a distance, it will no longer be uncharged as before, but will have a charge of the _opposite_ kind from that on A. B is now said to have been _charged by induction_.

It is instructive to view these phenomena in the light of the conception of lines of electric force. When B is brought up towards A, some of the lines of force associated with the charge on A, and originally linked to surrounding objects, will now, owing to the tendency of the lines to shorten themselves, be linked to B. At the same time an equal number of lines (of opposite direction relative to B) will link B to the nearest surrounding objects.

Since by definition a line of force starts from a positive charge and ends on a negative charge, the charge on the parts of B nearer to A will be of the _opposite_ kind to that on A, but the charge on the part farther from A will be of the _same_ kind as that on A. When the earth-connected conductor is brought near B, the lines formerly linking B to surrounding objects will link B to the earth-connected conductor. Finally, when the latter touches B, these lines shorten themselves indefinitely and disappear.

The attraction of light particles to a charged body is explained by electrostatic induction. The charge of opposite kind induced on the particle being nearer than that of the same kind, the particle is attracted. When it touches the charged body, the charge of opposite kind is neutralized, and the charge of like kind now left on the particle causes repulsion to take place. If the electrified body is an insulator, the neutralization of the charges only takes place slowly, and consequently it may be some time before the particle is repelled.

[Illustration: Fig. 4.--Induction, and Lines (or tubes) of Force]

If two charged conductors be connected by a wire, in general it will be found that a flow of electricity from one to the other will take place. This flow is said to be due to a _difference of electric potential_ between the two conductors. If no flow takes place, then the difference of potential is zero. Electric potential difference (the contraction P.D. is commonly used) is numerically equal to the work done in carrying a unit charge from the one conductor to the other. If the work is done _against_ the electric forces, in moving a unit positive charge from A to B, then B is said to be at a higher potential than A. Although actually it is with _differences_ of potential that we have always to deal, it is convenient in many cases to refer these differences to a zero, and speak of _the potential_ at a point. The ideal zero of potential would be the potential at a point infinitely far removed from all electrified bodies. In practice it is convenient to regard the potential of the earth as zero. The potential at a point is then numerically equal to the work done in carrying a unit positive charge from earth to the point. The potential at every point on a conductor is obviously the same, for if it were not so, a flow of charge would take place and equalize the potential. If an insulated uncharged conductor be connected by a wire to a charged conductor, a flow of charge will take place until every point on both conductors is at the same potential. The quantity of charge which each conductor will then have depends on what is called the _capacity_ of the conductor.

The _capacity of a conductor_ is defined as the quantity of electricity with which it must be charged in order to raise its potential from zero to unity. Thus if Q be the quantity, V the potential, and C the capacity, we have C = Q/V. The potential of a conductor is, therefore, directly proportional to the charge upon the conductor, and inversely proportional to the capacity of the conductor.

The capacity of a conductor may be increased by placing close to it another conductor which is kept at zero potential. Such an arrangement is called a condenser. The Leyden jar (see _Leyden Jar_) is a well-known example of a condenser. The capacity depends not merely on the dimensions of the conductors and the distance between them, but also upon the nature of the dielectric separating them. The ratio of the capacity of a condenser with a given dielectric to the capacity it would have with an air dielectric, is called the _specific inductive capacity_ of the dielectric. Numerically the specific inductive capacity of a dielectric is equal to the dielectric constant already mentioned.

[Illustration: Fig. 5.--Electrophorus]

[Illustration: Fig. 6.--Wimshurst Machine]

In the experimental investigation of electrostatic phenomena it is convenient to have appliances which will supply charges as they are required. The simplest appliance of this kind is the electrophorus, which consists of a disc of ebonite or other suitable material with a metallic base, and a metal disc of slightly smaller diameter having an insulating handle attached at right angles to its surface (see fig. 5). To use the electrophorus, the ebonite is given a negative charge by striking it with fur or flannel. The metal disc is then placed on top of the ebonite plate. Since the ebonite is an insulator, no general neutralization of the positive induced charge on the lower side of the metal disc can take place. The negative charge on the upper surface of the metal disc is then neutralized by touching with the finger. The disc is thus left positively charged. The disc is then lifted by the insulating handle, and the charge utilized as required. Theoretically speaking, this process may be repeated continuously without affecting the original charge on the ebonite plate, but in practice the ebonite has to be re-excited from time to time on account of the loss of charge by leakage. More elaborate appliances of many different forms have been used, but the only one of these _electric machines_, as they are called, which is now commonly employed is the _Wimshurst machine_. This machine consists of two circular plates of glass or ebonite carrying equal even numbers of tinfoil sectors symmetrically placed on their outer surfaces. A pair of brass arms carrying wire brushes, which simultaneously make contact with diametrically opposite sectors on each plate, is so arranged as to lie at an angle of about 45deg to the horizontal, and to be at right angles to one another. A pair of combs is placed at each end of the horizontal diameter of the plates, so that the sectors pass close to the teeth of these combs. The combs serve as collectors, and are connected one pair to the positive pole, and the other pair to the negative pole of the machine. The general appearance of the machine is shown in fig. 6. The machine acts on the induction principle, and if kept warm and dry is self-exciting.

The _electroscope_ is a simple piece of apparatus for detecting the presence of an electric charge, determining its sign (positive or negative), and making a very rough comparative estimate of its potential. It consists of a pair of strips of gold-leaf attached to a brass rod terminating in a brass cap. The whole is enclosed in a glass case, or a case having glass sides. The base is made of conducting material. The sides of the case are coated internally with tinfoil (or two rods connected to the base project upwards to the level of the gold-leaf strips). The general appearance of one form of electroscope is shown in fig. 7. The gold-leaf strips, the brass rod, and the cap must be carefully insulated. When a charged body is brought near the electroscope the leaves become charged similarly by induction. The repulsion due to the similar charges causes the leaves to diverge.

If the cap be touched with the finger, the charge on the leaves is neutralized, and the leaves collapse. On removing the charged body the leaves diverge again, owing to the spreading of the charge on the cap, which was held by the inducing charge, over the whole conductor, including the leaves. The electroscope is thus charged by induction. It may also be charged by conduction, i.e. by the direct transfer of a charge to the electroscope. When we know the kind of charge, positive or negative, which has been given to the electroscope, an unknown charge can be tested. If the approach of the unknown charge causes a further divergence of the leaves, then it is of the same kind as that with which the electroscope is charged.

[Illustration: Fig. 7.--Electroscope]

When accurate quantitative measurements have to be made, an instrument called an _electrometer_ is used. This instrument, the development of which is due chiefly to Lord Kelvin, is capable of making accurate measurements of electrostatic potential differences down to quite low values.

Essentially an electrometer consists of a light suspended conductor which moves within four fixed quadrants. Opposite pairs of these quadrants are connected together, one pair to one terminal, and the other pair to the other terminal of the instrument. The P.D. to be measured is applied at these terminals. The suspended conductor or 'needle' is charged to a definite high potential, and the deflection produced is observed from the movement of a spot of light reflected from a mirror attached to the suspending fibre. In this case the deflection is proportional to the P.D. between the quadrants. For measuring a high P.D., the needle may be connected to one pair of quadrants. With such an arrangement the instrument is less sensitive, and the deflection is proportional to the square of the P.D. between the quadrants.

_Current Electricity._ The phenomena connected with the flow of electricity through a conductor come under this heading. Such a flow of electricity will take place if by some means the ends of the conductor are maintained at different potentials. An _electric current_ is then said to exist in the conductor. The difference of potential may be maintained by chemical action (see _Daniell's Cell_; _Electric Battery_), by electro-dynamic action (see _Generator_), or by heat action (see _Thermo-electricity_). The magnitude of the current which will flow when a steady P.D. is maintained between the ends of the conductor is determined by what is called the electrical _resistance_ of the conductor. The resistance R is defined as the ratio of the applied potential difference V to the current I produced, i.e. R = V/I. This is a partial expression of Ohm's Law for the Electric Circuit, which in its most general form states that the current which flows at any instant in an electric circuit is equal to the algebraic sum of the electromotive forces existing in the circuit at that instant, divided by the total resistance in the circuit at that instant (see _Electromotive Force_).

For the particular case where the algebraic sum E of the electromotive forces is steady, and the total resistance R is not varying, we have I = E/R. This is the form which applies to steady direct currents. If the current is changing (whether alternating or merely varying in value), varying E.M.F.'s, in addition to the applied E.M.F., exist in the circuit, and the above expression no longer holds good.

The resistance of a conductor depends on its material, and varies directly as the length, and inversely as the cross-section of the conductor. Thus R = [rho](l/A), where [rho] is the specific resistance of the material, l the length of the conductor, and A the cross-sectional area of the conductor. The _specific resistance_ is the resistance between opposite faces of a unit cube of the material at a definite temperature (usually 0deg C.). The resistance of a conductor varies to a greater or less extent with variation of temperature.

For pure metals the resistance increases considerably with increase of temperature. With certain alloys the change is so slight as to be negligible. In some alloys, and in carbon and insulating materials, the resistance falls with increase of temperature.

