elevators, mills, foundries, ship-yards, dry-docks, and R.R. stations. It is laid out according to what is known as the "Governor's and Judges' Plan," by which the Campus Martius, the square on which the city-hall and soldiers' monument now stand, was selected as one center, and a circular park, called the Grand Circus, was selected as another, and from these were projected grand avenues, radiating in different directions, and intersected by streets running in concentric circles. The site of D. was visited by the French 1610, and permanently settled by French colonists under De la Motte Cadillac 1701, when Fort Pontchartrain was built as a defense against Indians. Owing to its great strategic importance it has never been without a military garrison since 1701. It has changed its flag five times; was at times under French and English dominion prior to the Revolutionary War; has owed allegiance to three different sovereigns; has been besieged by Indians twice, captured in war once, totally consumed by fire once, and has been the scene of 12 massacres and 50 battles. The English took possession of it 1763, and erected (1778) Fort Shelby, the site of which is now in the heart of the city. It was ceded to the U. S. by the peace of 1783, but possession was not taken till Gen. Arthur St. Clair established himself there, 1796; Gen. Hull surrendered it to the British 1812; and the Americans regained possession after Commodore Perry's victory on Lake Erie, 1813. The present city was laid out 1807, incorporated as a village 1815, chartered as a city 1824, and was cap. of the State 1837-47.

Detroit' Observatory is the name of the astronomical observatory of the University of Michigan, at Ann Arbor, erected by the citizens of Detroit in 1853-54, whence the

name.

It is equipped with a 13-in. Fitz equatorial, a 64-in. Pistor & Martin's meridian-circle, clocks, chronograph, etc. It was here that Bruennow and Watson labored, the latter discovering 21 asteroids. The observatory has not generally been called by its name, D. O., and a recent publication of a new determination of its latitude has been in some cases, especially abroad, referred to as a determination of the latitude of Detroit, a mistake that is likely to cause some confu sion among geographers who strive to be accurate.

Detroit' Riv'er is the name applied to the channel which discharges Lake St. Clair into Lake Erie. It is about 28 m. 1., with a minimum breadth of fully a m. It is navigable for vessels of any burden.

Det'tingen, a village of Bavaria, noted as the scene of a battle during the Austrian wars of succession, which took place on the 27th of June, 1743, and was the last occasion in which a king of England appeared in battle.

Deucalion, according to the Greek myth, was a son of Prometheus, grandson of Iapetus, and husband of Pyrrha. When Zeus had resolved to destroy the race of men by a flood, D. built and provisioned, by the advice of his father, an ark or ship, which he entered with his wife. The flood came, and all Hellas was submerged. D. floated about for nine days, and on the subsidence of the waters the ark rested on Mount Parnassus. D. and Pyrrha now offered up sacrifice to Zeus Phyxius, i. e., Zeus, the protector of fugitives, and prayed that he would re-people the world, which he did.

Ďe'us ex Mach'ina, an expression borrowed from the classical theater. In conformity with the popular mytholog ical beliefs of their age, the tragic poets of Greece, instead of bringing about the denouement of their plots by natural means, had often recourse to a more expeditious mode-viz., the intervention of a god, who descended in a machine, and abruptly solved whatever difficulty barred the proper termination of the piece. In modern tragedy, when a person or incident is introduced arbitrarily into the conduct of a plot, merely to remedy some inartistic negligence in its construction, such a contrivance is metaphorically called a D. ex M. Deuteronomy is the name given by the Septuagint translators to the fifth book of the Pentateuch, because it contains a repetition of the laws which had been already promulgated. It is commonly presumed to have been written by Moses himself, with the exception of the last four chapters, which narrate the closing events in the life of the great lawgiver. Many critics, however, affirm that the entire book itself in its present form is post-Mosaic. The repeated allusions to the kingdom, the prophethood, the temple at Jerusalem, as well as various other particulars far too numerous to specify, are held to render it probable that D. is a late recension and enlargement of some Mosaic abridgment of the previous portion of the Pentateuch. But the best biblical scholarship of the day holds that, notwithstanding some critical difficulties, the whole of D. originated in the time of Moses, and that he was its chief author.

