composed and wasted away, the harder calcareous corals stand out in relief, their erect stems sending out branches precisely as when they were living." Fine specimens of various species of coralline are obtained at this locality, and new are continually brought out by the action of the river upon the rocks, and may be collected at low stages of the water. But only 6 species found in this country in the whole Devonian series are identified with the 46 British Devonian corals described in 1853 by MilneEdwards and Jules Haime. The formation abounds with the greatest variety of fossil molluscous animals and crinoïdea, the genera of which, and some of the species, are identified with the Devonian fossils of Europe.

DEVONPORT, a parliamentary and municipal borough and naval arsenal in Devonshire, England, built on the Tamar, where that river makes a bold sweep toward the E., and widens into the fine estuary called the Hamoaze, just before its entrance into Plymouth sound, 218 m. S. W. of London, and 14 m. W. of Plymouth; pop. in 1851, 50,159. Its harbor, one of several remarkable natural havens opening into the sound, is 4 m. long, m. wide, from 15 to 20 fathoms deep, perfectly safe, and capable of sheltering the whole British navy at once; but it is difficult of entrance. The town is bounded S. and W. by the river, and E. by a creek which separates it from Stonehouse, contiguous to Plymouth. With these two places it is so closely connected, that the 3 may almost be said to form a single city, and it was not until 1824 that Devonport acquired separate municipal privileges, and changed its old name of Plymouth Dock for that which it now bears. A fluted column of the Doric order, approached by a flight of 140 steps, was erected in commemoration of the event. There are 6 churches, 2 chapels of ease, 17 places of worship for dissenters, 17 principal schools, including a naval and military free school, and an institution in which 100 girls are educated and clothed, a public library, orphan asylums, and a theatre. Water is brought from Dartmoor, in a winding conduit nearly 30 m. long. With the exception of some breweries and soap-boiling houses, Devonport contains no factories of importance. The density of the population is greater than that of any other place in England, there being no fewer than 26,000 people living on of a sq. m., with an average of 10 individuals to each house, whereas the proportion in Liverpool is but 7, and in Manchester but 6. Devonport is fortified on the N., S., and E. by a wall, a breastwork, and a deep ditch, while the entrance from the sea is commanded by several heavy batteries. These works were begun by George II. The chief feature of the town is the dock yard, commenced by William III., who built the basin and 2 docks. It has a river front of 3,500 feet, and a maximum breadth of 1,600 feet, the area enclosed being about 96 acres. There are 2 dry docks, one double and one single dock for ships of the line, one graving dock, 5 building slips,

and vast docks or basins at Point Keyham for fitting and repairing war steamers, commenced in 1844, and embracing an area of 72 acres. The immense roofs over the docks, consisting of single arches, without buttresses or pillars, are wonders of architectural skill. A canal 70 feet wide runs nearly through the yard, communicating with the boat pond. On the S. side are an outer mast pond and mast house, timber berths, saw pits, a smithery with 48 forges, an inner mast house and mast locks, a building in which planks are steamed and curved, a hemp magazine, and a rope factory, consisting of 2 stone and iron buildings, each 1,200 feet long and 3 stories high. The number of men employed in the whole establishment sometimes amounts to 3,000.

DEVONSHIRE, a maritime co. of England, second in size only to that of York, its greatest extent from N. to S. being 71 m., from E. to W. 72 m.; area, 2,585 sq. m.; pop. in 1841, 532,959; in 1851, 567,098. It is bounded on the N. and N. W. by the Bristol channel; on the W. by the river Tamar and Marsland-water, which separate it from Cornwall; on the S. and S. E. by the British channel; and on the E. and N. E. by the counties of Dorset and Somerset. The rivers of Devon are the Taw, Torridge, Tamar, Dart, Teign, Exe, Tavy, Plym, Yealm, Erme, Avon, Otter, Sid, Axe, and Lyn. Trout are found in great plenty in most of these; the Tamar and Tavy furnish valuable salmon fisheries; the Exe salmon are thought the best in England; and at the mouths of the various streams are found plaice, kingfish, torpedoes, and cuttle fish. The county has 3 canals: the Great Western, 35 m. long, connecting the S. E. coast with the Bristol channel, the Tamar canal, and the Tavistock canal. The Bristol and Exeter and the South of Devon railways also traverse the county. Devonshire is a rich mineral country, furnishing copper and lead in considerable abundance, with smaller quantities of tin, iron, bismuth, and many other mineral substances, beside coal and marble. It is supposed that the inhabitants worked the iron and other metallic mines before the arrival of the Romans. The tin mines were anciently numerous and valuable, but are now nearly abandoned, those of Cornwall being so much richer. There are several varieties of lead ore, one of which is very rich in silver. Cobalt, antimony, and native silver have been found in considerable quantities. The marbles quarried from the limestone rocks on the E. and S. coasts are of fine colors and beautifully veined, hard, susceptible of a good polish, and much resemble Italian marble. Fine pipe clay, potters' clay, which is exported to other countries, and slate of excellent quality, are found abundantly. The agriculture of Devonshire is in a flourishing condition. Of the 1,654,400 acres of land, about 1,200,000 are under cultivation. The S. and S. E. parts of the county contain extensive wastes, the surfaces of which are covered with immense rocks and detached masses of granite. To the N.