_Measurement of Resistance._--Low resistances can most conveniently be measured by a fall of potential method, based on the relationship R = V/I. The current may be read by an ammeter, and the potential difference by a low-reading voltmeter (see _Electrical Measuring Instruments_). Where greater accuracy is required, a constant current is sent through the resistance to be measured, and also through a known standard resistance of about the same value. A sensitive galvanometer (see _Galvanometer_) is used to compare the P.D. across the unknown resistance with that across the standard. Since the current is the same through both, the resistances will be proportional to the galvanometer deflections, and from the known value of the standard resistance the value of the unknown resistance can be calculated. Resistances of moderate value are best measured by a Wheatstone Bridge, or one of its modifications (see _Wheatstone Bridge_).

A substitution method is more suitable for high resistances. A galvanometer is connected in series with a standard high resistance and a steady source of E.M.F. The deflection is noted. The unknown resistance is now substituted for the standard, and the new deflection noted. Provided the resistance of the galvanometer and other parts of the circuit is negligible in comparison with the resistance to be measured, the resistances are inversely as the deflections. The unknown resistance is, therefore, equal to the ratio of the first to the second deflection multiplied by the value of the standard resistance. For insulation tests on installations, direct-reading instruments are frequently used (see _Ohmmeter_).

_Effects of an Electric Current._--When a current flows in a conductor, the temperature of the conductor is raised. This is due to the power dissipated on account of the resistance of the conductor. The power dissipated is equal to I^2R watts, and by giving suitable values to I and R any required amount of heat per second can be obtained. This _heating effect_ of the current is made use of in electric lighting, electric heating and cooking, in electric furnaces, and in certain electro-medical appliances.

If a magnetic needle is brought near a conductor carrying a current, it will be found to be deflected. This is due to the magnetic field, which is always associated with an electric current. This _electro-magnetic effect_ is of the utmost practical importance (see _Electro-magnetism_; _Generator_; _Electric Motors_).

When a current is passed through a conducting liquid, such as a solution of a metallic salt or a salt in a fused state, chemical action takes place. The behaviour of such a conductor is entirely different from that of a metallic conductor, since a current can flow in it only if chemical dissociation takes place (see _Electrolysis_).

Practical use of electrolysis is made in electroplating, the production of electrotype blocks for printing, the refining of copper, and the production of metallic sodium and potassium. Electrolysis is also used as a means of storing electrical energy in a chemical form (see _Secondary Cell_).

An electric current may be constant in direction (_direct current_), or may alternate in direction with a certain frequency (_alternating current_). Alternating currents have advantages for the transmission of large amounts of power over considerable distances (see _Electric Power Transmission and Distribution_), and may be used for electric lighting and the operation of electro-dynamic machines and apparatus (see _Electric Motors_).

BIBLIOGRAPHY: B. Kolbe, _Introduction to Electricity_; S. P. Thompson, _Elementary Lessons in Electricity_; Starling, _Electricity and Magnetism_; Poynting and Thomson, _Electricity_; W. E. Ayrton, _Practical Electricity_; C. R. Gibson, _Electricity of To-day_; Clerk-Maxwell, _Electricity and Magnetism_; E. E. Brooks and A. W. Poyser, _Magnetism and Electricity_.

ELECTRIC LIGHT, a light obtained by the conversion of electric energy into light energy. The usual method is to heat some material to incandescence by passing an electric current through it. The material may be carbon (arc lamps), tungsten wire (all modern incandescent lamps), mercury vapour (mercury vapour lamps), or volatilized metallic salts (flame arc lamps). Other materials have been used, such as zirconium, yttrium, and thorium oxides, and osmium and tantalum among the metals, but they have been displaced entirely by the materials mentioned above.

Ordinary arc lamps, and even flame arc lamps, are being displaced by the modern high-candle-power gas-filled tungsten lamp. Flame arc lamps have a high efficiency, and are still largely used for street lighting, but the cost of the frequent trimming required, even in lamps of the magazine type, gives the gas-filled lamp an advantage over them. Lamps of the mercury vapour class have a high efficiency, and the light has a high actinic value which is valuable for certain photographic processes, but the absence of the red and orange part of the spectrum gives the light a characteristically ghastly effect which limits the use of this type of lamp.

_The Carbon Arc._--Although the arc lamp has fallen into disuse, the carbon arc is still extensively employed for projection work, as in cinema projectors and in searchlights. The action of the carbon arc is as follows: If a potential difference of about 50 volts is maintained between a pair of carbon rods, and the tips of the rods are momentarily brought into contact and then separated by a short distance, then the current is maintained by an arc across the gap. The temperature of the positive tip rises to about 4000deg C., and the tip itself soon becomes hollowed, forming what is called the _positive crater_.

[Illustration: Fig. 1.--Positive and Negative Carbons]

The illustration below represents the two carbons of the arc light as they appear when cold, the positive carbon being marked + and the negative -. The central figure is a magnified representation such as can be obtained by throwing an image of the burning carbons on a screen by means of a lens. In fig. 1 the upper rod is the positive one, and the hollowed shape of the tip is clearly shown. The negative tip becomes roughly pointed in shape, and its temperature is about half that of the positive crater.

The positive crater has an extremely high intrinsic brilliancy, and nearly the whole of the light is emitted from its surface, the negative tip and the arc itself contributing very little. In order to stabilize the arc, a series resistance of a few ohms is necessary. The carbons gradually burn away, the rate of consumption of the positive carbon being about twice that of the negative. It is, therefore, necessary to 'feed' the carbons towards one another. This may be done automatically by the action of a pair of solenoids, one carrying the current which passes through the arc, the other carrying a current proportional to the potential difference across the arc. These solenoids, by means of a suitable mechanism, act in opposition, the current solenoid separating the carbons, and the potential difference solenoid bringing them closer together. The actions balance one another when the arc is of the correct length.

Such an arrangement also serves to strike the arc when the supply is switched on. In order to prevent the arc from wandering round the carbons, the positive carbon is cored, and sometimes the negative carbon also. The core consists of purer softer carbon of lower resistance, and the arc remains centrally placed.

_Flame Arc Lamps._--The carbon arc principle is modified in these lamps, so that the arc itself supplies nearly the whole of the light. The arc is made highly luminous by impregnating the carbons with metallic salts, which are volatilized and become incandescent in the arc. Their presence also lowers the resistance of the arc, so that its length can be greatly increased.

The tendency of the arc to wander is also increased, so that cored carbons are essential, and their diameter must be made as small as possible. These thin carbons burn away quickly, so that they must be made proportionately longer for the same time of burning. In order to reduce their resistance a soft-metal inner core is used. The carbons, instead of being placed one above the other, are inclined at a small angle with the arc between their lower ends. The arc is made as large as possible by the action of a small electromagnet placed just above the gap.

The feeding mechanism is similar in principle to that used for ordinary carbon arcs. For street lighting, lamps of the magazine type are used. In these lamps a number of pairs of carbons is placed in the magazine, and as each carbon is used up, a new one automatically takes its place.

_Mercury Vapour Lamps._--In these lamps the light is obtained from incandescent mercury vapour in a tube from which the air has been exhausted. The positive terminal is connected to a small iron electrode at one end of the tube. At the other end there is a small bulb, which contains a little pool of mercury, which is connected to the negative terminal. To start the lamp, the tube has to be tilted, so that a stream of mercury flows along it and makes contact with the iron electrode. The current which then flows vaporizes some of the mercury, and when the tube is tilted back to its original position, the discharge is maintained through the mercury vapour. A small series resistance is required in order to make the operation of the lamp stable. For small lamps a glass tube is used, but owing to the higher temperature reached in lamps consuming considerable power, it is necessary to use a quartz tube for large lamps. Quartz is transparent to ultra-violet light, and to avoid harmful effects the tube is usually enclosed in a larger one of flint glass, which stops the ultra-violet rays.

_Incandescent Lamps._--This is the name commonly given to the type of lamp in which the light is produced by an incandescent filament. The filament is enclosed in a glass bulb, which is either exhausted to a high vacuum, or else contains an inert gas under pressure. The filament is heated to incandescence by the current passing through it.

[Illustration: Stages in the Manufacture of an Incandescent Lamp

1, Bulb as received from furnace. 2, Stem attached for exhausting. 3, Filament sealed in. 4, Lamp exhausted of air. 5, Finished lamp.]

The first lamp of this type to come into general use was the carbon filament lamp. This has now been ousted by the much more efficient tungsten filament lamp. The earlier tungsten lamps were very fragile, owing to the brittleness of the filament. Later, a process was discovered whereby tungsten could be made malleable. The manufacture of drawn-wire filaments thus became possible, and the tungsten filament lamps which are now produced will stand a considerable amount of rough handling. This type of lamp is now in universal use for house lighting.

The limit of temperature at which the filament can be worked is set by the disintegration of the filament, which blackens the bulb and weakens the filament till it breaks. Recent research has revealed that this is due to a double chemical action between traces of water vapour and the incandescent metal. No method of entirely removing water vapour from the bulb has been found, but further research has brought to light the important fact that if the bulb is filled with an inert gas under pressure, the action is reduced to a minimum. This allows the filament to be worked at a much higher temperature, and since the light emitted increases with temperature much more rapidly than the power consumption does, the efficiency of the lamp can be greatly increased. These discoveries have led to the development of the modern _gas-filled lamp_. Owing to the high intrinsic brilliancy of the filament, high candle-power lamps of this type can be made which are not unduly bulky. For this reason, and because of their high efficiency and the absence of the need for any adjustment or attention, gas-filled lamps are coming into extensive use for street lighting and for factory and workshop lighting. Smaller lamps of this type are also being widely adopted for the illumination of shop windows.

