but it is to be hoped that our naturalists, in subsequent researches, may supply the desired information.

DEVIL'S ADVOCATE (advocatus diaboli) is the person appointed to raise doubts against the genuineness of the miracles of a candidate for canonization (q. v.), to expose any want of formality in the investigation of the miracles, and to assail the general merits of the candidate. After every thing is said pro and contra, and three papal advocates of the consistory have found the whole course of proceedings legal and formal, the canonization follows. It is said that in the beginning of the 17th century, the canonization of the cardinal Charles Borromeo was almost prevented by the accusations of the devil's advocate.

DEVIL'S BRIDGE; a famous bridge in Switzerland, over the Reuss, built of stone, from mountain to mountain, 75 feet in length, on the road over St. Gothard, from Germany to Italy. It owes its name principally to its antiquity, for there are higher, longer and wider bridges in Switzerland. The Devil's Bridge is a very common subject of prints and paintings, and is situated in a most romantic country. DEVIL'S WALL, in the south of Germany. It was very common for gigantic works of art, or peculiar formations of nature, to receive, in the middle ages, the name of the devil. This wall was originally a Roman ditch, with palisades behind it, to which, under the reign of the emperor Probus, a wall with towers was added. It was intended to protect the Roman settlements on the left bank of the Danube, and on the right bank of the Rhine, against the inroads of the Teutonic and other tribes. The wall extended for about 368 miles, over mountains, through valleys, and over rivers, running towards the Danube. Remains of it are found at present only from Abensberg, in Bavaria, to Cologne, on the Rhine. Sometimes these remains form elevated roads and paths through woods, sometimes tall oaks grow upon them, sometimes buildings stand upon the imperishable structure. A. Buchner has shown, in his Journey along the Devil's Wall (Ratisbon, 1821), that it was the work of nearly two centuries, commencing in the time of Adrian, and was at first a mere wall of earth, but was afterwards made a substantial stone wall, of from six to eight feet in width. Buchner followed the traces of this wall for two sum

mers.

He points out, also, the course of the Roman road behind it. The same book contains a plan of the canal by

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which Charlemagne intended to unite the Danube and the Rhine, and of which a dry ditch, called the Fossa Carolina, is the only remains. (See Carolina.) Buchner says, that six million guilders would be sufficient to complete this great plan, which others doubt. (See Danube.)

DEVISE, in law, is the disposition of real estate by will. It is distinguished from a bequest of personal estate by will, the personal estate so disposed of being called a legacy. The word devise is also sometimes applied to any gift by will, whether of real or personal estate. The person to whom a devise is made is called devisee.

DEVOLUTION. By the rule of devolution, the right of presentation to a vacant place, especially a clerical one, reverts, in case of neglect in exercising it, to a superior (bishop, prince or consistory).

DEVONPORT; a market-town of England, at the confluence of the Tamar with the sea in Plymouth sound. It is the seat of the naval and military government of the port, and contains the dock-yard and naval arsenal. Hence it was, until lately, called Plymouth dock, and viewed only as an appendage to the town of Plymouth. In the year 1824, it received the name of Devonport, which it has since borne. The dock-yard is well worthy of notice. It extends on the eastern bank of the Tamar, in a circular sweep along the shore, 3500 feet in length, with a width at the middle, where it is greatest, of 1600 feet, and at each extremity 1000, thus including an area of 96 acres. The harbor of Hamoaze, which bounds the dock-yard on the western side, is a commodious basin, formed by the estuary of the Tamar, half a mile wide, and extending four miles in length. Devonport, within the lines, contains about 20,000 inhabitants.

