PLATES

Adolphe Abrahams, O.B.E., B.A., M.D., late Major, R.A.M.C.

George E. Allan, D.Sc., Lecturer in Electricity, University of Glasgow.

C. O. Bannister, F.I.C., Assoc. R.S.N., Professor of Metallurgy, University of Liverpool.

F. F. P. Bisacre, O.B.E., M.A., B.Sc., A.M.Inst.C.E.

R. N. Rudmose Brown, D.Sc.

A. Y. Catto, O.B.E., Lieutenant, R.N.

Grenville A. J. Cole, F.R.S., Professor of Geology, Royal College of Science, Ireland.

W. G. Constable, M.A., Fellow of St. John's College, Cambridge.

Arthur O. Cooke, Author of A Book of Dovecotes.

J. R. Ainsworth Davis, M.A., F.C.P., former Principal of The Royal Agricultural College, Cirencester.

John Dougall, M.A., D.Sc., F.R.S.E., Gold Medallist of the Royal Society of Edinburgh.

Montagu Drummond, M.A., Director of Research, Scottish Station for Research in Plant Breeding.

S. L. Etherton, B.Sc.

Rev. William Fulton, D.D., B.Sc., Professor of Systematic Theology, University of Aberdeen.

R. N. Haygarth, B.A., B.Sc., Queens' College, Cambridge.

W. A. Hislop, M.B., late Captain, R.A.M.C.

D. J. Mackellor, B.Sc., Lecturer in Electrical Engineering, Royal Technical College, Glasgow.

Donald A. Mackenzie, Folklorist; Author of Egyptian Myth and Legend, &c.

Magnus Maclean, M.A., D.Sc., M.Inst.E.E., M.Inst.C.E., Editor of Modern Electrical Engineering, &c.

F. A. Mumby, Editor of The Great World War.

D. G. Ogilvy, LL.B.

R. F. Patterson, M.A., formerly Foundation Scholar of St. John's College, Cambridge, and Charles Oldham (University) Shakespeare Scholar.

Angelo S. Rappoport, Ph.D., B. ès L.

James Ritchie, M.A., M.D., Professor of Bacteriology, University of Edinburgh.

John J. Ross, M.A., F.R.A.S.

G. Elliot Smith, M.A., M.D., F.R.S., Professor of Anatomy, University of London.

C. S. Stocks, D.S.O., Major, Indian Army; Instructor in Military Organization, Royal Military College, Sandhurst.

M. M. J. Sutherland, D.Sc., F.I.C.

Alan C. Thomson, D.S.O., A.M.Inst.C.E., late Lieutenant-Colonel, R.E.

G. E. Toulmin, B.A., King's College, Cambridge.

Thomas Woodhouse, Head of the Weaving and Designing Department, Dundee Technical College and School of Art.

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:—

ā, as in fate, or in bare.

ä, as in alms, Fr. âme, Ger. Bahn = á of Indian names.

a˙, the same sound short or medium, as in Fr. bal, Ger. Mann.

a, as in fat.

a¨, as in fall.

a, obscure, as in rural, similar to u in but, ė in her: common in Indian names.

ē, as in me = i in machine.

e, as in met.

ė, as in her.

ī, as in pine, or as ei in Ger. mein.

i, as in pin, also used for the short sound corresponding to ē, as in French and Italian words.

eu, a long sound as in Fr. jeûne = Ger. long ö, as in Söhne, Göthe (Goethe).

eu, corresponding sound short or medium, as in Fr. peu = Ger. ö short.

ō, as in note, moan.

o, as in not, soft—that is, short or medium.

ö, as in move, two.

ū as in tube.

u, as in tub: similar to ė and also to a.

u¨, as in bull.

ü, as in Sc. abune = Fr. û as in dû, Ger. ü long as in grün, Bühne.

u˙, the corresponding short or medium sound, as in Fr. but, Ger. Müller.

oi, as in oil.

ou, as in pound; or as au in Ger. Haus.

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 rich.

d, nearly as th in this = Sp. d in Madrid, &c.

g is always hard, as in go.

h represents the guttural in Scotch loch, Ger. nach, also other similar gutturals.

n˙, Fr. nasal n as in bon.

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

s, always as in so.

th, as th in thin.

th, as th in this.

w always consonantal, as in we.

x = ks, which are used instead.

y always consonantal, as in yea (Fr. ligne would be re-written lēny).

zh, as s in pleasure = Fr. j.

[1]

Deposition of a Clergyman, the degradation of a clergyman from office, divesting him (in churches which do not, like the Church of Rome, hold the indelible nature of orders) of all clerical character.

Dépôt (dā'po or dep'ō), a French word in general use as a term for a place where goods are received and stored; hence, in military matters, a magazine where arms and ammunition are kept. The term is now usually applied to a military station situated in the centre of the recruiting district of a regiment, where recruits for this regiment are received and where they undergo preliminary training before joining their unit. In America it is the common term for a railway station.

Deprivation, the removing of a clergyman from his benefice on account of heresy or misconduct. It entails, of course, loss of all emoluments, but not the loss of clerical character.

De Profundis, in the liturgy of the Roman Catholic Church, one of the seven penitential psalms, the 130th of the Psalms of David, which in the Vulgate begins with these words, signifying 'Out of the depths'. It is sung when the bodies of the dead are committed to the grave.

Deptford (det'ford), a parliamentary and municipal borough, England, in the counties of Kent and Surrey, on the right bank of the Thames, now forming part of London. It has some manufactures of pottery, chemicals, and soap. The old naval dockyard was shut up in 1869, but the royal victualling yard is still the largest establishment of its kind. Deptford sends one member to Parliament. Pop. 109,496.

Deputies, Chamber of, the lower of the two legislative chambers in France and in Italy, elected by popular suffrage, and corresponding in some respects to the House of Commons in Britain.

De Quincey, Thomas, English author, was the son of a Manchester merchant, and born at Greenhay, near Manchester, on 15th Aug., 1785, died at Edinburgh, 8th Dec., 1859. In 1793 his father died, leaving the family a fortune of £30,000. After attending some time the Bath and Manchester grammar schools, where he showed precocious ability, especially in classical studies, he importuned his guardian to send him to Oxford University, and on being refused he ran away from school, ultimately arriving in London in an absolutely destitute condition. His sufferings at this time he has described in his Confessions of an English Opium Eater. At length, in 1803, he matriculated at Oxford, and it was in the second year of his course here that he began to take opium in order to alleviate severe neuralgic pains. On leaving college he settled at Grasmere, Westmoreland, in the vicinity of Wordsworth and Southey, and devoted himself to literary work. Here or in London he remained till 1828, reading voraciously, and writing for the London Magazine, Knight's Quarterly Magazine, and Blackwood's Magazine. From 1828 to 1840 he lived in Edinburgh, then removed with his family to Lasswade, which continued to be his head-quarters. His writings, nearly all contributions to magazines, are distinguished by power of expression, subtle thought, and an encyclopædic abundance of curious information. His work belongs to that class of literature which he himself called "the literature of power", as distinguished from "the literature of knowledge". He was eccentric in his habits, incapable of managing money matters, but amiable and polite.—Bibliography: A. H. Japp, Thomas De Quincey: his Life and Writings; H. S. Salt, De Quincey; J. Hogg, De Quincey and His Friends; Sir L. Stephen, Hours in a Library; Arvede Barine, Poètes et Névrosés.

Dera Ghazi Khan, a district and town in the Punjab, Hindustan. The former, which is in Derajat division, has an area of 5606 sq. miles, and a population of 445,000. The town has a population of 18,466, half Hindus and half Mohammedans. It has extensive manufactures of silk, cotton, and coarse cutlery. [2]

Dera Ismail Khan, a town in Hindustan, in the North-West Frontier Province, several miles to the west of the Indus, which is here crossed by boat-bridges, or boats, connecting the town with the Indus Valley railway. Dera Ismail Khan is a staple place for cotton goods, has a cantonment, and carries on a trade with Afghanistan. It is well laid out, has several schools and a large bazaar. Pop. 35,131.

Derajat (-jät´), a commissionership of Hindustan, in the west of the Punjab, occupying part of the valley of the Indus. It is well watered and fertile, and contains numerous towns and villages. Pop. 1,800,000, mostly Mohammedans.

Derbend´, or Derbent´, a fortified town in Daghestan, Transcaucasia, on the west shore of the Caspian, an ancient place formerly belonging to Persia. The manufactures consist of woollen stuffs, copper- and iron-ware, and rose-water; and there is some trade in saffron, largely grown in the vicinity. Pop. 32,718.

Derby, Edward Geoffrey Smith Stanley, fourteenth Earl of, an English statesman, born at Knowsley Park, Lancashire, 29th March, 1799, died there, 23rd Oct., 1869. In 1820 he was returned to the House of Commons as member for Stockbridge. At first inclining to the Whig party, he joined Canning's ministry in 1827, and in 1830 became Chief Secretary for Ireland in Lord Grey's Government, greatly distinguishing himself by his speeches in favour of the Reform Bill in 1831-2. The opposition led by O'Connell in the House of Commons was powerful and violent, but Stanley, while supporting a Bill for the reform of the Irish Church and the reduction of ecclesiastical taxation, was successful in totally defeating the agitation for the repeal of the Union. He warmly advocated the abolition of slavery, and passed the Act for this purpose in 1833; but in the following year a difference of opinion with his party as to the diversion of the surplus revenue of the Irish Church led him to join the Tories. In 1841 he became Colonial Secretary under Sir Robert Peel, but resigned on Peel's motion for repeal of the corn laws. In 1851 and 1858 he formed ministries which held office only for a short period; and again in 1860, when his administration signalized itself by the reform of the government in India, the conduct of the Abyssinian War, and the passing of a Bill for electoral reform (1867). Early in 1868, owing to failing health, he resigned office, recommending Disraeli as his successor. Lord Derby joined to great ability as a statesman, and brilliant oratorical powers, a high degree of scholarly culture and literary ability. Among other works he published a successful translation of Homer's Iliad in 1864.—Cf. T. E. Kebbel, English Statesmen Since the Peace of 1815: Derby.

Derby, Edward George Villiers Stanley, seventeenth Earl of, British politician, born in April, 1865. He served for some years in the Grenadier Guards, and entered the House of Commons in 1892. In 1895 he became a Lord of the Treasury, in 1900 Financial Secretary to the War Office, and in 1903 Postmaster-General. He succeeded to the earldom in 1908. Lord Derby became quite famous as the originator of the Derby Scheme, when he was Director-General of Recruiting in 1915. Under-Secretary for War in 1916, he succeeded Lloyd George as Secretary when the latter became Premier. In 1918 he was appointed British Ambassador in Paris, but resigned his position in Sept., 1920, and left Paris in Nov., greatly to the regret of the French people, to whom he had proved a staunch friend.

Derby, a municipal, parliamentary, and county borough in England, capital of Derbyshire, on the Derwent, here crossed by a graceful bridge of three arches, 115 miles N.N.W. of London. It is pleasantly situated in a wide and fertile valley open to the south, and is well and regularly built in the modern quarter. It has some fine public buildings, amongst which are the churches of All Saints, St. Alkmund, and St. Werburgh, the county hall, school of arts, and infirmary. There is also a very handsome free library and museum. The manufactures include silk, cotton, hosiery, lace, articles in Derbyshire spar, iron castings, and porcelain; and the principal engineering works of the Midland Railway are here. Derby is one of the oldest towns in the kingdom, and is supposed to owe its origin to a Roman station, Derventio. Under the Danes it took the name of Deoraby. Richardson, the novelist, and Herbert Spencer were natives. It returns two members to Parliament. Pop. 123,930 (1919).—The county of Derby, in the centre of the kingdom, is about 55 miles long and from 15 to 30 miles broad; area, 650,369 acres, five-sixths being arable or in permanent pasture. It exhibits much varied and romantic scenery, the southern and eastern parts having a fertile soil, while the north-western portion is bleak, with a rocky and irregular surface. Here is the loftiest range of the English Midlands, the mountains of the Peak. The Peak itself is 2000 feet high. The principal rivers are the Derwent, the Trent, the Wye, the Erwash, the Dove, and the Rother. Oats and turnips are important crops, and dairy-husbandry is carried on to a large extent. Coal is abundant in various parts of the county, iron-ore is also plentiful, and lead, gypsum, zinc, fluor-spar, and other minerals are obtained. The manufactures are very considerable, especially of silk, cotton, and lace, machinery, and agricultural implements. The county is divided into [3]eight parliamentary divisions, each with one member. Pop. 683,423.—Cf. J. C. Cox, Derbyshire.

Derby-day, the great annual London holiday, on which is run the horse-race for the stakes instituted by Lord Derby in 1780. It always takes place on a Wednesday, being the second day of the grand race-meeting which falls in the week after Trinity Sunday. The race is run on Epsom Downs, an extensive Surrey course 15 miles from London. The course is 1½ miles, and the time usually about 2 minutes, 42 seconds. The entry money of each subscriber is fifty guineas, and the stakes are run for by three-year-old colts and fillies entered when yearlings. In the first year of the Derby there were only thirty-six entries, but they are now very numerous, and the value of the winner's prize is at least £5000. The race is the most popular of British sporting events. The Ascot races are patronized by royalty; the world of fashion is to be found at Goodwood; but Derby-day draws to Epsom a vast crowd of every class. During the European War the race was suspended, but a substitute Derby was run at Newmarket from 1915 to 1918. In 1919 the Derby was again run at Epsom, and was won by Lord Glanely's Grand Parade. In 1920 it was won by Loder's Spion Kop, and in 1921 by Joel's Humorist.

Derby Scheme, a scheme produced by Lord Derby in 1915 with a view to making a final effort on behalf of voluntary recruiting. The National Register (q.v.), taken in August, 1915, of all persons between the ages of fifteen and sixty-five, had shown that over five million men of military age had not 'joined up'. As the number of recruits each week fell short of the number required by Lord Kitchener, Lord Derby, appointed Director of Recruiting, produced a scheme in which men were divided into 46 groups. Groups 1 to 23 were for single men, and groups 24 to 46 for married men. Thus a married man of eighteen was in group 24, whilst a single man of forty-one was in group 23. The scheme ensured that single men would be called up first, whilst men who had 'attested' could appeal to a tribunal and claim temporary or permanent exemption. Two and a half millions offered themselves in consequence of the Derby Scheme, and two millions were accepted.

Dereham (dēr´am), East, a town in England, nearly in the centre of the county of Norfolk, with manufactures of agricultural implements, iron-foundries, and a brisk trade. The poet Cowper was buried in the church there, and George Borrow was born there in 1803. Pop. 5524.

Der´elict, a vessel or anything relinquished or abandoned at sea, but most commonly applied to a ship abandoned by the crew and left floating about.

Derg, Lough: (1) a lake, Ireland, county of Donegal, about 3 miles long by 2½ miles broad at the broadest part, and studded with islets, one of which, called Station Island, is a great resort of Roman Catholic pilgrims; (2) an expansion of the River Shannon between County Tipperary and Counties Clare and Galway, about 24 miles long and averaging 2 miles in breadth.

Derham, William, English philosopher and divine, born in 1657, died 1735. He was long rector of Upminster in Essex. In 1696 he published his Artificial Clockmaker. His best-known works are entitled Physico-Theology, Astro-Theology, and Christo-Theology.

Derma, or Dermis, is the true skin lying under the epidermis (cuticle), which is known in contrast as the scarf-skin.

Dermes´tes, a genus of beetles, one species of which (D. lardarius) is known by the name of bacon-beetle, and is often found in ill-kept ham or pork shops.

Dermot Mac Murragh, the last Irish King of Leinster, attained the throne in 1140. Having carried off the wife of O'Ruare, Prince of Leitrim, he was attacked by the latter, and after a contest of some years driven out of Ireland (1167). He then did homage to the English king, and with the help of Richard, Earl of Pembroke, recovered his kingdom, but died in the same year (1170), and was succeeded by Pembroke, who had married his daughter.

Dernburg, Bernhard, German financier and administrator, born in Darmstadt in 1865. His father was an editor of the Berliner Tageblatt. At the age of nineteen he came to New York to study banking methods, stayed there for several years, and on his return to Germany became director of a financial company. In 1906 he succeeded Prince von Hohenlohe Langenburg as Colonial Secretary. During his administration the condition of German colonies, and especially of German East Africa, was greatly improved. From 1914 to 1915 he was a zealous organizer of German propaganda in the United States, but was subsequently compelled to leave the country.

Déroulède, Paul, French poet, politician, and agitator, born in Paris in 1846, died there in 1914. Called to the Bar in 1870, he served in the Franco-Prussian War, and afterwards carried on an active and passionate agitation for a war of revenge against Germany. He founded the Ligue des Patriotes, which was suppressed by the Government in 1889, was an ardent supporter of General Boulanger, and one of the leaders of the reactionary forces during the Dreyfus case. He sat in the Chamber of Deputies from 1893 to 1895 and from 1898 to 1899. In 1900 he plotted against the Republic, and sought to bring about a nationalist coup d'état with a view to overthrowing the parliamentary constitution. Found [4]guilty, he was sentenced to ten years' exile, but was allowed to return in 1905, under the law of amnesty. His works include: Chants de Soldat (1872); Nouveaux Chants de Soldat (1875); Chants du paysan (1894); Poésies Militaires (1896); La Moäbite, a religious drama (1880), forbidden by the Censor; and L'Helman, a patriotic play (1877).

Derrick, a simple kind of crane, chiefly used on board ship, consisting of a stout pole swung from a mast, and carrying hoisting-tackle at its upper end. The name is derived from that of a celebrated hangman.

Derringer, a small pocket pistol with a short barrel and a large calibre (usually .41), very effective at short range. It is named after its inventor, a gun-smith in the United States of America, and would seem to have been first used in about 1850. It is a single-shot weapon, and so has largely been superseded by revolvers and automatic pistols.

Der´vish, or Dervise (Pers., 'seeking doors' or beggar, and equivalent to the Ar. fakir), a Mohammedan devotee, distinguished by austerity of life and the observance of strict forms. There are many different orders of dervishes, the underlying idea of most of them being the revival and increase of the Moslem faith. Some live in monasteries, others lead an itinerant life, others devote themselves to menial or arduous occupations. They are respected by the common people, and the mendicants among them carry a wooden bowl into which the pious cast alms. One of their forms of devotion is dancing or whirling about, another is shouting or howling, uttering the name Allah, accompanied by violent motions of the body, till they work themselves into a frenzy and sometimes fall down foaming at the mouth. They are credited with miraculous powers, and are consulted for the interpretation of dreams and the cure of diseases. See Mohammedanism.—Bibliography: E. W. Lane, Modern Egyptians; J. P. Brown, The Dervishes, or Oriental Spiritualism; S. M. Zwemer, Arabia, the Cradle of Islam.

Der´went, the name of four rivers in England, in Derbyshire, Yorkshire, Durham, and Cumberland respectively, the last draining Derwentwater Lake. Also a river in Tasmania.

Derwentwater, James Radcliffe, third and last Earl of, one of the leaders in the rebellion of 1715, born in London 28th June, 1689. The standard of revolt having been raised in Scotland, Lord Derwentwater commenced the movement in England on 6th Oct., 1715, but was forced, along with the other Jacobite nobles, to surrender at discretion on 13th of Nov. He was executed on Tower Hill 24th Feb., 1716, his estates being confiscated, and in 1735 granted to Greenwich Hospital.

Der´wentwater, or Keswick Lake, a beautiful lake in Cumberland, England, in the vale of Keswick. It is about 3 miles in length and 1½ miles in breadth, and stretches from Skiddaw on the north to the hills of Borrowdale. Near the south-east corner is the celebrated cascade of Lodore. Its waters are carried to the sea by the Derwent.

Derzhavin (der-zhä´vin), Gabriel Romanovitsh, a Russian lyric poet, born in 1743, died in 1816. He entered the army as a private soldier, distinguished himself highly, and was eventually transferred to the Civil Service, in which he obtained the highest offices. In 1803 he retired from public life and devoted himself entirely to poetry. One of his most beautiful poems is Oda Bog, or The Address to the Deity.

Desaguadero (des-a˙-gwa˙-dā´rō), a river of Bolivia, in a valley of the same name, issuing from Lake Titicaca, and carrying its waters into Lake Aullagas. Also a river in the Argentine Confederation flowing into Lake Bevedero Grande, and separating the provinces of San Juan and Mendoza. Desaguadero signifies in Spanish 'a channel of outlet'.

Desaix de Veygoux (dė-sā dė vā-gö), Louis Charles Antoine, a distinguished French general, born in 1768 at St. Hilaire d'Ayat, in Auvergne, died 1800. He was of noble family, and entered the army as a sub-lieutenant. He distinguished himself greatly in 1794 under Pichegru, and two years later with the army of the Rhine under Moreau. In 1797 he accompanied Bonaparte to Egypt, and was very successful in reducing Upper Egypt. After the Treaty of El Arish he followed Bonaparte to Italy, took command of the corps of reserve, and, arriving on the field of Marengo at a critical moment, decided the victory by a brilliant charge, 14th June, 1800. He himself fell, mortally wounded by a musket bullet.

Desault (dė-sö), Pierre Joseph, one of the most celebrated surgeons of France, was born in 1744, and died in 1795. After some experience in the military hospital at Béfort, he went to Paris in 1764, studied under Petit, and two years afterwards became a lecturer on his own account. His reputation soon increased, and he became principal surgeon in the Hospital de la Charité, and in 1788 was put at the head of the great Hôtel Dieu in Paris. Here he founded a surgical school, in which many of the most eminent surgeons of Europe were educated. A digest of his surgical works was published by Bichat in 1798 (Œuvres chirurgicales de Desault).

Des´cant, in music, an addition of a part or parts to a subject or melody, a branch of musical composition which preceded the more modern counterpoint and harmony, coming into existence at the end of the eleventh or beginning of the twelfth century. [5]

Descartes (dā-kärt), René, a great French philosopher and mathematician, with whom the modern or new philosophy is often considered as commencing. He was born 31st March, 1596, at La Haye, in Touraine, died 11th Feb., 1650. Educated at the Jesuit College of La Flèche, where he showed great talent, he entered the military profession and served in Holland and in Bavaria. In 1621 he left the army, and after a variety of travels finally settled in Holland, and devoted himself to philosophical inquiries. Descartes, seeing the errors and inconsistencies in which other philosophers had involved themselves, determined to build up a system anew for himself, divesting himself first of all of the beliefs he had acquired by education or otherwise, and resolving to accept as true only what could stand the test of reason. Proceeding in this way, he found (Meditationes de Prima Philosophia) that there was one thing that he could not doubt or divest himself of the belief of, and that was the existence of himself as a thinking being, and this ultimate certainty he expressed in the celebrated phrase "Cogito, ergo sum" (I think, therefore I am). Here, then, he believed he had found the test of truth. Starting from this point Descartes found the same kind of certainty in such propositions as these: that the thinking being or soul differs from the body (whose existence consists in space and extension) by its simplicity and immateriality and by the freedom that pertains to it; that every perception of the soul is not distinct; that it is so far an imperfect finite being; that this imperfection of its own leads it to the idea of an absolutely perfect being; and from this last idea he deduces all further knowledge of truth. Descartes has been rightly called the father of modern philosophy, for in him the modern spirit came into existence. In an age of unrest and ferment his work was that of a great systematizer. He also contributed greatly to the advancement of mathematics and physics, the method of co-ordinates, which has revolutionized geometry, and is of fundamental importance in modern mathematical physics, being due to him. His system of the universe attracted great attention in his time. One of his fundamental doctrines was that the universe is full of matter, there being no such thing as empty space. On this basis he developed the hypothesis of celestial vortices, immense currents of ethereal matter, by which he accounted for the motion of the planets (Principia Philosophiæ, 1644). His works effected a great revolution in the principles and methods of philosophy. In 1647 the French court granted him a pension of 3000 livres, and two years later, on the invitation of Christina of Sweden, he went to Stockholm, where he died.—Bibliography: Sir J. P. Mahaffy, Descartes; A. Fouillée, Descartes; E. Boutroux, L'Imagination et les mathématiques selon Descartes; N. Smith, Studies in Cartesian Philosophy; E. S. Haldane, Descartes: his Life and Times.

Descent´, in law, is the transmission of the right and title to lands to the heir, on the decease of the proprietor, by the mere operation of law. The rule determining to whom an estate belongs, on the decease of the proprietor, is that of consanguinity, or relationship by blood, though with some exceptions, as in the case of the portion, or the use of a portion, of a man's property given by the laws of Britain to his widow. The rules of descent, designating what relations shall inherit, and their respective shares, will be determined by the genius and policy of the Government and institutions. Hence the practice of entailments in the feudal system. And wherever the Government is founded in family privileges, or very intimately connected with them, as is the case in all Governments where the hereditarily aristocratical part of the community has a great preponderance, the sustaining of families will very probably be a characteristic feature in the code of laws. Thus, in Britain, all the lands of the father, unless otherwise directed by will, go to the eldest son. (In England, however, this privilege may shortly be abolished, or the succession to real estate assimilated to the succession to personal estate.) In the United States of America this distinction in favour of the eldest son has been abolished, and the laws there are founded upon the principle of equal distribution both of real and personal estate among heirs of the nearest surviving degree. Kindred in blood are divided into three general classes, viz. 1, descendants; 2, ancestors; 3, collateral relatives, that is, those who have descended from the same common ancestor. The civil law computes the degrees by counting the generations up to the common ancestor, as father, grandfather, great-grandfather; or mother, grandmother, great-grandmother; and from him or her down to the collateral relative, as brother, cousin, &c., making the degree of relationship the sum of these two series of generations. Every person has two sets of ancestors, the paternal and maternal, and therefore two sets of collateral relatives. There is also a distinction of collateral kindred, into those of the whole blood and those of the half blood.—Cf. Pollock and Maitland, History of English Law.

Deschanel, Paul Eugène Louis, French statesman and tenth President of the French Republic, born at Brussels on 13th Feb., 1856, where his father was in exile for opposition to Napoleon III. Educated at the Collège Sainte Barbe and the Lycée Condorcet, Paris, he was private secretary first to De Marcère, the Home Secretary, in 1876, and then to the Premier, [6]Jules Simon, in 1877. Sub-prefect at Dreux, Brest, and Meaux, he was elected to the Chamber of Deputies in Oct., 1885, for Nogent le Rotrou. In the Chamber of Deputies he soon displayed his power of eloquence, and eventually became the leader of the Progressive Republicans and exponent of the separation of Church and State. His authority, which he owed not only to his eloquence but also to his great tact and correct and dignified conduct during debates, gradually increased in the Chamber of Deputies, and even his political enemies admired his courage and his superiority of intellect. He was consequently elected Vice-President of the Chamber in 1896 and in 1897, and succeeded Henri Brisson as President of the Chamber in 1898, retaining his office till 1902, when M. Léon Bourgeois became President of the Chamber. Re-elected President of the Chamber in 1912, and withdrawing his candidature to the presidency of the Republic in favour of Poincaré in 1913, Deschanel retained his post until 1920, when he was elected President of the Republic by 734 votes. In the meantime, however, his health had given way, and on 23rd May, 1920, he fell out of a moving train, an accident resulting in a prolonged illness. A prompt recovery was at first expected, but this hope soon proved vain. Unable to attend to the duties of his office, he resigned on 16th Sept., and was succeeded by Alexandre Millerand. He was elected to the Académie Française on 18th May, 1899, and his works include: La Question du Tonkin (1883), La Politique Française en Océanie (1884), Orateurs et Hommes d'État (1888), Figures des Femmes (1889), Figures Littéraires (1889), La Question Sociale (1898), Quatre ans de Présidence (1902), Politique Intérieure et étrangère (1906), Paroles Françaises (1911), La France Victorieuse (1919), and Gambetta (1920).

Deseada (de-se-ä´da˙), or Désirade, one of the Leeward Islands, belonging to the French, in the Caribbean Sea, about 10 miles long and hardly 5 miles broad. The soil is in some places black and good, in others sandy and unproductive. Pop. about 1500.

Deser´tion. In the military sense this implies the act of an officer or soldier who, either with the intention of not returning at all or of returning when by reason of his absence it has become impossible for him to perform a given duty, absents himself from His Majesty's service. The essence of the offence is intention, and this must be proved to the satisfaction of the court martial by which the offender is tried. The distance travelled is no criterion, and a man arrested while leaving the barracks in disguise may be tried for attempted desertion. In this connection it should be noted that an attempt to desert, or an attempt to procure another person to desert, is also an offence, and is punishable under Section 12 of the Army Act equally with the completed act. As far back as the middle of the fifteenth century the crime of desertion by a soldier was made a felony triable by the ordinary law of the land, and with certain interludes death remained the maximum penalty for desertion for some 200 years. The present existing Army Act recognizes two degrees of desertion, i.e. that committed on active service or when under orders for active service, and that committed under other circumstances. Under the former heading the maximum punishment is death; under the latter, imprisonment or penal servitude, according to the number of times the offence has been committed. A soldier convicted of desertion forfeits the whole of his service prior to conviction.

Desertion, in law, the term applied to the act by which a man abandons his wife or a wife her husband. Such desertion without due cause is, in England, ground for a judicial separation. Property a wife may have acquired since desertion is protected against her husband, and he may be forced to provide for her maintenance. By Scottish law, where either the husband or wife has deserted and remained separate without due cause for four years, divorce may be obtained.

Deshoulières (dā-söl-yār), Antoinette du Ligier de Lagarde, a French woman of much literary reputation in the seventeenth century, born 1638, died 1694. She was the centre of attraction in the best circles of the period, and was elected a member of several learned societies. She wrote in the Mercure Galant under the name of Amaryllis, and Boileau has described her in his tenth Satire. Among her works are odes, eclogues, idyls, and a tragedy (Genseric).

Desiccation, a process of dispelling moisture by the use of air, heat, or chemical agents such as chloride of calcium, quicklime, oil of vitriol, and fused carbonate of potash.—Desiccation cracks, in geology, are the fissures caused in clayey beds by the sun's heat, and seen in various rock strata.

Design, thought, arrangement, or grouping, imagination or invention in works of art. A design is a composition or invention, pictorial, architectural, or decorative. It may be simply an imperfect sketch, as a record of a first thought; or it may be a fully matured work, as a cartoon in preparation for fresco painting, or a drawing to illustrate a book.

Desmidia´ceæ, or Desmidie´æ, a family of microscopic, fresh-water Green Algæ, group Conjugatæ. They are green gelatinous plants composed of variously formed cells having a bilateral symmetry, which are either free, or in linear series, or collected into bundles or into [7]star-like groups, and embedded in a common gelatinous coat. Desmidiaceæ differ from Diatomaceæ in their green colour and absence of silica.

Desmo´dium, a large genus of leguminous plants, sub-ord. Papilionaceæ, natives of tropical and sub-tropical countries. D. gyrans is the telegraph plant, so called from the curious movements performed by the two small lateral leaflets of each leaf, which, at high temperatures, wave up and down like the arms of a semaphore.