ELECTRIC MOTORS, the name given to that division of dynamo-electric machinery in which electrical power is converted into mechanical power.

Electric motors are classified as _direct-current motors_ or _alternating-current motors_, according as the electric power taken by the motor is in the form of a direct current or an alternating current. Further subdivisions of each class are made on the basis of differences in the operating characteristics of the various types.

_Direct-current Motors._--The motor consists of a fixed magnetic field system with a rotating armature, which carries the conductors through which the supply current is passed. The magnetic field, produced in the air-gap between the poles and the armature, reacts with the current-carrying conductors of the armature and produces the _mechanical turning-moment_ or _torque_.

At the same time the motion of the conductors through the magnetic field generates an E.M.F. in the conductors. This E.M.F. is in the opposite direction to the applied E.M.F., and is, therefore, called the _back E.M.F._ of the motor. The current taken by the motor is equal to the difference between the applied and back E.M.F.'s divided by the resistance of the armature winding. Since the armature resistance is always low, and the back E.M.F. is zero at starting, some form of starter is necessary in order to limit the current to a safe value. Essentially the starter consists of a suitable resistance connected in series with the armature. As the motor gains speed this resistance is gradually reduced to zero.

The speed at which a D.C. motor runs varies inversely as the air-gap flux per pole, and very approximately, directly as the applied E.M.F. (directly as the back E.M.F. actually).

The torque produced is proportional to the product of the air-gap flux per pole and the armature current. The torque and speed characteristics of a D.C. motor, therefore, depend on the manner in which the air-gap flux per pole varies with the load current.

_Series Motor._--In this type the field magnet windings are connected in series with the armature winding, i.e. the same current flows in both windings. The air-gap flux per pole, therefore, depends on the current taken by the motor. Consequently, at light loads the speed of the motor is very high, and there is a very large fall in speed as the load increases. The torque increases rapidly with load for the same reason. At starting, a large torque is obtained at a low speed. These characteristics are specially suitable for traction purposes, for crane motors, and for the motors for certain machine tools.

[Illustration: Diagram of a Simple Motor

C, Conductor on surface of iron core A, which is free to rotate between the poles N S of an electro-magnet.]

_Shunt Motor._--In this case the field magnet windings are connected as a shunt to the armature windings, i.e. the current in the field coils depends upon the applied voltage, and is, therefore, constant in normal operation. Apart from the slight effect of the armature magneto-motive force, the air-gap flux per pole, therefore, remains almost constant at all loads. This means that the speed is practically constant at all loads (a very slight fall in speed with load occurs), and the torque, therefore, is almost directly proportional to the load current. The shunt motor is, therefore, suitable for all cases where an approximately constant speed at all loads is required.

_Alternating-current Motors._--There are wide differences between the various types, both in construction and operation. The type most commonly used is the polyphase _induction motor_. In this motor both the field system and the armature consist of a slotted core built up of iron laminations. The field system is called the _stator_, and the armature the _rotor_. Both carry conductors in their slots, and these conductors in each case form a polyphase winding. Current is supplied to the stator winding only. The currents in the rotor winding are _induced_ by the action of the rotating magnetic field set up by the stator currents. Hence the name induction motor. For starting, a polyphase resistance completes the circuits of the rotor winding. This resistance is gradually reduced to zero as the motor attains its full speed.

The rotor circuits are, therefore, closed upon themselves in normal operation. In many motors (especially small ones which are started unloaded) the rotor winding consists of a series of copper bars brazed to solid end-rings at each end of the core, thus forming a permanently short-circuited winding. Such a rotor is known as a _squirrel-cage rotor_.

The speed characteristic of the induction motor closely resembles that of the shunt D.C. motor, and induction motors are suitable for similar purposes. The induction motor gives its maximum torque at a speed only slightly below the synchronous speed (corresponding to the number of poles in the stator winding and the frequency of the supply); and the torque decreases very rapidly as the speed rises towards synchronism. The maximum torque has a definite value for a given motor, and if the load demands a greater torque than this, the motor slows down and stops.

_Synchronous motors_ are seldom used except for special purposes. They are exactly similar to the ordinary synchronous generator or alternator in construction, and the field system is almost invariably the rotating part. As their name implies, these motors have the characteristic of running at synchronous speed at all loads. If through overloading, or for any other reason, the motor is unable to maintain its synchronous speed, it immediately falls out of step and stops.

_Alternating-current Commutator Motors._--These motors are in general appearance similar to the induction motor, but the rotor is fitted with a commutator. According to the electrical connections, these motors may be given characteristics similar to direct-current series or shunt motors. Single-phase commutator motors with series characteristics are used on the L.B. & S.C.R. electric trains.

[Illustration]

ELECTRIC POWER TRANSMISSION AND DISTRIBUTION. In the public supply of electric power in this country, the usual practice is to use alternating-current generators in the power stations, and to transmit the power at a high voltage to substations. The substation plant reduces the pressure to a value suitable to the consumer, and in many instances also converts the alternating current into direct current. From the substations the power is distributed to the consumers.

For a given amount of power transmitted the cross-section of the cables required varies inversely as the square of the voltage. In order to reduce the outlay on cables, it is important that the transmission voltage should be as high as the circumstances permit. Naturally this becomes more and more important as the distance over which the power has to be transmitted increases. In America, where large amounts of power are transmitted over very great distances, the pressure used is in some cases 150,000 volts, and the tendency is to raise this till further, as switch gear, insulators, and other apparatus capable of withstanding this high pressure are becoming available. For high-tension underground cables, the pressure now coming into common use is 20,000 volts.

The nature of the low-voltage distribution from the substations, whether alternating current or direct current, depends largely on the requirements of the consumers.

There are certain advantages in the use of direct current, and in this country it is more commonly employed than alternating current, but the substation plant is more costly and requires skilled attendance. If the circumstances are such that these advantages are not important, the lower initial cost and running expenses of an alternating-current distribution would lead to its adoption.

In the Thury system of power transmission high-voltage direct current is used throughout. Only one supply in this country is of this kind, but several are in operation on the Continent. Pressures up to 100,000 volts are used.

ELECTRIC TELEGRAPH. See _Telegraph_.

ELECTRIC TRACTION and ELECTRIC TRAMWAY. In electric traction the mechanical power required for the propulsion of the vehicle is obtained from electric motors. These motors are usually _series direct-current motors_, but for railway work single-phase and three-phase A.C. motors have also been successfully employed (see _Electric Motors_). Up to the present, electric traction on railways has only been employed for suburban traffic in this country. In one instance (L.B. & S.C.R. electrification) single-phase alternating current is used. In all the others the power supply is direct current (see _Railways, Electrification of_).

In electric tramways, except in some few instances where there are objections to the use of an overhead construction, the current is conveyed to the motors through a trolley pole carrying a wheel running on an overhead bare copper wire. A hand-operated drum controller, directly controlling the driving and electric braking of the motors, is used. A hand-brake, and commonly a separate electro-magnetic brake, are provided.

Except in very small tramway systems, the power is generated as high-tension alternating current, and transformed and converted at substations suitably placed in the area covered by the tramway (see _Electric Power Transmission and Distribution_). The low-tension D.C. power is distributed from the substations to the trolley wire. The car rails are earthed, and provide a return path for the current. In order to minimize the flow of current to other conductors in the vicinity of the car rails, copper cables returning directly to the substation are connected to the rails at suitable intervals. These earth-return cables are connected in series with special low-voltage dynamos (called _negative boosters_) at the substation. This arrangement automatically keeps the P.D. between the most distant point of the car rails and the substation within a prescribed maximum, and effectively prevents the corrosion of pipes laid near the car rails.

ELEC'TRODE (Gr. _hodos_, a way), a term introduced by Faraday to denote the wires or other terminals by which electricity either enters or leaves a body which is undergoing electrolytic decomposition. He called the electrode at which the current enters the _anode_ (_ana_, upwards), and the electrode at which the current leaves the electrolyte the _cathode_ (_kata_, downwards). (See _Electrolysis_; _Electro-metallurgy_.) The word is now commonly used in a wider sense to denote the conductor by which contact is made with a medium. In this way electrodes are spoken of in connection with electric furnaces, electric welding appliances, vacuum tubes, and mercury vapour lamps, although the actions are not electrolytic.

ELECTROL'YSIS (Gr. _lysis_, loosening) is the name give to the decomposition of fused salts or solutions of salts, &c., by means of the electric current, and is thus a branch of electro-chemistry. The substance through which the current is passed is termed the _electrolyte_, and must be either an acid, base, or salt in a fused state or in solution. The current enters the electrolyte by an electrode called the _anode_, or the positive terminal. The electrode by means of which the the current leaves the electrolyte is termed the _cathode_, or negative terminal.