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Deutsch, (EMANUEL OSCAR,) b. of Jewish parents at Neisse, in Silesia, in 1829, an eminent Orientalist, connected with the British Museum. He is best known to the outside world by his brilliant article on the Talmud in the Quarterly Review, to which he also furnished an article on Islam; d. in 1873 at Alexandria.

Deut'zia, a genus of shrubs of the natural order Philadelphaceae, natives of the N. of India, China, and Japan, some of which are now reckoned among the favorite greenhouse plants of this country and Great Britain, in some situations even enduring the open air. They produce abundance of beautiful white flowers. The leaves of D. scabra are so rough with siliceous hairs that they are used in Japan for polishing wood.

Deux-ponts, a town of Rhenish Bavaria. It has among its principal buildings a Lutheran cathedral, also the remains of an ancient palace now used as a Catholic chapel; pop. 9,349.

Devel'opment, in Photography, the process which immediately follows exposure, and which renders the picture visible in all its details. It consists in the precipitation of new material on that portion of the sensitive surface which has been acted on by light; the same principle therefore prevails in all processes. A collodion negative is similarly "brought out" by the precipitation, by means of a deoxidizing agent, such as pyrogallic acid, or proto-sulphate of iron, on the actinized portion of the plate, of new material, composed of metallic silver and organic matter.

Development of Species. See DARWINISM. Deventer, (often called DEMTER,) a fortified town of Holland, prov. of Overyssel, on the Yssel, about 55 m. E.-S.-E. of Amsterdam. The principal buildings, besides the cathedral, in the early Gothic, are the town-house, the court-house, and prison. Tower-flanked walls surround the town, also a broad, deep ditch. The industry of D. consists in ironfounding, the manufacture of carpets, stockings, cotton, glue, etc. Its ginger-bread (called D. Koek) gives employment to several factories. There is also trade in grain, cattle, linen, ham, and butter; pop. 23,708.

De Vere, (MAXIMILIAN SCHELE, LL.D.,) b. near Wexio, Sweden, 1820. He received a thorough education, served some time in the Prussian army, and then in the diplomatic corps, and, removing to the U. S., was appointed Prof. of Modern Languages in the University of Virginia, 1844. He has contributed largely to current periodicals; published Outlines of Comparative Philology, (1853,) Stray Leaves from the Book of Nature, (1856,) Studies of our English, First French Reader, Grammar of the French Language, (1867,) Wonders of the Deep, (1869) Grammar of the Spanish Language, Americanisms, (1871,) Modern Magic, (1872,) The English of the New World, (1873,) and The Great Empress, a novel.

Dev'ereux, (JOHN HENRY,) a distinguished Amer. R.R. engineer, b. in Boston 1832.

Devia'tion of the Com'pass, the variation of a ship's compass from the true magnetic meridian, caused by the proximity of iron. In iron ships it depends upon the direction, with regard to the magnetic meridian, in which the ship was built. It is least when the ship has been built with her head to the S.

Devia'tion of the Plumb-line has been especially ob. served near mountains, in which case it is evident that the attraction of the mountain has drawn the line out of the perpendicular. The same phenomenon has been observed on plains, and is probably caused either by great caves under ground or by large masses of matter near the surface greatly surpassing in density the average of the earth near the point of observation.

Device', from the Middle-Age Lat. divisa, "a drawing or design," is a motto expressed by means of a pictorial emblem. The motto proper originated in the emblem, a written inscription coming to be added to the pictorial design, with the view of rendering the meaning more explicit. Ds. thus consist of two parts, a figure called the "body," and a motto in words called the "soul" of D. As early as the times of Eschylus the seven heroes before Thebes " all appear with Ds. on their shields; and the same is related by Xenophon of the Lacedæmonians and Sicyonians. In the Middle Ages Ds. on coat. armor came into regular and formal use, and chivalry em. ployed them in its courtly expressions of devotion to the fair

Device.

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sex.

crests.

