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DEW

production of dew were imperfectly comprehended previous to the researches of Dr. Wells, and the publication in 1814 of his essay upon the subject. This treatise, pronounced by Dr. Thomson to be "one of the most beautiful examples of inductive reasoning in the English language," presents in clear form the various phenomena as observed by him for two successive years in the vicinity of London. The observations are criticized by Sir John Leslie for want of address and delicacy in the experiments, and omission to make use of the hygrometer and pyroscope; and he expresses much regret that Dr. Wells should have sought to explain the production of the cold by the aid of the "very loose, cumbrous, and visionary hypothesis of M. Prevost of Geneva, concerning what is gratuitously called radiant heat." According to Prof. Leslie, the low temperature of the bodies upon which the dew collects is induced by the descent of cold air, which is precipitated in distinct pulsations, determined by the application of the aetheriscope, by which their intensity also is measured. Two requisites are essential, it appears, for the abundant precipitation of dew; one is the saturation of the atmosphere with moisture, and the other a chilled surface to condense it. The atmosphere is likely to contain the most moisture for its temperature after rains, when the air is cooled, and abundant evaporation is going on from objects upon the surface, and through the pores of the soil. This evaporation tends to chill the surfaces from which it is taking place, and the blades of grass and all shrubs and light bodies near the ground assume a much lower temperature than that of the air above them. Dr. Wells states that this difference of temperature between the grass and the air 4 feet above the ground amounts in clear and still nights to 8° or 9°, and in one instance he observed a difference of 14°; but in cloudy nights the grass was sometimes as warm as the air. Bodies of a filamentous structure, like cotton, flax, hair, silk, gossamer, &c., and of a downy nature, as swan's down especially, are particularly subject to be thus affected, and the deposit of dew first takes place upon them. Each growing plant has its own peculiar power of condensing moisture, which is no doubt proportioned to its requirements of this refreshing agent. When the rays of the sun cease to strike directly upon the surface, the dew-gathering objects soon manifest the want of that temperature which during the heat of the day had kept them above the dew point. If no wind is stirring to mix the air and produce uniformity of temperature, the blades of grass may exhibit moisture upon their surface before the sun has reached the horizon, and soon after having passed it drops are likely to collect. If it be a cool night of spring or autumn, succeeding a hot day, the deposition of dew is likely to increase as the night becomes colder; and in the latter half more is precipitated than in the early part of the night. Should clouds gather, the process ceases, these seeming VOL. VI.-28

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to reflect the heat that radiates from the surface, and turn it back, so that the requisite difference of temperature between the surface and the air can no longer exist. Any other overshadowing object, as a tree or a bush, has the same effect as the cloud; and the gardener, fearing that when the dew is changed to hoar frost the results of this radiation may reach upon the plants the freezing temperature, throws over them a thin sheet or mat, which retains the radiating heat as it is retained by a cloud. Numerous observations have been made upon the relative capacity of metals and other substances to receive dew. It is probable that they may be arranged in the same order as that which would represent the relative rapidity at which they would be cooled down when exposed under a clear sky. This rate of cooling would evidently vary in the same substance according to its structure and the smoothness or roughness of its surface. Twigs and bushes change their temperature much more rapidly than the same material would in a solid block. The polished surfaces of metals receive less dew than other substances; and bodies laid upon them lose in part their capacity for receiving this deposit by reason of the contact. Probably the worst conductors of heat as a general rule, other circumstances of texture, smoothness, &c., being the same, receive the most dew. It is deposited freely upon glass. The electrical condition of these objects has no influence upon their collecting dew. The quantity of dew which has gathered in a single night has been so great, that it could be determined by the rain gauge. Dr. Dalton estimates the amount precipitated annually in England to be 5 inches. In some countries it is so copiously produced, that the want of rains such as fall in other regions is not seriously felt by the vegetation. Along portions of the western coast of both North and South America rain clouds are rarely seen in many years; the Cordilleras have stripped the air passing over them in the trade winds of nearly all its moisture, and the pleasantly cool and clear nights along the Pacific coast are particularly favorable for the deposition of dew. In the dry regions of Palestine, according to Maundrell, the dew gathering upon the tents wets them as if it had rained all night. The great deserts alone receive no moisture by rain or by dews. Their heated surface presents no cool object to arrest any vapor that may pass over it; and the fall of the temperature of this surface can rarely reach a point at which the little moisture contained in the air above could be so condensed as to saturate it. The vapors of the Mediterranean may be swept by the Etesian winds over the sandy plains of Sahara, but the clouds are no sooner touched by the burning rays reflected from these than they disappear like the morning mists be fore the rising sun.