Des Moines (dė moin), a city of the United States, capital of the state of Iowa and of Polk County, on the Des Moines River, about 350 miles west of Chicago. Among its chief buildings are the new State house, the State arsenal, university, and opera-houses. There are coal-mines in the vicinity, and the manufactures and other industries are varied and rapidly increasing. Pop. 104,052 (1917).

Des Moines, the largest river in the state of Iowa, rises in the S.W. of Minnesota, and flows in a south-easterly direction till it falls into the Mississippi about 4 miles below Keokuk, after a course of 300 miles.

Desmoncus, a genus of tropical American climbing palms, scrambling by means of stout hooks which are modified leaflets.

Desmoulins (dā-mö-lan), Benoît Camille, born in 1760, was conspicuous during the first period of the French Revolution. He was amongst the most notable of the pamphleteers and orators who urged the multitude forward in the path of revolution. He, along with others, prepared the plan for the taking of the Bastille (July, 1789), was one of the founders of the club of Cordeliers, and the promoter of the assembly in the Champ de Mars. In 1789 he began his career as a journalist by the issue of a weekly publication (Les Révolutions de France et de Brabant). In 1793 he gave his vote for the death of the king. Having become closely connected with Danton and the party of opposition to Robespierre, and inveighing against the reign of blood and terror, he was arrested on the order of the latter on 30th March, 1794, tried on the 2nd April, and executed on the 5th. He met his fate in an agony of despair.—Cf. F. A. Aulard, Les Orateurs de la Législative et de la Convention.

Desna, a river in the Ukraine, which rises in the government of, and about 50 miles east of the town of Smolensk, flows through the governments of Orel and Tshernigov till it joins the Dnieper near Kiev. It is 500 miles in length and navigable nearly throughout.

De Soto, Hernando, a Spanish explorer and discoverer of the Mississippi, born about 1496, died in 1542. He accompanied expeditions to the New World under Davila and Pizarro, and played a distinguished part in the conquest of Peru. In 1536 he led an expedition to Florida, whence after many difficulties he penetrated to the Mississippi, where he was attacked with fever and died.—The name De Soto has been given to a county in the N.W. of Mississippi, and to several places in the United States.

Des´pot (Gr. despotēs), originally a master, a lord; at a later period it became an honorary title which the Greek emperors gave to their sons and sons-in-law when governors of provinces. At present despot means an absolute ruler, and in a narrower sense a tyrannous one.

Dessalines (dā-sa˙-lēn), Jean Jacques, Emperor of Hayti, born in Africa about 1760. He was a slave in 1791, when the insurrection of the blacks occurred in that island, but was set free along with the other slaves in St. Domingo in 1794. His talents for war, his courage, and unscrupulous conduct raised him to command in the insurrections of the coloured people, and after the deportation of Toussaint-L'Ouverture, and the subsequent evacuation of the island by the French, Dessalines was appointed Governor-General for life with absolute power; and the year following (1804) was declared Emperor with the title of Jacques I. But his rule was savage and oppressive, and both the troops and the people, sick of his atrocities, entered into a conspiracy against him, and on 17th Oct., 1806, he was slain by one of his soldiers.

Dessau (des´ou), a town in Germany, capital of the former Duchy of Anhalt, in a beautiful valley on the left bank of the Mulde, mostly well built, with fine squares and many handsome buildings. The manufactures consist of woollens, woollen yarn, carpets, machinery, and tobacco. The former ducal palace has a picture-gallery and interesting relics and antiquities. Pop. 56,606.

De Stendhal. See Beyle, Marie-Henri.

Dester´ro, now Florianopolis, a seaport of Brazil, capital of the state of Santa-Catharina. The harbour, next to Rio de Janeiro, is the best in Brazil. Pop. 9000.

Destructors, Refuse, the apparatus or plant used in the cremation of house and factory refuse. Formerly refuse from large towns and populous areas was either disposed of for manurial purposes or spread over waste land, where its presence speedily became a nuisance. The consequent danger to the public health, coupled with the increasing difficulty and cost of its disposal, led to attempts being made to deal with it by more sanitary methods. The first attempts to cremate it in a closed furnace on a large scale, made in London in 1870, were not successful, primarily owing to the unscientific design of the furnace. In 1877, however, there was built in Manchester the forerunner of the [8]modern destructor, to the designs of the late Mr. Alfred Fryer. This consisted of two simple cells, the primary feature of the design being 'the charging of the refuse into the back of the furnace, and drawing out the resulting clinker from the front'. With certain modifications, this design is in general use at the present time. The basic principles underlying their scientific design may be summed up in the following points: (a) Charging at regular intervals, the refuse being dumped into a hopper, and fed into the back of the furnace as a charge, means being taken to prevent undue escape of gases. The moisture having evaporated, the material may then be raked forward onto the fire-bars, where combustion takes place. (b) To avoid nuisance, the resulting gases must be inodorous, which requires a temperature of about 2000°F. This is obtained by passing the products of combustion over the hottest portion of the fire, prior to their passage into the main flue. (c) Removal of the fine dust and particles in suspension in the flue gases by means of spiral chambers at the base of chimney. (d) Provision of forced draught. A well-designed plant should show little, if any, suspended matter in the gases on emission from the chimney. Formerly no use was made of the heat generated, but modern installations now invariably have steam-raising plant incorporated in the design. This power is commonly used to generate electricity. Some portion may be utilized in crushing and screening the clinker, which is frequently used in making slab-paving, or ground fine and used as a substitute for sand in mortar. The following data may be found of service: (a) 60 per cent of the average refuse is combustible. (b) The calorific value may be taken as being one-seventh that of good steam-coal. (c) 100 electrical units may be obtained from each ton of refuse consumed. (d) With forced draught, as much as 100 lb. of refuse has been burnt per square foot of grate area per hour. (e) 250 tons of refuse per annum per 1000 of population may be estimated for.—Bibliography: W. H. Maxwell, Removal and Disposal of Town Refuse; Kempe, Engineer's Year Book.

Destutt de Tracy, Antoine Louis Claude, French philosophical writer, born in 1754 of a family of Scottish extraction, died in 1836. As a philosopher he belonged to the Sensationalist school, and considered all our knowledge to be derived originally from sensation. He has been called the logician and metaphysician of the school of Condillac. Among his chief works are: Idéologie (1801), Logique (1805), and Traité de la Volonté (1815).

Deter´minant, a mathematical expression which appears in the solution of a system of equations of the first degree.

The solution of the equations

is given by

Here x and y have the same coefficient a₁b₂ - a₂b₁. This is called a determinant of the second order, and is written

We may now write

Similarly with three equations,

we find

The coefficient of x, and the right-hand member, are here determinants of the third order, and the result is written

When the coefficient of x is expanded fully, it consists of six terms, half of them positive and half negative, each term being the product of three letters, one from each row and one from each column. Thus in every term, such as the leading term a₁b₂c₃, the three letters a, b, c, and the three suffixes 1, 2, 3, all occur once and once only. With regard to the signs, we note that if the letters a, b, c are always kept in this order, an interchange of two suffixes changes the sign. Thus, e.g. we may start from + a₁b₂c₃, interchange the suffixes 2 and 3, and thus find - a₁b₃c₂. Again, if in the latter term - a₁b₃c₂ we interchange the suffixes 1 and 3, we find + a₃b₁c₂. It is easy to verify that after any number of interchanges of this kind a particular term will always come up with the same sign.

Thus the interchange of two rows (and similarly of two columns) changes the sign of the determinant. It follows that if two rows (or two columns) are identical, the determinant is zero. It is now easy to define functions of n² letters, arranged in a square array of n rows [9]and n columns, with similar properties to those observed above in the case of determinants of the third order. Determinants are very extensively used in higher algebra, co-ordinate geometry, and other branches of mathematics. See also Elimination.—Bibliography: C. Smith, Algebra; T. Muir, Theory of Determinants.

Determinants, in biology, the name applied by Weismann to hypothetical particles contained in the nuclei of germ-cells, which determine the existence and nature of the various parts of the body of the embryo. The theory of determinants is part of an elaborate attempt to explain the facts of heredity on a mechanical basis. Although it may serve as a working hypothesis, it is regarded with disfavour by many experts, and may be regarded as an elaboration of the 'provisional theory of pangenesis' advanced by Darwin.

Deter´minism, a term employed by recent writers, especially since J. Stuart Mill, to denote a philosophical theory which holds that the will is not free, but is invincibly determined either—according to the older form of the theory—by a motive furnished by Providence, or—according to the modern form—by the aggregation of inherited qualities and tendencies. Biological determinism maintains that each of our voluntary acts finds its sufficient and complete cause in the physiological conditions of the organism. Psychological determinism ascribes efficiency to the psychical antecedents. Opposed to determinism is the doctrine of indeterminism or indifferentism. See Free-will.

Det´inue, in law, the form of action whereby a plaintiff seeks to recover a chattel personal unlawfully detained.

Det´mold, a town, Germany, capital of Lippe-Detmold, on the left bank of the Werra, 50 miles south-west of Hanover, with a new and an old palace (or castle), good public library, and museum. In the vicinity a colossal statue has been erected to the Hermann or Arminius who overthrew the Roman general Varus and his legions in a battle which was fought near this place. The Senner race of horses is bred near Detmold. Pop. 14,295.

Det´onating Powders, certain chemical compounds which, on being exposed to heat or suddenly struck, explode with a loud report, owing to one or more of the constituent parts suddenly assuming the gaseous state. The chloride and iodide of nitrogen are very powerful detonating substances. Mercuric fulminate or fulminating mercury (C₂HgN₂O₂) explodes violently when forcibly struck or when heated to 180°F. It is used for making percussion caps, and in detonators for exploding guncotton and nitroglycerin preparations. Silver fulminate (C₂Ag₂N₂O₂) explodes even more violently.

Detonating Tube, a species of eudiometer, being a stout glass tube used in chemical analysis for detonating gaseous bodies. It is generally graduated into centesimal parts, and perforated by two opposed wires for the purpose of passing an electric spark through the gases which are introduced into it, and which are confined within it over mercury and water.

Detroit (de-troit´; Fr. détroit, a strait or channel), a flourishing port and city of the United States, the largest town in Michigan, situated on the Detroit River, connecting Lakes Erie and St. Clair. The site rises gradually from the river, and the city is generally well built. Among the chief edifices are the city hall, the house of correction, post office, and opera-house. Detroit has increased very rapidly, a fact which is due to its admirable position for trade, and to its connections with a region into which a constant tide of emigration is flowing. Among the industrial establishments are saw-mills, flour-mills, building-yards for ships and boats, foundries, tanneries, blast-furnaces, pork-packing establishments, tobacco and cigar manufactories, and locomotive works. The harbour is one of the finest in the United States, and has a depth of water sufficient for the largest vessels. Detroit owes its origin to the French, who visited the site in 1648 and erected the Fort Pontchartrain in 1701. Pop. 688,028 (1919).

Detroit River, or Strait of St. Clair, a river or strait of North America which runs from Lake St. Clair to Lake Erie. It is 28 miles long, and of sufficient depth for the navigation of large vessels. It is about ¾ mile wide opposite Detroit and enlarges as it descends.

Dettingen (det´ing-en), the name of several places in Germany, amongst which is a village of Bavaria, on the right bank of the Main, famous for the victory gained by the English and Austrians under George II of England over the French in 1743.

Deuca´lion, in Greek mythology, the son of Prometheus and father of Hellen, ancestor of the Hellenes. According to tradition he saved himself and his wife, Pyrrha, from a deluge which Zeus had sent upon the earth, by building a ship which rested upon Mount Parnassus. To repair the loss of mankind they were directed by an oracle to throw stones behind them; the stones thrown by Deucalion became men, those thrown by Pyrrha women.

Deus ex Machinâ (mak´i-na; Lat., 'a god out of the machine'), a phrase used to designate the resorting to supernatural causes to explain phenomena that one is not able to account for by natural means. The phrase is taken from the practice on the classical stage of introducing a god from above by means of some mechanical contrivance in order to effect a speedy dénouement of the plot. [10]

Deuteronomy (Gr. deuteronomion, the second law), the name of the fifth book of the Pentateuch (q.v.). Until the seventeenth century it was believed to have been written by Moses, but now it is generally held to be a compilation, the bulk of it having been written in the reign of Manasseh, or according to other scholars in the reign of Josiah. At any rate the book was discovered or rediscovered while Josiah was king (2 Kings, xxii). It represents the latest phase in the development of the teaching of Moses. Its chief aim is to combat idolatry, and to concentrate the religious life of the country at Jerusalem. It has a lofty moral tone. Of one passage (vi, 4 and 5) Christ said: "On these two commandments hang all the law and the prophets" (Matt. xxii, 40), and all His answers to the Tempter in the Wilderness are taken from the book of Deuteronomy.

Deutz (doits), a town in Prussia, on the right bank of the River Rhine, opposite the city of Cologne, with which it communicates by a bridge. It is strongly fortified as part of the defences of Cologne, in which it is now incorporated. There are some manufactories of porcelain and glass, also an iron-foundry and machine-works. Pop. 17,060.

Deut´zia, a genus of plants, nat. ord. Saxifragaceæ, containing seven or eight species, all of which are interesting from the beauty of their flowers, some of them favourite garden and greenhouse plants. They are small shrubs indigenous to China and Japan, and Northern India.

De Valera, Eamon, Irish Republican, born at New York in 1883, his father being a Spaniard, and his mother an Irishwoman. Educated at the Royal University of Ireland, he early became known for his revolutionary activities. In 1917 he was elected president of the Gaelic League and was arrested as an agitator. Elected to Parliament in 1918, while he was in prison, he refused to take his seat. He was elected 'President' of the so-called 'Irish Republic' soon afterwards, and in Feb., 1919, escaped from prison and reached New York, where he started an active propaganda and began to raise funds for the Irish cause. He returned to Ireland in 1921.

Dev´enter, an old town in Holland, province of Overijssel, 8 miles north from Zutphen, at the confluence of the Schipbeek and Ijssel. Its industries embrace carpets, cast-iron goods, printed cottons, hosiery, and a kind of cake called Deventer Koek. It has a large export trade in butter. Pop. 32,483 (1918).

Dev´eron, a river of Scotland belonging to Aberdeenshire and Banffshire, 60 miles long. It flows into the Moray Firth at Banff.

Deviation of the Compass, the deflection of a ship's compass needle from the magnetic meridian, caused by adjacent iron. Hard iron is very retentive of a magnetic state, and is specially liable to become magnetized during a hammering process, as in the building of the ship. Soft iron easily receives or loses magnetism, and its magnetic state varies with every shifting of the ship's head. The effect of the former can be counteracted by magnets suitably placed near the compass, that of the latter by spheres of soft iron. The ship is swung, and the compass errors found in the various positions. The effects of the several contributing causes can then be separated, and the nature of the correctors necessary inferred with considerable accuracy. When these have been provided, the small residual errors for different positions of the ship are determined, and a table is constructed from which the navigator may read the slight correction to apply to the indication of his compass in steering any desired course.

Device´, a name common to all figures, ciphers, characters, rebuses, and mottoes which are adopted by a person or a family by way of badge or distinctive emblem, often a representation of some natural body, with a motto or sentence applied in a figurative sense.

Devil (Gr., diabolos, a slanderer or accuser), in theology, the name given to a fallen angel, who is the instigator of evil, and the ruler of darkness. Most of the old religions of the East acknowledge a host of devils. The doctrine of Zoroaster, who adopted an evil principle called Ahriman, opposed to the good principle and served by several orders of inferior spirits, spread the belief in such spirits among the people. The Greek mythology did not distinguish with the same precision between good and bad spirits. With the Mohammedans Eblis, or the devil, was an archangel whom God employed to destroy a pre-Adamite race of jinns, or genii, and who was so filled with pride at his victory that he refused to obey God. The Satan of the New Testament is also a rebel against God. He uses his intellect to entangle men in sin and to obtain power over them. But he is not an independent self-existent principle like the evil principle of Zoroaster, but a creature subject to omnipotent control. The doctrine of Scripture on this subject soon became blended with numerous fictions of human imagination, with the various superstitions of different countries, and the mythology of the pagans. The excited imaginations of hermits in their lonely retreats, sunk as they were in ignorance and unable to account for natural appearances, frequently led them to suppose Satan visibly present; and innumerable stories were told of his appearance, and his attributes—the horns, the tail, the cloven foot,—distinctly described. Theology has always treated the devil from a psychological or ethical [11]standpoint. From the New Testament we hardly learn more regarding the devil than that he has a distinct personality; that he is a spirit or angel who in some way fell; that he is devoid of truth and of all moral goodness, always warring against the soul of man and leading him towards evil; that he has demons, spirits, or angels under him who work his will, and enter into or 'possess' men; but of his or their origin, original state, or fall, we really learn nothing.—Bibliography: Mayer, Historia Diaboli; Lecanu, Histoire de Satan, sa chute, son culte, ses manifestations, ses œuvres; Carus, History of the Devil.

Devil-fish, the popular name of various fishes, one of them being the angler. Among others the name is given to several large species of ray (especially Ceratoptera Vampyrus which attains the breadth of 20 feet) occasionally captured on the Atlantic and Pacific coasts of America, and much dreaded by divers, whom they are said to devour after enveloping them in their vast wings. During gales of wind or owing to strong currents these immense fish are driven into shoal water, and, being unable to extricate themselves, fall an easy prey to the fishermen, who obtain considerable quantities of oil from their livers. The name is also applied to the larger eight-armed cephalopod molluscs belonging to Octopus and allied genera. A combat with one of these is described in Victor Hugo's Toilers of the Sea.

Devil's Bit, the common name of a British species of scabious (Scabiōsa succīsa), nat. ord. Dipsaceæ. It has heads of blue flowers nearly globular, and a fleshy root, which is, as it were, cut or bitten off abruptly. It flowers from June to October, and is common in meadows and pastures.

Devil's Bridge, a name for several bridges in wild situations; one being in Cardiganshire, spanning a gorge of the Mynach; another in Switzerland, over which the St. Gothard Railway crosses the Reuss.

Devil's Parliament, the name given to a Parliament convened by Henry VI, which met at Coventry in 1459 and unjustly accused the Duke of York of high treason.

Devil's Punch-bowl, a small lake of Ireland, near the Lakes of Killarney, between 2000 and 3000 feet above the sea, supposed to be the crater of an ancient volcano. The name is also given to Highcomb Bottom, a glen in Surrey.

Devil's Wall, in the south of Germany, a structure which was originally a Roman rampart, intended to protect the Roman settlements on the left bank of the Danube and on the right bank of the Rhine against the inroads of the Teutonic and other tribes. Remains of it are found from the Danube, in Bavaria, to Bonn, on the Rhine.

Devil-worship, the worship paid to the devil, an evil spirit, a malignant deity, or the personified evil principle in nature, by many of the primitive tribes of Asia, Africa, and America, under the assumption that the good deity does not trouble himself about the world; or that the powers of evil are as mighty as the powers of good, and have in consequence to be bribed and reconciled. There is a sect called devil-worshippers inhabiting Armenia and the valley of the Tigris, who pay respect to the devil, to Christ, and to Allah or the supreme being, and also worship the sun.

Devise, in law, usually the disposition of real estate by will, but also sometimes applied to any gift by will, whether of real or personal estate.

Devitrification. Glass which has been kept for a considerable time at a temperature just below its fusion-point gradually becomes opaque or crystalline in appearance; this phenomenon is spoken of as devitrification. Poor glass, badly prepared window-glass, and glass which has been subjected to strain tend to devitrify on exposure to air, some of the ingredients separating in a crystalline form.

Devi´zes, a town in England, county of Wilts, giving name to a parliamentary division, finely situated on a commanding eminence, 82 miles west by south of London. The name is derived from the Lat. divisæ (terræ, divided lands), because the ancient castle of Devizes was built at the meeting-place of three different manors. Agricultural engines and implements are made, and malting is carried on. Pop. 6740.

Devon, or Devonshire, a maritime county in the s.w. of England, its northern coast being on the Bristol Channel and its southern on the English Channel; area, 1,671,364 acres, the county being the third largest of England. Its principal rivers are the Torridge and the Taw, flowing north into the Bristol Channel; and the Exe, Axe, Teign, Dart, and Tamar, flowing into the English Channel. From Exeter to the confines of Cornwall extends the wide and barren tract called Dartmoor; but the vale of Exeter, comprising from 120,000 to 130,000 acres, and the south extremity of the county called South Hams, limited by a line drawn from Torbay to Plymouth Sound, are amongst the most fertile districts of England. Tin, lead, iron, copper, manganese, granite, and the clay used by potters and pipe-makers are the chief mineral products. The geological formation of the Old Red Sandstone is so largely developed that the term Devonian has to some extent become its synonym. Agriculture is in a somewhat backward state, owing, probably, to the general preference given to dairy husbandry, for which the extent and richness of its grass-lands make the county most [12]suitable. Wheat, barley, beans, pease, and potatoes are the principal crops. About three-fourths of the county is under crops or in pasture. There is a large trade in butter, cheese, and live-stock, and the 'clotted' cream and cider of Devonshire are well known as specialities of the county. There are seven parliamentary divisions, each with one member. Pop. 699,703.—Bibliography: Victoria County History, Devonshire; F. J. Snell, Devonshire, Historical, Descriptive, and Biographical.

Devo´nian System, in geology, a name originally given to rocks in Devonshire and Cornwall, intermediate between the Silurian and Carboniferous strata, and consisting of sandstones, calcareous slates and limestones, &c. They are divided into lower, middle, and upper series, the middle most abounding in fossils, including corals, crinoids, brachiopods, and molluscs. Devonian rocks occupy a large area in Central Europe, as well as in the United States, Eastern Canada, and Nova Scotia. The terrestrial and lacustrine equivalents are known as the Old Red Sandstone.

Dev´onport, formerly a county borough and port of England, county of Devon, contiguous to Plymouth. It is the seat of one of the royal dockyards, and an important naval and military station. A bastioned wall and fosse defend the town on the north-east and south sides, while the sea entrance is protected by heavy batteries on Mount Wise. Connected with the dockyards and fortifications are the gun wharf, foundries, machine-works, rope-walks, store-houses, and naval and military barracks. It has no special trade beyond that connected with the dockyards and Government works. Formerly a parliamentary borough, returning two members to Parliament, Devonport now gives its name to a parliamentary division of Plymouth, with which it is amalgamated since Nov., 1914. Pop. 84,370.

Devonshire, Spencer Compton Cavendish, eighth Duke of, long known as Marquess of Hartington, born in 1833, died 1908. He was the eldest surviving son of the seventh Duke of Devonshire, whom he succeeded in the dukedom in 1891. He was educated at Trinity College, Cambridge, where he graduated as M.A. in 1854. He was attached in 1856 to Earl Granville's Russian mission, and in 1857 was elected as a Liberal one of the members for North Lancashire. In 1863 he was for a short time a Lord of the Admiralty, and he then became Under-Secretary for War, being raised to Cabinet rank as War Secretary in 1866. In 1868 he lost his seat for North Lancashire, but became Postmaster-General under Gladstone, and was returned for the Radnor boroughs. In 1871 he was appointed Chief Secretary for Ireland. He went out with the Gladstone ministry in 1874, and on Gladstone's retirement he became the leader of the Liberal party. On the fall of the Conservative Government in 1880 he was elected for North-East Lancashire, and became Secretary for India under Gladstone, being transferred to the War Office in 1882. In the general election of 1885 he was returned for the Rossendale division of Lancashire. He strenuously opposed Gladstone's Home Rule Scheme of 1886, and became the leader of the Liberal Unionists, but long declined to take office in the Cabinet. In 1895, however, he became Lord President of the Council, and from 1900 to 1902 he was President of the newly-instituted Board of Education. In 1903 he withdrew from co-operating with Mr. Balfour as Premier, mainly because he disliked the fiscal changes proposed by Chamberlain. He then accepted the position of head of the Free-Trade Unionists.

Dew is the name given to the minute drops of water which at certain times appear by night upon grass, flowers, foliage, and other surfaces which readily radiate heat. The first attempts at a scientific explanation of dew were made early in the nineteenth century, when Dr. Wells propounded his theory on the subject. According to this, the origin is to be found in the moisture previously contained in a vaporous state in the atmosphere. During the day the earth both absorbs and emits heat, but by night its supply of warmth is cut off, while it continues, under favouring circumstances, to lose heat by radiation into surrounding space. For any given state of the atmosphere, in respect of the amount of aqueous vapour it contains in a specified volume, there is a certain temperature at which it can hold just that amount and no more in suspension. If it be cooled to that temperature, it begins to deposit its moisture in the liquid form, and if the cooling proceeds further, more and more is deposited. This particular temperature is the dew-point appropriate to the given state of humidity of the air. If the dew-point is below 32°F., the vapour will, when the dew-point is reached, pass directly into the solid form and be deposited as hoar-frost. While there is a certain amount of truth in the foregoing theory, it does not contain the whole facts of the case. Dr. John Aitken, of Falkirk, Stirlingshire, established by experiments that in most cases probably the dew found on plants does not come mainly from the atmosphere. To some extent it exudes from the plants themselves. They derive moisture from the soil, and in the process of supplying their tissues it passes to their outer surfaces, whence in the daytime it is evaporated into the air. By night the fall of temperature checks evaporation of this moisture, and when it reaches their surfaces, it may remain there in the form of dew-drops. Also, moisture [13]is condensed out of the atmosphere upon the cooler plant surfaces, but even this has more often been yielded not long before to the atmosphere through the medium of the plant tissues, so that upon the whole the plants play a much more important part in the process than had been supposed. Dew is most copiously produced when there is a large difference between the day and night temperatures. Hence it is favoured by the absence of clouds, which would throw back much of the heat radiated from the earth. Other favouring circumstances are a still condition of the atmosphere, good radiating surfaces, and an abundant supply of moisture in the soil.

Dewar (dū´a˙r), Sir James, scientist, born at Kincardine-on-Forth, 1842, educated at Dollar Academy, Edinburgh University—where he was assistant to Lord Playfair when professor of chemistry—and Ghent. In 1873 he was elected Jacksonian professor of experimental philosophy at Cambridge, an office which he still holds, and in 1879 a professorial fellow of St. Peter's College. In the latter year he also became Fullerian professor of chemistry at the Royal Institution, London. He is a fellow of the Royal Society, has been awarded several medals and prizes for his scientific researches, including the Rumford medal in 1894 for his investigations into the properties of matter at its lowest temperatures, this branch of science, with which the liquefaction of air and gases is connected, being peculiarly his own. He was the first to reduce hydrogen gas to the liquid and solid form. Together with Sir F. Abel, he was the discoverer of cordite. He is an honorary graduate of several universities, a late president of the Chemical Society and vice-president of the Royal Society, and was president of the British Association in 1902. He has contributed numerous papers to the proceedings of the learned societies of Great Britain, and was knighted in 1904. His collected papers on spectroscopy appeared in 1915.

Dewar Flask, a flask devised by Dewar for the examination of liquefied gases. It consists of an inner vessel surrounded by a vacuum, which much reduces loss or gain of heat by the liquid. The principle now finds practical application in the 'Thermos Flask'.

Dewás, a native state of Central India consisting of two combined states with two chiefs. Total pop. 250,000. Dewás, the chief town, has a pop. of 5200.

Dewberry (Rubus cœsius), a European plant belonging to the ord. of the Rosaceæ, and to the same genus as the bramble, from which it is distinguished by its smaller berries, with fewer grains, and by the bloom, resembling dew, with which they are covered, and from which the plant derives its name. It is common in some parts of England. The Canadian dewberry (R. procumbens) yields a much superior fruit.

De Wet, Christian Rudolf, Boer general, born 1854 in the Orange Free State. His father removing into the Transvaal, he fought as a field-cornet at Majuba. As member of the Volksraad (1889-97) he helped to draw the two Dutch republics together, and in the South African War commanded first in Natal, and then in the west under Cronje, whose rescue at Paardeberg he attempted, but unsuccessfully. After March, 1900, he distinguished himself by his attacks on the British lines of communication, and by his skill in evading capture. He became commander-in-chief of the Free State forces, and was the only undefeated Boer general at the end of the war, after which he, with Louis Botha and Delarey, came to Europe to collect funds for his countrymen. A member of the Legislative Assembly and Minister of Agriculture, Orange Free State, from 1907 to 1914, he joined the rebellion at the outbreak of the European War. Captured at Waterburg on 1st Dec., he was sentenced to a fine of £2000 and six years' imprisonment, but was soon released. He published The Three Years' War in 1902.

Dewey, George, American naval officer, born at Montpellier, Vermont, 26th Dec., 1837, died 16th Jan., 1917. He began active service in the Mediterranean squadron, and in 1862, under Farragut, he was present at the passage of Forts Jackson and St. Philip. Lieutenant-commander in 1865, commander in 1872, he was in command of the Asiatic squadron in 1898, when he destroyed the Spanish fleet at Manila on 1st May. He was made Admiral of the Navy and was thanked by Congress. From 1900 till his death he was President of the General Board of the Navy.

Dewey, John, American philosopher and psychologist, born at Burlington, Vermont, 20th Oct., 1859. Educated at the University of Vermont, he received his Ph.D. degree from Johns Hopkins University. Professor of philosophy at the Universities of Minnesota, Michigan, and Chicago, where he was also director of the School of Education, he became professor of philosophy at Columbia University in 1904. He is one of the two (William James being the other) American leaders of pragmatism, a philosophical conception according to which questions that have no bearing on experience and on life have no significance whatever, and are meaningless. (See Pragmatism.) His works include: Outlines of a Critical Theory of Ethics (1881), Study of Ethics (1894), My Pedagogical Creed (1897), The School and Society (1900), Studies in Logical Theory (1903), How we Think (1909), Interest and Effort in Education (1913), Democracy and Education (1916), Letters from China and Japan (1920). [14]

De Wint, Peter, English landscape painter in water-colours, born 1784, died 1849. He studied in the schools of the Royal Academy, where he occasionally exhibited; but most of his pictures were shown in the exhibitions of the Water-colour Society. English scenery was his favourite subject. He occasionally painted in oil with marked success. Several of his pictures are in the National Gallery and the Victoria and Albert Museum.

De Witt, Jan, Grand-Pensionary of Holland, celebrated as a statesman and for his tragical end, was the son of Jacob de Witt, burgomaster of Dort, and was born in 1625. He became the leader of the political party opposed to the Prince of Orange, and in 1652, two years after the death of William II, was made Grand-Pensionary. In 1665 the war with England was renewed, and conducted by De Witt with great ability till its termination in 1665. In 1672 Louis XIV invaded the Spanish Netherlands and involved Holland in war. De Witt's popularity, already on the decline, suffered still further in the troubles thus occasioned, and he felt it necessary to resign his office of Grand-Pensionary. At this time his brother Cornelius, who had been tried and put to torture for conspiring against the life of the young Prince of Orange, lay in prison. Jan de Witt went to visit him, when a tumult suddenly arose amongst the people, and both brothers were murdered, 20th Aug., 1672. De Witt was a man of high character, simple and modest in all his relations.—Cf. Motley, History of the United Netherlands.