During the passage of the current the electrolyte is decomposed, and the products of decomposition are released at the electrodes or terminals. According to the modern theory of electrolysis, all electrolytes contain a greater or smaller number of free _ions_. These ions are chemical radicles carrying a definite electric charge. The kind of charge, positive or negative, depends on the nature of the radicle. The ions exhibit none of the chemical properties of the uncharged radicle.

Thus, for example, in an aqueous solution of sulphuric acid, free ions of hydrogen H_2 carrying a positive charge, and free ions of SO_4 carrying a negative charge, exist. An _uncharged_ SO_4 radicle would react with the water present, and sulphuric acid would be formed and oxygen liberated. The _ion_ SO_4, however, is incapable of doing this. Owing to the nature of their charges, the hydrogen ions will move towards the negative electrode, and the SO_4 ions towards the positive electrode. On reaching the electrodes the ions give up their charges, and immediately exhibit their ordinary chemical properties. Hydrogen is given off at the negative electrode, while at the positive electrode the uncharged SO_4 radicle reacts with the water present, and oxygen is released.

This is an example of a secondary chemical reaction. This occurs in many cases, and where it occurs the final product is different from that first produced by the electrolytic action. Fresh ions are formed or _dissociated_ in the electrolyte as fast as the original ions give up their charges at the electrodes. If this were not so, the electrolytic action would soon cease, since there would be no ions left to move towards the electrodes. The stream of ions carrying their positive and negative charges constitutes the current flowing through the electrolyte. Since the ions carry definite charges, it follows that the amounts of the initial products of an electrolytic action are in the ratio of their chemical equivalents. Thus, if fused silver chloride be electrolysed, for every 108 grammes of silver deposited at one side of the vessel 35.5 grammes of chlorine are given off at the other side (see _Electrode_; _Electro-metallurgy_).

_The electrolytic action of the current is the same at all parts of the circuit._ If the current is made to traverse several vessels, each containing the same substance, all _in series_ (that is, the current that leaves the first entering the second, and so on), it will be found that in each of the cells precisely the same amount of decomposition goes on. There will be the same weight of silver deposited at one side, and a corresponding weight of chlorine set free at the other.

_The same quantity of electricity decomposes chemically equivalent quantities of different electrolytes._ If we pass the current through a series of cells containing different electrolytes, for example, dilute sulphuric acid, chloride of silver, sulphate of copper, and collect the products of decomposition, we find that the quantities of hydrogen, silver, and copper set free are strictly proportional to the chemical equivalents of these bodies.

_The quantity of the electrolyte decomposed in a given time is proportional to the strength of the current._ This fact is made use of in measuring electric currents for standardization purposes, and the practical unit of current (the ampere) is defined, "with sufficient accuracy for all practical purposes", as being "that steady and unvarying current which deposits silver from a specified solution of silver nitrate at the rate of 0.001118 grammes per second".

The practical applications of electrolysis include the refining of copper, the electro-deposition of metals, electroplating, electrotyping, and the production of metallic sodium and potassium (see _Electro-metallurgy_). Electrolytic action is also made use of in the storage of electric energy in secondary batteries (see _Secondary Cell_).

ELECTRO-MAGNETISM, that branch of science which deals with the mutual relations between electric and magnetic fields (see _Electricity_; _Magnetism_).

It may readily be shown that when an electric current flows in a conductor, a magnetic field is produced around that conductor, i.e. that a magnetic field is produced by the motion of an electric field. Similarly, if a magnetic field is moved at right angles to a conductor, a potential difference is established between the ends of the conductor, i.e. an electric field is produced by the motion of a magnetic field.

[Illustration: Fig. 1]

If a conductor is placed in a magnetic field so that its length is at right angles to the lines of magnetic force (see fig. 1), and a current is passed through the conductor, a mechanical force will act on the conductor, and this force will be at right angles both to the conductor and to the original magnetic field.

[Illustration: Fig. 2]

From the point of view of lines of magnetic force, the magnetic field produced by the current in the conductor (shown by the concentric circles in fig. 1) will react with the original magnetic field (shown by the horizontal straight lines in fig. 1), and the actual resultant magnetic field will have the form shown in fig. 2. The tendency of lines of force to shorten themselves and repel one another laterally results in a force tending to force the conductor vertically downwards. This force is, of course, mutual, and tends to move the original magnetic field in the opposite direction.

All the phenomena of electro-magnetic action have their basis in these three effects, viz. (1) the production of a magnetic field by an electric current; (2) the production of an E.M.F. or P.D. by the relative motion of a magnetic field and a conductor; and (3) the mutual mechanical action between a current-carrying conductor and a magnetic field system.

The strength of the magnetic field produced by the current may be increased by winding the conductor in the form of a helix or solenoid consisting of a number of turns. The effect can be very greatly increased by providing the solenoid with a soft-iron core. The iron is strongly magnetized as long as the current flows. Such an arrangement is called an _electromagnet_. Electromagnets specially designed to produce a very intense magnetic field are used commercially in handling scrap-iron, pig-iron, &c. The electromagnet takes the place of the crane-hook in an ordinary crane. When the current is switched on, the pieces of iron are attracted and held firmly until the current is switched off again.

Electromagnets are also used for extracting fragments of iron or steel from the eye, and for many laboratory purposes. The most important practical use is the production of the magnetic field required in dynamo-electric machinery (see _Generator_; _Electric Motors_). The magnetic field produced within a coil in which a current flows is made use of to give the deflecting couple in certain types of galvanometers and measuring instruments (see _Galvanometer_; _Electrical Measuring Instruments_).

The absolute C.G.S. unit of current is defined in terms of the magnetic field strength produced by it, viz. "when one absolute C.G.S. unit of current flows in a circular loop of one centimetre radius, the magnetic force produced at the centre of the loop is 2[pi] dynes".

The principle of the electromagnetic generation of an E.M.F. is dealt with under the article _Electro-motive Force_. The mechanical force produced when a current flows in a conductor placed in a magnetic field forms the basis of the action of electric motors, and certain types of galvanometers and measuring instruments. The mechanical force is a mutual one, and tends to move the conductor and the field system in opposite directions. The magnitude of the force varies as the magnetic field strength, the length of the conductor, and the intensity of the current, and also as the sine of the angle between the field and the conductor. Thus when the direction of the lines of magnetic force is parallel to the conductor, the force is zero; and when their direction is at right angles to the conductor, the force is a maximum. The direction of the force is always at right angles both to the conductor and the direction of the lines of magnetic force. In an electric motor the forces acting on the conductors produce the mechanical output of the machine. In a generator these mechanical forces come into existence as soon as current is taken from the machine. In this case they produce a torque which is opposite in direction to the mechanical torque which is applied to the shaft of the generator in order to drive it.

ELECTRO-MEDICAL APPARATUS. Electrical apparatus is now widely used in the treatment and diagnosis of disease. The action of the heart may be very accurately observed by means of the electric cardiograph. The cardiograph itself consists of a very sensitive 'string' galvanometer (see _Galvanometer_) and an arrangement whereby the spot of light is focused on a moving photographic plate. In this way a photographic record of the movements of the galvanometer mirror is obtained. The galvanometer terminals are connected to two different parts of the body of the patient (say to a hand and a foot placed in separate brine baths), and the variations of potential differences which occur during a heart-beat cause a movement of the galvanometer mirror.

The X-ray apparatus has recently been adapted for taking instantaneous photographs of the heart. A single powerful discharge from a static transformer takes place through the tube, and a photograph of the position of the heart at that instant is obtained. The X-ray apparatus is very well known from its use in locating fractures, foreign bodies, diseases of the bone, &c.

The X-ray discharge is used as a treatment for certain skin diseases (especially ring-worm), rodent ulcer, and cancer. Very high-frequency alternating currents may be passed through the body without producing the muscular contractions which are a feature of the passage of low-frequency currents through the tissues. Currents of considerable magnitude of very high frequency may thus be passed through the body without inconvenience to the patient. In this way general or local heating of the body may be obtained. This process is known as diathermy. The heating locally may be made sufficiently great to cause coagulation of the tissues, or even actual burning. This method is used in the treatment of tumours and other growths.

Another important electro-medical treatment consists of the local introduction of a drug, into the affected part, by electrolytic action. Thus in the treatment of rodent ulcer, a pad of lint saturated with a 5 per cent solution of zinc sulphate is placed over the ulcer. A zinc electrode is placed on the pad and connected to the positive pole of the supply. The negative pole is connected to a basin of brine in which the patient's hand is placed. The current is made as large as can conveniently be borne (say 30 to 60 milliamperes), and is maintained for about thirty minutes and then gradually reduced to zero. By this means zinc ions are carried into the ulcer. A number of diseases may be treated in this way, the ion used depending on the nature of the case.

Low-frequency intermittent currents from induction coils are frequently used where nerve stimulation or muscular contractions are required. Static electricity is also used for similar purposes. Large Wimshurst machines are used for the treatment of sciatica, and also for neurasthenia. In the latter case a brush discharge is used, and the patient experiences very little physical sensation. The high-frequency apparatus already referred to in connection with diathermy is valuable for the treatment of rheumatism in its earlier stages, and for the stimulation of the scalp in hair treatment. Suitable electrodes are passed backwards and forwards over the affected parts, a bluish brush discharge taking place between the patient and the electrode.