DEVONSHIRE; 1. Georgiana Cavendish, duchess of; famous for her beauty and poetical talents, and the patriotic friend of Fox. She was born in London, 1757, celebrated the passage of St. Gothard (translated into French by Delille, with the original, Paris, 1802), and died in 1806. 2. Elizabeth Hervey, duchess of Devonshire, lived, from 1815, in Rome, where she died, March 30, 1824. In Rome, she was surrounded by distinguished men, especially artists. She was the friend of cardinal Gonsalvi, Canova, Camuccini, Thorwaldsen and others. She published Virgil's poems, in the translation of Hannibal Caro, with engravings, from the designs of the first painters of Rome. This edition consisted of only 150 copies, which

the duchess distributed to the European sovereigns, the principal libraries, and her particular friends. She caused an edition of the fifth satire of Horace to be published on the same plan, and was about to undertake an edition of Dante, when she died. Her house in Rome was the resort of the most cultivated society.

DEVONSHIRE, William, duke of. (See Cavendish.)

DEW is a deposition of water from the atmosphere upon the surface of the earth. The conditions under which the phenomena of dew take place are the following: The most plentiful deposit occurs when the weather is clear and serene; very little is ever deposited under opposite circumstances. It is never seen on nights both cloudy and windy. It is well known, likewise, that a reduction in the temperature of the air, and of the surface of the earth, always accompanies the falling of dew, the surface on which it is deposited being, however, colder than the air above. These phenomena admit of an easy and elegant explanation from the well known effect of the radiation of caloric from bodies. This radiation constantly taking place in all bodies, it is obvious that the temperature of any body can remain the same only by its receiving from another source as many rays as it emits. In the case of the earth's surface, so long as the sun remains above the horizon, it continues to receive as well as to emit heat; but when the sun sinks below the horizon, no object is present in the atmosphere to exchange rays with the earth, which, still emitting heat into free space, must, consequently, experience a diminution in its temperature. It thus becomes not only many degrees cooler than in the day time, but also cooler than the superincumbent air; and, as the atmosphere always contains watery vapor, this vapor becomes condensed on the cold surface; hence the origin of dew, and, if the temperature of the earth is below 32°, of hoar frost. And since the projection of heat into free space takes place most readily in a clear atmosphere, and is impeded by a cloudy atmosphere, it is under the former condition that dew and hoar frost are formed; for if the radiant caloric, proceeding from the earth, is intercepted by the clouds, an interchange is established, and the ground retains nearly, if not quite, the same temperature as the adjacent portions of air. Whatever circumstances favor radiation favor also the production of dew; and, accordingly, under the same exposure, dew is much

more copiously deposited on some surfaces than on others. Gravel walks and pavements project heat and acquire dew less readily than a grassy surface. Rough and porous surfaces, as shavings of wood, take more dew than smooth and solid wood. Glass projects heat rapidly, and is as rapidly coated with dew. But bright metals attract dew much less powerfully than other bodies. Water, which stands at the head of radiating substances, is seen to condense the vapor of the superincumbent air in such a manner as to create thick mists and fogs over its surface. The unusual abundance of precipitated noisture over ponds and streams is attributable, however, not merely to the inferior temperature of their waters to the air, arising from radiation, but to the circumstance that more moisture is ordinarily contained in such air, since the sheltered situation it enjoys prevents its being borne away by those aerial currents prevailing elsewhere. An acquaintance with the cause which produces dew and hoar-frost enables us to understand the rationale of the process resorted to by gardeners to protect tender plants from cold, which consists simply in spreading over them a thin mat or some flimsy substance. In this way, the radiation of their heat to the heavens is prevented, or, rather, the heat which they emit is returned to them from the awning above, and they are preserved at a temperature considerably higher than that of the surrounding atmosphere. To ensure the full advantage of this kind of protection from the chill of the air, the coverings should not touch the bodies they are intended to defend. Garden walls operate, in part, upon the same principle. In warm climates, the deposition of dewy moisture on animal substances hastens their putrefaction. As this usually happens only in clear nights, it was anciently supposed that bright moonshine favored animal corruption. This rapid emission of heat from the surface of the ground enables us to explain the artificial formation of ice, during the night, in Bengal, while the temperature of the air is above 32°. The nights most favorable for this effect are those which are the calmest and most serene, and in which the air is so dry as to deposit little dew after midnight. Clouds and frequent changes of wind never fail to interrupt the congelation.