Dew-point, the temperature at which the air is saturated with the water-vapour which it contains. If the temperature of the air falls to the dew-point, dew is deposited. The dew-point is determined by means of an instrument called a hygrometer. When the air is 'dry', the dew-point is low, and evaporation proceeds rapidly, whilst a 'moist' atmosphere is one whose temperature is near the dew-point, and in which evaporation takes place slowly.

Dewsbury, a town, England, in the West Riding of Yorkshire, and 30 miles south-west of the town of York, chiefly engaged in the manufacture of heavy woollen cloths, including blankets, carpets, rugs, flannels, and baizes. In 1862 it was made a municipal borough; in 1867 a parliamentary borough, returning one member. Pop. of municipal borough, 53,351.

Dexter, a term meaning on the right-hand side, chiefly used in heraldry. The dexter chief point is a point in the right-hand upper corner of the shield, being in the dexter extremity of the chief.

Dex´trine, or British Gum, (C₆H₁₀O₅)x, a generic name applied to soluble gummy substances intermediate between starch and glucose. They are prepared from starch by the aid of dilute mineral acids or of enzymes, and are usually named according to the colour they give with iodine, e.g. erythro-dextrine, &c. When heated with dilute acids, they are transformed into glucose. They are white, odourless substances, and are good substitutes for gum-arabic. Dextrine is used in calico printing for thickening colours; for the preparation of gums, and for stiffening cloth.

Dextro-compounds, bodies which cause the plane of a ray of polarized light to rotate to the right. Dextrine itself, dextro-glucose, naturally occurring tartaric acid, malic acid, cinchonine, and many other bodies have this property; while others, which have the opposite effect, of causing the plane to rotate to the left, are called lævo-compounds.

Dey, an honorary title formerly bestowed by the Turks on elderly men, and assumed by the rulers (under the Turkish Sultan) of Algiers, Tripoli, and Tunis.

Dhalak (dha˙-la˙k´), an archipelago of the Red Sea, belonging to the Italian territory of Eritrea. It consists of nearly 100 islets, mostly uninhabited, clustering round the Island of Dhalak-el-Kebir, which is about 35 miles long by 30 miles broad. This island possesses a pearl-fishery.

Dhar (dhär), a small native state in Central India, with an area of about 1740 sq. miles. The soil is fertile, and yields wheat, rice, and opium. Pop. 169,474.—The capital is of the same name, is surrounded by a mud wall, and has some striking buildings. Pop. 19,000.

Dhárangaon, a town of Hindustan, in Khandesh district, Bombay. Pop. 15,000.

Dharmsála, a hill station with military cantonments, in Kangra district, Punjab, India. Pop. 6170.

Dharwar, the chief town of Dharwar district, in the Bombay Presidency, Hindustan, a straggling place with some trade. There is a fort well planned and strongly situated, but now falling into ruins, and military cantonments at 2 miles' distance. Pop. 32,000.—The Dharwar district has an area of 4535 sq. miles; pop. 1,051,314.

Dhawala´giri, or Dhaulágiri, one of the highest peaks of the Himalayas, in Nepál; height, 26,828 feet.

Dhole (dōl), the Cingalese name for the wild dog of India (Cyon dukhunensis). It is distinguished from the genus Canis or dog proper by its having one molar fewer in either side of the lower jaw. It is of a fox-red or rufous-fawn colour, in size between a wolf and a jackal, and hunts always in packs.

Dholera (dhō-lā´ra), a town of Hindustan, [15]Bombay Presidency, on a stream entering the Gulf of Cambay, an important cotton-mart. Pop. 10,190.

Dholka, a town of Hindustan, Bombay Presidency, probably one of the oldest towns in Gujarat. Pop. 16,700.

Dholpur, native state of Central India, Rájputána; area, 1155 sq. miles; pop. 263,188.—The capital is also called Dholpur. Pop. 9750.

Dhow (dou), an Arab sea-going vessel, ranging from a comparatively small size up to 200 tons burden, with one mast and a large triangular (lateen) sail. It is used for merchandise and is often employed in carrying slaves from the east coast of Africa to Arabia.

Dhúliá, a town of Hindustan, Khandesh district, Bombay Presidency. Pop. 22,000.

Diabase, originally an equivalent of diorite; then used for chloritic igneous rocks of the Intermediate series of various grain; and now usually for a type of dolerite in which the felspar is embedded in augite.

Diabe´tes is a disease characterized by great thirst, a voracious appetite, and the passage of large quantities of saccharine urine, while there is usually marked emaciation and debility. As a rule the skin is dry and the patient does not perspire. Skin irritations (pruritus) of an intense type occur frequently and cause much discomfort. Constipation is the rule, but the digestion usually remains good, and enormous quantities of food are taken without causing disturbance.

Acute and chronic forms are recognized, but there is no essential difference, except that in the former the patients are younger, the course more rapid, and the emaciation more marked. Beyond the large quantity, the outstanding feature of the urine is the presence of sugar, varying from 2 per cent in mild cases to 10 per cent in severe cases.

The disease is due to disturbance in the carbohydrate metabolism, with the result that these carbohydrates are not properly assimilated, but passed as sugar in the urine. Much research has been undertaken to find what organ or organs of the body cause this defect in metabolism, and recent work in connection with the pancreas has established a definite relationship between cells in that organ and the disease.

In treatment the main consideration is to reduce the carbohydrates in the dietary, and many diets have been produced for this purpose.

Diabetic patients may take:—liquids: clear soups, lemonade, coffee, tea, cocoa (without sugar), soda-water, and such like waters or milk (in moderation); animal foods: fish of all sorts, fresh meat, poultry, game, eggs, butter, cream-cheese; vegetables: lettuce, tomatoes, spinach, radishes, asparagus, water-cress, cucumbers, chicory, mustard; fruits: lemons, oranges, and in moderation currants, plums, cherries, pears, apples (tart), melons, raspberries, strawberries, nuts: bread: gluten bread, almond or coco-nut biscuits. A substitute for bread is one of the greatest difficulties, as many gluten foods are very unpalatable.

Further, it is important to observe strict personal hygiene and to take moderate exercise, lead a regular, quiet life in an equable climate, and above all to avoid worries of any sort. In acute cases the disease may run a very rapid course, coma frequently supervening a few days before death, but chronic cases may live for ten to twenty years.

Diabetic Sugar. Sugar is present in normal urine in very small amount—so small that it cannot be detected by the ordinary tests. In diabetes the percentage of sugar in the urine may rise, in mild cases, to 1½ to 2 per cent, and in severe cases it may reach to 10 per cent.

Diablerets (dē-a˙b-lė-rā), Les, a mountain group of the Bernese Alps, Switzerland, between the cantons Vaud and Valais. The highest peak has a height of 10,620 feet.

Diachylon (dī-ak´i-lon), a substance prepared by heating together oxide of lead or litharge, olive-oil, and water, until the combination is complete, and replacing the water as it evaporates. It is used for curing ulcers, and is the basis of many plasters. [16]

Di´adem (Gr. diadein, to bind round), an ancient ornament of royalty. It was originally a head-band or fillet made of silk, linen, or wool, worn round the temples and forehead, the ends being tied behind and let fall on the neck, as seen in old representations of the diadem of the Indian Bacchus. In later times it was usually set with pearls and other precious stones. The term is also used as equivalent to crown or coronet.

Diæ´resis, a separation of one syllable into two, also the mark (¨) by which this separation is distinguished, as in aërial.

Diagno´sis, in medicine, the recognition of diseases by their distinctive signs or symptoms; the discovery of the true nature and seat of a disease.

Diag´onal Scale, a scale which consists of a set of parallel lines drawn on a ruler, with lines crossing them at right angles and at equal distances. One of these equal divisions, namely, that at the extremity of the ruler, is subdivided into a number of equal parts, and lines are drawn through the points of division obliquely across the parallels. With the help of the compasses such a scale facilitates the laying down of lines of any required length to the 200th part of an inch. The length 1·67 inches, for example, is given by EF in the figure. Similarly AB = ·91 inch, CD = ·84 inch.

Diag´oras, ancient Greek poet and philosopher, born in Melos, an island of the Cyclades, and flourished about 425 B.C. He spent a great part of his life in Athens. Like his teacher, Democritus, he attacked the prevailing polytheism, and sought to substitute the active powers of nature for the divinities of the Greeks. On this account he had to leave Athens.

Di´agram (Gr. diagraphein, to describe), a figure or geometrical delineation applied to the illustration or solution of geometrical problems, or any illustrative figure in which outlines are chiefly presented, and the details more or less omitted.

Dial, or Sun-dial, an instrument for showing the hour of the day from the shadow thrown by a stile or gnomon upon a graduated surface while the sun is shining. This instrument was known from the earliest times amongst Egyptians, Chaldeans, and Hebrews. From those Eastern nations it came to the Greeks. It was introduced into Rome during the first Punic War. Dials are of various construction, horizontal, inclined, or upright, the principle in every case being to show the sun's distance from the meridian by means of the shadow cast by the stile or gnomon. The stile is made parallel with the earth's axis, and may be considered as coinciding with the axis of the sun's apparent diurnal motion. Consequently, as the sun moves westwards the shadow of the stile moves round opposite to it, in the same direction, falling successively on lines drawn to represent the hours of the day. The dial, of course, gives true solar or apparent time, which, except on four days of the year, is somewhat different from mean time. Dials are now rather articles of curiosity or ornament than of use.—Bibliography: Leybourn, The Art of Dialling; Dawbarn, The Sun-dial.

Di´alect, the language of a part of a country, or a distant colony, deviating either in its grammar, vocabulary, or pronunciation, from the language of that part of the common country whose idiom has been adopted as the literary language, and the medium of intercourse between well-educated people. Although the use of provincial dialects becomes inconvenient after a language has acquired a fixed literary standard, the study of such dialects is always valuable to the philologist for the light they throw on the history of the language. The diffusion of education and of printed books has much relaxed the hold which the provincial dialects of various countries once had on the people, and in general it may be said that the educated classes of any country now speak each of them a uniform language.

Dialec´tics (Gr. dialektice, from dialektos, discourse, dialogue), a philosophic term originally signifying investigation by dialogue. It was first [17]used by Plato to designate the Socratic method. Afterwards it came to denote the art of inference or argument, and in this sense was synonymous with logic. The term is used in Kant's philosophy to mean the logic of appearance, or that logic which treats of inevitable tendencies towards error and illusion in the very nature of reason.

Di´allage, an altered form of the mineral augite, with a lamellar structure, and a submetallic lustre on its planes of separation. Schillerstein, or schiller spar is a similar product of the allied but rhombic mineral hypersthene. It forms diallage rock, and enters into serpentine rock.

Dialling, the art, of making sundials; also the art and practice of mine-surveying, in which the theodolite and magnetic needle are employed.

Di´alogue, a conversation or discourse between two or more persons. The word is used more particularly for a formal conversation in theatrical performances, and for a written conversation or composition, in which two or more persons carry on a discourse. This form was much in favour amongst the ancient philosophers as a medium for expressing their thoughts on subjects. The Dialogues of Plato are the finest example. Many of the great French and Italian writers have used this form. In the seventeenth century Fontenelle and Fénelon both wrote Dialogues des Morts, a title borrowed from Lucian. Landor's Imaginary Conversations (1821-8) is the best production of this kind in English.

Dial´ysis, the process by means of which a crystalline substance may be separated from a colloidal body. Certain substances are capable of passing through parchment, others are not, e.g. a solution containing sugar and silicic acid may be separated by placing the solution in a parchment-paper tube suspended in water; the silicic acid remains in the parchment tube, and the sugar passes through into the surrounding water. The solution is said to be dialyzed.

Diamagnet´ic, a term applied to substances which, when under the influence of magnetism and freely suspended, take a position at right angles to the lines of magnetic force. From the experiments of Faraday it appears that all matter is subject to the magnetic force as universally as it is to the gravitating force, arranging itself into three divisions, the ferromagnetic, paramagnetic, and diamagnetic. Among the former are iron, nickel, cobalt, magnetic oxide of iron, and Heusler's alloy. The more feebly magnetic bodies are classed as paramagnetics, and those which behave as described above are called diamagnetic substances. Among the latter are bismuth, antimony, cadmium, copper, gold, lead, mercury, silver, tin, zinc, and most solid, liquid, and gaseous substances. A diamagnetic body is one which is not so magnetic as the medium in which it is suspended. The action of bismuth, the strongest diamagnetic substance, is weak when compared with the magnetic action of iron.

Diamanti´na, a town, Brazil, in the diamond-mining district in the state of Minas Geraes, the inhabitants of which are almost all engaged in the gold and diamond trade. Pop. about 14,000.

Diam´eter (Gr. dia, through, and metron, measure), the straight line drawn through the centre of a circle and terminated by the circumference. It thus divides the circle into two equal parts, and is the greatest chord. The length of the diameter is to the length of the circumference of the circle as 1 to 3.14159265..., the latter number being an interminable decimal. The name is also given to any chord of a conic which passes through its centre.

Di´amond, the hardest and one of the most valuable of gems, and the purest form in which the element carbon is found. (See Carbon.) It crystallizes in forms belonging to the regular or cubic system, the most common being the regular octahedron and rhombic dodecahedron (twelve faces). The finest diamonds are colourless, perfectly clear, and pellucid. Such are said to be of the finest water. But diamonds are often blue, pink, green, or yellow, and such are highly prized if of a decided and equal tint throughout. The hardness of the diamond is such that nothing will scratch it, nor can it be cut but by itself. The value of a diamond is much enhanced by cutting facets upon it inclined at certain angles to each other so as to produce the greatest possible play of colour and lustre. What is called the brilliant cut best brings out the beauty of the stone. Its upper or principal face is octagonal, surrounded by many facets. But this form of cutting requires an originally well-shaped stone. For other diamonds the rose cut is used. In this form six triangles are cut on the top so that their apices meet in a point called the summit. Round this are disposed other facets. Stones which are too thin to cut as rose-diamonds are cut as table-diamonds, which have a very slight play of colour. In the cut, fig. 1 is the diamond in its rough state; fig. 2 is the vertical, and fig. 3 the lateral appearance of a brilliant; fig. 4 the [18]vertical, and fig. 5 the lateral appearance of a rose-cut diamond; in fig. 6 the flat portion a in a cut stone is called the table; the part a b b, which projects from the setting, is the front, the part b b c, sunk in the setting, is the back or culasse, while the line b b is the girdle. The art of cutting and polishing the diamond was unknown in Europe till the fifteenth century, and the stone itself was not nearly so highly valued in the Middle Ages as the ruby. Diamonds are valuable for many purposes. Their powder is the best for the lapidary, and they are used for jewelling watches, and in the cutting of window- and plate-glass. When used as a glazier's tool the diamond must be uncut. Inferior kinds of diamonds are also extensively used by engineers in rock-boring, and by copperplate engravers as etching-points. Diamonds are obtained from deposits of various kinds, mostly alluvial (sands, clays, &c.), being separated by washing. They have been found in India, Borneo, and other parts of the East; sometimes in N. America and Australia; Brazil has produced large numbers; but the chief diamond-field of to-day is in Cape Province, the centre being Kimberley. Diamonds were discovered here in 1867, and since then the output has amounted to over £183,000,000 in value. The diamonds are no longer obtained by mere surface workings, but the excavations have been carried down to a depth of 2000 feet. 'River diggings' are also carried on on the banks of some of the rivers. Some of the S. African diamonds are very large. One of them, the Cullinan diamond, discovered in 1905, is a monster of 3025 carats, of very good colour, being by far the largest diamond known. A celebrated diamond is the Koh-i-noor (Mountain of Light), an Indian stone belonging to the British crown. Its history extends over five or six centuries. It weighed at one time 280 carats, but by cutting has been reduced to about 106 carats. The Orlov diamond, which belonged to the Emperor of Russia, weighed 194 carats; the Pitt diamond, among the French crown jewels, weighs 136½ carats.—Bibliography: A. Jeffries, A Treatise on Diamonds and Pearls; H. Emanuel, Diamonds and Precious Stones; E. W. Streeter, Precious Stones and Gems; idem, The Great Diamonds of the World; G. F. H. Smith, Gem-Stones; P. A. Wagner, The Diamond Fields of Southern Africa.

Diamond-beetle, Entimus imperialis, a handsome South American insect belonging to the family Curculionidæ or weevils. It is spangled with golden-green on a black background.

Diamond Harbour, a port on the left bank of the Hugli River, about 38 miles by the railway from Calcutta, formerly much used as an anchorage for ships waiting for the tide.

Diamond Lore. In Hellenic, Arabian, Chinese, and other literature the diamond is connected with the eagle and snakes. Diamonds, according to ancient belief, lie in deep valleys infested by snakes, or entirely surrounded by straight, high cliffs. Pieces of flesh are thrown down and eagles seize them. The birds are followed to their nests, where the diamonds that adhered to the flesh are found. Mixed with this legend is the older one regarding the 'eagle stone', which assists parturition. It was believed a woman was easily delivered if the 'eagle stone' were placed on her abdomen. The Chinese legend was imported with the diamond from Fu-lin (Syria). Indian diamond lore is mixed with pearl lore. According to the Buddha birth stories, diamonds are found in the sea. The ancients asserted that the diamond could not be injured by iron, fire, or smoke. Before it could be broken it had to be steeped in ram's blood. The alchemists used lead as a substitute for ram's blood. In Chinese lore diamonds are rulers of gold and have their origin in gold. A similar belief prevailed in mediæval Europe, adamantine gold being credited with the same virtues as the diamond. Both gold and the diamond were sacred. The diamond is a mediæval symbol of Christ; in the Far East it is connected with Buddha. The association of the diamond with snakes gave origin to the belief that it was poisonous, the saliva of the snakes clinging to it. Diamond dust is regarded in India as a deadly poison. Like the sacred pearl, the diamond has been credited with nocturnal luminosity. Certain varieties of diamonds when heated, rubbed, or exposed in bright sunshine emit slight rays of light for a short time in darkness. The belief in 'night shining gems', however, had origin in pearl lore, the pearl having been connected with the moon ('the pearl of heaven'). Coral, rhinoceros-horn, fern seed, the mandrake, &c., were likewise connected with the moon-goddess and credited with nocturnal luminosity.

Diamond Necklace, an affair of some note in French history immediately preceding the Revolution. See Marie Antoinette; La Motte; and Rohan, Louis.

Dian´a, in Roman mythology, an ancient Italian goddess, in later times identified with the Greek Artĕmis, with whom she had various attributes in common, being the virgin goddess of the moon, and of the chase, and having as attributes the crescent moon, bow, arrows, and quiver. The name is a feminine form of Janus. She seems to have been originally the patron divinity of the Sabines and Latins. She was worshipped especially by women, as presiding over births, no man being allowed to enter her temple. [19]

Diana-monkey (Cercopithēcus Diana), a species of monkey found in West Africa, and so named from the crescent-shaped band on the forehead resembling the crescent moon, which was the symbol of Diana. Another characteristic feature is the possession of a pointed white beard.

Diana of Poitiers, Duchess of Valentinois, born in 1499. She was the mistress of King Henry II of France, and descended from the noble family of Poitiers, in Dauphiny. At an early age she married the Grand-Seneschal of Normandy, Louis de Brézé, became a widow at thirty-one, and some time after the mistress of the young Duke of Orleans. On his accession to the throne in 1547, as Henry II, Diana continued to exercise an absolute empire over him till his death in 1559. After that event she retired to her castle of Anet, where she died in 1566.—Cf. Capefigue, Diane de Poitiers.

Diapa´son, in music, the concord of the first and last notes of an octave. The word is also used for the most important foundation-stops of an organ. They are of several kinds, as open diapason, stopped diapason, double diapason. The French use the term as equivalent to pitch in music.

Di´aper, a kind of textile fabric much used for towels and napkins, and formed either of linen or cotton, or a mixture of the two, upon the surface of which a flowered or figured pattern is produced by a peculiar mode of twilling.—As a term in ornamentation diaper is applied to a surface covered with a flowered pattern sculptured in low relief, or to a similar pattern in painting or gilding covering a panel or flat surface.

Diaphanoscope, (1) an apparatus by means of which transparent positive photographs may be viewed. The name is also given to (2) an instrument employed in obstetrical surgery; electric light, contained in a glass tube or bulb, is introduced into the female internal organs, and, thus illumined, their condition can be examined through the translucent walls of the abdomen.

Diaphoret´ics (Gr. diaphorein, to carry through) are agents used in medical practice to produce perspiration. The Turkish bath, hydropathic treatment, diluent drinks, &c., are employed for this purpose. The degree of perspiration produced is more than normal, but less than in sweating. See Sudorifics.

Diaphragm (dī´a-fram), in anatomy, a muscular membrane placed transversely in the trunk, and dividing the chest from the abdominal cavity. In its natural situation the diaphragm is convex on the upper side and concave on its lower, but when the lungs are filled with air it becomes almost flat. It is the principal agent in respiration, particularly in inspiration. A complete diaphragm is found only in Mammalia.

Diarbek´ir, a town in Armenia, formerly in Asiatic Turkey, capital of the vilayet of same name, on a high bank overlooking the Tigris, and surrounded by a lofty massive wall. It has manufactures of iron- and copper-ware, leather, silk, woollen, and cotton goods, and a considerable trade. Pop. about 38,000.—The province of Diarbekir has an area of 14,480 sq. miles, and a pop. of 471,500.

Diarrhœ´a is morbidly frequent evacuation of the bowels. Several forms are recognized. Choleraic diarrhœa; this form is acute, and is marked by great frequency, with serous stools, and accompanied by vomiting and collapse. Critical diarrhœa occurs at the crisis of a disease. Lienteric diarrhœa is marked by the passage of fluid stools containing scraps of undigested food. Mucous diarrhœa is marked by the presence of mucous in the stools. Summer diarrhœa occurs chiefly among young children and infants, most frequently in late summer. It is usually acute in type and associated with marked prostration. In epidemic form it may give rise to a high mortality in crowded districts and in [20]institutions. Nervous diarrhœa is produced by some emotional cause. The treatment, whatever the type, is to get rid of the cause of the irritation, and to avoid further irritation in the intestinal tract. For this purpose purgatives are given, and all solid food forbidden. This is followed by gastro-intestinal sedatives and a gradual return to normal diet—substances causing least digestive difficulty being first given.

Diastase is an unorganized ferment or enzyme produced in the germination of barley, oats, &c. It is soluble in water, and the solution has the property of inducing fermentation or hydrolysis of starch into dextrine and glucose. To prepare diastase, barley is allowed to germinate; germination is then interrupted by raising the temperature, and the grain is treated with a mixture of water and alcohol under pressure, and filtered. Diastase, being soluble, is obtained in the filtrate.

Diather´mancy, the property that is possessed in various degrees by different substances, of transmitting radiant heat. Bodies that are equally transparent, that is, bodies which have equal power of transmitting rays of light, are very different in their power of transmitting heat-rays. Thus a thin plate of glass and a thin plate of rock-salt may be nearly equally transparent, but the plate of rock-salt has far superior power of transmitting rays of heat. The latter, it has been found, allows 92 per cent of the total heat from most sources to pass; glass and other substances transmit a much smaller proportion, and the amount varies with the source. Rock-salt is diathermanous to heat from nearly all sources. It has been shown that rock-salt is extremely opaque or athermanous to the radiations from a piece of heated rock-salt. The diathermancy of the plates in every case decreases very rapidly as their thickness is increased. See Radiation.

Diath´esis is the term given in medicine to a constitutional predisposition to a disease; thus uratic diathesis is a tendency to gout; aneurysmal diathesis is an inherent predisposition to aneurysms.

Diatoma´ceæ, a family of Algæ, consisting of microscopic unicellular plants with brown chromatophores found in fresh, brackish, and salt water, and on damp ground. The cell wall contains a very large quantity of silica, and is formed in each cell into three portions, viz. two generally symmetrical valves and a connecting hoop. The species consist of single free cells, or the cells remain connected so as to form usually linear colonies, sometimes enclosed in a transparent gelatinous sheath. The ordinary method of increase is by cell division. A sexual process resembling that of the conjugatæ also occurs. Diatoms constitute an important source of food for the lower marine animals, and thus indirectly for the food-fishes. Diatomaceæ are found fossil, forming considerable deposits of tertiary age, as at Bilin, Richmond in the United States, &c. Fossil polishing-powders, as tripoli and bergmehl, are composed of them; also kieselguhr, which, impregnated with nitroglycerine, forms dynamite. They are abundant in guano.

Diat´omite (Ger. kieselguhr), a diatomaceous earth (see Diatomaceæ) generally found underlying peat. In Skye, at Loch Quire, it is found about 18 inches below the surface, and extends downward for about 7 feet, and in some places to a much greater depth. Another important area is north of Toome Bridge in the county of Antrim. Diatomite is principally used for the manufacture of dynamite on account of its value as an absorbent. It is described also as extremely well adapted for the manufacture of silicate paints, siliceous glazings, porcelain, boiler-coatings, and for isolating felt and bricks for cold-storage buildings.

Diaton´ic, a term originally applied by the Greeks to one of their three genera of music. In modern music it is applied to the natural scale, and to the intervals, chords, melodies, or harmony characteristic of it. A diatonic chord is a chord having no note chromatically altered. A diatonic interval is an interval formed by two notes of the diatonic scale unaltered by accidentals. A diatonic melody is a melody composed of notes belonging to one scale only.

Diaz, Bartolommeo, a celebrated Portuguese navigator of the fifteenth century, named in 1486 commander of one of that long succession of exploratory expeditions which the Portuguese court had during this century become distinguished for promoting. The two vessels composing the expedition sailed along the African coast till they reached Cape Negro (lat. 15° 50' S.), where Diego Cam, a previous explorer, had stopped. At 29° S. they anchored at a point to which they gave the name of Angra das Voltas (Bay of Detours). In sailing south from this point they doubled the Cape of Good Hope without knowing it, and landed at a bay on the east coast. Diaz now wished to continue his voyage in order to discover the country of Prester John, but the sailors refused to accompany him. In again doubling the Cape he gave it the name of Cabo Tormentoso (Cape of Storms), which the king changed to its present designation. In 1500 Diaz had command of a vessel in the expedition of Cabral which discovered Brazil. In returning home the vessel which he commanded was lost, 29th May, 1500.

Diazo Compounds, or Diazonium [21]Compounds, a name given to substances containing the chemical group - N:N -; thus diazo-benzene chloride, C₆H₅ - N:N·Cl, or diazo-toluene sulphate, C₆H₄(CH₃) - N:NH·SO₄, &c.

These substances are formed from the aromatic amines by treatment with nitrous acid at low temperatures. Primary amines all react with nitrous acid at moderate temperatures when the amino group (NH₂) is replaced by a hydroxyl group (OH); thus ethylamine (C₂H₅NH₂) reacts with nitrous acid (HNO₂), yielding alcohol (C₂H₅OH), C₂H₅NH₂ + HNO₂ - C₂H₅OH + N₂ + H₂O. The aromatic amines, however, if treated below 0° C. with nitrous acid, yield diazo compounds, and not hydroxy compounds, e.g. aniline treated with nitrous acid in hydrochloric acid solution yields diazo-benzene chloride, C₆H₅NH₂·HCl + HONO = C₆H₅ - N:N·Cl + 2(H₂O). Diazo salts are crystalline compounds soluble in water, sparingly soluble in alcohol, and are unstable, decomposing explosively if struck or suddenly heated. In solution in water they decompose as the temperature rises, liberating nitrogen, and forming hydroxy compounds, C₆H₅N:NCl + H₂O = C₆H₅OH + N₂ + HCl. Diazo salts are valuable in the synthesis of different classes of compounds, as the - N:N - group reacts readily with other groups. For this purpose it is usually only necessary to prepare a solution containing the diazo compound. In the preparation of the azo dyes the starting-point is a primary amine; the amino group is 'diazotized', i.e. treated with a solution of sodium nitrite and dilute mineral acid at low temperature. A diazo salt is formed, and is then made to react in solution with a hydroxy compound or an amino compound, &c., with the formation of a highly coloured azo compound. The diazo compound is then said to be coupled. Diazo compounds are therefore important intermediate substances in the manufacture of azo dyes.

The diazo group may also be exchanged for the hydroxyl group by warming the solution with water, or for the cyanogen group by warming with a solution of potassium cyanide, e.g. diazo-benzene chloride warmed with potassium cyanide solution is converted into the nitrile of benzoic acid, C₆H₅ - N:NCl + KCN = C₆H₅CN + KCl + N₂; or transformed into halogen derivatives of hydrocarbons by warming with cuprous chloride, e.g. diazo-benzene chloride is transformed into chlorobenzene, C₆H₅ - N:NCl + Cu₂Cl₂ = C₆H₅Cl + N₂ + Cu₂Cl₂. These reactions, where nitrogen is eliminated from the compound, and a group or element replaces the two atoms of nitrogen, afford a means of synthesizing a variety of compounds.

Dib´din, Charles, an English dramatic manager and poet, composer and actor, born in 1745, died in 1814. At the age of fifteen he made his appearance on the stage, and was early distinguished as a composer. He invented a new kind of entertainment, consisting of music, songs, and public declamations, which he wrote, sang, composed, and performed himself, and by this means succeeded in amusing the public for twenty years. In 1769 he composed some of the music for the Shakespeare jubilee at Stratford-on-Avon. His patriotic songs were very popular, and his sea-songs, amongst which are Tom Bowling, Poor Jack, and The Trim-built Wherry, are still favourites in the British navy. He also wrote a History of the Stage, and the novels The Devil and Hannah Hewitt.—His son, Charles Dibdin, composed and wrote many small pieces and occasional songs.—Another son, Thomas, early displayed the same dramatic tastes as his father, was connected with various theatres, and wrote a great many songs and a number of dramas.

Dibdin, Thomas Frognall, an English bibliographer, born in 1776, died in 1847, was the son of the elder brother of Charles Dibdin the celebrated naval song-writer. After studying law and practising as a provincial counsel, he took orders and became a popular preacher in London. Here his bibliographical tastes developed themselves, and the Roxburghe Club being established in 1812, he became its first vice-president. Among his numerous writings may be noted: Bibliomania, Bibliographical Decameron, Typographical Antiquities of Great Britain, and The Library Companion.

Dibranchia´ta. See Cephalopoda.

Dice, cubical pieces of bone or ivory, marked with dots on each of their six faces, from one to six, according to the number of faces. They are shaken in a small box and then thrown on the table. Dice are often loaded or falsified in some way so as to make the high or the low sides turn down. The origin of dice is ascribed to Palamedes of Greece (1244 B.C.), although Herodotus attributes the invention of knuckle-bones and of dice to the Lydians. Dice were well known amongst the ancient Egyptians and Greeks, and are still very popular in Japan, China, India, and other Asiatic countries.

Dicen´tra. See Diëlytra.

Dichasium. See Cyme.

Dichlamydeous (dī-klam-id´i-us), in botany, said of plants that have both calyx and corolla.

