Part 8

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 400degF.; 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 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 3/4 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-t[=a]'lin), a vegetable alkaloid, the active principle of the _Digit[=a]lis purpur[)e]a_ 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. Scrophulariaceae, containing about twenty species of tall herbs, natives of Europe and Western Asia. The purple foxglove (_D. purpur[)e]a_) 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 (d[=e]ny), 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 (d[=e]-zh[=o]n; Lat. _Castrum Divonense_), a town in Eastern France, capital of the department of C[^o]te-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. B['e]nigne, a building of vast extent with a lofty wooden spire above 300 feet high; the churches of N[^o]tre Dame and St. Michael; the ancient palace of the Dukes of Burgundy, now used as the h[^o]tel 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 _l[=e]mma_, 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-t[.a]n't[=a]), an Italian 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 _Athenaeum_, 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, _An[=e]thum grave[)o]lens_, 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'CEAE, an order of plants, chiefly fine trees, inhabiting the East Indies, allied to Ranunculaceae and Magnoliaceae.

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. 11deg 22' S.; long. 22deg 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. _d[^i]me_, 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 x^2, 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, x^3, 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, 3x^2y^2z^2 + 5xyz + 6x^3 + 3x^2y^2 is said to be of the sixth degree because x^2y^2z^2 = x x x x y x y x z x 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 pendulum of length l is given by the formula t = 2[pi]l/g, where g denotes the acceleration of a falling body. The dimensions of the expression on the right are L / (LT^{-2}), or T^2, whereas the term t on the left has dimensions T^1. 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 = 6[pi]/32, so that the period is 3[pi]/16 seconds. But if we change the unit of time to one minute, g becomes 32 x 60 x 60, and the formula gives t = 6[pi]/(32 x 60 x 60), so that the period is 3[pi]/(16 x 60 x 60) minutes.

The two results are obviously inconsistent. If, however, we take the correct formula, namely t = 2[pi][sqrt](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 T^1.

The principle of dimensions provides therefore a useful check on the accuracy of formulae. 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 (d[=e]-n[:a]n), a town, France, department of C[^o]tes-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 (d[=e]-n[:a]n), 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 Li['e]ge. 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 Leipzig, and died 1883. His chief publications were editions of the Greek dramatists (_Poetae Scenici Graeci_) and works elucidative of them and other Greek writers.

[Illustration: _Dinornis maximus_ (the Moa)]

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.

[Illustration: _Diplodocus Carnegii_, a gigantic Dinosaur. Length, 84 feet 9 inches; height at middle of back, 11 feet 5 inches]

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.

[Illustration: Skull of _Dinotherium giganteum_]

DINOTHE'RIUM (Gr. _deinos_, terrible, _th[=e]rion_, beast), a genus of extinct gigantic proboscidean mammals, precursors of the elephants, the 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 vertebrae resemble those of mastodon. Dinotherium may have inhabited rivers or estuaries.

DI'OCESE (Gr. _dioik[=e]sis_, 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 Moesia (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 Pers['e]cution de Diocl['e]tien_; 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 Caesar 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.

DIOECIOUS (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 _monoecious_. The willow, the yew, the poplar, &c., are dioecious.

DIOGENES LAERTIUS, 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.