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Typhus Fever. Acute disease with a sudden onset and markedly nervous symptoms lasting about two weeks. It is caused by overcrowding, insufficient food and unhealthy surroundings, as is indicated by the various names given to it, famine fever, ship fever, camp fever, jail fever. It is one of the most highly contagious of the fevers, but is not now known in the U. S., except possibly an occasional case in the most congested part of New York City.

Typography. See PRINTING.

Tyr. In Norse Mythology, god of war; son of Odin.
Tyrannidæ. See TYRANT BIRDS.

Tyrant. Ruler of an ancient Greek city, who had usurped his power. however he might exercise it.-In popular language, a cruel and oppressive sovereign.

Tyrant Birds (TYRANNIDE). Over 350 species, including tyrant chats, tyrant wrens, tyrant flycatchers, peewees, BEE MARTIN (q.v.), etc. They persistently attack other and larger birds. Most are tropical. The bill is hooked at the tip; the general color is grayish olive, with a yellowish wash, strongest on the belly, and a red spot on the top of the head of both sexes, visible when the crest-like feathers are raised. A noted member of this family is the Scissors Tail of Central America, but straying northward. Its body is 4 in. long; the outer tail feathers are 10 in.: they cross from the two sides, and open alternately. It is called the Bird of Paradise in Mexico.

Tyrants, THIRTY. See THIRTY TYRANTS.

Tyrconnel, RICHARD TALBOT, EARL OF, ab.1625-1691. Irish intriguer, banished for conspiracy 1677: created by James II. Earl 1685, commander of the army in Ireland 1686, and Lorddeputy 1687. He replaced the English Protestant officers by Irish Catholics, sought to place Ireland under French protection, supported James after the Revolution, was made Duke 1689. fled to France 1690, and brought French troops to Ireland 1691.

Tyre. Ancient city on the coast of Phoenicia, colonized from Sidon; ancient city on mainland, besieged by Assyrians ab.713 B.C.; taken after 13 years' siege by Nebuchadnezzar and destroyed 572 B.C. A new city on the island was taken after 7

Remains of Fort.

months' siege by Alexander 332 B.C.; captured by Crusaders 1124; destroyed by Selim I. 1516; taken by the French 1799, and by the allied fleet in war with Mehemet Ali 1841. Pop. ab. 5,000.

Tyre and Sidon were the two most famous commercial cities of early antiquity, of which Carthage was a colony. They were of Canaanitish race, but mostly in friendly relations with the Hebrews, on whom they depended for food.

Tyrian Purple. Ancient dye prepared from certain mollusks, species of Murex and Purpura. Each shell-fish contained a minute quantity, which was obtained at a great cost, hence symbol of imperial power.

Tyrol. Province of Austria, between Bavaria and Italy, e. of Switzerland; anciently Rhætia; held by Austria since 1363, except 1806-14. Area 11,324 sq. m. It is mountainous, largely covered with forests, and the residue suitable chiefly for pasturage. Capital, Innsbruck. Pop., 1890, 928,769, mostly German Catholics.

Tyrolite. Cu,As, O10+Aq. Natural hydrous copper arsenate, greenish or bluish, found in small quantity as one of the products of the alteration of other copper and arsenical minerals.

spirator, Earl 1587. He revolted 1597, defeated the English Tyrone, HUGH O'NEILL, EARL OF, ab.1550-1616. Irish contwice, and offered the sovereignty to Philip II. of Spain, but was defeated with his Spanish allies by Mountjoy 1601. Repeated rebellions led to confiscation of land, dispossession of Catholics, and planting of Protestant English and Scotch in Ulster, 1609-12.

Tyrosine. C,H,,NO,. Silky needles crystallizing in stellate forms, occurring abnormally in the liver and urine, and formed from casein, feathers and albumen by potash fusion.

Tyrotoxicon. Ptomaine extracted from putrid cheese by Vaughan; also formed in milk which has stood for some days. It is very poisonous, producing diarrhoea and vomiting. Tyrrhenia. See ETRURIA.

Tyrrhenian Sea. W. of Italy, e. of Corsica and Sardinia, and n. of Sicily; part of the Mediterranean.

Tyrtæus, 7th cent. B.C. Greek poet of Attica. Noted for his war songs and elegies, which encouraged the Spartans in their wars with the Messenians. Fragments remain.