Dichogamy, in flowers, the condition in which anthers and stigmas ripen at different times, whereby self-pollination is effectually prevented. If the anthers ripen first, as in borage, columbine, crocus, Caryophyllaceæ, Compositæ, Labiatæ, &c., the flower is said to be protandrous; protogynous flowers, with stigmas ripening and withering before the pollen is shed, occur, e.g. in Christmas rose, Colchicum, [22]horse-chestnut, and in the majority of wind-pollinated plants.

Dichotomy (dī-kot´o-mi), a cutting in two; a division by pairs. Hence, in botany, a mode of branching by constant forking, each branch dividing into two others. See Branching.

Dichroic, or more generally Pleochroic, Crystals (dī-krō´ik), crystals that have the property of exhibiting different colours, according to the direction in which they are traversed by rays of light. When polarized light is passed through a transparent plate of a pleochroic mineral, the colour will vary with the direction in which the light-vibrations take place. Hence, face-pleochroism, the colour of the plate, may be distinguished from the colours given by axis-pleochroism, the colours given by light vibrating parallel with certain optical directions in the crystal.

Dichroite (dī´kro-īt), or Iolite, a mineral, a silicate of magnesium, iron, and aluminium, which readily undergoes modifications and passes into hydrous silicate. It exhibits marked pleochroism, whence the name.

Dick, Thomas, LL.D., a Scottish author of popular scientific works, born at Dundee in 1774, died 29th July, 1857. He was for many years a teacher at Perth, but subsequently resided at Broughty-Ferry, where he devoted himself to astronomical science, especially in its relations to religion. Some years before his death a small pension was granted to him by the Government. Amongst his works are: The Christian Philosopher (1823), The Philosophy of Religion (1825), The Philosophy of a Future State (1828), and Celestial Scenery (1838).

Dickens, Charles, one of the greatest English novelists, born 7th Feb., 1812, at Landport, Portsmouth, died 9th June, 1870. His father, John Dickens, was then in the employment of the Navy Pay Department, but subsequently became a newspaper reporter in London. Young Dickens received a somewhat scanty education, was for a time a mere drudge in a blacking warehouse, and subsequently a clerk in an attorney's office. Having perfected himself in shorthand, however, he became a newspaper critic and reporter, was engaged on The Mirror of Parliament, and The True Sun, and in 1835 on The Morning Chronicle. For some time previously he had been contributing humorous pieces to The Monthly Magazine; but at length, in 1835, appeared in The Morning Chronicle the first of that series of Sketches by Boz which brought Dickens into fame. It was followed in quick succession by a pamphlet entitled Sunday under Three Heads, by Timothy Spark (1836); The Tuggs at Ramsgate (1836); The Village Coquette, a comic opera (1836); and a farce called The Strange Gentleman (1836). In the same year Chapman & Hall engaged the new writer to prepare the letterpress for a series of comic sketches on sporting subjects by Seymour, an artist who had already achieved fame, and suggested as a subject the adventures of an eccentric club. Seymour committed suicide soon after, and H. K. Browne joined Dickens as illustrator, the result being the immortal Pickwick Papers. The great characteristics of Dickens's genius were now fully apparent, and his fame rose at once to the highest point it was possible for a writer of fiction to reach. A new class of characters, eccentric indeed, but vital representations of the humours and oddities of life, such as Mr. Pickwick, Sam Weller and his father, Mr. Winkle, and others, was made familiar to the public. Under the name of The Posthumous Papers of the Pickwick Club this work was published in 2 vols. 8vo, in 1837. In the same year Dickens was engaged as editor of Bentley's Magazine, to which he contributed Oliver Twist, a work which opened up that vein of philanthropic pathos and indignant satire upon institutions which became a distinguishing feature of his works. Before the completion of Oliver Twist, Nicholas Nickleby was begun, being issued complete in 1839. As the special object of Oliver Twist was to expose the conduct of workhouses, that of Nicholas Nickleby was to denounce the management of cheap boarding-schools. Master Humphrey's Clock, issued in weekly numbers, contained among other matter two other leading tales, The Old Curiosity Shop and Barnaby Rudge, the latter a historical tale, going back to the times of the Gordon riots. It was published complete between 1840 and 1841. In 1841 Dickens visited America, and on his return he wrote American Notes for General Circulation (1842). His next novel, Martin Chuzzlewit (1844), dwelt again on his American experiences. This work also added a number of typical figures—Mr. Pecksniff, Mark Tapley, Sarah Gamp, and others—to English literature. The series of Christmas Tales, in which a new element of his genius, the power of handling the weird machinery of ghostly legend in subordination to his own peculiar humour, excited a new sensation of wonder and delight. These, enumerated consecutively, were: A Christmas Carol (1843), The Chimes (1844), The Cricket on the Hearth (1845), The Battle of Life (1846), The Haunted Man and The Ghost's Bargain (1847). The extraordinary popularity of these tales created for a time a new department in literature, that of the sensational tale for the Christmas season. In 1845 Dickens went to Italy, and on his return The Daily News, started on 1st Jan., 1846, was entrusted to his editorial management; but, despite his early training, this was an [23]occupation uncongenial to his mind, and in a few months the experiment was abandoned. His Pictures from Italy were published the same year. Next followed his novel of Dombey and Son (1848), and David Copperfield, a work which has a strong autobiographical element in it (1849-50). In 1850 Dickens became editor of the weekly serial Household Words, in which various original contributions from his own pen appeared. In 1853 his Bleak House came out. A Child's History of England, commenced in Household Words, was published between 1852 and 1854. Hard Times appeared in Household Words, and was published in 1854. Little Dorrit, commenced in 1856, dealt with imprisonment for debt, the contrasts of character developed by wealth and poverty, and executive imbecility, idealized in the Circumlocution Office. In 1859, in consequence of a disagreement with his publishers, All the Year Round superseded Household Words; and in the first number of this periodical, 28th May, was begun A Tale of Two Cities. Great Expectations followed in the same paper, on 1st Dec., 1860. In All the Year Round also appeared a series of disconnected sketches called The Uncommercial Traveller, published in 1868. Our Mutual Friend, completed in 1865, and published in the usual monthly numbers, with illustrations by Marcus Stone, was the last great serial work which Dickens lived to finish. It contained some studies of characters of a breadth and depth unusual with Dickens, and is distinguished among his works by its elaborate plot. The first number of his last work, The Mystery of Edwin Drood, was issued on 1st April, 1870, and only three numbers had appeared when he died somewhat suddenly, at his residence, Gad's Hill Place, near Rochester, on 9th June. He had considerably overtaxed his strength during his later years, more especially by his successive series of public readings from his own works, one series being delivered in America between 1867 and 1868. He was buried in Westminster Abbey. Dickens's work as a novelist is firmly based upon a wide and keen observation of men. The essence of his art was caricature, and for comic effect he, therefore, often exaggerated the abuses he attacked. His characters exhibit little more than one trait or quality, but the single trait or quality which they embody is truly conceived, and exhibited with great vitality and humour. His creative power was immense, and his great humour is admitted by all, even by those who consider his pathos as overdrawn. In spite, therefore, of all that is grotesque and overstrained in his work, he has been rightly placed amongst the great artists.—Bibliography: J. Forster, Life of Charles Dickens; George Gissing, Charles Dickens: a Critical Study; G. K. Chesterton, Charles Dickens; R. H. Shepherd, The Bibliography of Dickens; Sir F. T. Marzials, Life of Charles Dickens; E. Pugh, The Charles Dickens Originals; P. H. Fitzgerald, Memoirs of Charles Dickens.

Dicksonia, a genus of Leptosporangiate ferns, section Gradatæ, mostly large tree-ferns, such as D. antarctica, a native of Australia and New Zealand, often grown in greenhouses.

Dicotyledon (dī-kot-i-le´don), a plant whose seeds are readily recognized by the embryo containing a pair of cotyledons or seed-leaves, which are always opposite to each other. Dicotyledons are further characterized by their netted-veined leaves and their 'open' vascular bundles containing a cambium; the parts of the flower are commonly in fours or fives. In Bentham and Hooker's system the class is divided into four subclasses—Thalamifloræ, Calycifloræ, Corollifloræ, and Monochlamydeæ. Engler's system recognizes only two subclasses, viz. Archichlamydeæ and Sympetalæ.

Dictaphone, an adaptation of the gramophone, in which the principle of that invention is applied to the requirements of modern business. Letters or memoranda are spoken into the machine, which 'records' them on waxen cylinders. The machine is then passed on to a shorthand writer or typist (or the cylinder may be transferred to a duplicate machine), and the recorded matter is dictated. The [24]motive power is electricity; the speed of dictation is capable of adjustment to that of the writer; and by means of an accessory machine the records can be scraped and re-used.

Dicta´tor, an extraordinary magistrate of the Roman Republic, first instituted B.C. 501. The power of naming a dictator, when an emergency arose requiring a concentration of the powers of the State in a single superior officer, was vested by a resolution of the Senate in one of the Consuls. The dictatorship was limited to six months, and the person who held it could not go out of Italy. This rule was laid aside during the first Punic War. The dictator was also forbidden to appear in Rome on horseback without the permission of the people, and he had no control over the public funds without the permission of the Senate. He had the power of life and death, and could punish without appeal to the Senate or people. All the other magistrates were under his orders. Originally the dictator was a patrician, but in 356 B.C. the plebeian Marcius Rutilus was called upon to fill the office of dictator. The term is now often applied to rulers enjoying or exercising extra-constitutional power.—Cf. A. H. J. Greenidge, Roman Public Life.

Dictionary (from the Lat., dictio, a saying, expression, word), a book containing the words, or subjects, which it treats, arranged in alphabetical order. It may be either a vocabulary, or collection of the words in a language, with their definitions; or a special work on one or more branches of science or art prepared on the principle of alphabetical arrangement, such as dictionaries of biography, law, music, medicine, history, or philosophy. Amongst dictionaries of the English language, the earliest seem to have been those of Bullokar (1616) and Cockeram (1623). That of Dr. Johnson, published in 1755, made an epoch in this department of literature. Previous to this the chief English dictionary was that of Bailey, a useful work in its way. An enlarged edition of Johnson's dictionary, by the Rev. H. J. Todd, appeared in 1818; and this, again enlarged and modified, was issued under the editorship of Dr. R. G. Latham (1864-72). The best-known American dictionary of the English language is that by Noah Webster, published in 1828, and since entirely recast. Richardson's dictionary, published during 1836 and 1837, was valuable chiefly for its quotations. Ogilvie's Imperial English Dictionary, based on Webster, and first published between 1847 and 1850, has been issued in a remodelled and greatly enlarged form (4 vols. 1881-2 and subsequently, Charles Annandale, LL.D., editor). It is one of the encyclopædic dictionaries. Cassell's Encyclopædic Dictionary is another extensive work (1879-88). The largest completed English dictionary is the Century Dictionary (New York, 1889-91, 6 vols. quarto). The Standard Dictionary is another American work. A new English dictionary 'on historical principles', first edited by Sir J. A. H. Murray, LL.D., with the assistance of many scholars, and now edited by Dr. Henry Bradley, is being published at the Clarendon Press since 1884. Among foreign dictionaries are the polyglot dictionary of Calepino (1502), the Latin and Greek Thesaurus of Robert and Henry Stephanus, the Italian Vocabulario della Crusca (1612), &c. The chief etymological dictionary of English words is that by Professor Skeat (1882). Among French dictionaries (for French people) the chief is that of Littré; among German, the dictionary begun by the brothers Grimm.

Dictyotaceæ, a family of Brown Algæ, section Cyclosporeæ. Dictyota dichotoma, with a delicate, flattened, repeatedly forked thallus, is not uncommon in sandy pools on our coasts. The plants are of three kinds, viz. ♂, bearing antheridia; ♀, bearing oogonia; and neuter, producing tetraspores. The oospores give rise to neuter plants, the tetraspores to ♂ or ♀ plants. This is one of the best instances of 'homologous' alternation of generations, i.e. that type in which the different generations are identical in form, differing only in their reproductive organs and in the number of chromosomes in their nuclei. Another genus is Padina.

Didactic Poetry, that kind of poetry which professes to give a kind of systematized instruction on a definite subject or range of subjects. Thus the Georgics of Virgil and the De Rerum Natura of Lucretius profess to give, the one a complete account of agriculture and kindred arts, the other a philosophical explanation of the world. Other examples of purely didactic poetry are Horace's Ars Poetica, and Pope's Essay on Criticism. In a larger sense of the word most great poems might be called didactic, since they contain a didactic element in the shape of history or moral teaching, Dante's Divina Commedia, Milton's Paradise Lost, or Goethe's Faust, for example. The difference may be said to be this, that in the one case the materials are limited and controlled by nothing but the creative fancy of the poet, while in the other they are much more determined by the actual nature of the subject treated of.

Didel´phia, one of the three subclasses of the Mammalia (the others being Monodelphia and Ornithodelphia), comprising only one order, that of Marsupials or pouched mammals.

Diderot (dēd-rō), Denis, a French writer and philosopher, born in 1713, at Langres, in Champagne, died in 1784. He was educated in the [25]school of the Jesuits, and afterwards at Paris, at the College of Harcourt, but declined to study law, preferring to earn his living by teaching mathematics. His first works were the Essai sur le Mérite et la Vertu (1745); and the Pensées Philosophiques (1746), a pamphlet against the Christian religion. His Lettre sur les Aveugles à l'Usage de Ceux qui Voyent is in the same strain. These heterodox publications cost him an imprisonment for some time at Vincennes. Diderot now tried writing for the stage, but his pieces were failures. In 1749 he had begun, along with D'Alembert and some others, the Encyclopædia. At first it was intended to be mainly a translation of one already published in English by Chambers. Diderot and D'Alembert, however, enlarged upon this project, and made the new Encyclopædia a magnificently comprehensive and bold account of all the thought and science of the time. Diderot, besides revising the whole, undertook at first the mechanical arts, and subsequently made contributions in history, philosophy, and art criticism. But the profits of all his labour were small, and it was only the liberality of the Empress Catherine, who purchased his library for 50,000 livres and made him a yearly allowance of 1000 livres, that saved Diderot from indigence. In 1773 he visited St. Petersburg to thank his benefactress and was received with great honour. On his return to France he lived in retirement, passing the last ten years of his life in writing and conversations, wherein, as Marmontel said, he was at his best. Besides his articles in the Encyclopædia he wrote numerous works, some of which were published after his death. Among the best known are Le Neveu de Rameau, a kind of philosophical dialogue which Goethe thought worthy of translation; Essai sur la Peinture, and Paradoxe sur le Comédien, suggestive essays on the principles of painting and acting; two lively tales, La Religieuse and Jacques le Fataliste. On account of his great interest in almost every branch of human knowledge, Voltaire nicknamed him 'Pantophile Diderot'.—Bibliography: T. Carlyle, Essay on Diderot; F. Brunetière, Études Critiques; R. L. Cru, Diderot as a Disciple of English Thought.

Dido, or Elissa, the reputed founder of Carthage. She was the daughter of a king of Tyre, called by some Belus, by others Metten or Matgenus. After her father's death, her brother Pygmalion murdered her husband Sicharbas, or as Virgil calls him Sychæus, with the view of obtaining his wealth. But Dido, accompanied by many Tyrians of her party, fled with all the treasure over sea, and, landing on the coast of Africa, founded Carthage about 860 B.C. The story is told by Virgil, with many inventions of his own, in the Æneid (Books i and ii).

Didot (dē-dō), a famous house of printers, booksellers, and typefounders at Paris. The founder was François Didot, born in 1689, died 1757. Of his sons François-Ambroise (born 1720, died 1804) and Pierre-François (born 1732, died 1795) the first distinguished himself in the type-founding art as an inventor of new processes and machines, the second was equally eminent for his bibliographical knowledge, and contributed much also to the advancement of printing.—Pierre (born 1761, died 1853) succeeded his father François-Ambroise in the printing business. He made himself famous by his magnificent editions of classic authors in folio, amongst which his Virgil (1798) and his Racine (1801) may be particularly mentioned. He did much also for the improvement of types. He is known also as an author.—Firmin (born 1764, died 1836), the brother of Pierre, took charge of the type-founding, was the inventor of a new sort of script, and an improver of the stereotype process.—Ambroise-Firmin (born 1790, died 1876), and Hyacinthe-Firmin (born 1794, died 1880) occupied a distinguished position amongst the publishers of Paris. The former left a collection of MSS. which was worth, at the time of his death, about two million francs. The house has now extended its trade into everything connected with bookselling, paper-making, and bookbinding.

Didsbury, a district of Manchester, on the Midland Railway, 4 miles south by east of Manchester, a place of residence of many Manchester business men. There is an important Wesleyan Training College there. Pop. 9234.

Didun´culus, a genus of birds allied to the pigeons, and comprising only the one species, D. strigirostris, native to some of the Samoan Islands. This bird is of special interest as being the nearest living ally of the extinct dodo. It has a length of about 14 inches, with a glossy plumage verging from a velvety black on the back to greenish black on the head, breast, and abdomen. The large beak, which is nearly as [26]long as the head, is greatly arched on the upper half, while the lower is furnished with two or three tooth-like indentations.

Didym´ium, a rare metallic element, occurring along with lanthanum in the mineral cerite as discovered by Mosander in 1842. It has been resolved into two new elements: Praseodymium (Pr, 140.9) and Neodymium (Nd, 144.3).

Die, a metallic stamp for impressing a design or figure upon coins or other metallic objects. See Dies and Die-sinking.

Die (dē), an ancient town, France, department of Drôme, 26 miles south-east of Valence; with an ancient cathedral and Roman remains. Pop. 4000.

Dié (di-ā), St., a town, France, department of Vosges, on the Meurthe, 25 miles E.N.E. of Epinal. Both iron and copper are worked; there are marble quarries; and numerous manufactures are carried on. Pop. 19,029.

Diebitsch-Sabalkanski, Hans Karl, a Russian general, born at Grossleippe, in Silesia, in 1785, died 9th June, 1831. He was educated at the military school of Berlin, but in 1801 quitted the Prussian service for that of Russia. He was present at the battles of Austerlitz and Friedland, served with distinction in the campaign of 1812, took part in the battles of Dresden and Leipzig, and was made lieutenant-general at the age of twenty-eight. He had the chief command in the Turkish War of 1828-9, stormed Varna, and made the famous passage of the Balkans, for which the surname of Sabalkanski was conferred on him. In 1830 he commanded the army sent against the revolted Poles, but did not distinguish himself in this service.—Cf. Bantych-Kamenski, Biographies of Russian Field-marshals.

Dieffenbach (dē´fen-ba˙h), Johann Friedrich, German surgeon, born at Königsberg in 1792, died in 1847. After having studied at Bonn and Paris, he settled in Berlin, where his talent as an operator soon attracted notice. Surgery is particularly indebted to him for new methods of forming artificial noses, eyelids, and lips, and curing squinting and stammering.

Diego Garcia. See Chagos.

Di´electric, in electricity, a name applied by Faraday to any medium through or across which electrostatic induction can take place. See Electricity (Electrostatics). Faraday first showed that electrostatic induction was not action at a distance, but took place by means of the insulating medium separating the two conductors. The medium he named a dielectric, and measured its specific inductive capacity by taking that of common air as unity.

Diëly´tra, or Dicentra, a genus of plants, of the nat. ord. Fumariaceæ or Fumitories. The best known is D. spectabilis, a native of Northern China and Siberia, now common in European and other gardens. It blossoms in April and May, and its long drooping racemes of purplish-red blossoms present a very graceful appearance. It grows freely in the open air. It is sometimes called bleeding heart or virgin's heart from the shape of the blossoms.

Diemen (dē´men), Anton van, Dutch administrator, was born in 1593, died in 1645. Having gone to India, he speedily rose to the highest dignities, and was at length, in 1636, made Governor-General. He administered the government with much ability, and contributed much to the establishment of the Dutch commerce in India. Abel Tasman, whom he sent with a vessel to the South Seas in 1642, gave the name of Van Diemen's Land to the island now called Tasmania.

Dieppe (dē-ep´), a seaport town, France, department of Seine-Inférieure, on the English Channel, at the embouchure of the Arques, 93 miles N.N.W. of Paris. Almost the only public edifices worth special notice are the two Gothic churches, St. Jacques, begun in the thirteenth century, and St. Rémi, founded in 1522, and the old castle (1433), now a barracks. To the west of Dieppe proper is the suburb La Barre; and on the opposite side of the harbour Le Pollet, inhabited chiefly by sailors and fishermen. The old port is spacious, but a new channel with its own harbour system has been added, and vessels of 20-foot draft can now enter. Dieppe is one of the chief watering-places of France, and is much frequented by visitors in summer and autumn. The great bathing establishment forms a luxurious retreat for bathers and invalids, and includes a ballroom. The manufactures include works in ivory, horn, and bone, lace-making, sugar-refining, and shipbuilding. There is a busy fishery, and the foreign trade is still considerable. There is constant steam intercourse between this port and Newhaven. In early times Dieppe was the chief port of France, but its prosperity diminished after the revocation of the Edict of Nantes (1685). During the European War Dieppe was an important Allied base. Pop. 23,973.

Dierx, Léon, French poet, born in the Island of Réunion in 1838. Educated in Paris, he became one of the foremost of the Parnassians. His works include: Aspirations, Poèmes et Poésies, La rencontre, and Les Amants. His collected poems (1889-90) were crowned by the Académie. He died in Paris, 11th June, 1912.

Dies and Die-sinking. Die-sinking is the art of preparing dies, a die being a plate or block, usually of metal, so cut or shaped as to be capable, by means of stamping or pressure, of transferring a given design to some article which is to be manufactured in quantity. The [27]pressure may be applied by any sort of power, from hand to hydraulic.

The steel for the manufacture of steel dies is carefully selected, forged at a high heat into the rough die, softened by careful annealing, and then handed over to the engraver. After the engraver has worked out the design in intaglio, the die is put through the operation of hardening, after which, being cleaned and polished, it is called a matrix. This is not, however, generally employed in multiplying impressions, but is used for making a punch or steel impression for relief. For this purpose another block of steel of the same quality is selected, and, being carefully annealed or softened, is compressed by proper machinery upon the matrix till it receives the impression. When this process is complete, the impression is retouched by the engraver, and hardened and collared like the matrix. Any number of dies may now be made from this punch by impressing upon it plugs of soft steel.

There is hardly any article which does not in the course of its manufacture require the use of a die of some kind. For all sorts of metal-work, seals, rings, silverware, moulds and shapes of sheet steel or tin, dies are employed. For this class of work they are usually of steel. For embossing articles of leather, wood, celluloid, rubber, cloth, or clay, dies of brass and phosphor-bronze are commonly used, these being easier media to work in and yet sufficiently strong. The dies for letter headings and company seals are cut, in reverse to the design required, in steel; those for sealing-wax seals in steel or brass; the lettering being usually punched in by hand by separate letter punches, which themselves have been cut in relief on steel. Designs which are unusually ornate may be engraved by hand. Dies for embossing designs on leather, catalogue covers, cardboard articles, cards, and soft materials are usually modelled in brass. The design in reverse is cut out to a depth corresponding to the relief wanted. These dies are usually worked up by hand by the engraver. Dies for the reproduction of rubber stamps for printing on clay are cut in phosphor-bronze or hard brass in relief and reverse, and with an extreme bevel. The dies or blocks are then struck deeply into lead, and melted rubber is poured into the moulds so formed. When set, the rubber is removed and mounted as a hand-stamp ready to impress the clay in ink. Dies for wallpapers are cut on rollers. Steel dies for flower-shapes have a cutting edge, so that they can stamp out and emboss in one action. Of late years machinery has come much into use for relieving the engraver of some of his labour, but the designs are generally kept secret. One machine, called the pantograph or engraving machine, reproduces engravings in all metals and many shapes from patterns. Many of the stamp-duty steel dies made and issued by the Royal Mint are reproduced from this machine in reductions from brass patterns.—Bibliography: Lucas, Dies and Die-making; J. V. Woodworth, Dies: their Construction and Use.

Diesel, Rudolph, German inventor, born in Paris in 1858, died in 1913. Educated in England and at Munich, he proposed in 1893 to utilize directly the energy created by the combustion of fuel, a proposal which led to his invention of the Diesel engine. (See Internal Combustion Engines.) In 1913 he was called to England to consult with the Admiralty on the application of his motor, but was drowned in crossing the Channel. In 1894 he published a monograph entitled Theory and Construction of a Rational Heat Motor.

Dies Fasti et Nefasti, a Roman division of days, with reference to judicial business, into working-days and holidays. A dies fastus was a day on which courts and assemblies could be held and judgments pronounced; a dies nefastus, a day on which courts could not be held nor judgments pronounced.

Dies Iræ (dī'es ī'rē), one of the great Latin hymns of the Mediæval Church, generally used as part of the requiem or mass for the souls of the dead. It describes, as its name ('the day of wrath') denotes, the Last Judgment of the world, and seems to have been suggested by the description in Zephaniah, i, 15 and 16. It is supposed to have been written by Thomas da Celano, a Franciscan friar of the thirteenth century. It was translated by Crashaw and Dryden in the seventeenth century, and by Macaulay and others in the nineteenth, but none of these translations conveys the solemn force of the original.

Diest (dēst), a town, Belgium, province of Brabant, 32 miles E.N.E. of Brussels. It has some manufactures, but the chief products of the place are beer and gin, the former being largely exported. The town was occupied by the Germans in 1914, and re-entered by the Belgians in 1918. Pop. 8800.

Diesterweg, Friedrich Adolf Wilhelm, German educator, born in 1790, died in 1866. In 1820 he became director of the new Teachers' Seminary at Mörs, and soon gained a reputation as teacher and educator. He was a follower of Pestalozzi, and aimed at making every subject of instruction a means of education. In 1827 he founded the Rheinische Blätter für Erziehung und Unterricht, wherein he advocated his pedagogical views.

Di'et, a meeting of some body of men held for deliberation or other purposes; a term especially applied to the legislative or administrative assemblies of Austria, Germany, and Poland.

Dietet'ics (Gr. diaita, daily regimen), that [28]part of medicine which relates to the regulation of diet. The ideal diet is clearly that which, without burdening the viscera uselessly, furnishes all necessary nutritive elements, with due consideration for special physiological conditions in any given case. Under the head of Aliment the physiological properties of various foods have already been considered theoretically in respect of their capacity to supply physical waste in nitrogenous and non-nitrogenous matter. (See Aliment.) No single substance contains the elements needed to replace this waste in their requisite proportions, and a mixed diet is therefore necessary. For instance, to secure the required amount of carbon a man would need to eat about 4 lb. of lean beef, while 1 lb. would yield all the nitrogen required; thus, apart from the labour of digesting 4 lb. of beef, the body would be compelled to get rid of the excess of nitrogen. Bread, on the other hand, has carbon in abundance, but is deficient in nitrogen; so that by uniting 2 lb. of bread with ¾ lb. of lean meat, the due proportion of carbon and nitrogen is satisfactorily supplied. Milk and oatmeal taken together also contain nitrogenous and non-nitrogenous substances in nearly the required proportions. A certain proportion of saline matter is also necessary. The nature of the food most suitable for a healthy man is dependent in part upon general conditions, such as climate and season, and in part upon special conditions of individual habit. The inhabitants of the Arctic regions need large quantities of oleaginous food; those of the Tropics live chiefly on starchy products. With increased activity and exertion, as in training, an increase in the nitrogenous foods becomes necessary. In a state of health we need not draw hairbreadth distinctions as to the superior salubrity of the several sorts of diet, the quantity rather than the quality of food being the main consideration. Those persons who have been most remarkable for health and long life have generally been contented with two moderate meals a day, which are certainly quite sufficient during a state of health. In various countries the breakfast generally consists of tea, coffee, or cocoa, with a certain proportion of bread and butter; persons with delicate digestive powers, or who lead a sedentary life, cannot with safety or comfort eat animal food constantly to breakfast. At dinner all made-dishes highly spiced, such as curries, turtle-soup, &c., as provoking appetite, are hurtful; and the custom of late dining is not to be commended. Stewed and boiled meats are more difficult to digest than meat cooked by fire alone. The flesh of young animals seems to be more difficult of digestion than that of old; and the flesh of tame than that of wild animals. All sorts of fat meat must be taken in smaller quantities. Hence, also, ham, bacon, and salted meats cannot be eaten in such quantities as the tender flesh of poultry. Fish has the advantage of being easily soluble. All boiled vegetables are in general easy of digestion; raw vegetables and salads are rather more difficult. Fruit should be taken in the forenoon rather than after a hearty meal. The moderate use of fermented liquors is far from being invariably an evil, but the smaller the quantity habitually used the better in the majority of cases.

In all diseases attended with much fever or quickness of pulse the stomach loathes animal food, and there is generally a great increase of thirst, to quench which water, either quite cold, or iced, or tepid, or rendered acid, may be freely indulged. Infusions, too, of barley, sage, balm, &c., may be taken. In chronic diseases attended with hectic fever, milk is the most proper diet. The best food for infants is, of course, their mother's milk; but whenever they begin to cut teeth a little animal food, such as soft-boiled eggs, beef-tea, and even chicken minced very fine, may be given. Many infants suffer from having too much sugar given them in their food.—Bibliography: R. H. Chittenden, Physiological Economy in Nutrition, and Nutrition of Man; Hutchison, Food and Dietetics; Lusk, The Science of Nutrition.

Dietrich (dē´trih), Christian Wilhelm Ernst, a German painter and engraver, born in 1712, died in 1774. He studied under his father, and afterwards under Alexander Thiele at Dresden, where he became court-painter and professor in the academy. He adopted several different manners, successfully imitating Raphael and Mieris, Correggio, and Ostade.

Dietrich of Bern (dē´trih), the name under which Theodoric the Great, King of the Ostrogoths, appears in the old German legends. Bern stands for Verona, his capital.

Dieu, or D'Yeu (dyeu; ancient Insula Dei), an island off the west coast of France, department of Vendée. It is inaccessible on the west side, but on the east has a tolerable harbour defended by batteries. The chief industry is fishing. There are four lighthouses on the island. Pop. 3809.

Dieu et Mon Droit (dyeu e mon˙ drwä; 'God and my right'), the battle-cry of Richard I at the battle of Gisors (1198), signifying that he was not subject to France, but owed his power to God alone. The battle-cry was then adopted as the motto of the arms of England, and revived by Edward III in 1340, when he claimed the crown of France. Except during the reigns of Elizabeth and Anne, who used the motto Semper eadem, and of William III, who personally used Je maintiendray, it has ever since been the royal motto of England. [29]

Diez (dēts), Friedrich Christian, German philologist of the Romance languages, born in 1794, died in 1876. Having qualified himself as a lecturer at Bonn, he was appointed professor of the Romance languages there in 1830. His work stands in much the same relation to the Romance dialects which the researches of Grimm occupy with respect to German dialects. In addition to various works on the poetry of the Troubadours, he published a very valuable Grammatik der Romanischen Sprachen (1836-42, translated into English by Cayley in 1863), and an Etymologisches Wörterbuch der Romanischen Sprachen (1853).