ELECTRO-METALLURGY is that branch of metallurgy which uses electrical energy, wholly or in part, for the extraction or treatment of metals. The energy may be converted into heat and used for processes in which high temperatures are necessary, or it may be used for the decomposition of a compound by electrolysis, which may proceed in a fused bath at a comparatively high temperature, or in a solution bath containing a compound of the metal dissolved in a suitable solvent.

The former method of utilizing the energy embraces electrothermal processes, and the latter method, electrolytic processes.

In electrothermal processes, the heat developed by the electric current has been used in a number of industries, including welding, annealing, heat treatment, smelting, refining, &c. Laboratory apparatus, such as tubes, muffles, and crucibles, are also frequently heated by means of an electric current.

For the electric welding of metals there are two systems in use: resistance welding, in which the portions to be welded are pressed together and heated by the resistance they offer to the passage of a current; and arc welding, in which portions of metal of the same composition as that to be welded are fused on by striking an arc from a suitable electrode. In the electrical annealing of metals, case-hardened steel plates are locally softened where rivet-holes, &c., are required by passing an electric current through copper poles placed 1 or 2 inches apart on the smooth surface. Metallic wire is frequently heated to the annealing temperature between drawing operations, and various types of annealing furnaces are also electrically heated.

In electric smelting, the high temperature of the arc (3600deg C.) may be used for the reduction of certain metallic oxides, which at the lower temperature of furnaces heated by coal, coke, gas, &c. (2000deg C.), will not give up their oxygen to carbon; other ores are also sometimes smelted by electrical means, especially in localities where current is cheap and fuels are dear. The production of refined steel, special alloy steels, and certain non-ferrous alloys is also carried out in electric furnaces of various types.

The electric arc was first applied to fusion by Siemens in 1879; he fitted, into the bottom of a crucible to receive the charge, a water-cooled copper casing to form the positive pole, and suspended a carbon rod centrally in the crucible to form the negative pole. The current crosses the air-gap between the metal and the negative pole, forms an arc, and rapidly fuses the metal. In 1885 the Cowles Brothers, of Cleveland, Ohio, began to produce aluminium-copper and aluminium-iron alloys by arc smelting, and later produced other metals, difficult to reduce, by the same means. More recently, the development of electric smelting has made rapid strides. Electric furnaces not only yield higher temperature, but have other advantages over furnaces heated by carbon. They develop the heat in a small space, just where it is required for the operation, so that the furnace can be smaller, and less heat is lost by radiation; the charge can be kept free from gaseous products of combustion; the temperature and the whole operation is under better control; and the expense of running the furnace is limited to the time the current is used for doing useful work.

Electric furnaces are now used in the production of pig-iron, steel, ferro-alloys, brass, zinc, &c., and in the heat treatment of various metals. Classifying them according to the manner in which the electrical energy is converted into heat, we have:--

1. Direct resistance furnaces, in which the heat effect is produced within the metal itself by the resistance offered to the passage of the current through it. This type is used in the refining of steel.

2. Indirect resistance furnaces, to which class belong the various tube and crucible furnaces used in laboratories. The vessels to be heated are wound with wire or ribbon of high resistance, such as platinum, nickel-chrome alloys, &c., and a suitable current passed. Heat-treatment furnaces on a fairly large scale also use this method, a nickel-chrome alloy ribbon being wound on a suitable framework; the heating element in these furnaces, however, generally consists of granular carbon confined in carborundum fire-sand troughs.

3. Induction furnaces, in which a primary coil of copper wire is used, the secondary being formed by the metal charge itself, contained in a suitable annular groove. In this furnace the current passes through the primary and induces a current in the charge, thus melting it. This type of furnace has been largely used in the refining of steel, and to some extent in the melting of non-ferrous metals and alloys.

4. Direct arc-heating furnaces, as exemplified in the Siemens crucible furnace mentioned above.

5. Indirect arc-heating is used in the Stassano furnace, in which the heat is obtained by radiation from the arc, and by reflection from the roof and sides of the furnace. This furnace has been used in the production of steel from scrap, and also direct from ore. There are three electrodes, which nearly meet in the centre of the furnace.

6. Combined resistance and arc furnaces are very largely used for the production of ferrous alloys, such as ferro-silicon, ferro-chrome, and ferro-manganese; for the production of steel from scrap, and for the final refining of steel produced by other processes. In these furnaces the heat is generated largely by the arc, and to a smaller extent by the resistance offered by the whole or a portion of the furnace charge to a powerful electric current. There are several well-known commercial furnaces working on this principle, the best known probably being the H['e]roult. This furnace is designed for tilting, and is lined with basic material, and large electrodes pass through the roof. An alternating current of 4000 amperes at 110 volts is used for a 3-ton furnace, and the intensity of the current passing through the bath is regulated by raising or lowering the electrodes.

The effect of the European War has been enormous on the development of the electric furnace in this country, for prior to the war in 1914, although the use of the electric furnace for steel-making was increasing, there were only 5 furnaces in operation in Sheffield, and two or three more in other parts of the country, producing in all about 15,000 tons per annum. Soon after the commencement of the war, it became necessary to deal with the rapidly accumulating quantity of shell turnings, to make substitutes for Swedish iron and steel, which could not be imported, and to make large quantities of special alloy steel for various war purposes. As a result of these demands, within four years the number of electric furnaces increased to over 100, the steel produced being over 200,000 tons per annum. Since 1918 the number of furnaces has further increased, and probably reached 150 of various sizes and makes in 1920. In America a similar development has taken place, the number of furnaces increasing from 7 in 1907 to 363 in 1920, the output of electric steel in 1918 amounting to over 500,000 tons. In France, also, great strides have been made, and owing to the shortage of pig-iron, synthetic processes for its production from iron and steel scrap and ore were developed in open-pit arc-resistance furnaces, yielding 220,000 tons in 1916-8.

_Electrolytic Processes._--The application of electrolysis for the production of metals from a fused electrolyte is most important in the case of aluminium. This metal cannot be produced by direct electrolysis in aqueous solution, but is deposited electrolytically from a fused bath of cryolite, containing alumina in solution. As the metallic aluminium is extracted from the molten bath, further quantities of purified oxide are added. The anodes consist of carbon blocks suspended in the molten bath, and the cathode consists of the carbon lining of the furnace. Calcium, cerium, lithium, magnesium, potassium, sodium, and strontium are obtained by the electrolysis of fused chlorides, sodium being also obtained from fused hydroxide and fused nitrate.

Metallic magnesium was obtained by the electrolysis of the fused chloride by Bunsen in 1852, but the application of electrolysis as a means of recovering metals from ores by means of aqueous solutions dates back to 1836, in which year Becquerel obtained copper from sulphide ores by first extracting the copper as sulphate or chloride, and then recovering the copper by the electrolysis of the solutions, using insoluble anodes. The method has since chiefly been applied to the treatment of copper ores and products, but has also been used for the recovery of nickel, gold, zinc, &c. The production of electrolytic zinc from solutions has been encouraged as a result of the shortage of pure zinc for war purposes, and several processes have been developed. In these processes the solution used consists either of zinc sulphate or of zinc chloride, the anodes consisting of metallic lead or of carbon, and the cathodes of pure zinc sheets.

It is in connection with the refining of metals that electrolytic processes become of prime importance. Elkington, in 1865, was the first to refine impure metallic copper electrolytically and recover the silver contained in it. Pure copper is now commonly obtained from impure copper anodes in an electrolyte of copper sulphate containing free sulphuric acid, a current density of 12 to 15 amperes per square foot being used at 0.34 to 0.44 volt. Gold is also refined by a similar process, the electrolyte used consisting of gold chloride solution containing free hydrochloric acid. In this case a current density of 100 amperes at 1 volt is used. Silver is likewise refined in a silver nitrate bath, iron by the electrolysis of sulphate or chloride solution, and lead in a solution of lead fluosilicate containing free hydrofluoric acid.

In all the above-mentioned processes the anode is cast from the impure metal to be refined, and the cathode consists of a sheet or plate on which the pure metal is deposited.

It will be seen that these refining processes are very similar to electroplating methods.

ELECTROMOTIVE FORCE, the name given to the force tending to produce a flow of electricity in an electric circuit. The electromotive force, or E.M.F., is measured in terms of the work done in carrying unit quantity of electricity once round the circuit.

Thus unit electromotive force (absolute) is said to exist in a circuit if 1 erg of work is done in carrying 1 coulomb of electricity once round the circuit. The potential difference, or P.D. (in electromagnetic units), between two points in an electric circuit is similarly defined in terms of the work done in carrying 1 coulomb of electricity from the one point to the other.

_Production of an Electromotive Force._--There are several sources of E.M.F., e.g. (_a_) chemical action, as in primary and secondary cells; (_b_) thermo-electric action, as in the thermopile; (_c_) electro-magnetic action, as in generators, motors, transformers, and induction coils.

The electromotive force due to chemical action depends on the material of the electrodes and the nature of the electrolyte, and also to a slight extent on the temperature. Thus, for any given pair of materials (say zinc and copper) immersed in a certain electrolyte of given strength (say dilute sulphuric acid), the E.M.F. produced at a given temperature has a definite value. For a discussion of the electromotive force produced by thermo-electric action, see _Thermo-electricity_.