Tyrwhitt, THOMAS, 1730-1786. English philologist, editor of Chaucer, 1773-78, the Rowley poems, 1778, and Aristotle's Poetics, 1794.

Tyssens, PETER, 1624-ab.1678. Dutch painter.

Tytler, JAMES, 1747-1805. Scottish author, in America from ab.1796.

Tytler, WILLIAM, 1711-1792. Scottish historical writer. -His son, ALEXANDER FRASER. 1747-1813, prof. Edinburgh 1780, Judge-advocate of Scotland 1790, Judge of Session and Lord Woodhouselee 1802, pub. Elements of History, 101, and other books. His son, PATRICK FRASER, 1791-1849, wrote a valuable History of Scotland, 9 vols., 1828-43, and several biographies. -His daughter, SARAH FRASER, has pub. historical novels.

Tzana, or TANA. Fresh water lake on the plateau of Abys sinia, s. of Gondar. The Blue Nile flows into and out of it. It contains many islands, some inhabited. Length 60 m., breadth 30 to 40 m.

Tzarskoye. See TSARSKOYE SELO.

Tzetzes, JOHANNES, 12th cent. Constantinopolitan; Greek poet, whose voluminous works contain much information in a dull and uninteresting form. He quotes a vast number of authors, and treats of many grammatical and literary subjects. Tzschirner, HEINRICH GOTTLIEB, 1778-1828. Prof. Leipzig 1809; theological writer.

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Uffenbach, BERNARD VON, 1691-1759. Austrian Jesuit, missionary in S. America 1722-45; historian of the Guarani Indians 1755. Guarani Lexicon, 1756.

Uganda. African State, n.w. of Lake Victoria Nyanza;

first visited by Speke and Grant 1862; now partly under British influence. Here Bp. Hannington and many native Christians were slain 1885. The people are Bantus, and number ab. 2,750,000; area ab. 50,000 sq. m.

Ugolino, d.1288. Count of Gheradesca, podestà of Pisa; was vanquished or betrayed by Abp. Rubaldino, and confined with two sons and two grandsons in a tower, where they perished of hunger. The story is in Dante's Inferno, canto 33.

Ugolino, 14th century. Painter of Siena, as were three more of this family.

Ugrians. Mongolians occupying northern Europe at the time of the Slavonic migrations, which separated them into n. and s. branches; now represented by the Finns, Lapps, Samoyeds, and Magyars; originals of the Ogres of mythic child-lore.

Uhland, LUDWIG, 1787-1862. German poet, dramatist, and essayist, notable for scholarship, patriotism, and lyric power.

Uhlans. Prussian lancers, prominent 1870-71 for their bravery and marvelous activity; originally German and other light cavalry, partly Oriental in their accouterments. They

are of Asiatic origin and were introduced into the north of Europe by the Tartars, who established themselves in

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Uhlans on Reconnaissance Duty.

Poland and Lithuania. An attempt was made to introduce the Uhlans into France in 1734.

Uhlhorn, JOHANN GERHARD WILHELM, 1826-1895. Court preacher at Hanover 1855. Conflict of Christianity, 1874, tr. 1879; Ancient Ch., 1881, tr. 1883.

Uhrich, JEAN JACQUES ALEXIS, 1802-1886. French general, active in the Crimea 1854-55; defender of Strassburg, Aug.-Sept. 27, 1870.

Uintahite, or UINTAITE. See GILSONITE.

Uinta Range. In n.e. Utah, trending e. and w., and containing numerous peaks exceeding 13.000 ft. in height; composed mainly of older stratified rocks. Green River cuts a cañon through it.

Uist, N. AND S. Islands of outer Hebrides, 18 and 21 m. long. Pop. ab. 7,200.

Ujiji. African town, on Lake Tanganyika. Here Stanley found Livingstone Nov. 1871.

Ukase. Russian imperial or legislative edict. Ukraine. E. part of Poland, long defended against Tartars and Cossacks. The portion e. of the Dnieper was ceded to Russia 1686.

Ulbach, LOUIS, 1822-1889. French poet and novelist; ed. Revue de Paris, 1853-58. Gloriana, 1844; Mme. Gosselin, 1878; Steel Hammer, 1882; For Fifteen Years, 1882.