300 persons are employed in this operation at one place. The enclosures formed on the ground are four or five feet wide, and have walls only four inches high. In these enclosures, previously

bedded with dry straw, broad, shallow, unglazed pans are set, containing water. Wind, which so greatly promotes evaporation, prevents the freezing altogether; and dew forms, in a greater or less degree, during the whole of the nights most productive of ice. The straw is carefully preserved dry, since if, by accident, it becomes moistened by the spilling of water, it conducts heat, and raises vapor from the ground, so as greatly to impede the congelation. The radiation from the earth's surface is one of those happy provisions for the necessities of living beings, with which nature every where abounds. The heavy dews which fall in tropical regions are, in the highest degree, beneficial to vegetation, which, but for this supply of moisture, would, in countries where scarcely any rain falls for months, be soon scorched and withered. But, after the high temperature of the day, the ground radiates under these clear skies with great rapidity; the surface is quickly cooled, even to a great extent, and, as soon as this refreshing cold is produced, the watery vapor, which, from the great daily evaporation, exists in large quantities in the atmosphere, is deposited abundantly. This deposition is more plentiful, also, on plants, from their greater radiating power; while, on hard, bare ground and stones, where it is less wanted, it is comparatively trifling. In cold climates, the earth, being cold and sufficiently moist, requires little dew; accordingly the clouds, which are so common in damp and chilly regions, prevent the radiation of heat: the surface is thus preserved warm, and the deposition of dew is, in a great measure, prevented.

DE WETTE. (See Wette.)

DE WITT, John, grand-pensioner of Holland, celebrated as a statesman and for his tragical end, was the son of Jacob De Witt, burgomaster of Dort, and was born in 1625. His father was imprisoned for some time on account of his opposition to prince William II of Orange. John De Witt inherited from his father republican principles and a hatred to the house of Orange. After having carefully cultivated his talents, he entered into the service of his country, and was one of the deputies sent by the states of Holland to Zealand, in 1652, to dissuade this province from conferring the office of captain-general on the young prince of Orange, William III, who was but two years old. His eloquence procured him universal confidence; but to preserve this was almost impossible during the dissensions which raged in the

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states-general. One party was anxious, during the war between England and Holland, to have all power and honors conferred on prince William III; the other, with De Witt at its head, endeavored to withdraw all authority from this prince, and entirely to abolish the stadtholdership. The war with England, sometimes fortunate, sometimes adverse, was injurious to commerce, and excited the displeasure of the nation against the latter party, of which excitement the Orange party took advantage to effect their purposes, until, in 1654, the former concluded a peace with Cromwell, with the secret condition that the house of Orange should be excluded from all situations of authority. Thus the republican party was victorious, and De Witt, as grand-pensioner, employed the time of peace in healing the wounds under which the state was suffering. When Charles II again took possession of the crown of England, De Witt inclined to the side of France, which inclination became more powerful when, in 1665, the war recommenced between England and the states-general. The bishop of Münster, likewise, taking arms against the latter, the discontent of the people against De Witt became so great, that he was compelled, in order to pacify them, to give up some privileges to the prince of Orange, and to conclude peace with England, in 1667. To increase the danger of De Witt's situation, Louis XIV now began to manifest his intentions with regard to the Spanish Netherlands. The Orange party insisted on elevating prince William to the dignity of his ancestors. succeeded in separating the offices of stadtholder and captain-general, and provided that, in Holland at least, he should be entirely excluded from the latter. The number of De Witt's enemies increased. He was obliged to conclude an alliance with England and Sweden against France, which produced the peace of Aix-laChapelle, and was as quickly dissolved as it had been formed. Louis XIV, now united with England, invaded the Spanish Netherlands (1672). William's friends succeeded in procuring for him the post of commander-in-chief. The first campaign was unfortunate in its results, which were imputed to De Witt and his friends. The life of the former was endangered. William was nominated stadtholder by universal consent, and De Witt resigned his employments. But the disposition of the people was little changed by this voluntary act, nor was the hatred of the Orange party satisfied. His brother Cornelius