They were used both as charges on the shield and as

Dev'il, or Sa'tan, (Gr. diabolos, "false accuser; " Heb. satan, "adversary,") designates a mighty spirit of evil, according to some a fallen angel from heaven, who has, during unknown ages, ruled over a kingdom of wicked spirits, and is in constant opposition to God. The doctrine of the existence of a personal D., the chief of evil spirits, the author of all moral evil, is maintained by the Bible. It is found in the narrative of the Fall in Genesis, and the name serpent is again applied to the D. in the book of Revelation, where he is described as "the old serpent, he that is called the devil and Satan." The mention of the D. in the N. T. is held to be conclusive, not only of his existence, but of the belief in that existence among the older Jews; though not necessarily conclusive as to their early belief in all the accumulated tenets of later times regarding the D. The warnings and exhortations addressed to Christians are framed on the supposition of dangers arising from his violence, power, and subtlety. Devil Fish. See CEPHALOPTERA.

Dev'il's Dust, the name sarcastically given to old woolen materials manufactured into some variety of shoddy.

S.-W. of Devonshire, stands on high ground, with ramparts defended by batteries. The S.-E. and S. walls are 12 ft. h., with three gates, and externally a fosse cut 12 to 20 ft. deep in the solid rock. It owes its importance to the dock-yard established here by William III., and is still one of the chief naval arsenals in Britain; pop. 54,736.

Dev'onshire, a maritime county in the S.-W. peninsula of England, between the Bristol and English Channels. The general surface is hilly. The loftiest eminence is Yes Tor, in Dartmoor Forest, 2,050 ft. h. The rivers are very numerous, the chief being the Exe, 54 m. 1.; Dart, 36; Tamar, 59; Torridge, 53; and Taw. These rivers have tidal estuaries, 5 to 11 m. 1. There is an intermitting spring at Brixham. The climate is the finest in Britain, mild and equable at all seasons; pop. 631,767, area 1,655,208 acres.

Dew. For any assigned temperature of the atmosphere there is a certain quantity of aqueous vapor which it is capable of holding in suspension at a given pressure. Conversely, for any assigned quantity of aqueous vapor held in suspension in the atmosphere there is a minimum temperature at which it can remain so suspended. This minimum temperature is called the D.-point. During the day-time,

Dev'il-wor'shipers, or Yez'idees, an Armenian sect | who treat the devil with great respect, because they believe he will be restored to heaven, and wish then to have him as a friend. Other sects may be found who pay reverence to devils.

De Vin'ne, (DANIEL, D.D.,) b. in Londonderry, Ireland, Feb. 1, 1793; entered the M. E. ministry in Miss. in 1819; later he labored in New York city and vicinity; author of several volumes; d. 1883.

Devise', in Law, the conveyance of land by will. As personal property or chattels are said to be bequeathed, so lands are said to be devised.

Devi'zes, anc. Divisa, Divisis, De Vies, a borough in Wiltshire, Eng. ; is the seat of one of the most important corn-markets of the W. of England; pop. 6,839. The Corn Exchange has standing room for nearly 3,000 persons. The chancel of St. Mary's Church in D. is believed to be nearly as old as the Conquest. Roman household gods and coins have been found here. D. arose around a castle built by Roger, Bishop of Salisbury, in the time of Henry I. This castle, of which only the walls of one of the dungeons remain, was besieged and taken by Cromwell in 1645.

Devo'nian Sys'tem, the name proposed by Murchison and Sedgwick to replace the more characteristic and older term Old Red Sandstone, because the slaty and calciferous strata in Devonshire contain a much more copious and rich fossil fauna than the red arenaceous rocks of Scotland, Wales, and Herefordshire, with which they were shown to be contemporaneous.

Dev'onport, (before 1824 called PLYMOUTH DOCK,) in the

especially if there has been sunshine, a good deal of aqueous vapor is taken into suspension in the atmosphere. If the temperature in the evening now falls below the D.-point, which after a hot and calm day generally takes place about sunset, the vapor which can be no longer held in suspension is deposited on the surface of the earth, sometimes to be seen visibly falling in a fine mist. This is the chief form of the phenomenon of D. See DEW-POINT.

Dew'as, a town of Malwa, India, is the cap. of a petty state or raj under British protection; pop. 25,000.

Dew'berry, (Rubus cœsius,) a plant of the same genus with the Bramble, and very nearly allied to it, but having weaker and more prostrate roundish stems, which take root at the end, their prickles unequal and passing insensibly into hairs, the fruit consisting only of a few grains, which, however, are much larger than those of the brambleberry. The name is derived from the dew-like bluish bloom which covers the fruit. The latter is very sweet and agreeable, and makes an excellent wine. The D. of N. Am., (R. procumbens,) abundant in the forests of Canada, is a delicious fruit. It is of very humble growth, scarcely rising above the ground.