and N. W. are found large tracts of swampy ground and many peat bogs of great depth. The vale of Exeter, containing about 200 sq. m., consists of some very fine land, and is one of the richest valleys in the kingdom. The district called South Hams, extending from Torbay round to Plymouth, is known as the garden of Devonshire, and is finely diversified and very productive. In the vale of Exeter are raised wheat, beans, barley, peas, and flax. The pasture lands are chiefly devoted to dairy uses, though some attention is paid to raising sheep and cattle. In West Devon of the enclosed lands are alternated with corn and various kinds of grasses, such as red clover, rye grass, white clover, and trefoil. Irrigation is commonly practised, as also peat burning; orchards and apple trees in hedges are common, and oats,turnips, and potatoes are raised in many districts. The yield of wheat is from 16 to 25 bushels per acre; of barley, from 35 to 50. Devonshire is celebrated for the quantity and quality of its cider. Butter is made in considerable quantities, the average produce of cows being a pound per day. Devonshire cows are noted throughout England, and have been imported into the United States. The purest breeds are distinguished by a high red color, without white spots; they are fine in the bone and clean in the neck, thin skinned, and silky in handling; have horns of medium length bent upward, a small tail set on very high, a light dun ring around the eye, and are noted for feeding at an early age. A good Devonshire cow will yield, for the first 20 weeks after calving, about 3 gallons of milk per day. The cows weigh from 420 to 460 lbs., the oxen from 700 to 820 lbs. The North Devon cattle, another variety, are in great demand for the firm grain of their meat, and the superior qualities of the oxen for work. The native horses are small, but hardy, and much accustomed to the pack saddle. The breed of sheep is various, but mostly of the Dorsetshire kind. Landed property in Devonshire seems to be more regularly divided than in most other counties, there being few very large freehoids; the farms are held generally by leases of 3 lives, or for 99 years. As the lives drop, new ones are put in, on payment of an adequate sum. Farms average from 100 to 200 acres. Devonshire formerly manufactured thin woollen goods, and carried on a considerable woollen trade with Spain, but this branch of industry has greatly declined; the spinning and weaving of a species of serge, known as long ells, being the only remains of it. The spinning of linen yarn, and manufacture of linen goods, have superseded the former industry; also, in and about Tiverton, great quanti ties of lace and lace net are made, which find a market on the continent of Europe. Ship-building is another branch of labor giving employment to numbers of men. The chief ship yard is the royal dock yard at Devonport. The county contains 33 hundreds, 465 parishes, and 36 market towns. The annual value of real property as

sessed to property tax, 1850-'51, was £2,736,361. The county town is Exeter, where the assizes are held. The county is in the episcopal see of Exeter, and is included in the western circuit. It returns in all 22 members to parliament, viz.: 4 for the county (2 for the northern and 2 for the southern division), 2 for each of the towns of Barnstaple, Tiverton, Exeter, Devonport, Honiton, Plymouth, Tavistock, and Totness, and 1 each for Ashburton and Dartmouth. It has 1,614 day schools, with 64,266 scholars, and 772 Sunday schools, with 58,408 scholars; 1,297 places of worship, of which 549 belong to the established church. The county gives the title of duke to the Cavendish, and of earl to the Courtenay family. There are ancient ruins in various parts of the county, among which are several abbeys, and numerous old British cairns. The chief noblemen's and gentlemen's seats are Castle hill, seat of Earl Fortescue; Stover lodge, that of the duke of Somerset ; Endsleigh, of the duke of Bedford; Saltram, of the earl of Morley; Mount Edgecumbe, of the earl of Mount Edgecumbe; Bagtor manor, of Lord Cranstoun; Exeter palace, of the bishop of Exeter; Bicton, of the late Lord Rolle; Haldon house, of Sir L. Palk, bart.; and Escot, of Sir J. Kennaway, bart.