Ulcer. When inflammatory action has progressed so far that the integument becomes necrosed and is removed forming an open sore, the process is known as ulceration and the product as an ulcer. Ulcers may occur exteriorly, by the breaking

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down of the skin; or internally, through the mucous membrane, as an ulcer of the stomach.

Ulema. Collective term, in Mohammedan countries, for persons learned in religious law. They form the legal and judicial class, interpret the Koran, and are the prime movers in fanatical outbreaks.

Ulexite. NaCa B,O,+5aq. Natural sodium and calcium borate, containing 35.5 per cent of water, very soft and light, Occurring in aggregates of fine silky fibers, especially in Chili, where it is known as tiza, and in Nevada in the form of soI called cotton-balls.

Ulfeldt, LEONORA CHRISTINA, 1621-1698. Daughter of Christian IV. of Denmark; wife of an alleged traitor; imprisoned 1663-85. Her narrative was pub. 1869.

Ulfilas, ULPHILAS, or WULFILA, ab. 311-381. Bp. 341; apostle of the GOTHS (q.v.), laboring s. of the Danube from 348. Portions of his notable Gothic Bible exist, chiefly the gospels: for it he invented an alphabet.

Ullmann, JOHANN CHRISTOPH, 1771-1821. Prof. Marburg; author of valuable papers on mineralogy and on the geology of Hesse-Cassel.

Ullmann, KARL, 1796-1865. Prof. Heidelberg 1821-29 and 1836-56; prof. Halle 1829-36; prelate 1856-61. Gregory Nazianzen, 1825, tr. 1851; Sinlessness of Jesus, 1828, tr. 1841; Worship of Genius, 1840, tr. 1846; Reformers Before the Reformation, 1840, tr. 1842; Essence of Christianity, 1846, tr. 1860.

Ullmannite. NiSbS. Mineral containing ab. 28 per cent of nickel combined with antimony and sulphur.

Ulloa, ANTONIO DE, 1716-1795. Spanish naturalist and astronomer, in Peru with J. Juan 1735-44; historian of this expedition, 1748-72; head of naval school at Cadiz from 1780; founder of a naval observatory and a school of metallurgy. Ulloa, FRANCISCO DE, ab.1485-ab.1540. Spanish officer under Cortes 1520; explorer of the Gulf of California 1539-40. Ulloa, FRANCISCO DE, ab.1498-1574. Spanish Dominican, missionary in Peru 1538-49 and ab.1551-70.

Ulloa y Pereira, LUIS DE, 1590-1660. Spanish poet. Ullswater Lake. Between the counties of Cumberland and Westmoreland, Eng.; 9 m. long, 1 m. wide. See LAKE DISTRICT.

Ulm. City of Würtemberg, on the Danube, at the head of navigation. Its fine Lutheran cathedral, built 1377-1494 and

restored 1844-90, is 455 by 186 ft., 134 ft. in height, tower and spire 530 ft. high, and an organ with 6.286 pipes, the largest

in Germany. Here a peace was concluded July 3, 1620, between Catholics and Protestants; and here Mack surrendered an Austrian army of 30,000 to Napoleon, Oct. 19, 1805. It has manufactures of cotton, woolen, paper, leather and beer. Its ornamental pipe-bowls are noted. Pop., 1890, 36,201.

Ulmic Acid. Product of decaying vegetable matter. Found in earth-mould.

Ulna. Larger of the bones of the forearm, placed on the inner side. It forms, by its articulation with the humerus, the elbow joint, and extends as low as the wrist joint, but does not form a part of it.

Ulotrichaceæ. Small order of green Alga.

Ulotrichi. See MAN.

Ulphilas. See ULFILAS.

Ulpianus, DOMITIUS, ab.170-228. Roman jurist, b. at Tyre; prefect of Prætorian Guards 222; slain by them. Justinian's Digest includes 2,462 excerpts from his writings. Fragmenta, pub. 1549.

Ulric, ST., ab.890-973. Bp. of Augsburg 923; celebrated for his defense of that city 954; canonized 993.

Ulrich I., 1498-1550. Duke of Würtemberg; twice expelled and restored; active patron of the Reformation.

Ulrici, HERMANN, 1806-1884. Prof. of Philosophy at Halle from 1834; writer on Hegel and Shakespeare. Logik, 1852; Gott und der Mensch, 1866; Strauss, 1873, tr. 1874.