De Wet'te, (DR. WILHELM MARTIN LEBERECHT,) a Ger. biblical critic, b. at Ulla, near Weimar, Jan. 14, 1780. In 1810 he became Prof. of Divinity at Berlin, and as a preacher and writer he soon won a wide fame. He was a moderate rationalist in his opinions. In 1821 he became Prof. of Divinity at Basel, where he d. June 16, 1849. Among his works are a Commentary on the Psalms, Jewish Archæology, and Introduction to the Old and New Testaments.

Dew'ey, (CHARLES AUGUSTUS, LL.D.,) b. at Williamstown, Mass., March 13, 1793; was graduated at Williams Coll. in 1811. He began the practice of law in his native town in 1814, and removed to Northampton about 1826. He became judge of the Mass. Supreme Court in 1837, and retained the office till he died, Aug. 22, 1866.

Dew'ey, (CHESTER, D.D., LL.D.,) a botanist and teacher, b. at Sheffield, Mass., Oct. 25, 1781. He was for many yrs. Prof. of Natural Philosophy at Williams Coll. ; became Principal of the Collegiate Institute at Rochester, N. Y., in 1836, and in 1850 Prof. of Chemistry in the University of RochesHe wrote many excellent monographs on the Carices of N. Am., etc., for the American Journal of Science and other publications; d. Dec. 15, 1867.

ter.

Dew'ey, (ORVILLE, D.D., LL.D.,) a Unit. minister, b. in Sheffield, Mass., March 28, 1794; was graduated at Williams Coll. in 1814, and preached in the pulpit of Dr. Channing as his assistant for nearly two yrs.; was pastor at New Bedford 1823-33; then for about 14 yrs. in New York. In 1858 he became minister of New South Church, Boston; wrote The Unitarian Belief and The Education of the Human Race; d. March 21, 1882.

De Witt, (JAN,) a celebrated statesman of Holland, b. at Dort 1625, was the son of Jacob De W., a vehement opponent of William II., Prince of Orange. Jan inherited his father's hatred of the office of stadtholder, and the family that filled it. His education was carefully attended to, and he soon exhibited remarkable ability. He was one of the deputies sent by the States of Holland in 1652 to Zealand for the purpose of dissuading that province from adopting an Orange policy. In 1654, on the conclusion of the war with England, a secret article was inserted in the treaty drawn up between De W. and Cromwell, in virtue of which the House of Orange was to be deprived of all state offices. After the restoration of Charles II. De W. leaned more to the side of France. This tendency necessarily received an impetus from the renewal of hostilities between England and Holland in 1665. These lasted for two yrs.; and although De W. acted with great vigor his influence was diminished, and his party was compelled to concede a larger measure of power to the House of Orange. De W.'s prospects became still more clouded when the designs of Louis XIV. upon the Spanish Netherlands became manifest. The Orange party carried their point in the elevation of William to the family and dig. nity of stadtholder. On the invasion of the Netherlands by Louis XIV. in 1672, the Prince of Orange was appointed commander of the Dutch forces; and the first campaign proving unfortunate, the popular clamor against De W. greatly increased. His brother, Cornelius, accused of conspiracy against the life of the stadtholder, was imprisoned and tortured. De W. went to see him on his release. As they were coming out of prison they were attacked and murdered, 1672.

De Witt, (THOMAS, D.D.,) minister of the Collegiate Church, (Reformed,) New York; Pres. of the New York Historical Society, City Mission, Tract Society, etc.; b. 1791, d. 1874.

Dew-point, the temperature at which watery vapor in the air begins to be condensed. (See DEW.) Its determination is of great importance to the meteorologist, as by comparing it with the actual temperature he can tell the relative humidity of the air. He knows that at the actual temperature the air would be saturated if it contained a certain quantity of moisture, and also that the actual quantity present is only such as would suffice to saturate air at the observed D.; the ratio of this last quantity to the former expresses the relation between the actual humidity of the air and the humidity of saturation at the observed temperature. The D. in the evening further shows the temperature near which the minimum during the night is likely to be. When the temperature has fallen to the D., the vapor in the air will be condensed, and an amount of heat will he set free which will raise the temperature of the air. The temperature will again sink by radiation somewhat below the D., dew will be formed, and the temperature again be raised.