The principle of the electromagnetic generation of an E.M.F. may be stated in its most general form as follows: If lines of magnetic force are interlinked with an electric circuit, and if by any means the number of interlinkages of the lines of magnetic force with the circuit is made to change, then an E.M.F. will be generated in the circuit, the magnitude of this E.M.F. being proportional to the time rate of change of the interlinkages. Thus, if the interlinkages are changing at the rate of one per second, one absolute unit of E.M.F. will be generated; or if the interlinkages are changing at the rate of a hundred million per second, an E.M.F. of 1 volt will be generated. It is immaterial in what manner the change of interlinkages is brought about.

A permanent magnet may be moved so as to vary the lines of magnetic force linked with an electric circuit, as in magneto-generators; or the circuit may be moved through a magnetic field (see _Generator_; _Electric Motors_); or the magnetic field produced by a current in one coil linked with a second coil may be varied by varying the current in the first coil, as in static transformers and induction coils.

The electromagnetic generation of an E.M.F. is the fundamental principle which has made possible the generation and utilization of electrical energy on a large scale.

ELECTRON, the atom of electricity, more especially of negative electricity. The first light on the question of the structure of electricity came from the laws of electrolysis (q.v.), established by Faraday. These laws are explained very naturally if we make the assumption that electricity, like matter, is atomic, the atom being the charge carried by the hydrogen ion. Clerk Maxwell even proposed to call this charge 'one molecule' of electricity, but added the remark that "it is extremely improbable that when we come to understand the true nature of electrolysis we shall retain in any form the theory of molecular charges, for then we shall have obtained a secure basis on which to form a true theory of electric currents, and so become independent of these provisional hypotheses". To-day, however, so far are we from discarding the hypothesis of the atomic nature of electricity that we find ourselves compelled by the pressure of experimental facts to interpret all electrical phenomena, in metals as well as in electrolytes, in terms of this very hypothesis. Any statical charge is supposed to be made up of a very great number of electrons, just as a material body is composed of atoms of matter. A metallic conductor is supposed to contain many free electrons, which normally bear much the same relation to the material molecules as a saturated vapour bears to the liquid in equilibrium with it. When an electromotive force is applied, it causes a drift of the electrons in the opposite direction to the force, the charge on the electrons being negative. It is this drift of electrons which constitutes an electric current.

The striking advances that have been made in our knowledge of the nature of electricity since the last years of the nineteenth century have been due chiefly to the study of the electric discharge in gases. Hittorf in 1869 and Crookes in 1879 examined the rays, now called the cathode rays, which stream from cathode to anode in a tube containing gas of very low pressure. The phenomena suggested to Crookes that the rays consist of material particles carrying a negative charge and moving at a high speed; but many physicists rejected this explanation, holding that the rays were due to some form of wave motion in the ether. About 1897 it was conclusively shown by Perrin, Wiechert, and Sir J. J. Thomson that Crookes's view was the correct one. Sir J. J. Thomson measured the velocity of the particles, and also the ratio of the charge e, to the mass m of each. His method was to subject a fine beam to the action of two fields of force, one magnetic, the other electric, and both perpendicular to the line of motion and also to each other. The electric field being X, and the magnetic field H, the forces on a particle were in the same direction, and equal to eX, evH. Either field by itself deflected a fine beam, as was shown by the motion of a spot of light where the beam struck a fluorescent screen. The value of X was adjusted till there was no deflection in the combined fields. Hence X = vH, and v was found from the measured values of X and H. The deflections under the two fields acting separately were also observed. Either of these deflections, when v is known, gives the value of the ratio e/m. The values of the velocity v were found to depend on the E.M.F. between the terminals of the discharge-tube. They varied from 1/30 to 1/3 of the velocity of light. The fraction e/m, however, had always the same negative value, no matter how the material of the cathode and the nature and pressure of the gas were varied.

Many other ways of obtaining these negatively charged particles, or electrons, are now known. The [beta]-rays from radio-active substances (see _Radio-activity_) are simply electrons moving with great speeds, approaching sometimes within 2 or 3 per cent of the velocity of light. Hot metals give off electrons copiously: this property is used in the construction of the Coolidge X-ray tube and of the thermionic valve (q.v.). A metal plate illuminated by ultra-violet light, from an electric arc or spark, for instance, gives off electrons moving at all velocities below a certain maximum (see _Photo-electric Effect_). From whatever source the electrons are derived, their properties are found to be the same.

The determination of e and m separately is a much more difficult matter than the determination of their ratio. The first attempt to measure e directly was made by Townsend, and published in 1897. Townsend obtained his ions in the hydrogen and oxygen given off when caustic potash is electrolyzed. The charged gases when bubbled through water formed a cloud. This cloud could be completely removed by bubbling through concentrated sulphuric acid, but reappeared when the gas came out again into the atmosphere, owing to the condensation of water-vapour on the ions. Townsend determined the weight of the cloud and its total charge. He also found the average weight of the minute spherical drops forming the cloud by observing their rate of fall under gravity, and calculating their radius from a theoretical formula known as Stokes's law, viz. v = 2/9ga^2[rho]/[eta], where a is the radius, [rho] the density, v the velocity of the drop, and [eta] is the viscosity of air. The weight of the cloud divided by the weight of a drop gave the number of drops, which was presumably the same as the number of ions. Finally, dividing the total charge by the number of ions, Townsend found e, the average charge carried by an ion. His value came out about three-fifths of the value accepted now.

This pioneer method of Townsend's has been improved and modified in various ways by C. T. R. Wilson, Sir J. J. Thomson, H. A. Wilson, and notably by Millikan, of Chicago. Millikan's charge carriers were minute oil drops, which were given elementary charges by means of ionizing rays from radium. Observations were made of the equilibrium and motion of these charges under the combined influence of gravity and a strong vertical electric field, the intensity of which could be varied at will. A single drop could be kept in view for several minutes at a time, and note was taken of the effect of each new charge as it was picked up by the drop. On calculation, the charge was found in all cases to have very approximately the same value. It so happened, as a consequence of the method of producing the drops, that they carried a small frictional charge, and incidentally Millikan was able to verify that this was always an integral multiple of the electronic charge e. Millikan's result, which is most probably the best yet found, is that e = 4.774 x 10^{-10} absolute electrostatic units, or 1.591 x 10^{-20} absolute electromagnetic units.

An indirect but very interesting method of determining e was devised independently by Regener and by Rutherford and Geiger. The special feature of this method is the actual counting of the number of [alpha]-particles (see _Radio-activity_) shot out per second through a given solid angle by a small speck of radium. Each [alpha]-particle produces a scintillation on a sensitive screen placed in its path, and these scintillations are counted one by one by the observer. The total quantity of electricity carried by the [alpha]-particles emitted in one second is measured independently. The charge on each particle is then found by simple division. This charge is found to be almost exactly twice Millikan's value for e, as it ought to be, as it is practically certain that the [alpha]-particle is an atom of helium which has lost two electrons.

The value of e/m, as determined by Thomson's method described above, is 1.76 x 10^7 e.m.u. per gramme, or 5.29 x 10^{17} e.s.u. per gramme. Taking this with Millikan's value for _e_, we find n = 0.902 x 10^{-27} grammes. The exact determination of e has made it possible to assign precise values to several other important physical constants, which formerly were only known roughly from data depending on the Kinetic Theory of Gases. Thus Avogadro's constant N, or the number of molecules in one gramme-molecule (molecular weight in grammes) of any gas can be connected with e by the exact measurements of electrolysis, which give Ne = 9650 e.m.u. It follows that N = 6.06 x 10^{23}, and that the number of gas molecules per cubic centimetre at 0deg C and 76 centimetres pressure is 2.70 x 10^{19}. We find at once also the mass of the hydrogen atom as 1.66 x 10^{-24} grammes, the density of hydrogen being known to be .0899 grammes per litre. The mass of the electron is therefore about 1/1840 of the mass of the hydrogen atom, which till the isolation of the electron was the smallest mass known.

It is necessary, however, to scrutinize with some care the meaning of the word mass as applied to an electron. The determination of the mass of the hydrogen atom ultimately depends on weighing, that is, on finding its gravitational inertia. We cannot weigh an electron, but must determine its mass by experiments involving its motion, the word mass here meaning the ratio of the force acting on the electron to the acceleration produced, and the force being calculated from the charge and velocity of the electron on the principles of electrodynamics. An electron being entirely different in its physical nature from ordinary matter, the question arises whether its mass, as calculated in this way, is actually a definite constant, as it is for a material particle, according to the accepted principles of Newtonian dynamics. It can even be shown, as was first done by Sir J. J. Thomson, that a moving charged body possesses inertia in virtue of the mere fact that it carries a charge. The value of this inertia, or electromagnetic mass, when the velocity is small compared with that of light is, in a vacuum, for a small sphere of radius a, 2/3e^2/a, where e is the charge. If the velocity is greater than, say, 1/10 the velocity of light, the formula for the electromagnetic mass is more complicated, and, indeed, cannot be calculated without some assumption as to the internal distribution of charge in the electron itself. Two formulae for the mass have been given, one by Abraham, the other by H. A. Lorentz. Abraham started from the supposition that the electron is a rigid sphere carrying a uniform surface charge. Lorentz showed that a simpler theory could be obtained by the hypothesis that the electron contracts, in the direction of its motion, by a certain definite amount depending on its velocity. On both theories the value found for the mass depends on the relation between the direction of the force and the direction of the motion. On Lorentz's theory the longitudinal mass, or mass when the force is in the direction of the motion, is m_0/(1-[beta]^2)^{3/2}; and the transverse mass, or mass when the force is perpendicular to the velocity, is m_0/(1-[beta]^2)^{1/2}; where m_0 is the mass for very small speeds, and [beta] is v/c, the ratio of the velocity of the electron to the velocity of light. The two theories have been tested by various experimenters, with somewhat conflicting results. On the evidence of experiments by Bucherer, however, Lorentz's theory of the contractile electron is now generally accepted, and it is regarded as highly probable that electrons are devoid of all mass except the electromagnetic mass due to their charge of negative electricity.