Ultimate End. One to be sought for of itself, and not as a means to some other end; commonly identified in ethics with the Supreme Good.

Ultimate Good. That which is to be sought for as the proper object of reasonable human action.

Ultimate Strength. Force of tension, compression, or shear, which will cause the rupture of a body 1 sq. in. in section under tensile, compressive, or shearing stress. For ductile materials, like wrought iron or soft steel, it is less than the maximum strength, owing to the flow of metal. See STRENGTH OF MATERIALS.

Ultima Thule. See THULE.

Ultimus Hæres. In Law, final heir. The State, which receives the property of those who die intestate, without leaving next of kin.

Ultramarine. Blue coloring matter, occurring in nature as LAPIS-LAZULI (q.v.); made in large quantities by melting kaolin, sulphur and dry sodium carbonate, or clay, calcined sodium sulphate and charcoal. A number of ultramarines are now on the market; a red, a yellow, a white, a green, and a number of blue varieties are known.

Ultramontanism. Italian theories ascribing doctrinal infallibility and a universal episcopate, with ordinary and immediate authority, to the Pope. Both articles were established as necessary to Catholic faith by the Vatican Council 1870. The opposing principle was that of a national church, as Galiicanism.

Ultra Red. See DARK HEAT.

Ultra Violet. That part of the solar spectrum which is more refrangible than the visible violet. This invisible stretch beyond the violet comprises a very large part of the total spectrum and may be studied by receiving it on some fluorescent surface, as a piece of paper which has been dipped in a solution of sulphate of quinine.

Ultra Vires. Act beyond the legal authority of a corporation. An ultra vires contract is unenforceable, but if it has been executed by one party, the other may be liable on a quasicontractual obligation. The term is inapplicable to torts of corporations.

Ulugh Beg, 1394-1449. Grandson of Timur-Lenk; prince of Samarkand 1447; murdered by his eldest son. He is more widely known as an astronomer than as prince, his most enduring work being a catalogue of 992 stars, the first of the kind attempted since the time of Ptolemy. It is accompanied by an introduction which throws much light upon the methods then in use.

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ULWAR-UMRITSUR

Ulwar. Town of India, 85 m. s. w. of Delhi. Pop. 52,357. It is the capital of the U. State, which is ab. 75 m. long and

Temples of the King at Ulwar.

has an area of ab. 3,573 sq. m. It is governed under British direction. The people are called Mewatties. Pop. 778,596.

Ulysses, or ODYSSEUS. One of the chief Greek heroes of the Trojan war; son of Laertes, husband of Penelope, and father of Telemachus; distinguished for valor and sagacity; hero of Homer's Odyssey, which recounts his ten years' wanderings and adventures, and his return to Ithaca.

Uma. Name given to Kali, wife of Siva.

Umatilla. Branch of the Columbia, in n.e. Oregon. Length ab. 150 m.

Umballa, or AMBALA. Town of n. India, 150 m. n.n. w. of Delhi; commercially important. Pop., 1891, 79,270.

Umbel. Flower-cluster having the pedicels all diverging

Garden Angelica.

Umberto. See HUMBERT.

from the same point, and nearly equal in length, as in Carrot and Milkweed.

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Umbelliferæ. family of flowering plants of the class Angiosperma, subclass Dicotyledons, and series Polypetala, comprising 180 genera and ab. 1,400 species, distributed throughout the whole earth, especially through the temperate regions of the n. hemisphere; called the Parsley family.

Umber, RAW. Variety of ocher, dark brown, owing to the presence of manganese oxides; used in the manufacture of pigments. When the raw umber is heated to a redness, the brown hydrated oxide of iron is changed into the red oxide, and it is called Burnt Umber. It is redder in color.

Umbilical Cord. Cord-like structure, consisting chiefly of two arteries and a vein, uniting the foetus with the placenta in the higher vertebrates.

Umbilicus. 1. Navel. 2. Aperture in the base of the Columella of Univalve shells. 3. Pit at the point of union of the calamus and the rhachis of the feather. 4. Passage from the intestine and ventrum of the embryo to the vitellus and allantois, or the various structures that go to make the navel string, as the vitelline duct, the allantoic stalk and the allantoic blood vessels.

Umbo. Eminence near the hinge in each valve of the shell of clans, etc., which marks the point where it began its growth. It usually points anteriorly.