Dews'bury, a manufacturing town in the West Riding of Yorkshire, Eng.; is the center of the D. Union; pop. 29,847. D. is noted for its manufactures of low woolen goods, as pilots, sealskins, unions, etc., and carpets and blankets.

Dexip'pus, (PUBLIUS HERENNIUS,) an Athenian of great learning, 3d c. A.D., and general of the army which repelled the Goths from Attica. A still-existing statue was erected to his honor.

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Dex'ter, Penobscot Co., Me., on R.R., 70 m. N.-E. by N. from Augusta; pop. 2,732. Dex'ter, (FRANKLIN, LL.D.,) son of SAMUEL D., noticed below, b. at Charlestown, Mass., Nov. 5, 1793; was graduated at Harvard 1812; practiced law in Boston; was a member of the State Legislature and Senate, and in 1849 was appointed U. S. District Attorney for Mass. ; d. Aug. 14, 1857.

Dexter.

Dex'ter, (HENRY MARTYN, D.D.,) an eminent Cong. minister, b. at Plympton, Mass., Aug. 13, 1821; was graduated at Yale in 1840, and at Andover in 1844; was pastor in Manchester, N. H., 1844-49, and of the present Berkeley Street Church, Boston, 1849–67. From 1859 to 1865 he was one of the editors of the Congregational Quarterly, and in 1867 became editor-in-chief of the Congregationalist. He was the author of Congregationalism and History of the Plymouth Colony. D. 1890.

Dex'ter, (SAMUEL, LL.D.,) a jurist and statesman, b. in Boston May 14, 1761; was admitted to the bar in 1784; attached himself to the Federal party, and was elected U. S. senator in 1798; was appointed Sec. of War in 1800 by John Adams, and became Sec. of the Treasury early in 1801. He had no superior and few equals as an advocate before the Supreme Court of the U. S.; d. May 4, 1816.

Dex'trine. When starch is carefully heated to 400° Fahr., or until vapors arise from it, it becomes soluble in cold and hot water, and loses its gelatinous character; it also has the property, when viewed by polarized light, of turning the plane of polarization to the right; hence its name. It is often used as a substitute for gum-arabic in the processes of calico-printing, and for stiffening different goods; it is also applied to the back of postage-stamps. Its value as a substitute for gum consists in its being more flexible and less brittle when dry than that substance. Starch may be converted into D. by the long-continued action of dilute acids at a high temperature; also by the action of diastase. Dextrog'yrate, crystals which rotate a plane of polarization toward the right; opposed to lavogyrate.

Dey, a word of doubtful origin, but appropriated by the ruler of Tripoli, and also of Algiers until its conquest by the French. At one period Tunis likewise was governed by a D., but this title has long been supplanted by that of Bey.

Dhal'ac, an island in the Red Sea, on the coast of Abyssinia. It is 30 m. 1., 15 m. in average w., and 120 m. in circumference. Doobelloo, a village on the E. side, trades with Loheia and Ghizan, ports on the Arabian coast. The groups of islands in the vicinity of D. are called the Dhalac Archipelago.

Dhamee', a hill-state of India, of about 25 sq. m., on the left bank of the Sutlej; pop. 5,500.

Dhar, a town situated on the table-land of Malwa, in central India, having an area of 2,061 sq. m.; pop. 15,000. Dhar'war, a town in the prov. of Bombay, British India, close to the frontier of Madras. It has government schools, for Mahrattas and Canarese, besides schools established by the natives themselves; pop. 27,136.

Dhar'war, the district of which the town above mentioned is the cap., containing 4,565 sq. m., and 988,037 inhabitants. The most interesting feature of the country is its suitableness for the growth of Amer. cotton. In 1842, after several previous failures, the New Orleans staple was cultivated with success to the extent of 25 acres; and within five yrs. the breadth of land thus sown had increased a thousand-fold. In connection with this enterprise a good road has been constructed to Coompta, on the Arabian Sea, where the cotton is shipped for Bombay. It is hence commonly called "Coompta cotton."