DEW, THOMAS RODERIC, an American writer on government, history, and political economy, born in King and Queen co., Va., Dec. 5, 1802, died in Paris, France, Aug. 6, 1846. He was

graduated at William and Mary college, and began the study of the law; but his health failing, he spent 2 years in the south of Europe, in the autumn of 1827 was elected professor of political economy, history, and metaphysics in William and Mary college, and in 1836 was made president of that institution. In 1829 he published his "Lectures on the Restrictive System," which had been delivered before his college class. It was brought out at a moment when feeling ran high on the subject of the tariff, between protectionists and freetraders; and though emanating from the closet of a thinker removed from the agitations of political warfare, it took a strong hold on the public mind, and the subsequent adoption of the compromise of 1832 may be attributed in part to its silent influence. About the same time, a serious, and it was thought at first alarming rebellion of the slave population was quelled in Southampton co., Va. So great were the terrors inspired by this event, that, combining with a preexistent desire to abolish slavery on the part of the leading men of the commonwealth, they led to an able and protracted debate in the Virginia legislature, in which the diversity of sentiment was by no means so great upon the policy of emancipation as with respect to the mode in which this should be effected. At this juncture, Mr. Dew's essay on "Slavery" appeared. The change of opinion it brought about was extraordinary and instantaneous. Whatever may be thought of the positions taken by the writer, it must be admitted by all that he sustained them with great ability, and it is certain that the essay set at rest, at that time, the question of emancipation in Virginia. Mr. John Quincy Adams declared that this essay inaugurated a new era in the history of the country, and it is believed that the pro-slavery doctrines now so generally entertained in the southern states of the Union are chiefly due to the moral weight of the novel argument in favor of domestic servitude. When the "Southern Literary Messenger" was established in the year 1834, Mr. Dew became one of its regular contributors, and published in its pages a series of papers on the distinguishing characteristics of the sexes, which attracted much attention. But his most elaborate work was published in New York, in 1853, 7 years after his death, under the title of "A Digest of the Laws, Customs, Manners, and Institutions of the Ancient and Modern Nations.' It was modestly called by the author "Notes on History," and had been previously printed in sheets, though in an unfinished state, for the use of his classes in college. It is a treatise on the history of the world from the earliest ages down to the first French revolution, and deals more with the philosophy of history than the mere relation of events, but it exhibits all the best traits of the author's mind. In person, Mr. Dew was tall and lithe, his temperament was nervous, and his movements were somewhat awkward and constrained; yet in the social circle he was always