Difference, a stock-exchange term. When stock is bought or sold merely as a speculation for the rise or fall, with no intention of the buyer to 'take up' the stock, or of the seller to deliver it, the 'difference' is the movement in price which may take place between the date of the transaction and the following 'settling-day'. If the price falls, the buyer has to pay the difference upon 'carrying over' his purchase to the next account; if it rises, the seller is at the loss. Since the first weeks of the European War all stock-exchange transactions have been made, in theory at least, for cash, and speculative business of this nature has been consequently much reduced.

Differences, Finite, a calculus much used in actuarial work, which deals with a series of numbers by considering the differences of the successive terms.

If u₁, u₂, u₃, ... are the terms of the series, then u₂ - u₁, u₃ - u₂, u₄ - u₃,... form another series called the series of first differences. The notation used is u₂ - u₁ = Δu₁, u₃ - u₂ = Δu₂,...

These first differences may themselves be differenced, giving the second differences Δu₂ - Δu₁, Δu₃ - Δu₂, ..., which are written Δ²u₁, Δ²u₂,...

Similarly, we form the third differences Δ³u₁ = Δ²u₂ - Δ²u₁, and so on.

As an example, let the original series be the cubes of the natural numbers.

Here we begin by writing down the series of cubes as far, say, as 216; beneath these we write the first differences 8 - 1 = 7, 27 - 8 = 19, &c. We thus obtain the part of the table to the left of the diagonal line.

We observe that the third differences are constant, each being 6. (It is easy to prove generally that the nth differences of the series, 1ⁿ, 2ⁿ, 3ⁿ,..., are constant.) Knowing the third differences, we can now extend the table as far as we wish to the right of the diagonal line. We get first 6 + 30 = 36, 36 + 91 = 127, 127 + 216 = 343. We infer that 7³ = 343.

Since u₁ - u₀ = Δu₀, we have u₁ = u₀ + Δu₀ = (1 + Δ)u₀.

Similarly, u₂ = (1 + Δ)u₁ = (1 + Δ)²u₀; and, generally,

a formula much used by calculators, and known as Newton's interpolation formula.

The above symbolic method of proof only applies when x is a positive integer, but the result is used in practice even for fractional values of x, as in most cases the high differences become negligible.

If n is a positive integer, it is easy to prove that

If the nth differences vanish, or are negligible, this gives

another useful interpolation formula, by which we can calculate any missing term of a series.—Bibliography: G. Boole, Finite Differences; Textbook of the Institute of Actuaries.

Differential Equation, an algebraical relation involving derivatives or differentials. Examples:

An ordinary differential equation involves only one independent variable, a partial differential equation involves more than one. Examples of ordinary equations:

Examples of partial differential equations:

Equations, whether ordinary or partial, can [30]also be classified as linear or non-linear. A linear equation is a rational integral equation of the first degree in the dependent variable or variables and their derivatives. The equation

is linear, but

are non-linear. The order of an equation is the order of the highest derivative or differential which it contains. Of the three equations last written, the first is linear of the second order, the other two are of the first order and second degree. To integrate a differential equation or system of equations is to find a relation or relations among the variables, equivalent to the given equation or equations. Thus the integral of

where A and B are arbitrary constants. An ordinary equation of the nth order with one dependent variable has exactly n arbitrary constants in its complete integral, or solution. In a practical problem the arbitrary constants are determined by the initial, or boundary, conditions. The solution of d²z/dt² = g, e.g. is completely determinate if the values of z and dz/dt when t = 0 are given. The solution of partial equations may involve arbitrary functions, which become definite when proper initial or boundary conditions are assigned. Thus the equation du/dx = du/dt has for its complete solution u = φ(x + t), where φ may be a function of any form whatever; if now we are given that, when t = 0, u = a given function f(x), we obtain f(x) = φ(x), so that the solution required is u = f(x + t). Certain ordinary linear equations of the second order are specially important, both from the beauty of their theory and from their usefulness in Mathematical Physics. Some of these equations are: Bessel's equation, Legendre's equation, the hypergeometric equation, Mathieu's equation, Lamé's equation. Linear partial equations of the second order are fundamental in Physics. Such are: Laplace's equation,

the wave equation,

the equation of conduction of heat,

These involve one dependent variable only. Equations with several dependent variables occur in Elasticity, Electrodynamics, and Hydrodynamics. A notable feature of the hydrodynamical equations is that they are not linear.

No general rules exist enabling us to deal with a differential equation taken at random, and only a few types have been completely solved. Of soluble equations, the most important are those which are linear with constant coefficients.

Example 1. d²x/dt² - 7dx/dt + 12 = 0. To solve this, try x = e^mt. We find e^mt(m² - 7m + 12) = 0. Thus m = 3 or 4. It is now easy to show that x = Ae^3t + Be^4t is a solution, where A and B are arbitrary constants. This is the general solution. We can determine A and B if the values of x and dx/dt are given for a definite value of t, say t = 0.

Example 2. d²y/dt² = c² d²y/dx². Try y = e^{lx + mt}. We find m² = c²l², or m = ±cl. Hence y = Ae^{l(x + ct)} + Be^{l(x - ct)} is a solution for all values of A, B, l; so, also, is the sum of any number of terms of similar forms. We may infer that the general solution is

where f and F are arbitrary functions. It is only in exceptional cases that an equation can be solved, as in these two examples, by an analytical formula; indeed, differential equations are the most fertile source of new functions in analysis. But, as in the analogous cases of algebraic equations and definite integrals, it may be quite possible to find, by methods of approximation, an arithmetical solution which is sufficient for the purpose in hand.—Bibliography: H. T. H. Piaggio, Differential Equations; J. M. Page, Ordinary Differential Equations; A. R. Forsyth, A Treatise on Differential Equations; E. T. Whittaker and G. N. Watson, Modern Analysis.

Diffrac´tion, a term applied to the bending that rays of light undergo in passing close to the edge of an opaque body. Thus when a beam of direct sunlight is admitted into a dark room through a narrow slit, and falls upon a screen [31]placed to receive it, there appears a line of white light bordered by coloured fringes; these fringes are produced by diffraction, and in the case given it may be seen that the red or long-wave rays are diffracted more than the blue rays. See Interference.

Diffu´sion, the gradual mixing of gases, liquids, or solids when brought into direct contact. When a block of lead is placed on a block of gold, with their smooth surfaces in close contact, it is found that, after several weeks, gold has diffused into the lead, and lead into the gold. In the case of gases, when a jar of oxygen and a jar of hydrogen are connected together by a tube or opening of any kind, they rapidly become mixed; and their mixture does not depend on gravity, but takes place in opposition to that force, as may be shown by placing the jar of hydrogen gas above the other. Oxygen is sixteen times heavier than hydrogen, bulk for bulk, but the heavier gas moves upwards and the lighter downwards, and the process of intermixture, or diffusion, goes on till the two gases are apparently equably distributed throughout the whole space. After that they have no tendency whatever to separate. Similarly, if two vessels, one containing oxygen and the other hydrogen, be connected by a tube which is stuffed with a plug of porous material, such as plaster of Paris, the gases gradually diffuse one into the other through the porous plug. The two gases, however, do not pass through the porous separator at equal rates, but in inverse proportion to the square roots of the densities of the gases. Thus in the case of two vessels, one containing hydrogen and the other oxygen, which is sixteen times as heavy as hydrogen, the hydrogen will pass towards the oxygen jar four times as quickly as the oxygen will pass towards the hydrogen jar. Kindred phenomena occur when two liquids that are capable of mixing, such as alcohol and water, are put in contact, the two gradually diffusing one into the other in spite of the action of gravity. In some cases, however, as where ether and water are employed, the diffusion is only partial, this result arising from the fact that these two liquids are not miscible in all proportions. When solutions of various solid bodies are placed in contact, interdiffusion also takes place. On the results of his examination of the phenomena of diffusion of liquids and salts across porous membranes or septa, Graham founded a method of separating colloid from crystalloid bodies, which he called dialysis.

Digam´ma, a letter which once belonged to the Greek alphabet, and which remained longest in use among the Æolians. It resembled our letter F, and hence was called digamma, that is, double Γ. It appears to have had the force of f or v. Its existence was first pointed out by Richard Bentley.

Digby, Sir Everard, an English gentleman, born of a Roman Catholic family in 1578. He enjoyed some consideration at the court of Elizabeth and James I, by whom he was knighted. Having contributed money to the Guy Fawkes conspiracy, he was tried and hanged in 1606.

Digby, Sir Kenelm, eldest son of the preceding, born in 1603, died in 1665. He studied at Oxford, was knighted in 1623, and on the accession of Charles I was created a gentleman of the bedchamber, a Commissioner of the Navy, and a governor of Trinity House. He soon after fitted out at his own expense a small but successful squadron against the French and Venetians. In 1636 he became a Roman Catholic, and was imprisoned as a Royalist during 1642-3, when he was allowed to retire to the Continent. At the Restoration he returned to England, became a member of the Royal Society, and was much visited by men of science. He wrote numerous works: a Treatise on the Nature of Bodies, a Treatise on the Nature and Operation of the Soul, and Of the Cure of Wounds by the Powder of Sympathy.

Di´gest, a name originally given to a collection or body of Roman laws, digested or arranged under proper titles by order of the Emperor Justinian. Hence applied to any somewhat similar collection.

Diges´ter, a strong vessel of copper or iron, on which is screwed an air-tight cover with a safety-valve, the object being to prevent loss of heat by evaporation, and to enable boiling to take place at a high pressure. Water may be thus heated to 400°F.; at which temperature its solvent power is so greatly increased that bones are converted into a jelly.

Diges´tion is that process in the animal body by which the aliments are so acted upon that the nutritive parts are prepared to enter the circulation, and separated from those which cannot afford nourishment to the body. The organs effecting this process are called the digestive organs, and consist of the stomach, the great and small intestines, &c. (see Intestine, Stomach), the liver, and pancreas. When the aliments, after being properly prepared and mixed with saliva by mastication, have reached the stomach, they are intimately united with a liquid substance called the gastric juice, by the motion of the stomach. By this motion the aliments are mechanically separated into their smallest parts, penetrated by the gastric juice, and transformed into a uniform pulpy or fluid mass. The gastric juice acts upon the albuminous parts of the food, converting them into peptones, which can pass through organic membranes and thus enter the blood. This [32]action is aided by the warmth of the stomach. The pulpy mass, called chyme, proceeds from the stomach, through the pylorus, into that part of the intestinal canal called the small intestine, where it is mixed with the pancreatic juice, bile, and intestinal juice. The pancreatic juice converts starch into sugar, albumins into peptones, and emulsionizes fats, so that all these kinds of food are rendered capable of absorption. The process is aided by the intestinal juice. The bile also acts upon fats, and thus the food is formed into the chyle, which is absorbed into the system by the capillary vessels called lacteals (see Chyle; Chyme), while the non-nutritious matters pass down the intestinal canal and are carried off.—Bibliography: F. Hare, Food Factor in Disease; Taylor, Digestion and Metabolism.

Digit (dij´it; Lat. digitus, a finger), in arithmetic, any one of the ten numerals, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0. Digit is also a measure of a finger's breadth, equal to ¾ inch.

Digit, in astronomy, is the measure by which we estimate the quantity of an eclipse. The diameter of the sun or moon's disk is conceived to be divided into twelve equal parts, called digits; and according to the number of those parts or digits which are obscured, so many digits are said to be eclipsed.

Digitalin (dij-i-tā´lin), a vegetable alkaloid, the active principle of the Digitālis purpurĕa or foxglove. It has a bitter taste, and is a strong poison, but is used medicinally, especially for the heart. See next article.

Digita´lis (dij-), a genus of plants, nat. ord. Scrophulariaceæ, containing about twenty species of tall herbs, natives of Europe and Western Asia. The purple foxglove (D. purpurĕa) is a common wild flower in Britain, and several species are grown in gardens. Various preparations from the foxglove receive this name, and are used in medicine, principally in cases of heart disease.

Digitigra´da (digitus, finger, toe, and gradi, to walk), a section of the Carnivora, so called from their walking on the ends of their toes; as the dog, cat, and their allies. See Plantigrade.

Digito´rium, a small portable dumb instrument having a short keyboard with five keys like those of a piano, used by piano-players for practice, to give strength and flexibility to the fingers.

Digne (dēny), a town, France, capital of the department of Basses-Alpes, picturesquely situated on a mountain slope, 60 miles north-east of Marseilles. In 1629 a plague reduced the population from 20,000 to 1500. Pop. 7317.

Dijon (dē-zhōn; Lat. Castrum Divonense), a town in Eastern France, capital of the department of Côte-d'Or, in a fertile plain, at the foot of a range of vine-clad slopes, formerly surrounded by ramparts, which now furnish beautiful promenades. At some distance it is surrounded by a series of forts. Some of the buildings belong to the period when Dijon was capital of the dukedom of Burgundy, the chief being the cathedral of St. Bénigne, a building of vast extent with a lofty wooden spire above 300 feet high; the churches of Nôtre Dame and St. Michael; the ancient palace of the Dukes of Burgundy, now used as the hôtel de ville and museum; and the palais de justice, formerly the Parliament House of Burgundy. Dijon is the birth-place of Bossuet. It has important educational institutions and a valuable library. Industries: woollens, hosiery, candles, mustard, vinegar, chemicals, paper-hangings, tanneries, foundries, machine factories, cotton- and oil-mills. The trade is considerable, particularly in the wines of Burgundy. Pop. 76,847.

Dike, or Dyke (connected with the Gr. teichos, wall), a word variously used in different localities to represent a ditch or trench, and also an embankment, rampart, or wall. It is specially applied to an embankment raised to oppose the incursions of the sea or of a river, the dikes of Holland being notable examples of work of this kind. These are often raised 40 feet above the high-water mark, and are wide enough at the top for a common roadway or canal, sometimes for both. The Helder Dike, one of the largest, is about 6 miles in length and costly in upkeep. See Embankment.

Dike, or Dyke, in geology, a term applied to intrusive igneous masses, such as basalt, which fill up veins and fissures in the other rocks, and sometimes project on the surface like walls through their superior resistance to weathering.

Dilapidation, in English ecclesiastical law, is where an incumbent of a church living suffers the parsonage-house or outhouses to fall down, or be in decay for want of necessary repairs; or it is the pulling down or destroying any of the houses or buildings belonging to a spiritual living, or destroying of the woods, trees, &c., appertaining to the same. An outgoing incumbent (or his heirs) is liable for dilapidation to his successor. In general, the term is applied to the act of allowing or causing any lands, houses, &c., to become waste or to decay.

Dilem´ma (from Gr. di-, double, and lēmma, proposition, assumption), in logic, a form of argument used to prove the falsehood or absurdity of some assertion, as in the following instance: If he did so he must be either foolish or wicked; but we know he is neither foolish nor wicked; therefore he cannot have done so. The two suppositions, which are equally untenable, are called the 'horns' of the dilemma.

Dilettante (di-let-ta˙n´tā), an Italian [33]expression, signifying a lover of the arts and sciences, who devotes his leisure to them as a means of amusement and gratification, being thus nearly equivalent to amateur. It is also used in reference to the trifler and dabbler in art and science. In 1734 a number of gentlemen founded in London a Dilettanti Society, which published a splendid work on Ionian Antiquities, 1769, 1881 (4 vols.); Specimens of Ancient Sculpture, 1809, 1835.

Dilke, Sir Charles Wentworth, English writer and politician, son and grandson of men well known in their day, was born in 1843, died in 1911. He graduated at Cambridge, and was called to the Bar. His first work, Greater Britain, the result of a tour round the world from 1866 to 1867, became very popular. In 1868 he was elected member of Parliament for Chelsea, and he remained so up to 1885. After a few years' retirement (due to a divorce case) he became member of Parliament for Forest of Dean. He was Under-Secretary for Foreign Affairs, President of the Local Government Board, &c. He succeeded his father as owner of the Athenæum, and became the proprietor of Notes and Queries. The Present Position of European Politics, and Problems of Greater Britain, are among his works.

Dill, an umbelliferous plant, Anēthum graveŏlens, a native of the southern countries of Europe, the fruits, commonly but erroneously called seeds, of which are moderately warming, pungent, and aromatic, and are employed medicinally as a carminative.

Dillenia´ceæ, an order of plants, chiefly fine trees, inhabiting the East Indies, allied to Ranunculaceæ and Magnoliaceæ.

Dillingen (dil´ing-en), an old town, Bavaria, on the Danube, formerly the seat of a Jesuit university. Pop. 6291.

Dillon, John, Irish politician and agitator, born in Dublin in 1851, the son of John Blake Dillon (1816-66), a leader of the Young Ireland party. Educated at the Catholic University of Dublin and at the Royal College of Surgeons, he became a doctor of medicine. He identified himself with the Parnellite movement, and entered Parliament for Tipperary in 1880. An ardent Nationalist, not hesitating to incite his compatriots to lawlessness, he was sent to prison in 1888. Without a seat in Parliament from 1883 to 1885, he was returned in the latter year for East Mayo, which he represented thereafter. In 1918, after the death of John Redmond, he was elected chairman of the Irish Nationalist party, which, however, owing to the rise of the Sinn Fein party, was a nominal distinction only.

Dilman´, a town, Persia, province of Azerbijan, 75 miles west of Tabreez. Pop. estimated at 15,000.

Dilo´lo, a small lake in Angola, near the southern boundary of Belgian Congo, lat. 11° 22' S.; long. 22° 34' E.: regarded as the source of the Zambesi.

Dil´uents (Lat. diluere, to wash away), in medicine, are those substances which are taken to increase the proportion of fluid in the blood. They consist of water and watery liquors.

Dilu´vium, the name formerly given by geologists to certain gravels and comparatively recent deposits, which seemed to have been the result of a rush of water or deluge.

Dime (Fr. dîme, Lat. decimus, tenth), the term for the tenth part of a dollar or ten-cent piece in the United States of America, a silver coin whose English equivalent is about 5d. Hence the phrases dime novels, dime museums, &c.

Dimensions, Algebraical. There are three dimensions in space: length, breadth, and height or depth. An area is said to be of two dimensions because it has length and breadth only; a volume is of three dimensions. In algebra terms like x², xy are said to be of two dimensions because there are two letters multiplied together, and their product would measure an area if each letter denoted a length. Similarly, x³, xyz are said to be of three dimensions, and the meaning is extended to cover the product of any number of letters. An expression of more than one term is said to be of the same degree as its term of highest dimensions. For example, 3x²y²z² + 5xyz + 6x³ + 3x²y² is said to be of the sixth degree because x²y²z² = x × x × y × y × z × z is of six dimensions.

Dimensions, Physical. One of the aims of physical science is to express all its measurements in terms of the three fundamental units of length, mass, and time. A velocity, for example, is specified by the number of units of length traversed in the unit of time, so that we may write v = l ÷ t, or v = lt^-1. On this account velocity is said to have the dimensions LT^-1. Similarly, acceleration, being velocity added per unit time, has the dimensions of velocity ÷ time, or LT^-2; and force, being proportional to mass and acceleration jointly, has the dimensions MLT^-2.

When a physical law is expressed as an equation connecting the numbers of units of the quantities involved, every term in this equation must be of the same dimensions in any one of the fundamental units. This is the Principle of Dimensions, first stated by Joseph Fourier, founder of the theory of the conduction of heat. In order to see its truth, we have only to observe that an equation containing terms of different dimensions would give inconsistent results if the unit of length were varied. Suppose it to be suggested, for example, that the period of vibration t of a simple [34]pendulum of length l is given by the formula t = 2πl/g, where g denotes the acceleration of a falling body. The dimensions of the expression on the right are L ÷ (LT^-2), or T², whereas the term t on the left has dimensions T¹. Suppose the unit of length is the foot and the unit of time the second, so that g = 32, and let l = 3. We find in this case t = 6π/32, so that the period is 3π/16 seconds. But if we change the unit of time to one minute, g becomes 32 × 60 × 60, and the formula gives t = 6π/(32 × 60 × 60), so that the period is 3π/(16 × 60 × 60) minutes.

The two results are obviously inconsistent. If, however, we take the correct formula, namely t = 2π√(l/g), we find on trial that we obtain the same value for the period however we change the unit of time or the unit of length. Both sides are in this case of dimensions T¹.

The principle of dimensions provides therefore a useful check on the accuracy of formulæ. But it does much more than this. It often gives very valuable information about the relations of physical phenomena in cases where these relations are far too complicated to be completely worked out by mathematical analysis. To mention but one example, it is by the use of this principle that modern naval architecture is able to predict the behaviour of ocean-going ships from experiments in ponds on small-scale models.

Dimin´utive, in grammar, a word having a special affix which conveys the idea of littleness, and all other ideas connected with this, as tenderness, affection, or contempt. The opposite of diminutive is augmentative. In Latin, diminutives almost always ended in -lus, -la, or -lum; as Tulliola, meum corculum, little Tullia my dear, or little heart; homunculus, a manikin. The Italian is particularly rich in diminutives and augmentatives, such compound diminutives as fratellinucciettinetto (a diminutive of frate, brother) being sometimes employed. Among English diminutive affixes are -kin, as in manikin, a little man; pipkin, a little pipe; -ling, as in gosling, a little goose; darling, that is, dearling, or little dear; and -et, as in pocket, from poke, a bag or pouch; tablet, a little table. Diminutives are not confined to nouns, and dandle, scribble, tipple, are examples of diminutive verbs, and greenish, whitish, are diminutives of adjectives. Diminutives are also formed, in colloquial and familiar language, by adding -y or -ie to the names, as Charley, Mousie, &c.

Dim´ity, a stout cotton fabric, ornamented in the loom either by raised stripes or fancy figures. It is usually employed white, as for bed and bedroom furniture.

Dimorph´ism, in crystallography, the crystallization of a body in forms belonging to two different systems, or in incompatible forms of the same system, a peculiarity exhibited by sulphur, carbon, &c.

Dimorphism, in botany. See Heterostyly.

Dinajpur´, a town, Hindustan, Bengal, capital of a district of same name, 205 miles north of Calcutta; pop. 12,500.—The district covers an area of about 4118 sq. miles; pop. 1,687,860.

Dinan (dē-nän), a town, France, department of Côtes-du-Nord (Brittany), on the Rance, 14 miles south of St. Malo. It was besieged and captured by the English under the Duke of Lancaster in 1359, but retaken by Du Guesclin. It stands on a steep hill nearly 200 feet above the river, is surrounded by high old walls pierced with four gates, and is a picturesque and interesting old place. In the cathedral of St. Sauveur the heart of Bertrand du Guesclin is buried. Pop. 11,410.

Dinant (dē-nän), a town, Belgium, in the province and 14 miles S. of Namur; picturesquely and strongly situated on the Meuse; a place of antique appearance. The town house was once the palace of the Princes of Liége. The town was destroyed by the Germans in 1914. It is one of the most popular Belgian summer resorts. Pop. 7690.

Dina´pur, a town, Hindustan, Patna district, Bengal, on the right bank of the Ganges, about 12 miles north-west of Patna, cantonment and military head-quarters of the district, with extensive barracks. The environs are studded with handsome bungalows. Pop. 31,025.

Dinar (Lat. denarius), formerly an Arab gold coin, also a Persian coin; at present the chief Serbian coin, value one franc.

Di´nas Bricks, an infusible kind of brick made of a peculiar rock, containing 98 per cent of silica, with a little alumina, which occurs at Dinas, in the Vale of Neath, in Glamorganshire, S. Wales. The rock is crushed, moistened with water, and moulded by a machine.

Dindigul, a town of India, Madura district, Madras, with a fort on a rocky height; manufactures cigars. Pop. 21,000.

Dindings, The, properly two small islands, also called Pangkor Islands, in the Straits of Malacca, belonging to the Straits Settlements, off the coast of Perak (British). The name now includes a strip of territory on the Malay Peninsula opposite; total area about 265 sq. miles, two-thirds of which is covered by dense forests. Coco-nuts, coffee, and pepper are grown with success. Lumut, on the mainland, has a fine natural harbour.

Din´dorf, Karl Wilhelm, German classical scholar, born 1802, lived most of his life at [35]Leipzig, and died 1883. His chief publications were editions of the Greek dramatists (Poetæ Scenici Græci) and works elucidative of them and other Greek writers.

Dingo, the native wild dog of Australia (Canis Dingo), of a wolf-like appearance and extremely fierce. The ears are short and erect, the head elongated, the tail rather bushy, and the hair of a reddish-dun colour. In habit the dingo is rather fox-like, usually lying concealed throughout the day and making predatory expeditions at night. It is very destructive to sheep, killing more than it eats. It was probably introduced by prehistoric man.

Ding´wall, a royal and parliamentary burgh and seaport of Scotland, county town of Ross and Cromarty, situated at the head of Cromarty Firth. This town, erected into a royal burgh in 1227, unites with Wick and other places in returning a member to Parliament. Pop. 2590.

Dino´ceras (Gr. deinos, terrible, keras, a horn), a fossil mammal found in the Eocene strata of North America, in some respects akin to the elephant and of equal size, but without a proboscis. Its bones were very massive; it had two vertical tusks in the upper jaw, three pairs of horns, and the smallest brain, proportionally, of any known mammal.

Dinor´nis (Gr. deinos, terrible, ornis, a bird), an extinct genus of large wingless birds—classed with the small existing Apteryx. The bones of several species have been found in New Zealand. The largest must have stood 12 feet in height, several of its bones being at least twice the size of those of the ostrich. The body seems to have been even more bulky in proportion, the tarsus being short and stout in order to sustain its weight. They do not appear to have become extinct until the seventeenth or eighteenth century, and are spoken of as moas by the natives, who buried the eggs (more than 1 foot long) with their dead as provision for their journey to the other world.

Dinosau´ria (Gr. deinos, terrible, and sauros, a lizard), a group of extinct reptiles, allied in skeletal structure both to the lizards and the birds. While some were only 3 feet long, a large number attained gigantic size. Atlantosaurus being 115 feet long. Many were carnivorous, but some of the large heavy forms were herbivorous, and protected by bony spines or plates. The Dinosaurs were the dominant land animals of the Jurassic and Cretaceous periods.

Dinothe´rium (Gr. deinos, terrible, thērion, beast), a genus of extinct gigantic proboscidean mammals, precursors of the elephants, the [36]remains of which occur in Miocene formations in several parts of Europe. The type-species (D. giganteum) is calculated to have attained the length of 18 feet. It had a proboscis and also two tusks placed at the anterior extremity of the lower jaw, and curved downwards somewhat after the manner of those in the upper jaw of the walrus. The skull is best known from that found in 1835 at Eppelsheim; but the skeleton can now be pieced together from remains in various localities. The vertebræ resemble those of mastodon. Dinotherium may have inhabited rivers or estuaries.

Di´ocese (Gr. dioikēsis, administration), the circuit or extent of a bishop's jurisdiction. Each English diocese is divided into archdeaconries, each archdeaconry (nominally) into rural deaneries, and each deanery into parishes. In the Eastern Churches the term eparchy is used for diocese. See Bishop.

Diocle´tian (Gaius Valerius Diocletianus, surnamed Jovius), a man of mean birth, a native of Dalmatia, proclaimed Emperor of Rome by the army A.D. 284. He defeated Carinus in Mœsia (286), conquered the Allemanni, and was generally beloved for the goodness of his disposition, but was compelled by the dangers threatening Rome to share the government with M. Aurelius Valerius Maximian. In 292 Galerius and Constantius Chlorus were also raised to a share in the empire, which was thus divided into four parts, of which Diocletian administered Thrace, Egypt, Syria, and Asia. As the result of his reconstitution of the empire there followed a period of brilliant successes in which the barbarians were driven back from all the frontiers, and Roman power restored from Britain to Egypt. In 305, in conjunction with Maximian, he resigned the Imperial dignity at Nicomedia, and retired to Salona, in Dalmatia, where he cultivated his garden in tranquillity until his death in 313. In the latter part of his reign he was induced to sanction a persecution of the Christians.—Bibliography: Gibbon, Decline and Fall; P. Allard, La Persécution de Dioclétien; A. J. Mason, The Persecution of Diocletian.

Dioda´ti, Giovanni, Italian Protestant divine, born at Lucca, about 1576, of a noble Catholic family. He was for some time professor, first of Hebrew, then of theology, at Geneva, and in 1619 represented the Genevan clergy at the Synod of Dort, and aided in drawing up the Belgic confession of faith. He is most celebrated for a translation of the Bible into Italian (1607), which is superior to his translation of it into French. He died at Geneva in 1649.

Diodo´rus of Agyrium, in Sicily, and therefore called Siculus; a Greek historian in the time of Julius Cæsar and Augustus. His universal history, in the composition of which he travelled through a great part of Europe and Asia, occupied him thirty years, and consisted of 40 books, but only books 1-5 and 11-20, with certain fragments, are now extant.

Diœcious (Gr. di, double, oikos, a house), in botany, a term applied to plants which have flowers with stamens on one individual and those with pistils on another; as opposed to monœcious. The willow, the yew, the poplar, &c., are diœcious.

Diogenes Laërtius, author of a sort of history of philosophy in Greek, appears to have been born at Laerte, in Cilicia, and to have lived towards the close of the second century after Christ; but no certain information exists either as to his life, studies, or age. The work is divided into ten books, and bears in MSS. the title, On the Lives, Doctrines, and Apothegms of those who have distinguished themselves in Philosophy. It is full of absurd and improbable anecdotes, but contains valuable information regarding the private life of the Greeks, and many fragments of works now lost. It was the foundation of the earlier modern histories of philosophy. A translation of his work by C. D. Yonge was published in Bohn's Classical Library.

Diogenes (di-oj´ē-nēz) of Apollonia (Crete), known also as the Physicist, a Greek philosopher of the fifth century B.C., who belonged to the Ionian school, and considered air as the element of all things. He was a pupil of Anaximenes and a contemporary of Anaxagoras.

Diogenes of Sinopē (on the Black Sea), the most famous of the Cynic philosophers, born about 412 B.C., died about 323 B.C. Having been banished from his native place with his father, who had been accused of coining false money, he went to Athens, and thrust himself upon Antisthenes as a disciple. Like Antisthenes he despised all philosophical speculations, and opposed the corrupt morals of his time; but while the stern austerity of [37]Antisthenes was repulsive, Diogenes exposed the follies of his contemporaries with wit and good humour. As an exemplar of Cynic virtue he satisfied his appetite with the coarsest food, practised the most rigid temperance, walked through the streets of Athens barefoot, without any coat, with a long beard, a stick in his hand, and a wallet on his shoulders, and by night, according to the popular story, slept in a tub (or large earthenware vessel). On a voyage to the Island of Ægina he fell into the hands of pirates, who sold him as a slave to the Corinthian Xeniades. The latter emancipated him, and entrusted him with the education of his children. He attended to the duties of his new employment with the greatest care, commonly living in summer at Corinth and in winter at Athens. It is at Corinth that he is said to have had his famous interview with Alexander the Great. The Macedonian conqueror was so struck with the philosopher's self-possession that he went away remarking: "If I were not Alexander, I should wish to be Diogenes". Of the many stories related of him the majority are probably fictions; many, indeed, are chronologically impossible. Concerned with practical wisdom, Diogenes established no system of philosophy. To gain virtue, he maintained, man must avoid physical pleasure, despise the conventions of society, and adopt a simple and natural life. His enemies accused him of various scandalous offences, but there is no ground for supposing him guilty of any worse fault than that of elevating impertinence to the rank of a fine art. See Cynics.