Umbonate. Projecting in the center, like the boss of a

shield.

Umbra. Consider a luminous body and an opaque body in

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its vicinity. If a cone be developed, every element of which is an external tangent to the surfaces of the two bodies, that region within the conical surface and beyond the opaque body is the umbra or complete shadow. See PENUMBRA.

Umbreit, FRIEDRICH WILHELM KARL, 1795-1860. German theologian; prof. Heidelberg 1820.

Umbrella. General body of a jelly-fish, its shape being like two open umbrellas, put one within or below the others uniting at their edges. The lower one (subumbrella) represents the ventral and peristomial surface, the upper (ex-umbrella) the dorsal surface.

Umbrella. Of high antiquity in the East, appearing on Assyrian and Persepolitan reliefs. Among the Arabs it is a mark of distinction, and generally throughout the East it iş regarded as connected with royalty. Its origin has been traced by some to the tree under which sovereigns held court. In Siam, an umbrella with several rings is a prerogative of the sovereign; in Burmah, part of the royal title was Lord of the 24 Umbrellas. The first Englishman to carry an umbrella was Joseph Hanway, who died 1786; women used them a century earlier.

Umbrella-Bird (CEPHALOPTERUS ORNATUS). S. American, crow-like, fruit-eating bird, having a large crest of hair-like

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Umbrella-Bird (Cephalopterus ornatus).

feathers that, when erected, radiate, and curve down at the ends producing an umbrella-like structure. It also has a fleshy plume-bearing process hanging from its breast.

Umbrella Leaf. Diphylleia cymosa. White-flowered herb of the natural family Berberidaceae, native of the s.e. U. S.

Umbrella-Tree. Magnolia tripetala. Small tree of the natural family Magnoliaceae, bearing large white flowers, native of the s.e. U. S.

Umbria. Part of ancient Italy, on the Adriatic, e. of Etruria; finally conquered by Rome 295 B.C.

Umbrian. Italic dialect, akin to Latin, with a few inscriptions preserved from ab. 300 B.C.

Umlaut. In German Philology, influence exerted upon a vowel in the root of a word by a vowel in the succeeding syllable. Umlaut in English is best seen in certain plurals like men, geese, feet, mice, and is here due to an i formerly present in the plural of the noun, but not in the singular. The syllable containing this i fell away, but left its influence upon the preceding vowel.

Umnak, or OUMNAK. Alaskan island, of the Aleutian group; ab. 65 m. by 10; visited 1757.

Unalashka. Aleutian island, e. of Umnak; ab. 75 m. by 20; mentioned in a celebrated line by Campbell, "The wolf's long howl from Oonalaska's shore."

Umritsur, or AMRITSAR. Commercial city of the Punjab. India, 32 m. e. of Lahore; founded by Guru Ram Das, an

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apostle of the Sikhs, in 1574, round a sacred tank, from the midst of which rises the great temple of the Sikh faith. U.

Temple of Umritsur and the Lake of Immortality. manufactures shawls; inferior, however, to those of Kashmir. Pop., 1891, 137,000, including cantonment.

Unam Sanctam. Bull of Pope Boniface VIII., claiming unbounded authority. It provoked Philip the Fair of France to the outrages which caused the death of Boniface 1303, resulting in the removal of the Papacy to Avignon, and ultimately in the Great Schism.

Unanue, JOSÉ HIPPOLITE, 1758-1833. Peruvian scholar and statesman.

Uncas, ab.1600-1683. Chief of the Mohegan Indians in Conn.; ally of the English in their conflicts with the Pequots and other tribes; not to be confounded with Cooper's hero.

Uncial Letters. Prevalent in MSS. ab.320-720; distinguished from the angular capitals which they superseded. Uncinaria. Form of spicule like a needle, but bearing spines along its sides. It is derived from a hexactine, and is present in the sponge genus Valvulina.

Unconformable Strata. When one stratum overlies the upturned edges of another with no parallelism of dip or position. In the figure, the lower series (a) must first have

Unconformable Strata.

been deposited and subsequently folded and eroded, which partly removed the anticlinal arches, and afterward (b) was deposited.

Unconscious Cerebration. Action which so far resembles physiological functions as to be called unconscious, like the reflexes, and which yet so closely resembles mental function as to be taken for it. Carpenter used the term to express brain action reproducing past mental experience. Subliminal mental action is a better term.