Dhole, (Canis scylax,) an Indian species of dog existing in a wild state in the western Ghauts and some other mountainous districts. It is in size between a wolf and a jackal, with rather long legs, sharp muzzle, wide and pointed ears, straight and not bushy tail, light-bay color, fierce keen eyes, and great courage. The name D. is extended to some other very similar species or varieties, natives of Ceylon, Nepaul, and other parts of the East, to which the common name Red Dogs has been sometimes applied, and for which Col. Hamilton Smith has proposed the sub-generic name Chryseus.

Dhol'ka, a town of India, in the British district of Ahmed. abad; pop. 20,854.

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Dhol'pore, a town of Hindustan, on the left or N.-W. bank of the Chumbul. D. is the cap. of a protected State stretching along the left bank of the Chumbul, containing 900 sq. m. and 200,000 inhabitants.

Dhubbor'ee, a decayed town in Guzerat, belonging to the Guicowar. It presents many memorials of ancient grandeur. The population, which is inconsiderable in number, shares the place with swarms of monkeys.

Dhun'chee, or Dhan'chi, a plant of the natural order Leguminosa, sub-order Papilionacea, of a genus having an elongated many-seeded pod, alternately swollen and contracted, as if it contained a string of beads. The D. is an annual herbaceous plant, much cultivated in Bengal.

Dhwalagi'ri, once supposed to be the highest peak of the Himalaya, but now ascertained to be at most only the third in point of altitude, its h. being 26,826 ft. above the sea. The mountain is within the limits of Nepaul.

Diabetes, (Gr. dia, "through," and baino, "I flow,") a disorder of the general system, of which the principal symptom is a very much increased flow of urine. D. is of two distinct kinds: the one, diabetes insipidus, is a mere exaggeration of the water-excreting function of the kidneys, accompanied by extreme thirst, and hence called polydipsia by some authorities; the other is a more complex disorder of the assimilation, consequent on the formation first, and the excretion by the kidneys afterward, of an enormous excess of animal sugar, the sugar being found in excess, not only in the renal excretion, but in the blood, and in nearly all the secretions which have been examined. Unhappily, the cure of it is still entirely unknown, except in so far as it may be controlled or retarded by good management of the diet, drink, and clothing. Diet in D.-Allowed: Meats of all kinds, (except liver,) poultry, game, and fish; eggs, cheese, butter, and cream in moderation; lettuce, celery, cucumbers, watercress, chicory, dandelion, young onions, cabbage, cauliflower, spinach, string-beans, beet-tops, radishes, mushrooms, truffles, asparagus, oyster-plant, artichokes, and tomatoes; filberts, pecan nuts, almonds, butternuts, walnuts, and cocoa-nuts. Glycerine may be used as a substitute for sugar in coffee and tea. Avoid: Sugar and syrups of every sort; and honey, wheat and rye flour and corn meal, arrowroot, sago, tapioca, oatmeal, barley, potatoes, beets, parsnips, carrots, rhubarb, peas and beans, chestnuts, sweet fruits of any kind; chocolate, cider, malt liquors, champagne and other sparkling wines, sweet wines, etc. Medicines proper should be used only under the advice of the physician. There is no specific. Flannel should be worn next the skin, and the languid function of the cutaneous perspiration aided by the warm bath.

Diablerets, a remarkable mountain of the Bernese Alps, Switzerland, situated between the cantons of Bern and Valais, in lat. about 46° 18' N., and long. 7° 15′ E. of Greenwich, with an elevation of 10,670 ft. The D. is composed of limestone strata, the lower beds of which are so soft and shaly that they are easily disintegrated by the infiltration of water given off from the glaciers on the N.-E. The consequence is that, the foundation being worn away, the peaks tumble over into the valley, occasioning the most terrible catastrophes. Three peaks have already fallen in this way, and the two that yet remain threaten to follow sooner or later. In the fall of 1714 15 people, 100 head of cattle, and 55 châlets were destroyed; and the result would have been much more appalling had not premonitory noises given the inhabitants timely warning to escape. In 1749 the fall of another peak arrested the course of the Liserne, which thereafter formed two small lakes known as Derborenze.

Dia'chylon, the common healing or adhesive plaster, made by combining litharge, or the red oxide of lead, with olive-oil so as to form a kind of soap. The preparation of this plaster is now entirely taken out of the hands of drugists, it being prepared on the great scale by machinery.