De Witt

was accused of having attempted to assassinate the prince. He was imprisoned and put to the rack; but, as he would not confess any such design, he was banished from the country, and his property confiscated. Hearing that his brother wished to speak to him while in prison, John de Witt hastened thither, when a tumult suddenly arose among the people at the Hague. The militia could not disperse the mob, the greater number of the officers being devoted to the prince. The people broke into the prison, and both brothers fell victims to their rage (Aug. 20, 1672). The states demanded an investigation of this affair, and the punishment of the murderers, from the stadtholder, which, however, never took place. That the opinions of De Witt's contemporaries respecting him did not agree, may well be supposed; but all acquitted him of treason against his country. He was simple and modest in all his relations. He fell a victim to party spirit, nor could the friends of the house of Orange accuse him of any other crime than that of not belonging to their party, and of aiming to elevate his own party at their expense. De Witt was an active political writer, and has left many excellent observations on the events of his time.

DEXTER, Samuel, an eminent American lawyer and statesman, was born at Boston, in 1761. His father was a distinguished merchant, and a benefactor of Harvard college. The son was graduated at that institution, in 1781, with its first honors. He then engaged in the study of the law. He had not been long at the bar before he was elected to the state legislature, from which he was transferred to congress, first to the house of representatives, and then to the senate. He was in congress during a period of strong party excitement, and succeeded in gaining much influence and honor by the force of his talents and character, proving himself an enlightened politician and superior orator. President Adams made him, successively, secretary of war and of the treasury. He discharged these offices in a masterly manner. Towards the end of Mr. Adams's administration, he was offered a foreign embassy, but declined it. When Mr. Jefferson became president, he resigned his public employments, and returned to the practice of the law. In 1815, president Madison requested him to accept an extraordinary mission to the court of Spain, but he declined the offer. For many years, he continued to display extraordinary powers in his profession, having no

superior, and scarcely a rival, before the supreme court at Washington, in which he appeared every winter, in cases of the highest importance. On his return from that capital, in the spring of 1816, he fell sick at Athens, in the state of New York, and died there May 4, aged 55. Mr. Dexter was tall and well formed, with strong features and a muscular frame. His eloquence was that of clear exposition, and cogent, philosophical reasoning; his delivery in general simple, and his enunciation monotonous; but he often expressed himself with signal energy and beauty, and always gave evidence of uncommon power. He devoted much of his leisure to theological studies, and died a zealous Christian. In the party divisions of the American republic, he held, at first, the post of an acknowledged leader among the federalists: eventually, however, he separated himself from his colleagues, on some questions of primary interest and magnitude. In the fine sketch of his life and character, drawn by judge Story, it is truly said of him, "He considered the union of the states as the main security of their liberties; whatever might be his opinion of any measures, he never breathed a doubt to shake public or private confidence in the excellence of the constitution itself."

DEY; the chief of Algiers, which is a military aristocratic state. In Tunis and Tripoli, the same officer in these similarly regulated military republics, is named bey. The bey of Tripoli is, however, assisted by a pacha. Since 1520, Algiers has recognised the authority of the Turkish sultan. Turkish soldiers, under the command of a pacha, sent to Algiers by the sultan, once governed there, and, not receiving their pay from the pacha, they prayed permission of the Porte, at the commencement of the 17th century, to choose a chief from their number, with the title of dey. The pacha was to remain, but to have no share in the government. This was agreed to by the Porte. In the year 1710, the dey banished the pacha from Algiers, and obtained permission of the Porte to enjoy both titles. Since that period, every dey chosen by the soldiers must apply to the sultan for confirmation and for appointment as pacha. The sultan, therefore, reckons Algiers amongst his possessions, and sends orders to the pacha and the divan. In time of war, the people of Algiers must assist the Porte, if required, with soldiers and ships. All money coined here bears the stamp of the sultan, and public prayers are offered for

him, as through the whole of Turkey. The dey sends an annual tribute to Constantinople. The highest authority is with the divan, or the council of state; but "the greater and lesser members of the invincible militia of Algiers" make decrees according to the majority of votes, in all things which concern the government.