Unconsciousness. Lapse of mental continuity. The possibility of absolute discontinuity of consciousness is doubtful. At the same time there are apparent breaks in an individual's mental history which demand recognition and to which the terms unconscious or subconscious may be applied. Such states are seen in sleep, fainting, hypnotic trance, etc. The main characteristic of these lapses is loss of memory on awakening for what may have occurred either objectively or subjectively during the state. The evidence for mental activity of some sort in such periods is strong: e.g., dream consciousness during sleep, the complex mental activity of hysterics and hypnotics in somnambulistic conditions, etc. The term now ordinarily used to denote this state in which the ideas do not rise above the threshold into the mental focus, is subconsciousness or subliminal consciousness. See PERSONALITY.

Unction. See EXTREME UNCTION.
Undecagon. Polygon of eleven sides.
Underbasals. See DICYCLIC CRINOIDS.

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Under Consumption. Rapidity of consumption of certain kinds of goods insufficient to absorb the amount produced.

Undercroft. Subterranean chapel or apartment. In the cloisters of Hereford Cathedral, Eng., there is a place called Mary-croft.

Undercutting. See HOLING.

Underground Railroad. Secret movement which began with Pa. Quakers, became organized 1838, and till the Civil War aided the escape of fugitive slaves. There were various routes from the Northern slave States to Canada; on each of these were stations one day's journey apart, where the runaways were fed and cared for. The reputed pres., Levi Coffin, 1798-1877, is said to have helped ab. 100 slaves annually to freedom.

Underground Railway. See SUBWAY and TUNNEL. Underhill, JOHN, 1597-1672. English emigrant, in Mass. 1630-37, on Long Island from 1646. Newes from America, 1638. Underlay, or UNDERLIE. See HADE.

Underpinning. Lowest timbers in a wooden house, resting upon the cellar walls.

Undershot Wheel. Water motor, in which the water acts more by its velocity than by its weight, being laid on in a sluice or apron below the horizontal diameter of the wheel, which turns on a horizontal axis. It is a low BREAST WHEEL (q.v.) in its better forms, and is adapted only for very low falls with large volume of water, from which large power is sought. Efficiency of the wheels with straight blades is ab. . The

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Poncelet undershot or breast wheel, with curved vanes in which a reaction was manifested, gave an efficiency of 50 per cent when drowned, and 60 per cent when not. These wheels are but little used, except along the banks of streams where water can be led to them without the expense of building dams. They generally move slowly.

Understanding. Mental faculty of conception and judg ment as opposed to perception on one hand, and to ratiocina tion and intuition, functions of reason, on the other.

Undertaker, IN ECONOMICS. Person who assumes the risks and management of business, supplying or borrowing capital, employing labor, administering the buying of materials and selling of the product, and taking as his remuneration the net returns to the business enterprise.

Underwood, FRANCIS HENRY, LL.D., 1825-1894. U. S. Consul at Glasgow 1885-89, and Leith 1893-94; author of novels, Handbooks of English and American Literature, 1871-72, and Lives of Longfellow. Lowell, and Whittier, 1882-83. Quabbin, 1893; Dr. Gray's Quest, 1895.-His cousin, LUCIUS MARCUS, b.1853, prof. Syracuse Univ. 1883-91, De Pauw Univ. 1891-93, Columbia Univ. since 1896, has pub. Our Native Ferns, 188182, and Hepaticæ, 1884-93.

Underwood, JOSEPH ROGERS, 1791-1876. Ky. Judge of Appeals 1828-35; M.C. 1835-43; U. S. Senator 1847-53.

Underwriter. One who carries on the insurance business, especially marine insurance. See INSURANCE.

Undetermined Coefficients. Assumed quantities in the statement of known relations; their definite value becomes known in the process of reduction. The term is used as synonymous with indeterminate coefficients, but applies rather to the assumed constants in these, the values of which become known by the principles of indeterminate coefficients.

Undines. Female water-spirits of the Paracelsus system, who intermarry with human beings, and receive a soul, upon bearing a child. See SYLPH.

Undulatory Theory. Propounded by Hooke 1664; developed later by Huygens, Fresnel, and Young, to explain the phenomena of light. It supposes light to consist of a wave motion set up by a luminous body in an elastic, rare, and all

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