Di'adem was the name given to the fillet of silk, woolen, or linen which served as the distinguishing ornament of kings. It was generally narrow, being only a little broader on the forehead. The D. of the Egyptian goddesses and kings bore the symbol of the sacred serpent. The D. of Bacchus, as it appears in antique sculptures, was a plaited band going round the forehead and temples, and tied behind, with the ends hanging down. Among the Persians the D. was bound round the tiara or turban, and was of a blue color worked with white.

Diadumenia'nus, (MARCUS OPELIUS MACRINUS ANTONINUS,) Emperor of Rome 217, killed by the soldiers of Heliogabalus 218.

Diagno'sis, (Gr. dia, "through," and gnosis, knowledge,") the through-knowledge or thorough knowledge of a disease, embracing its points of distinction from other diseases, its symptoms, their relation to one another, and to the state of the different organs and functions of the body, in so far as this can be appreciated during life. D. is usually spoken of in contrast with Prognosis, which implies the judgment framed by the physician as to the issues of the disease and also with Prophylaxis, which refers to the warding off disease, when supposed to be impending.

Diagom'eter, an electric instrument, the invention of M. Rousseau, for determining the conducting power of fixed oils and for detecting adulteration of olive oil.

Diag'onal, in Plane Geom., is a straight line joining any two angles, not adjacent, of a rectilineal figure. A line drawn between two adjacent angles would coincide with the boundary-line. A triangle has no D., because any two of its angles are adjacent; a 4-sided figure has two Ds.; a 5-sided, five; a 6-sided, nine, etc. The number of possible Ds. in any figure is found by taking three from the number of sides, multiplying the remainder by the number of sides, and taking half the product.

4680

Diagonal Scale.

Diag'onal Scale, a system of lines by means of which hundredths of units may be laid down or measured with compasses. Diag'oras, a Greek poet and philosopher, b. in Melos, an island of the Cyclades. He flourished in the 5th c. B.C., but beyond his reputation for atheism nothing very positive is known regarding his career. Di'al and Di'aling. A sun-dial is an instrument for measuring time by means of the motion of the sun's shadow cast by a stile erected on its surface. It is an instrument of very great antiquity, an early mention of it being in Isa. xxxviii, 8; and before clocks and watches became common it was in general use as a timekeeper. The art of constructing dials to suit any place and situation was then an important branch of mathematical study; now the subject is more an object of curiosity than utility. Di'alect. The name of D. is given to those varieties or peculiar forms which a language assumes among the various tribes or other local divisions of people. It is clear that the wider the separation comes to be between the several tribes, and the more they differ in mode of life and other circumstances, the more marked will the difference of D. become. Also, when a particular tribe of this people increases in numbers, and also extends its territory, the same process is repeated, and its D. becomes broken into a number of sub-Ds. The principal check to this tendency to seemingly endless subdivision of language is furnished by the increase of culture and civilization.

Sun-dial. Clock or Watch Dial.

Di'alogue, a conversation between two or more persons, implying, however, greater unity of subject and formality than an ordinary conversation. The ancient Greek philosophers were fond of this way of conducting their investigations and conveying their instructions. The Socratic D. is a conversation in the form of question and answer, so contrived that the person questioned is led himself to originate those ideas that the questioner wishes to bring before him. The Ds. of Plato are, as it were, philosophical dramas, in which the Socratic method of investigation is brought to bear upon speculative subjects. The form of D. is but ill adapted to the modern state of science. Landor's Imaginary Conversations are a happy effort of this kind. When D. is combined with action we have the drama. Dial'ysis, a Greek word meaning "separation," and denoting the separation of certain substances by means of liquid diffusion. See ENDOSMOSE.

Diamag'netism. The fact that iron is attracted by the magnet has been known from very remote times; that bismuth exhibits a repulsive action toward the magnetic needle has been known for nearly 100 yrs. Dr. Faraday was the first (1845) to show that all bodies are more or less affected by magnetic influence, and his beautiful researches on the subject have opened up a new field in the domain of science. He found that the magnetism of bodies was manifested in two ways-either in being attracted by the magnet, as iron, or in being repelled, like bismuth. The following list gives the kind of magnetism displayed by the more common sub