Diomedes (dī-o-mē´dēz), in Greek mythology, (1) the son of Mars and Cyrene, and King of the Bistŏnes in Thrace, who fed his horses on human flesh, and used to throw all strangers who entered his territories to those animals to be devoured. He was killed by Hercules, who carried off the horses. (2) One of the heroes at the siege of Troy, the son of Tydeus and Deïpyle, and King of Argos, one of the suitors of Helen. After she was carried off, Diomedes engaged in the expedition against Troy, in which his courage and the protection of Pallas rendered him one of the most distinguished heroes. He wounded Aphrodite and Ares, and thrice assailed Apollo; and by carrying off the horses of Rhœsus from the enemies' tents, and aiding Ulysses in the removal of Philoctetes from Lemnos, he fulfilled two of the conditions on which alone Troy could be conquered. Finally he was one of the heroes concealed in the wooden horse by which the capture of Troy was at length accomplished. Different accounts were given of his after-life. He is often called Diomede.

Dionæ´a, a genus of plants, nat. ord. Droseraceæ. Only one species is known, D. muscipŭla (Venus's fly-trap), a native of the sandy savannas of Carolina and Florida. It has a rosette of root-leaves, from which rises a naked scape bearing a corymb of largish white flowers. The leaves have a dilated petiole and a slightly stalked 2-lobed lamina, with three short stiff bristles on each lobe. The bristles are remarkably irritable, and when touched by a fly, or other insect, the lobes of the leaf suddenly close on and capture the insect. It dissolves the food thus captured by means of digestive fluid similar to ordinary gastric juice.

Dion Cassius, or Dio Cassius, a Greek historian, born about A.D. 155 at Nicæa, in Bithynia. After accompanying his father to Cilicia, of which he held the administration, he came to Rome about 180, and obtained the rank of a Roman Senator. On the accession of Pertinax Dion was appointed Prætor, and in the reign of Caracalla he was one of the Senators whom it had become customary to select to accompany the emperor in his expeditions, of which he complains bitterly. In 219 he was raised to the consulship, and about 224 became Proconsul of Africa. In 229 he was again appointed Consul; but feeling his life precarious under Alexander Severus, he obtained permission to retire to his native town of Nicæa. The period of his death is unknown. The most important of his writings, though only a small part is extant, is a History of Rome, written in Greek and divided into eighty books, from the arrival of Æneas in Italy and the foundation of Alba and Rome to A.D. 229.

Dion Chrysostom, a Greek sophist and rhetorician and a favourite of Trajan; born A.D. 50, died about A.D. 110. Eighty of his orations (in excellent Attic) have been preserved.

Dion of Syracuse, in Greek history, a connection by marriage of the elder and the younger Dionysius, tyrants of Syracuse, over whom he long exercised great influence. He attempted to reform the younger Dionysius, but his enemies succeeded in effecting his banishment. He afterwards returned and made himself ruler of the city, but became unpopular, and in 353 B.C. one of his followers, Callipus of Athens, caused him to be assassinated.

Dionys´ia. See Bacchanalia.

Dionys´ius, St., a disciple of Origen, and Patriarch of Alexandria in A.D. 248. He was driven from the city in 250, and in 257 was banished to Libya, but was restored in 260. He died in A.D. 265.

Dionysius of Halicarnassus, in Caria, a Greek critic and teacher of eloquence, born about 70 B.C. He went to Rome about 30 B.C., where he wrote his Roman Antiquities, in twenty books, in which he relates (in Greek) the early history of Rome and its government up to the [38]times of the first Punic War. We have the first nine books of this work entire, the tenth and eleventh nearly so, and some fragments of the others. His rhetorical writings are of greater value, especially his essays on the Greek orators. He died about 6 B.C.—Cf. Sir J. E. Sandys, A History of Classical Scholarship.

Dionysius the Areopagite, that is, one of the judges of the Areopagus, at Athens, a convert to Christianity by the Apostle Paul about the middle of the first century, and the first Bishop of Athens, where he suffered martyrdom. Certain writings formerly ascribed to him consist of obscurely written treatises on mystical subjects. Scotus Erigena translated them into Latin. In France, where a certain Dionysius (see Denis, St.) established the first Christian community at Paris in the third century, they were readily received, this Dionysius being without further inquiry taken for the Areopagite, because the origin of the Gallican Church could thus be carried back to the first century; and France gained a patron who was a martyr and the immediate disciple of an apostle.—Cf. article in Smith's Dictionary of Christian Biography.

Dionysius the Elder, in Greek history, tyrant or absolute ruler of Syracuse, born about 430 B.C. of obscure parentage. He obtained the rank of general, and afterwards of commander-in-chief; and, gaining the support of the army, he seized the supreme power in Syracuse, though only twenty-five years of age. He extended his rule over other cities in Sicily; and after some successes and reverses in the struggle with the Carthaginians, he gained a complete victory over them under the walls of Syracuse. In his expeditions into Lower Italy he reduced the city of Rhegium by famine (387). After another short war with Carthage he lived some time in peace, occupied with writing poems and tragedies, with which he contended for the Olympian prize. In 368 he commenced a new war against the Carthaginians, but failed to drive them entirely out of Sicily. He is said to have died from a potion administered at the instigation of his son Dionysius the Younger (367 B.C.).

Dionysius the Little (so called on account of his short stature), a Scythian monk who was abbot of a monastery at Rome in the beginning of the sixth century, and died about the year A.D. 530, according to others about 545, celebrated as the first to introduce the computation of time from the Christian era. This mode of computation, however, was not publicly used until the eighth century.

Dionysius the Younger, a tyrant of Syracuse, who succeeded his father, Dionysius the Elder, in 367 B.C. For the purpose of recalling him from the excesses to which he was addicted, his kinsman Dion persuaded him to invite Plato to his court, but the influence of the philosopher effected no permanent change. Becoming suspicious of Dion, the tyrant banished him and confiscated his property, but in 357 B.C. Dion made himself master of Syracuse. Dionysius fled to Locri, but after the murder of Dion recovered his power in Syracuse. His misfortunes, however, had rendered him more cruel, and Timoleon, who came to Syracuse with aid from Corinth against the Carthaginians, deposed him in 344 B.C. He was carried to Corinth, where he is said to have gained a living by giving lessons in grammar, or as one of the attendants on the rites of Cybele.

Diony´sus, the original Greek name of the god of wine, the name Bacchus, by which he was also called both by the Greeks and the Romans, being at first a mere epithet or surname.—Cf. R. Brown, The Great Dionysiak Myth.

Dioon, a genus of Cycads, natives of Mexico, where meal is prepared from the starchy seeds.

Diophan´tus of Alexandria, the first Greek writer on algebra, flourished, according to some authorities, about the middle of the fourth century after Christ. He is called the Father of Algebra, and left behind him thirteen books of Arithmetical Questions, of which only six are extant; and a work on Polygonal Numbers.

Diop´side, a calcium magnesium silicate, of the pyroxene series, occurring in igneous rocks and altered limestones, with a vitreous lustre, and of a pale-green, or a greenish- or yellowish-white colour.

Diop´sis, a genus of two-winged flies of which the species are native to India and Africa. Each side of the head is drawn out into a long lateral horn, which bears the eye and antenna at its extremity.

Di´optase, emerald copper ore, hydrated silicate of copper, a translucent mineral, occurring crystallized in six-sided prisms. It occurs in Siberia, Hungary, and Chile. It has been used as a gem-stone, notably in Persia and Russia.

Diopter, the unit in terms of which the power of a lens or curved mirror can be expressed. It is obtained by taking the reciprocal of the focal length of the lens or mirror in metres. Thus, a lens with focal length 1 metre has a power of 1 diopter. If the focal length is 2 metres, the power is ½ diopter. The power may also be obtained by dividing 39.37 by the focal length in inches. The unit is employed in classifying spectacle lenses.

Di´orite, a coarsely crystalline igneous rock, sometimes of a whitish colour speckled with black or greenish-black, sometimes very dark [39]in colour, consisting of hornblende and calcium sodium felspar. Dark mica sometimes takes the place of hornblende (mica-diorite). The 'greenstones' of older authors are mostly diorites.

Dioscoreaceæ, a nat. ord. of monocotyledons, with alternate reticulate-veined leaves, tuberous root-stocks, and twining stems. The flowers are small and unisexual. There are 6 genera, with about 100 species. The typical genus is Dioscorea, which includes the yam. Black bryony is the only British representative.

Dioscor´ides, Pedanius, a Greek physician, born in Cilicia in the first century of the Christian era. He was the author of a celebrated work on materia medica, in five books, particularly valuable in regard to botany.

Dioscu´ri. See Castor and Pollux.

Dios´pyros, a large genus of trees or shrubs, natives of the warmer regions of the world, nat. ord. Ebenaceæ. The trees of this genus supply ebony wood. That from Ceylon is the wood of D. Ebĕnum; from India, of D. melanoxylon and other species; and that from Mauritius, D. tesselaria. The Chinese date-plum (D. kaki) is an apple-like tree which produces large red fruits resembling tomatoes. In China and Japan this tree is as important as the apple is in Northern Europe.

Dip, of the horizon, the angle of depression of the visible horizon at sea below the true horizontal direction, due to the height of the eye above the level of the sea. The dip in minutes of arc is approximately equal to the square root of the height in feet.—Dip, magnetic, or Inclination, is the angle which a magnetic needle free to move in a vertical circle in the magnetic meridian makes with the horizon. See Dipping Needle.

Dip, in geology, the inclination or angle at which strata slope or dip downwards into the earth. The degree of inclination or amount of the dip, which is easily measured by a clinometer, is the steepest angle made with a horizontal plane by a line drawn in the surface of the stratum. The line of dip is hence perpendicular to the intersection of the stratum with the horizontal, which is called the strike.

Dip Circle. See Dipping Needle.

Diphthe´ria is an acute infectious disease characterized by the formation of membrane in the throat and air-passages, and associated with severe disturbances affecting especially the heart and nervous system. It is due to a bacillus described by Koch in 1883. It is essentially a disease of the early years of life, and the period between two and twelve years covers the vast majority of cases. The commonest modes of infection are direct and indirect contact, infected milk, and defective drains. Of late years, the domestic cat has been held to be a source of infection. The disease runs a rapid course, beginning with fever, headache, chilliness, lassitude, and occasionally vomiting, while usually there is early complaint of sore throat. The membrane, which appears on the side of the throat, is usually of a dirty yellowish-white colour. It may be limited to a small area, but usually, if untreated, it would spread extensively over the throat, involving the palate and uvula. Diphtheria beginning in the larynx (windpipe) is what is popularly called croup (q.v.). There is danger of death in severe cases during the first few days from early heart failure, and almost any time during convalescence late heart failure may occur. Late heart failure is one of the forms of post-diphtheritic paralysis which arise from disturbances of the nervous system. The other common varieties are paralysis of the palate, of the pharynx, of the eye muscles, and of the respiratory muscles. An effective treatment is found in diphtheric antitoxin, which should be administered as early as possible in the disease. It is given under the skin, and the dose is regulated by the severity of the attack.—Bibliography: W. F. Litchfield, Diphtheria in Practice; W. R. Smith, Harben Lectures.

Diphthong (Gr. di-, double, and phthongos, sound), a coalition or union of two vowels pronounced in one syllable. In uttering a proper diphthong both vowels are pronounced; the sound is not simple, but the two sounds are so blended as to be considered as forming one syllable, as in void, bough. The term improper diphthong is applied to the union in one syllable of two or more vowels of which only one is sounded, as in bean.

Di´phyodont, a term applied to those animals which develop two sets of teeth, a deciduous or milk set, and a permanent set—as distinct from the monophyodonts, which develop only one set. The majority of mammals are diphyodont, though the number of teeth replaced may vary: thus in man twenty teeth of the adult are preceded by a milk set.

Diplacan´thus, a genus of ganoid fishes, found only in the Old Red Sandstone. They have small scales, a heterocercal tail, and two dorsal fins with a strong spine in front.

Diplei´doscope, an instrument for indicating the passage of the sun or a star over the meridian, by the coincidence of two images of the object, the one formed by single and the other by double reflection. It consists of an equilateral hollow prism, two of whose sides are silvered on the inside so as to be mirrors, while the third is formed of glass. The prism is adjusted so that one of the silvered sides shall be exactly in the plane of the meridian, and the transparent side towards the object. [40]

Diploid Phase, in botany. See Generations, Alternation of.

Diplo´ma (Gr. diplōma, from diploō, to double or fold), literally a document folded but once, and therefore divided into two parts. It is used to signify a document signed and sealed, in which certain rights, privileges, or dignities are conferred, especially a university degree.

Diplo´macy, the science or art of foreign politics. In a more restricted sense the term denotes the science or art of conducting negotiations and arranging treaties between states and nations; the branch of knowledge which deals with the relations of independent states to one another; the agency or management of envoys accredited to a foreign court; the forms of international negotiations. The word, borrowed from the French, was first used in England in 1796 by Burke. The Cardinal de Richelieu is generally considered as the founder of that regular and uninterrupted intercourse between Governments which exists at present between almost all the Christian powers; though the instructions given by Machiavelli to one of his friends, who was sent by the Florentine Republic to Charles V (Charles I of Spain) show that Richelieu was not the first to conceive the advantages that might be derived from the correspondence of an intelligent agent accredited at the seat of a foreign Government. As a uniform system, however, with a fixed international status, diplomacy was only established in the nineteenth century at the Congresses of Vienna (1815) and Aix-la-Chapelle (1818). Amongst the European powers it is agreed that of ministers of the same rank he who arrives first shall have the precedence over his colleagues.—Bibliography: D. J. Hill, History of Diplomacy in the International Development of Europe; E. C. Grenville-Murray, Embassies and Foreign Courts: a History of Diplomacy; P. Pradier-Fodéré, Cours de droit diplomatique; L. Oppenheim, International Law; D. P. Heatley, Diplomacy and the Study of International Relations.

Diplomat´ics, originally the science of deciphering ancient MSS. It laid down certain principles for the systematic examination of public documents, and taught the forms and styles adopted in them, and the titles and rank of public officers subscribing them. Among the earliest exponents of diplomatics were Daniel van Papenbroeck, an Antwerp Jesuit (1675), and Mabillon (De Re Diplomatica, 1681).

Diplomatic Service, The, as now existing, may be said to have originated in the Venetian Republic, which employed ambassadors as early as the thirteenth century. At first these officials had a very brief term of office, rarely remaining at their post in a foreign country for more than two or three months. By the middle of the fifteenth century, however, a permanent Milanese embassy had been established at Genoa, followed by one at Paris in 1494; while two years later Venice was officially represented at London. The clergy, who for the most part alone possessed the requisite accomplishments for such work, were the usual ambassadors of the Middle Ages; but by the sixteenth century lawyers, or not seldom merchants, were employed. It was not till two hundred years later that the modern attachés, junior officials of an embassy, came into being. The diplomatic service of Great Britain, controlled by the Foreign Office, includes (1) ambassadors, and (2) envoys and ministers plenipotentiary, both of which ranks represent the person of their sovereign and enjoy numerous special privileges in the country to which they are sent. Of lower standing are (3) ministers resident and (4) chargés d'affaires; the last-named are accredited, not to a sovereign, but to his foreign minister, and frequently act merely as temporary substitutes for an ambassador. Secretaries of more than one grade, with naval, military, and, of late years, commercial attachés, also form members of an embassy. Candidates for the British diplomatic service require a nomination from the Foreign Secretary, must be between the ages of nineteen and twenty-five, are subjected to an examination, and are almost invariably young men of good birth and position. The service is distinguished and affords a pleasant, if to some extent an idle life; but it does not offer any prospect of financial fortune. Lord Stratford de Redcliffe (the 'Great Elchi') and Lord Lyons rank high among distinguished British ambassadors. See Civil Service.

Diplozo´on, a parasitic trematode worm which infests the gills of the bream, and which appears to be formed of two distinct bodies united in the middle, and resembling an or St. Andrew's cross, two sexually mature individuals being thus united.

Dip´noi, mud-fishes or lung-fishes, an ancient order now represented by three genera—Neoceratodus, Protopterus, and Lepidosiren. Like some adult Amphibia they possess both gills and lungs, the latter corresponding to a specialized swim-bladder. The heart has two auricles instead of one only, as in all other fishes. The single species of Neoceratodus (N. forsteri) is a large form with paddle-like fins and large overlapping cycloid scales. It is native to the Burnett and Mary Rivers of Queensland. Protopterus is represented by three African species, which inhabit rivers and swamps from the Senegal to the Zambezi. It is smaller than Neoceratodus, somewhat eel-shaped, with very narrow fins, and small cycloid scales embedded in the skin. It spends the summer in a torpid condition, buried [41]in the mud, and is dug up by the natives as an article of food. Lepidosiren includes a single South American species (L. paradoxa) ranging from the Amazon to Paraguay. It is closely related to Protopterus, which it resembles in shape and the character of the fins.

Dippel, Johann Conrad, German theologian and alchemist, born 1672, died 1734. He studied theology, defended the orthodox party against the Pietists, led a turbulent life at Strasbourg, and then joined the Pietists until an unfortunate tractate placed him in disfavour with both parties. He then turned his attention to alchemy, and during a residence at Berlin produced the oil called after him, from which indirectly followed the discovery of Prussian or Berlin blue. After various adventures and wanderings in Sweden, Denmark, and Germany, he died at Berleburg.

Dippel's Oil, a pharmaceutical preparation obtained by the destructive distillation of animal matter, such as horn, ivory, blood. The crude form was refined by Dippel, and at one time was a good deal used in medicine as a diaphoretic and hypnotic. It is a form of bone oil, a product obtained in the manufacture of bone-black, or animal charcoal, by the distillation of bones. Crude bone oil has a most offensive smell. It contains the carbonate and other salts of ammonium, and a large variety of organic substances.

Dipper, a bird of the genus Cinclus, allied to the wrens. The common dipper, water-ouzel, or water-crow (Cinclus aquaticus), is a familiar European bird; it is about 7 inches in length, with a very short tail, small rounded wings, and large powerful feet; the bill is of moderate length, straight, and slender. The male has the upper part of the body dark brown, the throat and breast white, belly rusty. The dipper frequents streams, and feeds largely on water-insects and larvæ. It can dive and walk under water, effecting its progress by grasping the stones with its feet. The song is sweet and lively. Other species are found in North Asia, America, and North Africa.

Dipping-needle, or Inclination Compass, an instrument for showing the direction of the earth's magnetic force. In essentials the instrument consists of a light magnetized steel bar supported on a horizontal axis which passes, as nearly as possible, through the centre of inertia of the bar. When a needle thus mounted is placed anywhere not in the magnetic equator, it dips or points downward; and if the vertical plane, in which it moves, coincides with the magnetic meridian the position of the needle shows at once the direction of the magnetic force. The angle between the magnetic axis of the dipping-needle and the horizontal is called the dip or inclination. This varies from 90° at the magnetic poles to 0° at the magnetic equator. The dip is 70° at Glasgow, and varies slowly with the passage of time. In the northern hemisphere, the north-seeking pole of the dipping-needle dips downwards, the reverse being the case south of the magnetic equator.

Dipro´todon, a gigantic fossil marsupial from Pleistocene beds in Australia, allied to the kangaroos. The skull is 3 feet long.

Dipsas, a genus of tree-snakes of which the species are native to tropical South America. Some of the hinder teeth in the upper jaw are grooved for the conduction of poison, but this is not sufficiently deadly to be dangerous to human beings. The related genus Dipsadomorphus includes a number of Indian species.

Dipsoma´nia (Gr. dipsa, thirst, and mania, madness), a term used to denote an insane craving for intoxicating liquors, when occurring in a confirmed or habitual form. It is a form of acute alcoholism seen in persons with a strong hereditary tendency to drink. The only remedy appears to be seclusion, with enforced abstinence and healthy occupation. Homes for this purpose have been established in Britain under the Habitual Drunkards Act of 1879 and Inebriates Act of 1888. There are corresponding institutions in the United States.

Dip´tera, two-winged flies, an order of insects embracing a vast number of species, of which about 40,000 have been named. The two transparent wings correspond to the fore-wings of other insects, the hind-wings being often represented by small club-shaped structures (halteres or balancers). See diagram, p. 42. There are two large compound eyes, and the mouth-parts are often modified for piercing and sucking. There is a well-marked metamorphosis, the larvæ being usually limbless maggots. The Diptera include many agricultural and horticultural pests, and a number are notorious as disease carriers. See Blow-fly; Bot-fly; Crane-fly; Gnat; House-fly; Hover-fly; Midge; Mosquito; Tsetse-fly. [42]

Dipteris, a genus of Leptosporangiate ferns, section Mixtæ, formerly included in Polypodium, but now recognized as the sole living genus of the Dipteridineæ, a family which was largely developed in Mesozoic times. They are Indo-Malayan ferns with creeping rhizomes and long-stalked, fan-shaped, forked, leathery fronds.

Dipterocarpaceæ, an important order of Asiatic dicotyledonous trees, allied to the mallows (Malvaceæ). The different species produce a number of resinous, oily, and other substances; one, a sort of camphor; another, a fragrant resin used in temples; and others, varnishes; while some of the commonest produce pitches, and sal (Shorea robusta) yields valuable timber.

Diptych (dip´tik), in Greek originally signified the same as diploma, something folded; the double tablets of metal, ivory, &c., used by the Greeks and Romans. Diptychs became important in the Christian Church, in them being written the names of Popes, and other distinguished persons, who had deserved well of the Church, to be mentioned in the church prayers. Diptychs also often contained pictures of biblical scenes.—Cf. Sir W. Smith, A Dictionary of Greek and Roman Antiquities.

Dipyre (dī´pīr), or Mizzonite, a mineral—aluminium calcium sodium silicate—of the scapolite series. Its name indicates the double effect of fire upon it (Gr. di, double, pyr, fire) in producing first phosphorescence, and then fusion.

Diræ, one of the names under which the Eumenides were known to the Romans. See Furies.

Directors, persons elected to meet together at short fixed intervals and consult about the affairs of corporations or joint-stock companies, and to advise and assist the manager. These are termed Ordinary Directors, as in many companies there is a body called Extraordinary Directors, who have little or no business functions, and are chosen as a rule on account of their social position imparting a degree of distinction to the concern. Directors are appointed by a general meeting of the shareholders in the undertaking, and a certain number of them, usually a third, retire every year. Ordinary directors are granted a certain remuneration for their services. The duties and responsibilities of directors are defined by the constitution of the company, or by the various Acts of Parliament affecting joint-stock and other companies.

Direc´tory, the name given to a body of five officers to whom the executive authority in France was committed by the Constitution of the year III (1795). The two legislative bodies, called the councils, elected the members of the Directory: one member was obliged to retire yearly, and his place was supplied by election. This body was invested with the authority which, by the Constitution of 1791, had been granted to the king. By the Revolution of the 18th Brumaire the Directory and the Constitution of the year III were abolished. It was succeeded by the Consulate, with Napoleon as First Consul.

Direc´trix, a fixed line that is required for the description of a curve. The term is chiefly used in connection with the parabola, ellipse, and hyperbola, which are the loci of points that move so that their distances from a fixed point (the focus) are in a constant ratio to their distances from the directrix. The directrix of a parabola is a line perpendicular to the axis produced, and at a distance from the vertex equal to the distance of the vertex from the focus. Thus AB is the directrix of the parabola VED, of which F is the focus.

Dirk, a kind of dagger formerly used as a weapon of offence by the Highlanders of Scotland. Dirks are worn by midshipmen and cadets of the Royal Navy, and still form part of the full Highland costume.

Dirk-Hartog Island, on the west coast of Australia, 45 miles long, north to south, and 10 miles broad.

Dirt-beds, in geology, layers of ancient soil, such as those in the Oolitic strata of the Isle of Purbeck (Dorset), which contain the stumps of trees that once grew in them.

Disability, in law, incapacity to do any legal act. It is either absolute, which wholly disables the person, such as outlawry or [43]excommunication—or partial, such as infancy, coverture, insanity, or drunkenness.

Disbarring, or Disbarments, expelling a barrister from the Bar, a prerogative which, in England, is possessed by the benchers of each of the four Inns of Court. The party disbarred may lodge an appeal with the judges in their capacity of visitors.

Disc, or Disk, the central part of the capitulum of compositæ, surrounded by the ray. Also a part of a flower, sometimes cup-shaped, at the base of the stamens, consisting in some cases of rudimentary stamens, in others of the modified receptacle.—In astronomy the term is applied to the visible face or figure exhibited by the sun, moon, or a planet. In the case of the moon and certain planets it may be of gibbous, semicircular, or crescent form.

Discharging Arch, an arch formed in the substance of a wall to relieve the part which is below it from the superincumbent weight. Such arches are commonly used over lintels and flat-headed openings.

Discipline, Books of, two books connected with the Church of Scotland. The First Book of Discipline was drawn up by John Knox and four other ministers, and laid before the General Assembly in 1560. Though not formally ratified by the Privy Council, it was secretly subscribed by the greater part of the nobility and barons who were members of the Council. Another similar document, the Second Book of Discipline, was prepared and sanctioned by the General Assembly of 1578, and has from that time been recognized as the authorized standard of the Church of Scotland in respect of government and discipline.

Disclaim´er, in its stricter legal sense, a plea containing renunciation or a denial of some claim alleged to have been made by the party pleading.

Discomycetes, a large section of the ascomycetous Fungi, distinguished by the fact that the hymenium covers the surface of an open, disc-like or cup-shaped fruit-body called an apothecium. It includes many important genera, such as Dasyscypha, Peziza, and Sclerotinia.

Discopho´ra, (1) a sub-class of the Hydrozoa, comprising most of the organisms known as sea-jellies, jelly-fishes, and sea-nettles; (2) leeches (q.v.).

Dis´count, the charge made by a banker for interest of money advanced by him on a bill or other document not presently due. In advancing money on such a security the banker deducts the charge for interest on his advance from the total amount represented on the security, pays the difference, which is called the proceeds of the bill, to the person parting with it, and collects the full amount to reimburse himself for outlay and interest at maturity. Popularly the term discount is applied to any deduction from the full amount of an account made by the party to whom it is paid, especially on prompt or early payment. When a bill which has been discounted is paid by the acceptor before it is due, the discount allowed for prepayment is called rebate.

Discov´ery, in law, the act of revealing or making known any matter by a defendant in his answer to a bill in chancery. The word is also used in reference to the disclosure by a bankrupt of his property for the benefit of his creditors, and to the right of a party to a lawsuit to obtain from his adversary, on oath, full disclosure of the facts within his knowledge, and production of the documents in his possession, pertinent to the action.

Discus, Disc, or Disk, among the Greeks and Romans a quoit of stone or metal, convex on both its sides, sometimes perforated in the middle. The players aimed at no mark, but simply tried to throw the quoit to the greatest possible distance. It was sometimes furnished with a thong of leather to assist in the throwing. The thrower of the discus was called discobolus.

Disease, any morbid state of the body, or of any organ or part of the body. Diseases are described as local or constitutional, epidemic, endemic, contagious, acute, and chronic. As to their classification, see Nosology. The influence of the parents on the organization of the child is so great that not only peculiarities of external form, but the peculiar constitution, the greater or less activity and development of the organs, are found to pass from parent to child. As it is in the particular state of the several tissues and functions that certain diseases have their foundation, the liability to such affections is inherited with the organic structure, and children are not infrequently attacked by ailments from which one of their parents or grand-parents had previously suffered. In spite of the emphasis that has recently been put on the facts of heredity, the present tendency of preventive medicine holds out a larger hope by impressing upon us the fact that in such affections, for example, as tuberculosis and insanity, the individual's environment and personal history are perhaps more [44]potent than hereditary influence in the causation or the prevention of disease.

Diseases of Plants. See Plant Pathology.

Disestablishment, the severance of connection between Church and State, with the resultant emancipation of the Church from civil control, is a movement in which there has been considerable growth during the last half-century. The Church of the West Indies was disestablished in 1868, and all Colonial Churches, with the exception of the Church in India, are now free from State authority. In 1869 an Act, taking effect two years later, was passed for the disestablishment of the Church of Ireland, in which country the mass of the inhabitants are Roman Catholics. In France all recognition of Roman Catholicism as the State religion ceased in 1905, the French Government now tolerating all religions. In 1914 was passed a Bill for disestablishing the Church in Wales, though its effect was, owing to the war, deferred till 1920 by the Suspensory Bill. The Church of Scotland has been practically free from State control since 1874, in which year patronage was abolished; and the presence of the Lord High Commissioner, who represents the sovereign at the opening of the General Assembly, and the precedence enjoyed by the Moderator during his term of office, are little more than decorative courtesies. Among a section of the English public there has been from time to time an agitation for the disestablishment of the Church of England; and the movement is even said to be viewed with favour by some advanced High Churchmen, who believe that it would result in increased freedom for the adoption of their special views; but, though a Disestablishment Society exists, there seems no immediate prospect of a decisive step in this direction.

Dishonour of a Bill, the refusal or neglect to accept or pay when due a bill of exchange, or promissory note, or draft on a banker. It is absolutely necessary that the holder of a dishonoured bill should give immediate notice of the non-payment to the drawer or endorsers.

Disinfection, the means employed for killing the germs of infectious or contagious disease by physical or chemical agencies. The former are the more important, and consist in applying water or steam at the boiling-point, or hot air at 160°C. Ten minutes' boiling, or half an hour in hot air, kills all ordinary disease germs, but a longer exposure is necessary to kill germs (especially those of putrefaction), which form spores (see Bacteria). The most important chemical agents are chlorine, iodine, carbolic acid, bleaching powder, Condy's red fluid (containing permanganate of potash), perchloride of mercury, formalin, and flavine. Carbolic acid is one of the most effective, needing, however, care in the handling, as it is very poisonous and in strong solution causes severe burns. It does not in its common form mix with water, but solutions can be made by using hot water. A greater dilution than 1 part in 40 of water is useless as a disinfectant. For application to the skin, tincture of iodine is one of the readiest preparations. In cases of infectious disease the most important points are the immediate disinfection of all the excretions of the patient. Expectoration should be received into a sputum-cup containing 1-20 carbolic acid, and all handkerchiefs when soiled should be similarly treated. The personal linen and sheets of the patient should be placed in carbolic acid (1-40) in a slop-pail, and should be boiled before being sent to the laundry. All plates, spoons, &c., used for the patient's food, should be boiled or scalded immediately after use. The excretions of the bowels or kidneys should be treated with bleaching powder. Those in attendance should wear an overall when in the sickroom, and should wash the hands and face before coming into contact with anyone outside. They should wash out the mouth frequently with Condy as strong as can be tolerated. Their linen should be treated in the same way as that of the patient. At the close of the illness all bedding should be baked in the hot-air oven which most local authorities now provide for the purpose. Everything washable in the sickroom should be washed with soft soap, and it is better that the room should be repapered.