eagerly welcomed for the richness and variety of his conversation. In the summer of 1846 he married, and immediately afterward embarked with his bride for a short European tour. He lived only to reach Paris, and died there suddenly on the night of his arrival. His remains repose in the cemetery of Montmartre. DEWEES, WILLIAM POTTS, an American physician, professor of obstetrics and diseases of women and children in the university of Pennsylvania, born at Pottsgrove, Penn., May 5, 1768, died in Philadelphia, May 18, 1841. His greatgrandfather, who was a Swede, was one of the early settlers on the banks of the Delaware river, before the arrival of William Penn. The father of Dr. Dewees died while the subject of this notice was yet young; and being left without any pecuniary means, he was emphatically the architect of his own fortune. He attended several courses of lectures at the university of Pennsylvania, and in 1789, without taking any formal degree, commenced the practice of medicine at Abington, Penn. The degree of M.D. was at a subsequent period conferred on him by the university. The yellow fever, which visited Philadelphia in the summer and autumn of 1793, having sadly thinned the ranks of the physicians there, in December of that year Dr. Dewees resolved upon selecting this new and enlarged field for his labors. Here he achieved for himself a high and enduring reputation, more especially in that important department to which he devoted particular attention, midwifery, previously much neglected in America. To no one in this country is the medical profession more indebted for its progress in this branch of the science than to Dr. Dewees. In 1812, being threatened with a pulmonary affeetion, he relinquished the practice of his profes sion, and for the 5 subsequent years devoted himself to the severe physical labor of agriculture, at Phillipsburg, Penn. In 1817, however, he returned to the field of his former triumphs. Subsequently he published "Inaugural Essays," "Medical Essays," "System of Midwifery," of which latter 12 editions have been printed; in 1825, "A Treatise on the Physical and Medical Treatment of Children," and in 1826, "A Treatise on Diseases of Females," of which 2 last named volumes 10 editions have been printed. His last systematic work was his "Practice of Medicine," which was published in 1830. In 1826 he was elected adjunct professor, and in 1834 professor of obstetrics and diseases of women and children in the university of Pennsylvania. In this latter year, although attacked by paralysis, he was not prevented from delivering the full course of lectures for the season of 1834-5. At the commencement of the following year he was obliged to resign, and to seek a more genial climate. After spending one winter in Cubs, and the following summer in the North, he settled in Mobile. About a year before his death he returned to Philadelphia, where he resided when he died.

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D'EWES, SIR SYMONDS, an English antiquary, born in Coxden, Dorsetshire, Dec. 18, 1602, died April 18, 1650. He was admitted to the bar, but never practised law, and lived on his property at Stow Hall, in Suffolk. He was high sheriff of Suffolk in 1639, and was one of the Puritan members expelled from the house of commons by "Pride's purge." He commenced collecting materials for a history of England at the age of 18, and though the fruits of his research were not published by him, they were of great use to Selden and other writers. After his death a valuable compilation of his was given to the world by his nephew Paul Bowes, under the title of "The Journals of all the Parliaments during the Reign of Queen Elizabeth" (folio, London, 1682). His "Autobiography and Correspondence," edited by J. O. Halliwell (2 vols. 8vo., London, 1845), contains some interesting pictures of his times and contemporaries, intermixed with much that is useless and with a comical display of vanity.

DE WETTE, WILHELM MARTIN LEBERECHT, a German theologian and biblical critic, born at Ulla near Weimar, Jan. 14, 1780, died at Basel, June 16, 1849. Having studied at Weimar and Jena, he was appointed professor of philosophy, and subsequently of theology, at Heidelberg, and received in 1810 a professorship at the university of Berlin. This situation he lost in consequence of a letter of consolation written to the mother of Sand, the murderer of Kotzebue, which was regarded by the government as extenuating this act of political fanaticism. He retired to Weimar, and was afterward elected professor of theology by the university of Basel. Here he met with an undisturbed acknowledgment of his merits, was made citizen of Basel, member of the committee of education, and shortly before his death rector of the university. De Wette distinguished himself by his lectures and sermons as well as by numerous works. The latter belong to the most remarkable productions of German theological science and criticism. The most important of them are: "Contributions to an Introduction to the Old Testament" (2 vols., 1806-'7); "Commentary on the Psalms" (1811); “Manual of Jewish Archæology" (1814); "Religion and Theology" (1815); "Christian Dogmatics" (2 vols., 1813, 1816); "Critical and Historical Introduction to the Old and New Testaments" (1817-'26; the Introduction to the Old Testament was translated and enlarged by Theodore Parker, Boston, 1843, 2d ed. 1858; and that to the New, by Frederic Frothingham, Boston, 1858); "Christian Morality" (3 vols., 1819-'21); "Theodore, or the Sceptic's Conversion" (1822; translated by James F. Clarke, Boston, 1841); "Lectures on Practical Ethics" (1823; translated by Samuel Osgood, Boston, 1842); Opuscula Theologica (1830); "The Essence of Christian Faith" (1846); a new translation of the Bible, executed together with Augusti in 6 vols. (1809-'14); and an unfinished edition of Luther's works.-LUDWIG, son of the preceding, born at Berlin about

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1814, published a "Journey through the United States and Canada in 1837" (Leipsic, 1838).