DHIOLIBA. (See Niger, and Timbuctoo.) DIADEM; a band of silk or woollen, invented, according to some, by Bacchus, to relieve the headache produced by excessive drinking. It more probably belonged to him as coming from the East (the Indies). It afterwards became the distinguishing ornament of royalty. The diadein of the Egyptian deities and kings bore the symbol of the sacred serpent. Among the Persians, it was twined about the tiara of the kings, and was purple and white. The diadem of Bacchus, particularly of the Indian Bacchus, as seen in very old representations, consisted of a broad, plaited band, encircling the forehead and temples, and tied behind, with the ends hanging down. When unfolded, it formed, in fact, a veil; and, for this reason, it was often called, by the Greeks, calyptra, i. e., a veil. It was afterwards attributed to other deities, and finally became the badge of kings. In the earliest times, it was very narrow. Alexander the Great adopted the broad diadem of the Persian kings, the ends of which hung over his shoulders; and this mark of regal dignity was retained by his successors. On coins we see queens, also, with the diadem, with the addition of a veil. The early Roman emperors abstained from this ornament, to avoid giving offence to the people. Constantine the Great was the first who used it, and he added new ornaments to it. After his time, it was set with a single or double row of pearls and other precious stones, so that it was somewhat similar to a Turkish turban.

DIECIOUS, in botany; plants which have their stamens on one individual and their pistils on another. The willow, the ash, the poplar, &c., are diæcious. On this account, the weeping willow and several other trees never produce seeds in the U. States, as the male plants only have been introduced.

DIAGLYPHON (Lat.; diayλúpov, Gr.); in ancient sculpture; the name by which the Greeks designated works in sculpture when sunk in with the chisel. Among the most celebrated of these were the buckler and pedestal of a colossal statue of Minerva at Athens. When it was in re

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lief, the work was called anaglyphic. (See Anaglyphic.)

DIAGNOSIS, in medicine; the distinction of one disease from others resembling it, by means of a collected view of the symptoms.

DIAGNOSTIC Symptoms are the leading symptoms, or those which are most characteristic of any particular form or seat of disease.

DIAGONAL, DIAGONAL LINE; a straight line, joining two angles not adjacent, in a rectilinear figure, having more than three sides. Every rectilinear figure may be divided by diagonals into as many triangles as it has sides, minus two.

DIAGRAM; a figure or geometrical delineation, applied to the illustration or solution of geometrical problems, or a description or sketch in general. Anciently, it signified a musical scale. Among the Gnostics, the name diagram was given to a figure formed by the superposition of one triangle on another, and inscribed with some mystical name of the Deity, and worn as an amulet.

A

DIAL SUN. This instrument has been known from the earliest times: the Egyptians, Chaldeans and Hebrews (Isaiah xxxvii. 8) were acquainted with the uses of it. The Greeks derived it from their eastern neighbors, and it was introduced into Rome during the first Punic war. dial constructed for the latitude of Catana was carried off from that city and placed in the forum by Valerius Messana; but, as there was a difference of 4° of latitude between the two cities, it could not, of course, indicate the true time at Rome. Before this period, the Romans ascertained the hour by the rude method of observing the lengths of shadows, or, in the absence of the sun, by the clepsydra (q. v.), which a slave was employed in tending.Sun-dials have lost much of their value in modern times, by the general introduction of instruments which indicate the time at any period of the day or night; but clocks and watches require to be regulated, and the shadows projected by the sun are the most convenient standard for this purpose. Dials are of various kinds; but the horizontal and vertical are most commonly used. In this place, we can give only the general rules of construction applicable to all of them. Suppose 12 planes, making with each other angles of 15°, passing through the axis of the earth and dividing the sphere into 24 equal parts, one of these planes being the meridian of the place of the observer; start from the meridian, and, moving towards