Disin´tegrator, a machine for pulverizing and sometimes for mixing various materials, such as rock, asphalt, ore, artificial manures, sugars, corn, and the ingredients of mortar.

Disloca´tion, a surgical term applied to cases in which the articulating surfaces of the bones have been forced out of their proper places. The particular dislocation takes its name either from the joint itself or its farthest bone, and is called compound when accompanied by an external wound. The most common dislocations are those of the hip, shoulder, elbow, knee, and ankle, and the chief obstacle to their reduction is the spasmodic and violent contraction of the muscles consequent upon them, the application of considerable force being often necessary to set the joint. Chloroform is of great use, not only in preventing pain but in relaxing the muscles. The most dangerous dislocations are those of the bones of the spine.—In geology it signifies the displacement of parts of rocks or portions of strata from the situations they originally occupied.

Dismal Swamp, a large tract of marshy land in America, beginning a little south of Norfolk, in Virginia, and extending into North Carolina, containing 150,000 acres; 30 miles long, from [45]north to south, and 10 miles broad. This tract was entirely covered with trees, with almost impervious brushwood between them, but it has now in part been cleared and drained. In the midst of the swamp is a lake, called Drummond's Pond, 7 miles in length. A navigable canal through the swamp connects Chesapeake Bay and Albemarle Sound.

Dispensa´tion is the act by which an exception is made to the rigour of the law in favour of some person. The Pope may release from all oaths or vows, and may sanction a marriage within the prohibited degrees of the Mosaic law, or exempt from obedience to the disciplinary enactments of the canon law. In England the monarch claimed, in former times, a similar dispensing power in civil law, but the prerogative was so much abused by James II that it was abolished by the Bill of Rights. The power of commuting sentences in capital cases is the only form in which the dispensing power of the Crown still exists. In ecclesiastical matters a bishop may grant a dispensation allowing a clergyman to hold more than one benefice, or to absent himself from his parish.—Cf. F. W. Maitland, Constitutional History of England.

Dispersal of Seeds and Fruits serves (a) to scatter these reproductive structures and so reduce internecine competition; (b) to bring the seeds into new surroundings, which may be more favourable than those of the parent plant. The chief agents of dispersal are wind and animals. Very minute seeds, like those of orchids, are carried away by the gentlest air-currents. Larger wind-borne seeds are winged, as in the pine, most Bignoniaceæ, &c.; or provided with a tuft of hairs acting as a parachute, as in willow, willow-herb, cotton, &c. Winged fruits are exemplified by ash, elm, sycamore, many docks, &c.; parachute fruits by Compositæ, Clematis, cotton-grass, &c. In the case of animal dispersal, the whole fruit is usually involved, being either edible, with hard indigestible seeds which are cast up or voided with excreta (fleshy fruits), or hooked so as to adhere to fur or wool, as in bidens, cleavers, enchanters' nightshade, and other 'burs'. A small number of fruits and seeds, such as the coco-nut and the seeds of water-lilies, are adapted for water transport. In certain cases seeds are scattered for short distances by an 'explosive' mechanism, as in wood-sorrel, impatiens, sand-box tree, squirting cucumber, and other 'sling' fruits.

Dispersion, in optics, the angular separation of light rays of different colour, that is, of different wave-length. Dispersion may be caused either by refraction or by diffraction. When a [46]beam of composite light passes obliquely from air into a second transparent medium, each constituent of the light is bent or refracted through a different angle from the original direction of the beam, with the result that the different colours are separated fanwise, or dispersed at the surface of the second medium. In the refraction spectrum of white light, when caused by passage through a glass prism, the red rays are least deviated and the violet rays most deviated, if we consider only the visible spectrum. The difference of the angles of deviation for two selected rays measures their dispersion, and if this angle is divided by the deviation of the mean ray, we obtain the dispersive power of the prism. Transparent media vary in their dispersive powers; for example, carbon disulphide has more than three times the dispersive power of crown glass. The true nature of dispersion was first demonstrated by Newton, who concluded that the colours of the spectrum were homogeneous and caused by simple vibrations of definite wave-length, the different colours being unequally refrangible. Newton was, however, led to the erroneous view that the dispersion was proportional to the refraction. This was later disproved by the construction of achromatic lenses, or lenses which caused deviation without dispersion, and of direct-vision spectroscopes, or instruments which caused dispersion with no deviation of the central part of the spectrum. The dispersive power is not the same for all parts of a refraction spectrum; besides, the same colours do not occupy the same positions in spectra formed by prisms of different material. This arises from the fact that there is no simple relation between the deviation of a ray and its wave-length; consequently, such spectra are called irrational, and the property is known as the irrationality of dispersion. In the diffraction spectrum, the order of the colours is reversed, red undergoing the greatest deviation; also, the deviation for a given colour is nearly proportional to the wave-length. The diffraction spectrum is therefore termed a normal spectrum.

All substances do not give the same order of colours in their spectra; certain exceptions are known in which the usual order of the colours is changed. Christiansen showed that an alcoholic solution of fuchsine gave a spectrum containing only violet, red, and yellow; the violet is least refracted, and the yellow most, and a dark band lies between the violet and the red. This has been called anomalous dispersion, and similar effects have been observed in iodine and sodium vapours, and in solutions of colours derived from aniline which exhibit surface colour.

The theory of dispersion now generally accepted is that of Sellmeier, which was published in 1871. Sellmeier assumed that when light waves pass through a material substance, they set the particles of the substance in vibration, and these resonant vibrations react in such a way as to modify the velocity with which the waves are transmitted. Applying the dynamical principles of wave motion to the case of an elastic solid in which heavy particles are embedded, Sellmeier obtained an equation which connected the refractive index of the substance with the wave-length of the incident light. Equations of similar form were subsequently derived by Ketteler and Helmholtz. The consideration of Sellmeier's equation leads to important conclusions. If the period of vibration of the incident waves is very short, as compared with those of the particles forming the solid, no refraction will take place, and the rays will travel through the solid without deviation and without change of velocity. This is verified in the case of X-rays, which consist of extremely short waves and which are not deviated on passing through light-opaque solids. Sellmeier's equation may also be modified to apply to the case of anomalous dispersion. The phenomenon is always associated with absorption of light of a particular wave-length or range of wave-lengths, and the conclusion is drawn that the medium will possess an abnormally high refractive index for waves slightly longer than those which it absorbs, and an abnormally low index for waves slightly shorter than those which it absorbs. This result has been verified by various investigators. Rubens has determined the values of the constants in Sellmeier's equation for rock-salt, sylvine, fluorspar, and quartz, and has shown that the equation gives correct values for the refractive indices of these substances over the entire range of wave-lengths to which they are transparent.—Bibliography: T. Preston, Theory of Light; E. Edser, Light for Students; P. Drude, Theory of Optics.

Displacement. The position of a point in space is fixed by means of its distances x, y, z, from three mutually rectangular planes. If the point moves to another position, it is said to be displaced, and the rates of displacement parallel to these planes measure the velocities dx/dy, dy/dt, dz/dt parallel to these planes. If the acting forces be resolved in directions parallel to these planes, relations may be found between the forces, the accelerations parallel to the planes and the mass of the body. These relations are called the equations of motion. In hydrostatics a body immersed in a liquid displaces a certain volume of the liquid, and the upthrust of the liquid in the body is, by the principle of Archimedes, equal to the weight of liquid displaced. It follows [47]that, in the case of a floating ship, the weight of the ship is equal to the weight of water displaced. This weight is called the displacement of the ship, and is measured in tons.

Disposition, in Scots law, is, in its general acceptation, a deed by which a person provides for the general disposal of his property heritable and movable, after his death, equivalent to a will or testament; also a conveyance of property.

Disraeli, Benjamin. See Beaconsfield.

D'Israeli (diz-rā´e-li), Isaac, man of letters, and father of the well-known statesman, was born at Enfield, Middlesex, in 1766, died in 1848. His father, Benjamin D'Israeli, a descendant of a family of Spanish Jews which had settled at Venice in the fifteenth century to escape the Inquisition, came over to England in 1748 and made a large fortune. Isaac D'Israeli, however, showed a strong repugnance to commerce, and was finally permitted to follow his literary bent. An anonymous reply to Peter Pindar, entitled On the Abuse of Satire, was followed during 1791 to 1793 by the appearance of his Curiosities of Literature, the success of which determined much of his afterwork. His Essay on the Literary Character was published in 1795, and some time afterwards a volume of romantic tales, The Loves of Mejnoun and Leila. Between 1812 and 1822 appeared his Calamities of Authors, Quarrels of Authors, and Inquiry into the Literary and Political Character of James I; the three being afterwards published collectively under the title of Miscellanies of Literature. In 1828 appeared the commencement of his Life and Reign of Charles I, a work completed in 1831. An affection of the eyes put an end to a projected Life of Pope and a History of English Freethinkers, but in 1841 he published a selection from his MSS. under the title of Amenities of Literature. The greater part of his life was passed in his library. For his son, see Beaconsfield.

Disrup´tion, the name commonly applied in Scotland to the act by which, in 1843, 474 ministers and professors of the Established Church gave up their livings to vindicate principles which they held to be essential to the purity of the Church, and in harmony with its earlier history. See Free Church.

Diss, a town, England, Norfolk, on the slope of a hill 18 miles south by west of Norwich. It was formerly noted for the manufacture of 'Suffolk hempen cloth', worsted yarn, and knit hosiery. Pop. 3763.

Dissection, a word, derived from Latin, that is etymologically equivalent to the word anatomy, derived from Greek. Its literal meaning is 'cutting up', and it is used to define the technical procedures for acquiring a practical knowledge of the anatomy or structure of the body. Dissection of the human body is an essential part of the education of a medical practitioner, for it is the only means whereby he can acquire a thorough and practical familiarity with the geography of the territories in which all his professional activities lie. Therefore the medical student is required thoroughly to explore every part of the human body, to examine all its constituent parts, to learn to recognize their properties, positions, and relationships, and to train his eyes and fingers to appreciate their distinctive qualities. This process of exploration usually occupies about eighteen months or more of the student's time; but it represents the foundation upon which all his professional knowledge and experience are built up. For this purpose it is of the utmost importance that he be provided with ample facilities for acquiring the training which is essential to the medical practitioner. But the supply of subjects for dissection is difficult to acquire. Until a century ago teachers in medical schools, being unable to get an adequate supply of bodies for dissection by legal means, were forced to deal with 'body snatchers' who plundered cemeteries. Eventually the terrible scandals associated with the names of Burke and Hare forced the Government to pass an Anatomy Act to make better provision for this necessary part of medical education. Within recent years the action of Boards of Guardians has so hampered the administration of the Act that teachers in medical schools are threatened with the same dilemma as their colleagues a century ago had to face. The Guardians of the Poor in some localities prefer to bury the unclaimed bodies of the dead at the ratepayers' expense rather than allow them to be used for the necessary instruction of surgeons and physicians. Offers are repeatedly made by men and women, often well-known and distinguished people like the late Miss Florence Nightingale, to place their bodies at the service of medical education; but in accordance with the law of the land such bequests are invalid, because once a person is dead the corpse is not his property but belongs to his relatives. Hence it is only the unclaimed bodies that are legally available for dissection.

Dissei´zin, or Disseisin, in law, is the dispossessing one of a freehold estate, or interrupting his seisin. Of freeholds only can a seizin be had, or a disseizin done. Whether an entry upon lands is or is not a disseizin, will depend partly upon the circumstances of the entry, and partly upon the intention of the party as made known by his words or acts.

Dissent´ers, the common name by which in Britain all Christian denominations, excepting those of the Established Churches, are usually designated, though in Acts of Parliament it generally includes only Protestant dissenters, [48]Roman Catholics being referred to under their specific name. The most important bodies of English dissenters are the different bodies of Methodists, the Congregationalists, and the Baptists; and of Scottish dissenters, the United Free Church and the Free Church. The Nonconformists were dissenters from the English Church, and the name is sometimes used as meaning simply dissenters, though it has properly a wider meaning.

Dissentis´, a Swiss town, canton of Grisons, 3800 feet above the sea, at the junction of the Middle and Vorder Rhine, with a Benedictine abbey established so long ago as A.D. 614. Pop. 1420.

Dissociation. Certain substances tend to break down into simpler substances with change of temperature; thus ammonium chloride on heating gives a mixture of hydrochloric acid (HCl) and ammonia (NH₃), and on cooling these substances recombine to give ammonium chloride (NH₄Cl) again. Dissociation is therefore a particular case of decomposition, where the products of decomposition recombine on obtaining the original conditions.

Dis´sonance, in music, that effect which, results from the union of two sounds not in accord with each other. The ancients considered thirds and sixths as dissonances; and, in fact, every chord except the perfect concord is a dissonant chord. The old theories include an infinity of dissonances, but the present received system reduces them to a comparatively small number. The most common are those of the tonic against the second, the fifth against the sixth, or (the most frequent of all) the fourth against the fifth.

Dis´taff, the first instrument employed in spinning. It consisted of a staff, on one end of which the wool or flax was rolled. The spinner held it in the left hand, and drew out the fibres with the right, at the same time twisting them. A small piece of wood called a spindle was attached to the thread, the weight of which carried it down as it was formed. When the spindle reached the ground, the thread which had been spun was wound round it, and it was then again fastened near the beginning of the new thread. In ancient and modern art the Fates are usually represented with the distaff, engaged in spinning the thread of life.

Distemp´er, a disease of the dog commonly considered as of a catarrhal nature. In most cases a running from the nose and eyes is one of the first and chief symptoms, the defluxion becoming after some time mucous and purulent. The animal is subject to violent fits of coughing combined with vomiting, loses its appetite, its flesh begins to waste, and if the disease be virulent, symptoms of affection of the brain manifest themselves, accompanied by fits, paralysis, or convulsive twitchings. In the first stage of the disease laxatives, emetics, and occasional bleeding are the principal remedies; diarrhœa should be checked by astringents, and to reduce the violence of the fits warm bathing and antispasmodics should be resorted to. The distemper is generally contagious, and occurs but once in a lifetime.

Distemper (It. tempera), in painting, a preparation of colour mixed with size, yolk of egg or white of egg. Prepared with size, it is used chiefly in scene painting and household decorations, but in other forms it is much used for easel and mural paintings. Before the introduction of oil as a medium in the fifteenth century, fresco and distemper were the principal methods of painting. Distemper is usually but not necessarily applied to a dry ground, fresco always to a wet.

Distich (dis´tik), a couplet of verses, especially one consisting of a Latin or Greek hexameter and pentameter, making complete sense. Distichs have been frequently made use of by the modern German poets.

Distillation, the volatilization and subsequent condensation of a liquid in an apparatus known as a still and heated by a fire or flame. The operation is performed by heating the crude liquid or mixture in a retort or vessel known as the body of the still. This is made of various shapes and materials, and is closed, with the exception of a slender neck which opens into the condenser, a long tube through which the hot vapour from the still is passed. The tube is kept at a sufficiently low temperature to cause the vapour to condense, the common method of securing this being to surround the tube with a constantly renewed stream of cold water. In some cases ice or a freezing mixture may be required to effect condensation. In a large-scale apparatus the condensing tube is coiled round and round in a tub or box, and is known as a worm. From the end of it the vapour condensed into a liquid drops into a receiver. The simplest case of distillation is that of water containing solid matter in solution, the solid matter remaining behind in the still or retort while the water [49]trickles pure into the receiver, through a worm made of block-tin, as most other metals are attacked by distilled water. When the mixture to be distilled consists of two or more liquids of different boiling-points, such as alcohol and water, the more volatile comes off first, accompanied by a certain proportion of the vapour of the other, so that it is hardly possible completely to separate bodies by one distillation. This is effected by repeated successive distillations of the liquid with or without the addition of substances to retain the impurities. When the production of one of the ingredients only is aimed at by this process, it is called rectification, but when it is desired to separate and collect all the liquids present, or to divide a mixture into portions which volatilize within certain ranges of temperature, the process is called fractional distillation. In the laboratory, distillation is employed for purifying water, for recovering alcohol and ether, and for the preparation, purification, and separation of a great number of bodies. Substances which decompose at their boiling-points can be distilled under reduced pressure. On the large scale distillation is employed in the preparation of potassium, sodium, zinc, mercury; of sulphuric acid, ether, chloroform, carbon bisulphide, essential oils and perfumes; in the purification of coal and wood tar, and the products obtained from them; and on an extensive scale in the manufacture of whisky, brandy, or other spirit. The distillation of whisky has long been familiar in Britain, especially in Scotland and Ireland, and, when performed by means of the old pot-still, is a simple operation indeed, and one that even yet is practised surreptitiously in out-of-the-way localities. On the large scale a more elaborate apparatus is employed, and for alcohol of a cheap class Coffey's or other patent still is much used. Copper is the metal that suits best as the material for the stills used in distilling whisky. Sea-water is distilled in many cases for drinking or cooking purposes. This water is, of course, very pure, but its taste is far from agreeable. Destructive distillation, or dry distillation, differs from the preceding in this respect, that the original substance is not merely broken up into bodies by the mixture of which it is formed, but is so treated that it is further decomposed, and products are obtained which were not present uncombined in the original material. (See Coal-tar.) The term is restricted to the action of heat upon complex organic substances out of contact with the air. The products of destructive distillation are numerous and varied. On the manufacturing scale the process is conducted sometimes for the sake of one part of the products, sometimes for the sake of another. Coal, for example, may be distilled not solely for the gas, but also for ammoniacal water, benzene, anthracene, as well as for the sake of the fixed carbon or coke, the volatile portions being too often neglected and practically wasted. But much more economical methods of making coke are now practised than formerly. Wood is distilled partly for the sake of the pyroligneous acid and the tar, partly for the charcoal. Bones are distilled for the sake of the charcoal, though the oil is also collected. Shale is distilled both for the oil and for the paraffin wax, ammonia, &c., obtained.

Distinguished Conduct Medal, a medal instituted in 1854 under the name of the Meritorious Service Medal as "a mark of the Sovereign's sense of the distinguished service and gallant conduct in the field of the army then serving in the Crimea". The regulations concerning this medal were revised in 1862, when it received its present name. It is given to warrant-officers, non-commissioned officers, and privates. As from the 1st Aug., 1918, the medal is awarded for services in action only. The medal is silver, 1.4 inches in diameter; on the obverse is the Sovereign's head, and on the reverse the inscription "For Distinguished Conduct in the Field". It is suspended from a ribbon 1¼ inches wide, crimson, blue, and crimson, the colours being of equal width. Bars may be awarded for additional deeds of [50]gallantry; in service uniform the possession of a bar is indicated by a silver rosette worn on the ribbon. The letters D.C.M. are placed after the name of the recipient, who receives either a gratuity of £20 on discharge, or an increase in pay of 6d. a day.

Distinguished Flying Cross, a decoration instituted during the European War, and awarded to officers and warrant-officers of the Air Force for acts of gallantry when flying in active operations against the enemy. The ribbon is 1¼ inches wide, and has narrow purple and white alternate diagonal stripes. The letters D.F.C. are placed after the name of the recipient. A corresponding medal, the Distinguished Flying Medal, is awarded to non-commissioned officers and men.

Distinguished Service Cross, a naval decoration formerly known as the Conspicuous Service Cross, and instituted in 1901. It is awarded to naval officers below the rank of lieutenant-commander, and to warrant-officers, for services before the enemy. The ribbon is dark-blue, white, and dark-blue, in stripes of equal width. The letters D.S.C. are placed after the name of the recipient.

Distinguished Service Order, The, was instituted by Royal Warrant on 6th Sept., 1886. All commissioned officers of the Navy, Army, or Air Force are eligible to be appointed Companions of this Order. It is conferred upon officers who have been specially mentioned in dispatches for meritorious or distinguished services. Towards the end of the European War (1st Aug., 1918) it was decided that this decoration was only to be given for services in action, i.e. (1) for service under fire, or (2) distinguished individual service in connection with air-raids, bombardments, or other enemy action. Bars may be awarded for additional deeds of gallantry; in undress uniform the possession of a bar is indicated by a silver rosette worn on the ribbon. The ribbon is red, edged with blue, and is 1 inch wide. It is the same as the ribbon of the Waterloo and Peninsular medals, only narrower. The badge of the order is a gold cross patée enamelled white, edged gold, having on one side thereof, in the centre, within a wreath of laurels enamelled green, the Imperial Crown in gold, upon a red enamelled ground, and on the reverse, within a similar wreath and on a similar red ground, the Imperial and Royal cipher (G.R.I.) The letters D.S.O. are placed after the name of the recipient, who ranks between Commanders of the Order of the British Empire and Members of the Royal Victorian Order (4th class).

Dis´tomum, a genus of trematode or suctorial parasitic worms or flukes, infesting various parts in different animals. D. hepaticum, the common liver fluke, when adult inhabits the gall-bladder or ducts of the liver in sheep, and is the cause of the disease known as the rot. It may also occur in ox and man. In form it is ovate, flattened, and presents two suckers (whence the name), of which the anterior is perforated by the aperture of the mouth. The digestive tube divides into two branching halves, the excretory organs consist of delicate branching tubes, and there is a complex set of hermaphrodite reproductive organs. The minute larvæ live in a small water-snail (Limnæa truncatula), from which they ultimately escape to encyst on grass, &c., by which sheep may become infested. The adults of other species of Distomum live within the bodies of various fishes, amphibia, reptiles, birds, and mammals.

Distress´ (Lat. distringere, pull asunder), in law, is the taking of a personal chattel of a wrong-doer or a tenant, in order to obtain satisfaction for the wrong done, or for rent or service due. If the party whose goods are seized disputes the injury, service, duty, or rent, on account of which the distress is taken, he may replevy the things taken, giving bonds to return them or pay [51]damage in case the party making the distress shows that the wrong has been done, or the service or rent is due. Wrongful distress is actionable. Another kind of distress is that of attachment, to compel a party to appear before a court when summoned. The distresses most frequently made are on account of rent and taxes and damage-feasance.—Cf. Blackstone, Commentaries on the Laws of England.

Distribution is that part of the subject-matter of economics which deals with the division, among the individuals composing a community, of the product of their labour and of land and capital at their command. It is the most contentious part of economics, as well as that which has most social interest and importance, for in it there is a sharper conflict than anywhere else between economic considerations and ideals of social justice, and the problem is to secure such a distribution as will satisfy social justice, without abandoning the incentive to effort provided by the possibility of a greater reward.

The present position is one of unresolved discord between the economic and the equalitarian schools. The economic analysis in based upon a division of the factors of production into three, viz. Labour, Capital, and Land. These are represented as competing among themselves for employment, which is given to each in accordance with the return which will be secured as a result of an addition to the amount already employed; the rewards of each fall roughly under the headings of Wages and Salaries, Interest and Rent, respectively. The demarcation cannot be exact, as much that in common life is regarded as interest on capital partakes really of the nature of wages, as being earnings of management or reward for risk-taking, while certain forms of capital, whose quantity is temporarily fixed, may receive a return which is more of the nature of rent.

The fundamental assumption of the economists is that competitive distribution is indispensable, both in order to secure a fruitful distribution of the resources and efforts of society between the three factors of production, and also owing to the need of an incentive to keep individuals working hard enough to ensure a supply of goods sufficient to maintain and improve the standard of life of the community. Economists do not assume that men would not work at all if they were guaranteed a living wage whether they did or not, but that men would not work enough, and would be guided in the direction of their efforts by personal idiosyncrasy rather than by the needs of the community. The only alternatives to a great falling off in national wealth are, in their view, either competitive distribution or enforcement of work by a rigid discipline, which would be as hard as the present system, while being less adaptable.

Against this analysis idealist thinkers rebel, on the ground that it fails to justify the great inequality in the distribution of wealth between different individuals and classes of society. Their protest dates from the harsh dogmatism of the economists who propounded the now discredited 'Iron Law of Wages' and 'Wages Fund Theory', which both consigned wage-earners to lives of unremitting toil for a reward inevitably limited to a very small amount. Against these views appeal is made to justice and equality, and the result is summed up in the phrase 'to each according to his needs, from each according to his ability', i.e. the community should be so organized that each member receives that which he needs, while giving in return work according to the best of his ability. An alternative and cruder theory is that which demands absolute equality in the distribution of wealth. The economic basis for these theories is the claim that all production is the result of labour, and that the workers are entitled to the 'whole produce of their labour', interest and rent being 'surpluses' appropriated by the capitalist owing to the exploited workers being kept at the level of subsistence. The economic statement of the case is generally associated with the name of Marx, who was, however, greatly influenced by English writers; but the driving force of the movement is moral and emotional.

District Courts, an important series of courts in the United States, each under a single judge, and having original jurisdiction in civil, criminal, and admiralty causes. Generally there is one for each state. By the Judiciary Code, enacted by Congress in 1911, the circuit courts, which had hitherto shared original jurisdiction with the district courts, became only appellate tribunals.

Distringas (Lat., that you distrain), a notice proceeding upon an affidavit filed in the High Court by a party not the registered holder of shares or stock but beneficially interested therein, and served upon the particular company or public body, whereby it is precluded from registering any transfer of the shares or stock or any mandate for payment of the dividends without previous intimation to such party. The latter has thus the opportunity, if desired, to apply for an interim injunction, and, should he not do so within eight days from the date upon which the transfer or mandate was lodged, the restraint flies off.

Dithyram´bus, or Dith´yramb, in Greek literature, a poem sung in honour of the god Bacchus or Dionysus, at his festivals. The choral portion of Greek tragedy arose out of the [52]dithyramb. It was composed in a lofty and often inflated style: hence the term is applied to any poem of an impetuous and irregular character.

Ditmarshes (Ger. Dithmarschen), a district of Holstein, in Germany, consisting of a monotonous flat stretching along the North Sea, between the mouths of the Elbe and the Eider, and so little raised above the sea as to require the protection of strong embankments. Ditmarshes was incorporated in Prussia in 1866. The area is 500 sq. miles, and the total pop. 96,373.

Dit´tany, the popular name of the plants of the genus Dictamnus, an herb of the rue family (Rutaceæ), found in the Mediterranean region. The leaves are pinnate, the large white or rose-coloured flowers are in terminal racemes. The whole plant is covered with oily glands, and the secreted oil is so volatile that in hot weather the air round the plant becomes inflammable. D. Fraxinella and D. albus are found in gardens.

Dittay, in Scots law, a technical term signifying the matter of charge or ground of indictment against a person accused of a crime; also, the charge itself.

Diuret´ics are agents used to increase the flow of urine. Many drugs are used for this purpose: caffeine and theobromine, digitalis and squills, potassium salts, carbonates, calomel and blue pill.

Divan´, a Persian word having several significations. It is used in Turkey for the highest Council of State, the Turkish ministry; and for a large hall for the reception of visitors. Low couches, covered with rich carpets and cushions, are ranged along the walls of the room. Hence in Western Europe the term is applied to a café, and to a kind of cushioned seat. In India the term is applied to the Prime Minister of a native State. Among several Oriental nations this name is given to certain collections of lyric poems by one author. The divans of Hafiz and Saadi, the Persian poets, are among the most important.

Divergent, in algebra, opposed to convergent, a term applied to an infinite series which cannot be said to have a sum because there is no definite limit towards which the sum of its terms tends as the number of terms is increased indefinitely.

Divers, birds remarkable for the habit of diving. The divers (Colymbidæ) are a family of swimming birds, characterized by a strong, straight, rather compressed pointed bill about as long as the head; a short and rounded tail; short wings; thin, compressed legs, placed very far back, and the toes completely webbed. They prey upon fish, which they pursue under water, making use partly of their wings, but chiefly of their legs and webbed feet in their subaqueous progression. The leading species are the great northern diver (Colymbus glaciālis), the red-throated diver (C. septentrionālis), and the black-throated diver (C. arcticus). These birds inhabit the Arctic seas of the New and Old Worlds; they are abundant in the Hebrides, Norway, Sweden, and Russia. The great northern diver, loon, or ember goose is about 2¾ feet long, and is of handsome plumage.

Div´idend, literally what is to be divided, a term used in arithmetic and in reference to stocks. In the latter sense it is the interest or profit of stocks divided among, and paid to, the proprietors. No dividend must be paid except out of profit (Companies Act of 1862). The term also signifies the payment made to creditors out of the estate of a bankrupt.

Dividing Engine, a machine for marking the divisions on the scales of scientific, mathematical, or other instruments. Some of these perform work of extraordinary fineness and accuracy. It may also be employed to measure lengths accurately, or to divide a given length into any number of equal or unequal parts. See Graduation.—Cf. Stewart and Gee, Practical Physics (vol. i).

Dividing Range, Great, an Australian chain of mountains, forming the watershed between the rivers flowing into the Pacific and those running westward. It is situated at an average distance of 30 miles from the sea, though in some places it recedes as much as 60 miles, and stretches from Cape York on the north to Wilson's Promontory on the south. The culminating point is Mount Townshend (7353 feet).

Divi-divi, the pods of Cæsalpinia coriaria, a tree which grows in tropical America, and a member of the family which yields sapan, brazil, and other red woods. The pods are about 1 inch broad and 3 inches long, but are generally bent or curled up; are excessively astringent, containing a large proportion of tannic and gallic acid, for which reason they are used by tanners and dyers.

Divination, the act of divining; a foretelling [53]future events, or discovering things secret or obscure, by the aid of superior beings, or by other than human means. Cicero divided it into two kinds, natural and artificial, or intuitive and inductive. Natural divination was supposed to be effected by a kind of inspiration or divine afflatus; this method of divination is familiar as represented by oracles; artificial divination was effected by certain rites, experiments, or observations, as by sacrifices, observation of entrails and flight of birds (ornithomancy), of the behaviour of fishes (ichthyomancy), lots, omens, and position of the stars. Among modes of divination were: axinomancy, by axes; belomancy, by arrows; bibliomancy, by the Bible; oneiromancy, by dreams; pyromancy, by fire; hydromancy, by water; coscinomancy, by observing the results of the turning of a sieve hung on a thread. Cf. Bouché-Leclercq, Histoire de la divination dans l'antiquité.

Divine Right, the claim set up by some sovereigns or their supporters to the absolute obedience of subjects as ruling by appointment of God, insomuch that, although they may themselves submit to restrictions on their authority, yet subjects endeavouring to enforce those restrictions by resistance to their sovereign's acts are considered guilty of a sin. This doctrine, which came into general use in the seventeenth century, and is so celebrated in English constitutional history, especially in the time of the Stuarts, may now be considered to be exploded. Hobbes was one of the chief supporters of the theory of Divine Right, whilst Milton was a strong opponent. Cf. J. N. Figgis, Theory of the Divine Right of Kings.