DEWEY, CHESTER, D.D., LL.D., an American clergyman and teacher, born at Sheffield, Mass., Oct. 25, 1784. He was graduated at Williams college in 1806; studied for the ministry; was licensed to preach in 1808, and during the latter half of that year officiated in Tyringham in western Massachusetts. The same year he accepted a tutorship in Williams college, and in 1810 was appointed professor of mathematics and natural philosophy, an office which he discharged for 17 years. During his connec tion with the college he did much to advance the standard of scholarship, and enlarge the course of study in his own and kindred departments. Over the students his influence was often beneficially exerted. Between 1827 and 1836 he was principal of the "Gymnasium," a high school for boys in Pittsfield, Mass., and in the latter year he removed to Rochester, where he was principal of the Rochester collegiate institute until 1850, when he was elected professor of chemistry and natural philosophy in the university of Rochester, which position he still holds. Professor Dewey has been a frequent contributor to the " American Journal of Science and Arts," and is the author of several special botanical treatises, including a "History of the Herbaceous Plants of Massachusetts," written for the state government. Until recently he has been in the habit of employing his vacations in lecturing at the medical colleges of Pittsfield and Woodstock, Vt. In the course of his long career as a teacher of youth he has delivered over 4,000 lectures, and preached nearly as many sermons. He has effected much for the advancement of public schools, and was active in the establishment of the "Teachers' Institute," of which he has been president.

DEWEY, ORVILLE, D.D., an American clergyman, born at Sheffield, Mass., March 28, 1794, was graduated at Williams college in 1814; pursued his divinity studies at Andover theological seminary from 1816 to 1819; preached 8 months as agent for the American education society; declined an immediate and permanent settlement on account of unfixed opinions in theology, but accepted a temporary call at Gloucester, Cape Ann (with a candid explanation of his unsettled views), and here became a Unitarian; soon after became an assistant of Dr. Channing, preaching two years in his pulpit, and forming with him a life-long intimacy; in 1823 accepted the pastorate of the Unitarian church in New Bedford, where he remained 10 years, until, broken in health, he sought restoration in his first voyage to Europe, June, 1833. The "Old World and the New" (2 vols., 1836), one of the freshest and most instructive records of travel, contains the history of his two years' absence. In 1835 he was called to the 2d Unitarian church in New York, which, during his ministry, built the

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church of the Messiah," and became a very large and prosperous society. In 1842, his health

again failing, he went abroad for two years, and returning in 1844 to his post, was compelled by continued ill health to dissolve his connection with his church in 1848, and retire to his paternal farm in Sheffield, long and piously preserved by him, at great sacrifices, for the use of his mother and sisters. Here he devoted the remnants of his strength to the preparation of a course of lectures for the Lowell institute at Boston, on the "Problem of Human Life and Destiny," which was repeated twice in New York, and in Brooklyn, New Bedford, Baltimore, Washington, Charleston, St. Louis, Louisville, Nashville, Madison, Cincinnati, and Sheffield. This course was followed, in 1855, by another Lowell course on the "Education of the Human Race," which was almost as widely repeated. Meanwhile he filled the Unitarian pulpit in Albany one winter, and in Washington two. In 1858 he was again settled as pastor over the Unitarian society in Church Green, Boston, known as the "New South," where he now is. The first book which Dr. Dewey published was a little work, which made a noise in its day, entitled "Letters on Revivals." During his ministry at New Bedford he contributed much to the "Christian Examiner" and the "North American Review." On leaving New Bedford, he published a volume of sermons, which produced a marked sensation. His various works since have been collected and published in 3 vols. (New York, 1847). They consist of "Discourses on Human Nature,' "Discourses on Human Life," "Discourses on the Nature of Religion," "Discourses on Commerce and Business, ""Miscellaneous and Occasional Discourses," "The Unitarian Belief," "Discourses and Reviews," including several articles which first appeared in the "Christian Examiner." His works have been reprinted in London, 1844, in an octavo volume of nearly 900 pages.-The application of religion to the whole sphere of human life is the characteristic of Dr. Dewey's writings, and the central purpose of his mind. For this work he is admirably fitted both by native endowment and the discipline of experience. His writings exhibit a philosophical tendency, much practical knowledge, wide and lively sympathies, and rare dramatic talent. As a pulpit orator, he enjoys a high reputation for earnestness, originality, and power of impres