No fundamental positive electron has been isolated which at all corresponds to the negative electron, or corpuscle, as it is called by Sir J. J. Thomson. The nearest approach to a positive electron is the nucleus of the hydrogen atom, which carries a positive charge of the same magnitude as the charge on an electron. Practically the whole mass of the atom resides in this nucleus. According to the modern theory of the structure of matter, the neutral atom of any element is built up of a comparatively small number of electrons and an equal number of these positive nuclei. Electrons being present everywhere, and their action influencing all natural phenomena, their properties will naturally come up for consideration from various points of view in other articles. See _Ionization_; _Isotopes_; _Matter_; _Radio-activity_; _Rays_, _Electric._--BIBLIOGRAPHY: J. A. Crowther, _Ions, Electrons, and Ionizing Radiations_; R. A. Millikan, _The Electron_; N. R. Campbell, _Modern Electrical Theory_; O. W. Richardson, _The Electron Theory of Matter_; H. A. Lorentz, _Theory of Electrons_.

ELECTRO-PLATING, the process of depositing a coating of some selected metal on a given surface by means of electrolysis (q.v.). The most important classes of electro-plating commonly carried out are nickel-plating, used very largely for a variety of articles made of iron, steel, &c.; copper-plating, used for facing printing-blocks and as a first coating to non-metallic substances prior to silver- or gold-plating; silver-plating, for imitation silverware and for cutlery, &c.; gold-plating, for ornamental ware, jewellery, &c. Previous to plating it is necessary to remove all grease, dirt, oxide, &c., from the surface, this cleansing of the articles being the first step in the operations necessary. The exact procedure for cleansing varies with the nature of the articles to be plated, but for the removal of grease a strong caustic alkali bath is generally used. To remove oxide and dirt, scratch-brushing is used, also scouring with pumice-stone. Acid-dipping baths are also employed, muriatic acid or sulphuric acid for iron or steel articles, dipping-acid, which is a mixture of sulphuric acid and nitric acid, for brass. For the actual deposition an electrolytic cell is prepared, containing a solution of a suitable salt of the metal to be deposited, with an anode, generally consisting of a plate of the same metal, attached to the positive pole of the battery used, the article to be treated being connected with the negative pole and thus forming the cathode. When a current of electricity is passed through the solution, a thin coating of metal is deposited on the article forming the cathode, and an equivalent portion is carried into solution from the anode. In the case of nickel-plating, the solution used is made from the double chloride or sulphate of nickel and ammonium, to which salt, sal-ammoniac, &c., may be added. The bath is used at a temperature of 100deg F., and cast-nickel plates are used as anodes. For copper-plating the bath used generally consists of an acid solution of sulphate or acetate of copper, cyanide of potash also being added; in case the article is made of zinc, an alkaline bath is used. The bath may be used cold, but is sometimes kept at about 120deg F. For iron simple dipping is sometimes used, as copper is readily deposited on iron without the use of an electric current. For electroplating of copper, anodes of metallic copper, having a surface equal to that of the articles to be coated, are used. For silver-plating the solution consists of the double cyanide of silver and potash, and may be used either hot or cold. An article to be silver-plated is often prepared by a preliminary dip in a solution of nitrate of mercury, which causes a slight amalgamation with mercury. After this preliminary treatment it is placed in the bath and a slight deposit of silver obtained, after which it is removed, well brushed, washed, and replaced in the bath. A silver plate is used as an anode. A density of 1-1/4 to 1-1/2 ounces of silver to the square foot gives an excellent plate about the thickness of common writing-paper. In gold-plating baths, a hot solution of the double cyanide of gold and potash is used at 170deg F., and for the anode platinum foil is frequently used, the strength of the bath being maintained by the addition of fresh quantities of chloride of gold. After all kinds of plating as described above, the goods are thoroughly washed in water, and dried by means of saw-dust or in a drying-chamber. In ordinary circumstances the deposited metal presents a dead or matted appearance, and if a bright polished effect is desired, it is burnished and buff-polished. Certain chemicals added to the solution will cause the original deposit to have a metallic lustre.

ELECTROTYPE. The production of copper facsimiles by the electric current is called _electrotype_, and is the oldest branch of electro-metallurgy. One of its most important applications is the copying of type set up for printing, and of wood blocks for wood-cuts. A mould is first obtained in gutta-percha or some similar material. This, being a non-conductor, is brushed over with plumbago in its interior, so as to give it a conducting surface to receive the deposit. After several hours the deposit is detached from the mould and backed by pouring in melted solder, the surface being first moistened with chloride of zinc to make the solder adhere. In the copying of steel engravings the mould is obtained by electro-deposition of copper on the steel, the surface of which must first be specially prepared to prevent adhesion; and a second electro-deposition of copper, on the mould thus obtained, gives the required copy, from which impressions can be printed.

ELEC'TRUM (Gr. _[=e]lektron_), in antiquity, a term applied to native gold, which frequently contains notable quantities of silver, copper, and other metals. According to Pliny, the term electron was applied to native gold containing at least 20 per cent of silver. The term was afterwards transferred from this native alloy to the artificial alloy of gold and silver on account of its colour and inferior lustre. The word originally meant 'amber', and was given to impure gold on account of a supposed resemblance. Electrum was used since the eighth or seventh century B.C.

ELEC'TUARY, or CONFECTION, is a pharmacopoeial preparation. It is solid, but of soft consistence, and contains sugar or honey, impregnated with some more active body. The best known is the confection of senna.

ELE'GIT, in English law, a writ by which a creditor who has obtained a judgment against a debtor, and is hence called the _judgment-creditor_, may be put in possession of the lands and tenements of the person against whom the judgment is obtained, called the _judgment-debtor_, until the debt is fully paid. The writ is addressed to the sheriff, who enforces it. The writ of elegit was first authorized by the Statute of Westminster the Second, which gave the _judgment-creditor_ the right to choose between a writ against the debtor's land, and until 1883 his goods also, and an execution by writ against the latter's person or chattels. The new writ, representing the choice of the creditor, was therefore called an elegit, Lat., he has chosen. See _Fieri Facias_.

EL'EGY (Gr. _elegos_, mourning, song), a mournful and plaintive poem or funeral song, or any serious poem of a melancholy contemplative kind. In classic poetry what is known as _elegiac verse_ is composed of couplets consisting of alternate hexameter and pentameter lines. In English we generally understand by elegies lyric poems which are laments over the dead, such as Milton's _Lycidas_, or Shelley's _Adonais_.

ELEMEN'TAL SPIRITS, according to a belief common in the Middle Ages, spirits proper to and partaking of the four so-called elements, viz. salamanders or fire spirits, sylphs or aerial spirits, gnomes or earth spirits, and undines or water spirits.

EL'EMENTS, the simplest constituent principles or parts of anything; in a special sense, the ultimate indecomposable constituents of any kind of matter. In ancient philosophies the term was applied to fire, air, earth, and water. The mediaeval chemists, however, absorbed in the study of metals and mineral substances, supposed that the metals consisted of an elemental sulphur and an elemental mercury mixed together more or less perfectly and in different proportions. To these were subsequently added salt and some others, so that about the middle of the seventeenth century the first principles amounted to five, divided into two classes; the active, consisting of mercury or spirit, sulphur or oil, and salt; and the passive, consisting of water or phlegm, and earth or the terrestrial part. The names remained, not so much as denoting substances or ultimate principles as gradually coming to denote functions; the first great modification being the expansion of the idea of elemental sulphur into phlogiston by Stahl, as the result of which the adherents of the phlogistic theory applied the term phlogiston to the gases then discovered, the mineral, vegetable, and animal acids, the alkalies, earths, and metallic calces, oil, alcohol, and water. The substances considered as simple naturally changed with the change of theory introduced by Lavoisier, who considered as elements, oxygen, nitrogen, hydrogen, sulphur, phosphorus, and carbon, the metals and the earths, and, as Boyle had already suggested, practically defined an element as a body not yet decomposed, the definition now commonly adopted. For list of known elements see _Chemistry_.

EL'EMI, the fragrant resinous exudation from various trees, such as the _Canarium commune_, from which the Eastern or Manila elemi is obtained; the _Ic[=i]ca Ic[=i]car[=i]ba_, the source of the American or Brazilian elemi; and the _Elaphrium elemif[)e]rum_, from which the Mexican elemi comes. It is a regular constituent of spirit varnishes, and is used in medicine, mixed with simple ointment, as a plaster.

