Chapter M: M. J. SUTHERLAND, D.Sc., F.I.C (5)

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 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 160degC. 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 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_.

1, Ash. 2, Sycamore. 3, Hornbeam.]

1, Ripe fruit of willow-herb, dehiscing. 2, Single fruit of clematis. 3, Single fruit of dandelion.]

1, Geum and single fruit. 2, Burdock.]

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 Bignoniaceae, &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 Compositae, 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.

1, _Ecbalium Elaterium_, flowers and fruit, one fruit detached from its stalk and with its seeds squirting out. 2, _Oxalis Acetosella_, entire plant, with one unripe fruit on a hooked stalk, and one ripe fruit on an erect stalk ejecting its seeds. 3, Ripe fruit of _Oxalis Acetosella_ ejecting the seeds (enlarged).]

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 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 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-r[=a]'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, 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 (NH_3), and on cooling these substances recombine to give ammonium chloride (NH_4Cl) 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; diarrhoea 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.

A, Emptying pipe. B, Wash inlet. C, Vacuum safety valve. D, Worm. E, Cooling water inlet.]

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 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 1-1/4 inches wide, crimson, blue, and crimson, the colours being of equal width. Bars may be awarded for additional deeds of 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 L20 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 1-1/4 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 _pat['e]e_ 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 larvae live in a small water-snail (_Limnaea 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 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 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 (Rutaceae), 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 caf['e], 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 (Colymbidae) 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 glaci[=a]lis_), the red-throated diver (_C. septentrion[=a]lis_), 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 2-3/4 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 _Caesalpinia 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 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. Bouch['e]-Leclercq, _Histoire de la divination dans l'antiquit['e]_.

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.

1. Ordinary diving-dress with (2) helmet. 3. Front view and (4) back view of self-contained diving apparatus.

Reproduced by courtesy of Messrs. Siebe, Gorman, & Co]

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, 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 Trait['e] de la baguette divinatoire_.