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DE WITT. I. AS. E. co. of Texas, drained by the Guadalupe river; area, 898 sq. m.; pop. in 1858, 3,786, of whom 1,189 were slaves. It abounds in fine scenery, and has a hilly or rolling surface. The soil, particularly in the valley of the Guadalupe, is fertile. In 1850 it produced 547 bales of cotton, and 67,560 bushels of corn. Value of real estate in 1858, $545,000. The county was named in honor of De Witt, an empresario under the Mexican government of what was called De Witt's colony. Capital, Clinton. II. A central co. of Illinois, mostly level, comprising forests of valuable timber and fertile prairies, remarkably easy of cultivation;

area, 675 sq. m.; pop. in 1855, 18,508. In 1850 the productions were 704,600 bushels of corn, 22,401 of wheat, 45,737 of oats, 2,083 tons of hay, and 18,833 lbs. of wool. There were 6 churches. Bituminous coal is the chief mineral product. The county was named in honor of De Witt Clinton. Capital, Clinton.

DE WITT, JAN, a Dutch statesman, born in Dort, Sept. 1625, murdered at the Hague, Aug. 20,1672. From his father, who had been a member of the states of Holland, he inherited republican principles opposed to the power of the house of Orange, which had been regarded with suspicion from the time of Barneveldt. In 1652 he became grand pensionary of Holland, an office which gave him great influence in the federal assembly of the Seven United Provinces; and he immediately exerted himself to break up that combination of offices in the hands of the princes of Orange, which had made their power almost sovereign. The last stadtholder had died in 1650, and his son, afterward William III. of England, was an infant; and at this favorable time the party of De Witt succeeded in abolishing the office of stadtholder, and declaring the statesgeneral supreme. In 1654 he negotiated the peace of Westminster with Cromwell, by a secret article of which the members of the house of Orange were in future excluded from the highest offices of state. After the restoration of Charles II., England declared war against Holland; but though her arms were at first suecessful, the sagacity of De Witt restored the fortunes of his countrymen, and obliged her to sue for peace. The negotiations were hastened by the appearance of De Ruyter with a powerful fleet in the Thames, where he burned the English shipping in the Medway; and a treaty was concluded at Breda in July, 1667. When the aggrandizing policy of Louis XIV. began to aim at the possession of the Spanish Netherlands, De Witt became obnoxious to a strong party in the state, which sought to elevate William of Orange to the dignity of his ancestors. He hastened to form a triple alliance with Sweden and England, but violated the federal constitution by causing the treaty to be at once ratified by the states-general, instead of being first referred to the council of each province. Though the measure may have been justified by the emer gency, it was a principal cause of the hostility to De Witt. Louis XIV. succeeded in detaching England from the alliance, and in forming a counter alliance between England and France against Holland; and in 1672 the United Provinces were invaded by French armies, which advanced nearly to Amsterdam. The blame was thrown on the grand pensionary; and by the popular voice the young prince of Orange was called to command the Dutch forces by land and sea, and was nominated stadtholder. Cornelius, the brother of Jan De Witt, was suspected of having plotted against the life of the prince, and was imprisoned at the Hague. The grand pensionary resigned his office, went to visit his brother, and perished with him by the violence

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of a mob. His abilities and exemplary private character were applauded even by his political opponents. His principal political work, on the "True Interest and Political Maxims of the Republic of Holland," was translated into English by Dr. Campbell (London, 1746).