[Illustration: Head of African Elephant (_Elephas afric[=a]nus_)]

[Illustration: Head of Indian Elephant (_Elephas indicus_)]

EL'EPHANT, the popular name of a genus, family, or sub-order of five-toed proboscidian mammals, usually regarded as comprehending two species, the Asiatic (_Elephas indicus_) and the African (_E. afric[=a]nus_). From a difference in the teeth, however, the two species are sometimes referred to distinct genera (Euelephas and Loxodon). The so-called white elephants are merely albinos. The African elephant is distinguished from the Asiatic species by its greater height, its larger ears, its less elevated head and bulging or convex forehead, the closer approximation of the roots of the tusks, and the greater density of the bone. It has also only three external hoofs on the hind-feet, while the Asiatic has four. All elephants are remarkable for their large, heavy, short bodies supported on columnar limbs, a very short neck, a skull with lofty crown and short face-bones, with the exception of the premaxillaries, which are enlarged to form tusk-sockets. To compensate for the short neck, they have the long proboscis, often 4 or 5 feet in length, produced by the union and development of the nose and upper lip. It is made up of muscular and fibrous tissue. The trunk is of great strength and sensibility, and serves alike for respiration, smell, taste, suction, touch, and prehension. The tusks, which are enormously developed upper incisor teeth, are not visible in young animals, but in a state of maturity they project in some instances 7 or 8 feet. The largest on record (undoubtedly that of an extinct species) weighed 350 lb. Elephants sometimes attain the height of 12 feet or more, but their general height is about 9 or 10 feet. Their weight ranges from 4000 to 9000 lb. The period of gestation is twenty months, and the female seldom produces more than one calf at a birth: this, when first born, is about 3 feet high, and continues to grow till it is sixteen or eighteen years of age. It is said that they live to the age of 150 years. They feed on vegetables, the young shoots of trees, grain, and fruit. They are polygamous, associating in herds of a considerable size under the guidance of a single leader. An elephant leaving or driven from a herd is not allowed to join another, but leads a lonely, morose, and destructive life. Such solitary elephants are known as 'rogues'. Elephants are caught either singly or in herds. In the former case it is necessary to catch adroitly one of the elephant's legs in the noose of a strong rope, which is then quickly attached to a tree; another leg is then caught, until all are securely fastened. His captors then encamp beside him, until under their treatment he becomes tractable. When a herd is to be caught a strong enclosure is constructed, and into this the elephants are gradually driven by fires, noise, &c. With the aid of tame elephants the wild ones are tied to trees and subjected to the taming process. The domesticated elephant requires much care, and a plentiful supply of food, being liable to many ailments. The daily consumption of a working elephant is, according to Sir J. E. Tennent, 2 cwt. of green food, about half a bushel of grain, and about 40 gallons of water. Their enormous strength, docility, and sagacity make them of great value in the East for road-making, building, and transport. They are used by the great on occasions of pomp and show, being often richly caparisoned, and bearing on their back a howdah containing one or more riders, besides the mahout or driver sitting on the animal's neck. Tiger-shooting is often practised from an elephant's back. Several extinct species are known, the most notable being the mammoth (_E. primigenius_), a contemporary of prehistoric man. The allied genus Mastodon was of very wide distribution, and the Tertiary deposits of the Fayum (Egypt) have yielded the remains of types that bridge over the gap between elephants and more typical quadrupeds. See _Mammoth_; _Mastodon_.--BIBLIOGRAPHY: Andersson, _The Lion and the Elephant_; Sir. J. E. Tennent, _The Wild Elephant in Ceylon_; Sanderson, _Wild Beasts of India_; R. Lydekker, _The Game Animals of Africa_.

ELEPHAN'TA ISLE, or GHARAPURI, a small island in the Bay of Bombay, between Bombay and the mainland, 6 miles north-east of the former; circumference about 5 miles. It consists of two long hills chiefly overgrown with wood. A city is supposed to have flourished on the island between the third and tenth centuries, but now it has only a few inhabitants, who rear sheep and poultry for the Bombay market. It is celebrated for its rock temples or caves, the chief of which is a cave-temple supposed by Fergusson to belong to the tenth century, 130 feet long, 123 broad, and 18 high. It is supported by pillars cut out of the rock, and containing a colossal figure of the trimurti or Hindu Trinity: Brahma, Vishnu, and Siva. The temple is still used by the Bania caste for the Sawa at certain festivals.

ELEPHANT-FISH (_Callorhynchus antarcticus_), a fish of the sub-class Elasmobranchii (rays and sharks), so named from a proboscis-like structure on the nose: called also Southern Chimaera. It inhabits the Antarctic seas, and is palatable eating.

ELEPHANTIASIS is a disease characterized by progressive enlargement of a limb, or portion of the body, and occurs most frequently in the legs. The enlargement begins below the knee and gradually involves the entire limb. The onset may be slow and painless, or sudden with fever and rapid swelling. The disease is common in all countries in which the Filariae prevail. No drug destroys the embryos in the blood, and in infected districts the drinking-water should be boiled or filtered. In rapid cases rest, liquid diet, purgation, and firm bandaging of the legs are indicated. Surgical treatment for removal of adult Filariae in enlarged glands has met with some success.

ELEPHANTI'NE, the Greek name of a small island of Egypt, in the Nile, just below the First Cataract and opposite Assouan (Syene). It is partly covered with ruins of various origins--Egyptian, Roman, Saracen, and Arabic, the most important being a gateway of the time of Alexander, a small temple dedicated to Khnum and founded by Amenophis III, and the ancient Nilometer mentioned by Strabo. The latter was restored in 1870 by the Khedive Ismail Pasha. The northern part is low, the southern elevated and rocky.

ELEPHANT LORE. The cult of the elephant is found among many nations in Asia and Africa. It exists in Indo-China, Cambodia, Abyssinia, Siam, and Sumatra. The Aryo-Indian god Indra rides on an elephant. Buddha had a white elephant form. One of the Sanskrit names for the elephant is _Naga_, which connects the animal with the sacred snake, possibly on account of its trunk; another name is _Hastin_, 'having a hand'. The Wambuwegs believe the elephant to be the abode of the souls of their ancestors. It is a bad omen, according to the _Talmud_, to dream of an elephant.

ELEPHANT RIVER, a river of Cape Colony, running into the Atlantic after a course of 140 miles,

[Illustration: Elephant-seal]

ELEPHANT-SEAL, the Proboscis Seal, or Sea-elephant, the largest of the seal family (Phocidae). There are probably two species, one (_Macrorhinus angustirostris_) found only on the coast of California and Western Mexico, the other (_Macrorhinus leoninus_) found in Patagonia, Kerguelen Island, Heard's Island, and other parts of the Southern Seas. They vary in length from 12 to 30 feet, and in girth at the chest from 8 to 18 feet. The proboscis of the male is about a foot long when the creature is at rest, but elongates under excitement. The females have no proboscis and are considerably smaller than the male. Both species are becoming rare owing to the wholesale slaughter of them which takes place.

ELEPHANT'S-FOOT, the popular name of _Testudinaria elephantipes_, a plant of the nat. ord. Dioscoreaceae (yams, &c.), distinguished by the shape of its rootstock, which forms a nearly hemispherical mass rising a little above the ground, covered with a thick corky bark. It has a slender climbing stem growing to a length of 30 or 40 feet, with small heart-shaped leaves and greenish-yellow flowers. It is known in the Cape Province as Hottentots' Bread.

ELEUSI'NE, a genus of grasses, several of which, e.g. _E. coracana_, are cultivated as grain plants in India, Japan, and Tibet.

ELEUSINIAN MYSTERIES, the sacred rites anciently observed in Greece at the annual festival of D[=e]m[=e]t[=e]r or Ceres, so named from their original seat Eleusis. According to the Homeric hymn to D[=e]m[=e]t[=e]r, the goddess, while wandering in search of Persephone, came to Eleusis, where she was hospitably received by King Celeus. He directed the establishment of a temple in her honour, and showed the use of grain to Triptolemus and other princes. As a preparation for the greater mysteries celebrated at Athens and Eleusis, lesser Eleusinia were celebrated at Agrae on the Ilissus. The greater Eleusinia were celebrated in the month Boedromion (September-October), beginning on the 15th of the month and lasting nine days. The celebrations, which were varied each day, consisted of processions between Athens and Eleusis, torch-bearing and mystic ceremonies attended with oaths of secrecy. They appear to have symbolized the old conceptions of death and reproduction, and to have been allied to the orgiastic worship of Dionysus (Bacchus). They are supposed to have continued down to the time of Theodosius I.

ELEU'SIS, in ancient geography, a small city of Attica, about 14 miles from Athens, near the shore opposite the Island of Salamis. Its temple of D[=e]m[=e]t[=e]r was one of the most beautiful buildings of Greece. The sacred buildings were destroyed by Alaric in A.D. 396. In 1882 the Greek Archaeological Society undertook excavations, and numerous remains have been unearthed. There is now a large straggling village here.

ELEU'THERA, one of the largest of the Bahama Islands. It is of very irregular shape, its length being about 70 miles, and its breadth in general from 2 to 4 miles, though in one