Divine Service, Tenure by, a species of tenure, now obsolete, by which the tenant held the land on condition of performing some divine service, such as saying so many masses or distributing a certain amount in alms.

Diving, the art or act of descending into the water to considerable depths, and remaining there for a time. The uses of diving are important, particularly in searching for pearls, corals, sponges, examining foundations of bridges, salvage of wrecked ships, recovering valuables, clearing propellers, valves, and cleaning bottoms of ships when no dry docks are available. Without the aid of artificial appliances a skilful diver may remain under water for two, or even three minutes; accounts of longer periods are doubtful or absurd. Various methods have been proposed, and engines contrived, to render diving more safe and easy. The great object in all these is to furnish the diver with fresh air, without which he must either make but a short stay under water or perish.

Diving-bell, a contrivance for the purpose of enabling persons to descend and to remain below the surface of water for a length of time, for various purposes, such as laying foundations of bridges, blasting rocks, and recovering treasure from sunken ships. Diving-bells have been made of various forms, more especially in that of a bell or hollow truncated cone, with the smaller end closed, and the larger one, which is placed lowermost, open. The air contained within these vessels prevents them from being filled with water on submersion, so that the diver may descend in them and breathe freely for a long time, provided he can be furnished with a new supply of fresh air when the contained air becomes vitiated by respiration. The diving-bell is usually made of cast iron, and weighted, and has several strong convex lenses set in the sides or roof, to admit light to the persons inside. It is suspended by chains from a barge or lighter, and can be raised or lowered at pleasure upon signals being given by the persons within, who are supplied with fresh air pumped into a flexible pipe by means of force-pumps carried in the lighter, while the heated air escapes by a cock in the upper part of the bell. Modern diving-bells are usually rectangular in shape, and have a trunk or tube on top reaching to the surface of the water, and fitted with an air-lock to enable men to go into or out of the bell without moving it from the bottom; they are fitted with telephones and electric lights. A constant flow of fresh air is kept up, and all excess of air escapes from the lower part of the bell, the pressure of the air being kept slightly above that of the water outside. The diving-bell has long been found highly useful for carrying on work under water, a steam-crane being usually employed for the movements required. A form, called the nautilus, has been invented which enables the occupants, and not the attendants above, to raise or lower the bell, move it about at pleasure, or raise great weights with it and deposit them in any desired spot.

Diving-dress, a waterproof dress of india-rubber cloth used by professional divers, and covering the entire body except the head. The dress has a neck-piece or breastplate, fitted with a segmental screw bayonet joint, to which the head-piece or helmet, the neck of which has a corresponding screw, can be attached when wanted. The helmet has usually three eyeholes, covered with strong glass, and protected with guards. Air is supplied by means of a flexible air-pipe which screws on to a non-return valve on the helmet, and is connected with an air-pump on the surface. To allow of the escape of excess air a valve is fitted in the helmet, so constructed as to prevent water getting in, though it lets the air out. It can be adjusted by the diver to suit his convenience, no matter at what depth he may be. Leaden weights are attached to the diver, [54]and his boots are weighted, so that he can descend a ladder and walk about on the bottom. Communication can be carried on with those above by signals on the breast-rope between the diver and his attendant, or he may converse with them through a speaking-tube or by telephone, which is usually fitted in the breast-rope. One form of diving-dress makes the diver independent of any connection with persons above water except by breast-rope. It is elastic and hermetically closed. A reservoir containing highly compressed air is fixed on the diver's back. This supplies him with air by a self-regulating apparatus at a pressure corresponding to his depth. When he wishes to ascend, he simply inflates his dress from the reservoir. Another form, known as the Fleuss dress, also makes the diver independent of exterior aid. The helmet contains a supply of compressed oxygen, and the exhaled breath is passed through a filter in the breast-piece which deprives it of its carbonic acid, while the nitrogen goes back into the helmet to be mixed with the oxygen, the supply of which is under the diver's own control, and to be breathed over again. A diver has remained for an hour and a half under 35 feet of water in this dress. The safe limit for diving is 200 to 300 feet, the deepest dive in this country being 210 feet; but great care must be exercised in bringing the diver to the surface. Diving for pearls, sponges, valuables, &c., is now to a great extent carried on by means of diving-dresses.—Bibliography: C. W. Domville-Fife, Submarine Engineering of To-day; G. W. M. Boycott, Compressed Air Work and Diving.

Divining Rod, a rod, usually of hazel, with two forked branches, used by persons who profess to discover minerals or water under ground. The rod, if carried slowly along by the forked ends, dips and points downwards, it is affirmed, when brought over the spot where the concealed mineral or water is to be found. Divination by means of rods is of great antiquity, and has been described by Cicero and Tacitus; their rods, however, were short bits of stick, and the forked hazel twig does not seem to have come into use before the early sixteenth century. Dr. H. Mayo gave a collection of discoveries made by it in his work On the Truth contained in Popular Superstitions (1847-51). The use of the divining rod is still common in many parts.—Cf. P. L. L. de Vallemont, La Physique Occulte: ou Traité de la baguette divinatoire.

Divisibil´ity, that general property of bodies by which their parts or component particles are capable of separation. The study of radioactivity has shown that larger atoms may be broken up into smaller ones, and the old conception of the atom as an absolutely indivisible unit is no longer entertained by physicists. (See Matter.) Numerous examples of the division of matter to a degree almost exceeding belief may be easily instanced. Thus glass test-plates for microscopes have been ruled so fine as to have 225,000 spaces to the inch. Cotton yarn has been spun so fine that one pound of it extended upwards of 1000 miles, and a Manchester spinner is said to have attained such a marvellous fineness that one pound would extend 4770 miles. One grain of gold has been beaten out to a surface of 52 sq. inches, and leaves have been made 367,500 of which would go to the inch of thickness. Iron has been reduced to wonderfully thin sheets. Fine tissue paper is about the 1200th part of an inch in thickness, but sheets of iron have been rolled much thinner than this, and as fine as the 4800th part of an inch in thickness. Wires of platinum have been drawn out so fine as to be only the 30,000th part of an inch in diameter. Human hair varies in thickness from the 250th to the 600th part of an inch. The fibre of the coarsest wool is about the 500th part of an inch in diameter, and that of the finest only the 1500th [55]part. The silk line, as spun by the worm, is about the 5000th part of an inch thick; but a spider's line is only the 30,000th part of an inch in diameter; insomuch that a single pound of this attenuated substance might be sufficient to encompass our globe. The trituration and levigation of powders, and the perennial abrasion and waste of the surface of solid bodies, occasion a disintegration of particles almost exceeding the powers of computation. The solutions of certain saline bodies, and of other coloured substances, also exhibit a prodigious subdivision of matter. A single grain of sulphate of copper, or blue vitriol, will communicate a fine azure tint to five gallons of water. In this case the sulphate must be attenuated at least 10,000,000 times. Odours are capable of a much wider diffusion. A single grain of musk has been known to perfume a large room for the space of twenty years. At the lowest computation the musk had been subdivided into 320 quadrillions of particles, each of them capable of affecting the olfactory organs.

Division, in arithmetic, the dividing of a number or quantity into any parts assigned; one of the four fundamental rules, the object of which is to find how often one number is contained in another. The number to be divided is the dividend, the number which divides is the divisor, and the result of the division is the quotient. Division is the converse of multiplication.

Division, in the army, the smallest formation of troops which is a mixed force. A division, besides three brigades of infantry, includes artillery, engineers, and administrative troops. It is commanded by a major-general, and if at full strength consists of about 20,000 men.

Division, in Parliament, the mode of determining a question at the end of a debate. In the House of Commons the Speaker puts the question, and declares whether in his opinion the 'Ayes' or the 'Noes' have it. Should his opinion not be acquiesced in by the minority, the House is cleared, and the 'Ayes' directed to go into the right lobby and the 'Noes' into the left, where they are counted by two tellers appointed for each party. In the House of Lords the two sides in a division are called 'Contents' and 'Not-contents'.

Division of Labour, a method employed in productive undertakings for the simplifying of the work to be done by each of the workmen engaged therein. The separation of the process of production into a series of simple operations means that less ability on the part of the workman is required in order that he may acquire the necessary skill in performing any particular operation, and saves much time, partly because practice leads to each operation being more quickly performed, and partly by avoiding the waste which takes place in workmen moving from one operation to another. Owing to both of these causes, the cost of producing complicated articles may be immensely reduced. By standardizing operations division of labour tends to the invention of machinery; increases the skill and dexterity of the individual workman in the particular operation in which he is engaged; enables semi-skilled or unskilled labour to replace skilled; makes a more continuous and economical use of capital possible; and conduces to the more economical distribution of labour by classing work-people according to their capacity. It has, however, a deteriorating effect on the labourer's usefulness as an all-round workman, and is liable to kill his interest in his work, thereby reducing the incentive to industry. What is called division of labour in English economics has been sometimes termed co-operation by foreign economists.

Divorce (Lat. divortium, from divertere, to turn apart, separate), a separation, by law, of husband and wife, which is either a divorce a vinculo matrimonii, that is, a complete dissolution of the marriage bonds, or a divorce a mensâ et thoro (from bed and board), whereby the parties are legally separated, but not unmarried. The causes admitted by different codes of laws as grounds for the modification or entire dissolution of the marriage contract, as well as the description of tribunal which has jurisdiction of the proceedings, and the form of the proceedings, are various. Divorce was permitted by the law of Moses, but forbidden in the New Testament, except for adultery. The early laws of Rome permitted the husband to divorce his wife for adultery and many other alleged offences. The facility of divorce continued, without restriction, under the Roman emperors, but as the modern nations of Europe emerged from the ruins of the Roman Empire, they adopted the doctrine of the New Testament. Marriage, under the Roman Church, instead of a civil contract, came to be considered a sacrament of the Church, which it was unlawful to dissolve. The ecclesiastical courts could indeed annul a marriage, but only for a cause that existed at the time the marriage was contracted, such as prior contracts or impotency. For any cause arising after marriage they could only pronounce a divorce a mensâ et thoro, which did not leave either party free to marry again, except by Papal dispensation. A divorce a vinculo matrimonii, for any cause arising subsequent to marriage, could formerly be obtained in England only by an Act of Parliament, and the ecclesiastical courts must have previously pronounced a divorce a mensâ et thoro. The Act passed in 1857, however, established a new court for trying divorce causes, called the Court for Divorce and Matrimonial [56]Causes, since absorbed into the Probate, Divorce, and Admiralty Division of the High Court of Justice. According to present practice the husband may obtain a divorce for simple adultery; but if the wife is the petitioner, she must show that her husband has been guilty of certain kinds of adultery, or of adultery coupled with desertion or gross cruelty. Either party may marry again after divorce. A divorce cannot be obtained if it appear that the petitioner has been guilty of the same offence, or has been accessory to or has connived at the offence, or if there has been collusion between the parties to obtain a divorce, or if they have condoned the offence by living together as man and wife after discovery. The husband may claim damages from the adulterer, and the court may also order the adulterer to pay the costs of the proceedings, in whole or in part. The Act also abolished divorces a mensâ et thoro, substituting, however, judicial separations. (See Judicial Separation.) A decree for a divorce is always in the first instance a decree nisi (q.v.). A Matrimonial Causes Bill, introduced in the House of Lords in 1920, proposes to abolish the legal disabilities of a wife in this matter, and to grant divorce to husband or wife on any of the following grounds: (a) adultery; (b) desertion for at least three years; (c) cruelty; (d) incurable insanity coupled with at least five years' confinement under the lunacy laws; (e) incurable habitual drunkenness coupled with three years' separation under a temporary separation order granted on the ground of habitual drunkenness; and (f) imprisonment under a commuted death sentence. In Scotland, from the time of the Reformation, divorce might be obtained by either party on the ground of adultery, marriage being held to be only a civil contract, and as such under the jurisdiction of the civil courts. Condonation, or connivance, or collusion is sufficient to prevent a divorce from being obtained on the ground of adultery, but not recrimination, that is, a counter charge of adultery. Wilful desertion for at least four years is also held a valid reason for divorce. The action is carried on before the Court of Session. In other countries, including British colonies, the law relating to divorce varies greatly. In the United States of America, marriage, though it may be celebrated before clergymen as well as civil magistrates, is considered to be a civil contract, and the laws as to divorce, and the facility or difficulty of obtaining it, differ greatly in the several states. In France divorce was legalized in 1884, with conditions, after having been prohibited for many years.—Bibliography: Lehr, Le mariage, le divorce et la séparation de corps dans les principaux peuples civilisés; Stephen, Commentaries on the Laws of England; Bryce, Marriage and Divorce.

Dixmude, a town of Belgium, in Flanders. It was the scene of severe fighting during the European War. Captured by the Germans, it was retaken by the Belgians on 29th Sept., 1918. Pop. 4040 (1911); 450 (1919).

Dixon, William Hepworth, miscellaneous writer, born at Manchester, 1821, died in London, 1879. In 1849 he published a memoir of Howard the philanthropist, which was followed by the Life of William Penn (1851), and by a work on Admiral Blake (1852). In 1853, after having been a contributor, he became chief editor of The Athenæum, a post which he retained till 1869. During this period he published several very popular works, including the Personal History of Lord Bacon, The Holy Land, and New America, the last being followed by Spiritual Wives. After his retirement from The Athenæum, and in the last ten years of his life, he gave to the world about twenty-five volumes of history, travel, and fiction, among others, Free Russia; Her Majesty's Tower; The Switzers; History of Two Queens, Catherine of Aragon and Anne Boleyn; Diana Lady Lyle, and Ruby Grey (both novels); and his last work, Royal Windsor.

Dizful, a town of Persia, near the western boundary, on the River Dizful; a place of great trade and manufactures. Pop. about 25,000.

Djavid Bey, Hussein, a Turkish Jew, one of the leaders of the Committee of Union and Progress, and Minister of Finance from 1914 to 1918. His advice that Turkey should adhere to strict neutrality during the European War was, unfortunately for his country, not followed by his colleagues, who decided to join Germany.

Djemal Pasha, Turkish soldier and politician, and one of the leaders of the Committee of Union and Progress. Minister of Marine in 1914, he commanded the Turkish forces in Palestine from 1915 to 1917, and became notorious on account of his oppression of and cruelties against the inhabitants of Syria and Palestine, and by his hatred of Zionism. Accused in 1918 of various crimes, such as misappropriation of funds, and compelled to flee from Constantinople, he was condemned to death in his absence in 1919. He was nevertheless one of the Turkish delegates who signed the Peace Treaty on 11th May, 1920.

Djokdjokarta, a Dutch residency in the Island of Java, on the south coast, with a capital of the same name. Its forests abound in teak. Its natural fertility is great, and rice, coffee, and tobacco are extensively cultivated. It is ruled by a sultan who is dependent on the Dutch. Pop. 441,800. The town is large and regular, and contains the sultan's water-palace, and the seat of the Dutch Resident, which is a fort commanding both the palace and the town. Pop. 97,058.

Dnieper (nē´pėr; Russ. Dnjepr, dnyepr; [57]anciently Borysthĕnēs, or Danapris), a great river of Russia which rises in the government of Smolensk, flows first south-west, then south-east, and again south-west to the Black Sea. It begins to be navigable a little above Smolensk, and has a total length, including windings, of 1230 miles. Among its tributaries are the Beresina, the Pripet, the Desna, and the Psiol. In its lower course there are important fisheries. The region watered by the river in its lower course is famous for its great fertility, and is known as the black-soil. Between Kiev and Alexandrovsk it forms a series of cataracts. Since 1838 there have been steamboats on the river, and the trade carried by it is considerable. Through the Beresina Canal the Dnieper communicates with the Baltic Sea.

Dniester (nēs´tėr; Russ. Dnjestr; ancient Tyras), a large river of Europe (Poland, Roumania, and Ukraine), which has its source in the Carpathian Mountains, in Austrian Galicia, enters Russia at Chotin, and empties itself into the Black Sea, after a course of about 750 miles. Its navigation is difficult on account of frequent shallows and rapids.

Doab´ (that is, Two Waters), a name in Hindustan applied indiscriminately to any tract of country between two rivers, like the Greek Mesopotamia. The tract between the Ganges and the Jumna is usually called the Doab; other similar tracts have their distinctive names, the Punjab being divided into five districts of this kind.

Dobell´, Sydney, English poet and man of letters, born in 1824, died 22nd Aug., 1874. His first poem, The Roman, appeared in 1850, and was favourably received by the critics. Among his other works are: Balder, Sonnets on the War, and England in Time of War.

Döbeln (deu´beln), a town of Saxony, about 40 miles south-east of Leipzig, with a great trade in grain, and manufactures of cloth, yarn, leather, and lacquered wares. Pop. 17,920.

Döbereiner's Lamp, a contrivance for producing an instantaneous light, invented by Professor Döbereiner, of Jena, in 1824. The light is produced by throwing a jet of hydrogen or a mixture of oxygen and hydrogen gases upon recently prepared spongy platinum, when the metal instantly becomes red-hot, and then sets fire to the gas. The action depends upon the readiness with which spongy platinum absorbs both oxygen and hydrogen. The intimate contact of the two gases leads to chemical combination with evolution of heat. Coal-gas may be employed instead of hydrogen, and this has led to the application of the principle to self-lighting devices for igniting gas flames.

Dobritch, or Bazarjik, a town in Roumania, was, till the end of the second Balkan War, the chief town in Bulgarian Dobrudja. It is situated on a small tributary of the Danube, and is on the Cernavoda-Constanza railway. At one time it was famous for its panair or great annual fair, but it is now no longer an important centre. Pop. 10,000.

Dobrudja, or Dobrud´scha, The (anciently Scythia Minor), a territory forming part of the kingdom of Roumania, included between the Danube, which forms its boundary on the west and north, the Black Sea on the east, and Bulgaria (to which it belonged before 1878) on the south. Its area, formerly 6000 sq. miles, was increased by the Treaty of Bucharest of 10th Aug., 1913, and is now 8969 sq. miles. During the European War the Dobrudja was invaded in 1916 by an army of Germans, Bulgarians, and Turks, under General von Mackensen. In 1918 Roumania was compelled by the Treaty of Bucharest to cede the Dobrudja to Bulgaria, but it was restored to her in 1919. There are some fertile spots, but on the whole it is marshy and unhealthy. The population is of various nationalities, Roumanians, Bulgars, Greeks, Turks, and Jews. The inhabitants engage in tillage and stock-rearing. The principal towns are Kustendje and Tultcha. See Roumania. Pop. 381,306.

Dobson, Henry Austin, poet, born at Plymouth in 1840. He was educated at Beaumaris, Coventry, and Strasbourg; in 1856 obtained a clerkship under the Board of Trade, where he rose to be one of the officials known as principals. His earliest verses first appeared in book form under the title Vignettes in Rhyme and Vers de Société (1873). His other volumes of verse include: Proverbs in Porcelain (1877); Old World Idylls (1883); and At the Sign of the Lyre (1885), which The Athenæum pronounced to be "of its kind as nearly as possible perfect". Among his prose works may be mentioned his lives of Hogarth, Fielding, Steele, Goldsmith, Horace Walpole, Richardson, and Fanny Burney; Thomas Bewick and his Pupils; Four Frenchwomen, a study on Charlotte Corday, the Princesse de Lamballe, and Mesdames Roland and de Genlis; three series of Eighteenth Century Vignettes; A Paladin of Philanthropy; Sidewalk Studies; Old Kensington Palace; At Prior Park; A Bookman's Budget; and several editions of standard works. His collected poems were published in one volume in 1897. Many of Mr. Dobson's poems are written in various French forms, such as the rondeau and ballade, and all are marked by gracefulness and ease. He died in Sept., 1921.

Doce´tæ (from Gr. dokein, to seem or appear), the name given, in the earlier ages of the Church, to those who denied the reality of the human form of Christ, maintaining it to be merely a phantom or shadow. In the sense of regarding Christ's body as a heavenly and ethereal, instead [58]of a human one, docetism had its partisans even among the orthodox.

Dock, a name applied to different plants of the genus Rumex, belonging to the rhubarb family (Polygonaceæ). These are large herbaceous plants, with stout roots, alternate and often entire leaves, and bearing panicles of small greenish flowers. They are very troublesome as weeds, but the roots of some of them are used medicinally as astringents.

Docket, or Docquet (dok´et; from dock, to shorten; Icel. dokr, stumpy tail), in law, a term variously used, as for a summary of a larger writing; a small piece of paper or parchment containing the heads of a writing; an alphabetical list of cases in a court, or a catalogue of the names of the parties who have suits depending in a court.

Docks, are artificial enclosures for the reception of shipping, for the purpose of loading, discharging, or repairs. They may be divided into four types, viz. tidal docks or basins, wet docks, dry or graving docks, and floating docks.

Tidal Docks or Basins are open permanently to the main channel or river, and the water-level therefore varies with the rise and fall of the tide. This variation of level is a serious hindrance in the work of loading or discharging cargo, unless the tidal range be small. It should be noted that this form is more properly termed a tidal basin.

Wet Docks have a water entrance normally closed by gates or caissons, which permit the water-level of the enclosed area being maintained at high-water level. This uniformity of level is of great service in dealing with cargo, but this type has the disadvantage of only permitting traffic in and out of the dock at high water. This disadvantage may be modified by the provision of a lock at the dock entrance.

Dry or Graving Docks are used for the purpose of examining and repairing ships. The entrance is controlled by either gates or caissons. The ship having entered, the gates are closed, and the water pumped out, allowing the vessel to [59]settle down gradually upon a row of keel blocks, running up the centre line of the dock. The sides of the docks are built in the form of large continuous steps or 'altars', which support the ends of the timber shores which serve to keep the ship in an upright position. The floor is graded to channels, leading to powerful pumps, usually of the centrifugal type, and capable of emptying a large dock in one hour.

Floating Docks fulfil the same functions as dry docks. In their modern form, they consist of a hollow steel box or pontoon, carrying hollow longitudinal walls at each side. These walls contain the pumps and controlling machinery, the pontoon portion being capable of being filled with or emptied of water, thus raising or sinking the dock. This lower portion is subdivided into a great number of compartments, all of which may be filled separately, so that errors of trim can be corrected. In making use of this type the dock is lowered by flooding the lower compartments. The ship is then floated into position and shored.

The initial cost of these two latter types is in favour of the floating dock, the annual maintenance charges of which, however, may be five to ten times those of an ordinary masonry dock. The mobility of a floating dock may be considered an advantage, allowing it to be easily removed to another locality to meet changing conditions, but this adaptability should not be overvalued.

The average life of a steel dock may be assumed to be 40 years, whereas a masonry dock may be said to last indefinitely, subject only to the fact that it may outlive its usefulness.

The first wet docks constructed in England were those now called the Commercial Docks, in London, which existed in a much less extensive form so early as 1660. In 1800 the West India Docks were constructed, and were followed by the East India Docks, Millwall Docks, London Docks, the St. Katharine Docks, and the Victoria Docks, affording, together with those at Tilbury, more than 600 acres of water accommodation, besides wharf and warehouse grounds, where all kinds of appliances and machinery for the speedy and convenient transfer of goods and cargoes are in use. Some of the warehouses are extremely capacious, the tobacco warehouse of the London Docks being itself nearly 5 acres in extent. Next after the London docks come those of Liverpool, which extend more than 6 miles along the north bank of the Mersey, and cover, together with the Birkenhead docks, nearly as large a total acreage as those of London. The other important British docks are those at Southampton, Bristol, Cardiff, Hull, Great Grimbsy, Newcastle, Shields, Barrow, Leith, Glasgow, Dundee, &c. A floating dock at Hamburg has a length of 728 feet, inside width of 123 feet, and a lifting capacity of 46,000 tons.—Bibliography: W. Shields, Principles and Practice of Harbour Construction; L. V. Harcourt, Harbours and Docks; Kempe, Engineer's Year Book.

Dock-warrants, orders for goods kept in the [60]warehouses connected with a dock. They are granted by the proper officer at the dock to the importer in favour of any one that he may name. These warrants are held to be negotiable, so that they may pass from one holder to another, the property of them being always vested in the holder.

Dock-yards, establishments supplied with all sorts of naval stores, materials and conveniences for the construction, repairs, and equipment of ships of war. In England the royal dock-yards are at Chatham, Sheerness, Portsmouth, Devonport, and Pembroke, besides the Deptford and Woolwich store-yards. There are also royal dock-yards or naval victualling yards at Haulbowline in Cork Harbour, Rosyth, Invergordon, at the Cape of Good Hope, Gibraltar, Malta, Bermuda, Bombay, Calcutta, Hong-Kong, Sydney, and Wei-hai-wei. Others in the colonies have been given up. The dock-yards are under the direct control of the Admiralty. The chief officer of the greater or home dock-yards is generally an admiral, with a considerable staff of officials under him, professional and other. Since the introduction of steam the engineering department has become an important one in such establishments.

Doctor, a term literally signifying teacher. In the Middle Ages, from the twelfth century, it came into use as a title of honour for men of great learning, such as Thomas Aquinas (Doctor Angelicus) and Duns Scotus (Doctor Subtilis). It was first made an academical title by the University of Bologna, and emperors and Popes soon afterwards assumed the right of granting universities the power of conferring the degree in law. The University of Paris followed in the footsteps of Bologna, and in 1145 the title was bestowed on Peter Lombard. The faculties of theology and medicine were soon included, but for a long time the faculty of arts retained the older title of Magister, till the German universities substituted that of Doctor. In England the Doctor's degree was introduced into the universities during the reign of John or Henry III. The title of Doctor is in some cases an honorary degree, and in other cases (as in medicine and science) conferred after examination. The title of D.C.L. (Doctor of Civil Law), for example, at the Universities of Oxford and Durham, is frequently an honorary degree, and so also are those of D.D. (Doctor of Divinity) and LL.D. (Doctor of Laws) at various universities. The Popes and the Archbishops of Canterbury exercise the right of conferring the degree of Doctor both in law and divinity. Oxford and Cambridge, and many other universities, create doctors of music (Mus.D.).

Doctors' Commons was a college founded in 1567 for the Doctors of the Civil Law in London, and was at one time the seat of the Court of Arches, the Archdeacon's Court, and the Court of Admiralty. The practitioners in these courts were called advocates and proctors. In 1857 an Act was passed empowering the college to sell its property and dissolve, and making the privileges of the proctors common to all solicitors.

Doctors of the Church, a name given to four of the Greek Fathers (Athanasius, Basil, Gregory Nazianzen, and Chrysostom) and five of the Latin Fathers (Hilary, Ambrose, Jerome, Augustine, and Gregory the Great). The Roman Catholic Church, however, recognizes eighteen 'Doctors of the Church', including, besides those already mentioned, Chrysologus, Leo, Isidore, Peter Damian, Anselm, Bernard of Clairvaux, Thomas Aquinas, Bonaventura, and Alphonsus of Liguori. The title is conferred only after death.

Doctrinaires, a section of French politicians, represented by the Duc de Broglie, Royer-Collard, Guizot, and others, who became prominent after the Restoration in 1815. They favoured a constitutional monarchy similar to that which then existed in Britain. In the Chambers they thus occupied a place between Radicals and ultra-Royalists. They received the name of doctrinaires because they were looked upon more as theoretical constitution-makers than practical politicians, and the term is now used with a wider application to political theorists generally.

Dodder, the common name of the plants of the genus Cuscŭta, a group of slender, branched, twining, leafless pink or white annual parasites, nat. ord. Convolvulaceæ. The seeds germinate on the ground, but the young plant speedily attaches itself to some other plant, from which it derives all its nourishment. Four species are common in England—C. europæa, found on nettles and vetches; C. Epithymum, on furze, thyme, and heather (these two being natives); C. trifolii, on clover; C. Epilīnum, on cultivated flax (both introduced from abroad).

Doddridge, Philip, D.D., an English Dissenting divine, born in London in 1702, died in 1751. He was an earnest pastor, and the author of many hymns and devotional treatises. The Rise and Progress of Religion in the Soul and The Family Expositor are amongst his best known works. Many of his hymns are still sung, such as O God of Bethel, by whose hand; and O happy day that fixed my choice.

Dodecanese (Gr., twelve islands), a name applied since the Turko-Italian War of 1912-3 to a group of islands lying off the south-west coast of Asia Minor, the base of the Italian troops. The group, consisting of the Southern Sporades, includes the Islands of Patmos, Cos, [61]Lipsos, and others near Rhodes. Italy agreed to restore the islands to Turkey, but was prevented from carrying out the agreement by the breaking out of the Balkan War. The Treaty of Peace with Turkey (11th May, 1920) allotted these islands to Italy, who ceded them again to Greece (with the exception of Rhodes).

Dodgson, Charles Lutwidge. See Carroll, Lewis.

Dodo (Didus ineptus), an extinct genus of birds once abundant on the Island of Mauritius, and assigned by naturalists to the ord. Columbæ or pigeons, though an extreme modification of the type. It was a massive clumsy bird, larger than a swan, covered with down instead of feathers, with short ill-shaped legs, a strong bulky hooked beak, and wings and tail so short as to be useless for flight. Its extinction was due to its organization not being adapted to the new conditions which colonization and cultivation introduced. It probably became extinct soon after 1681.

Dodo´na, a celebrated locality of ancient Greece, in Epirus, where was one of the most ancient Greek oracles. It was a seat of Zeus (surnamed the Pelasgian), whose communications were announced to the priestesses in the rustling of the leaves on its oak tree, and the murmuring of water which gushed forth from the earth.

Dods, Marcus, theologian, born at Belford, Northumberland, in 1834, his father being minister of the Scottish Church there, died in 1909. He was educated in Edinburgh, where he took his M.A. degree at the age of twenty. In 1858 he was licensed as a minister of the Free Church of Scotland, and eight years afterwards was ordained to Renfield Free Church, Glasgow, where he remained until his appointment in 1889 to the chair of New Testament Exegesis in New College, Edinburgh. Of his works some of the most important are: The Prayer that Teaches to Pray (1863, 6th edition, 1889); Epistles to the Seven Churches (1865); Israel's Iron Age (1874); Mohammed, Buddha, and Christ (1877); The Book of Genesis (1882); Parables of Our Lord (1883 and 1885); How to become like Christ (1897); Forerunners of Dante (1903); The Bible: its Origin and Nature (1905); and articles in the Encyclopædia Britannica.

Dodsley, Robert, English poet, dramatist, and publisher, born in 1703, died in 1764. His first volume of verses, The Muse in Livery, appeared in 1732. The Toy Shop was performed at Covent Garden in 1735. In 1737 his King and the Miller of Mansfield was performed at Drury Lane, and met with an enthusiastic reception. He also wrote a tragedy, entitled Cleone, which had an extraordinary success on the stage. A selection of Fables in Prose, with an Essay on Fables prefixed, was one of his latest productions. He planned the Annual Register (commenced in 1758); the Collection of Old Plays (12 vols. 12mo), which now chiefly sustains his name as a publisher; and the Collection of Poems by Different Hands (6 vols. 12mo).