DEXTER, SAMUEL, an American statesman and jurist, born in Boston in 1761, died while on a journey at Athens, N. Y., in 1816. He was graduated at Harvard university in 1781, with the highest honors of his class, and received in 1813 the degree of LL.D. from the same university. Immediately after leaving college he began the study of law, and being admitted to the bar in 1784, after some years of practice in Lunenburg, in Chelmsford, in Billerica, and in Charlestown, he removed to Boston, and had his home there during the remainder of his life. He was repeatedly chosen to the legislature of Massachusetts, and in 1798 was elected senator of the United States. While senator he was appointed secretary of war by John Adams in 1800, and in the same year secretary of the treasury. He was afterward, at different times, offered foreign missions, but always refused them. About the year 1802 he withdrew from political life, and returned to his profession; and there he occupied a high, and in some respects the highest place. He was not regarded as a man of extensive professional learning, or as eloquent in the ordinary sense of that term; but he was well acquainted with the leading principles of law, and possessed the faculty of learning rapidly and well all that was needed in any particular case, by study in rem. While he seldom indulged in figures or ornaments of any kind, his powers of argument were almost irresistible. He was often spoken of as "the lawyer for desperate cases," because no case seemed desperate in his hands. As a politician he was in early life a decided federalist; and he never approved all the principles or doings of the republican party of that day. He argued against the validity of the embargo with all his strength, and always maintained the unconstitutionality of that measure. But, on the other hand, he differed from his party in reference to the war of 1812. While, however, he left his own party, he could not be said to have joined the other; and when they nominated him as the republican candidate for governor, in 1814, he immediately published an address to the electors of Massachusetts, in which he declared that he did not belong to the party which had nominated him, and differed radically from them. He was, how ever, retained as their candidate; and his competitor, Gen. Brooks, the candidate of the federalists, was elected by a majority of only 2,000 out of 47,000 votes. He was the first president of the first society formed in Massachusetts for the promotion of temperance.

DEXTRINE, also known as BRITISH GUM, a soluble variety of starch, obtained by boiling starch in water, or heating it to the temperature of 392°, or by the action upon it of diastase or acids. In the malting of grain it is pro

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duced with the forming of the sprout, the diastase and acetic acid first appearing, and then converting the starch of the grain into dextrine, from which it passes into sugar, and this into alcohol. When starch is boiled to produce this gum for stiffening linens, its change into sugar may be effected by continuing the boiling. No change in the chemical composition takes place in this process, but the alteration is probably in the arrangement of the particles among themselves. In both starch and dextrine the constituents are, carbon 12 atoms, and hydrogen and oxygen 10 atoms each. Grape sugar, into which they pass, differs from them only by taking another atom of hydrogen and oxygen, or, what is the same thing, one atom of water. Dextrine forms a mucilaginous solution with hot or cold water, from which it is precipitated by alcohol. It is prepared in France to considerable extent from potato starch, to be afterward fermented and converted into brandy. It is also used by the French pastry cooks and confectioners. In medicine it may serve the same uses as gum arabic, and in surgery it is applied to the preparation of bandages for fractures. For this purpose it is triturated with of its weight of camphorated spirit, till it acquires the consistency of honey. Water is then added, and the bandage is immersed in the mixture. As British or "artificial" gum, it is employed by the calico printers for thickening their colors. It is sold in the form of a brilliant white powder, as a mucilage, and in lumps like those of natural gums. Its smell and taste of potato oil distinguishes it from gum arabic, and it differs from natural gums in not forming mucic acid by the action of nitric acid, and in being convertible into grape sugar. The name is derived from its property of turning more than any other body the plane of polarization to the right hand side.

DEY, in Algiers, from 1600 to 1710, the commander of the armies of the state, subject to a pasha appointed by the Porte. In 1710 the dignity of pasha was united with that of dey, and the dey was the highest officer of Algiers from that time till the conquest of the country by the French in 1830.

DEYRA DOON, or DEHRA DOON, a fertile valley of British India, between the S. W. base of the lowest and outermost ridge of the Himalayas, and the N. E. slope of the Sewalik mountains, the former having an elevation of 7,000 or 8,000 feet, and the latter of about 3,000; lat. 30° and 30° 32′ N., long. 77° 43′ and 78° 24' E.; area, 673 sq. m.; length, 5 m.; breadth, from 15 to 20 m. It is bounded S. E. by the Ganges and N. by the Jumna, is drained by their tributaries, and with the hilly region called Jounsar Bawur forms a district under the lieutenant-governorship of the N. W. provinces. The productions are rice, maize, grain, cotton, sugar, opium, indigo, plantain, and hemp. Every English plant is said to thrive luxuriantly, and considerable success has attended the cultivation of tea. The climate during part of the year is

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