DEVRIENT, the name of a distinguished family of German actors, of whom the most eminent are: I. LUDWIG, born in Berlin, Dec. 15, 1784, died Dec. 30, 1832. His father, a silk mercer, intended him for a mercantile life, but in obedience to his instincts he forsook the paternal mansion at the age of 18, joined a company of strolling actors, and made his first appearance upon the stage in Schiller's "Bride of Messina." He afterward travelled with the same company through Saxony, and in 1806 accepted an engagement at the court theatre of Dessau, from which he was tempted to retire on the promise of his father to pay his debts if he would renounce the stage. Devrient, however, rejected the offer. Soon after the demands of his creditors compelled him to take refuge in Breslau, where he acted with great success for several years. At the suggestion of the actor Iffland, who at the close of his career recognized in Devrient a fit successor to himself, he was induced to go to Berlin, where in 1815 he appeared for the first time as Franz Moor, in Schiller's "Robbers." From that time until his death he stood at the head of his profession in Germany, and was in the highest degree popular with Berlin audiences. A fatal passion for spirituous liquors, which he had indulged for many years, brought him to a premature grave. Devrient was not less esteemed for his amiable and almost childlike character than for his histrionic powers. His eminence as an actor was the offspring of his natural genius, rather than the result of study or reflection. He was equally great in comedy and tragedy. He was married at the outset of his career, but left no children. II. KARL AUGUST, nephew of the preceding, born in Berlin, Aug. 5, 1798. He served in a regiment of hussars, in the campaign

of 1815 against France, and was present at the battle of Waterloo; was afterward engaged in mercantile pursuits, and in 1819 made his début on the stage at Brunswick. In 1823 he was married to the celebrated singer, Wilhelmine Schroeder, from whom he was divorced in 1828. He has acted in all parts of Germany, but for many years past has been established at Hanover. He was long celebrated for his spirited personation of leading parts in genteel comedy. III. PHILIPP EDUARD, brother of the preceding, born in Berlin, Aug. 11, 1801. He commenced his artistic career as a bariton singer, but afterward appeared almost exclusively in the spoken drama. He has less natural genius than any of his family, but is a careful and cultivated actor, a successful writer of dramas, and an authority on all that pertains to the profession. His chief works were published in 6 vols., in Leipsic, in 1846-'9, under the title of Dramatische und dramaturgische Schriften, and include several plays, miscellaneous publications relating to the stage, and a history of the drama in Germany. IV. GUSTAV EMIL, brother of the preceding, born in Berlin, Sept. 4, 1803. Like his two brothers and his uncle, he was intended for the mercantile profession; but an irresistible inclination led him in 1821 to the theatre, where he soon rose to great eminence. He is well known on almost every stage in Germany, and has assumed with success many of the parts, both in tragedy and comedy, with which his uncle Ludwig's name is identified. His wife, Dorothea Boehler, from whom he was divorced in 1842, was an excellent comic actress, and ably seconded her husband for many years. On Nov. 11, 1857, the 98th anniversary of Schiller's birthday, 3 members of the Devrient family, Gustav Emil, Karl August, and Karl's son, appeared together at Hanover, in the play of "Don Carlos." V. WILHELMINE Schroeder DevRIENT, a wellknown singer on the German stage, born in Hamburg, Oct. 6, 1805. From her mother, the celebrated actress Sophie Schroeder, she inherited considerable dramatic talent, and in 1820, having from the age of 5 upward distinguished herself in children's parts, and in the corps de ballet, she appeared in Vienna as Aricie in Schiller's translation of the Phedre of Racine. She soon after devoted herself to the study of music, and in 1821 made her début as Pamina in Mozart's Zauberflote. The beauty of her voice, her artistic skill and dramatic powers, soon placed her in the first rank of German prime donne, and for many years she had no superior on the German stage in such parts as Donna Anna in Don Giovanni, Leonora in Fidelio, the Vestale in Spontini's opera of that name, the Euryanthe of Von Weber, and others of a similar character. She has also sung in Paris and London, but her chief laurels have been gained in Germany. She was married in 1823 to Karl August Devrient, was divorced from him in 1828, and in 1850 contracted a second matrimonial engagement with a Livonian nobleman, named Von Bock. DEW, the humidity of the air deposited on

surfaces with which it comes in contact. The atmosphere always contains within it more or less aqueous vapor in an invisible form. The vapor appears to be dissolved in it, as salt is held dissolved in clear sea water; and as the capacity of a fluid to hold salts in solution depends commonly on its temperature, so does that of the air to retain vapor. If the temperature be depressed, the vapor begins to appear. When a body of warm air strikes the summit of a cold mountain, the moisture is precipitated in the form of rain. Partially cooled, it takes the form of mist or fog, and floats in a dense cloud in the low places where the soil is warmer than the air. A current of warm air dissolves the vapor, and the fog "lifts." Dew is the vapor of the air, extracted by the greater chilliness of the surfaces upon which the moisture is deposited. It may be made to separate from the apparently dry air of a warm room, by placing in it a pitcher of cold water. The air in contact with the pitcher sheds its moisture, which collects in minute drops, and more is added from adjoining strata of air, so long as the temperature of the pitcher is kept sufficiently below that of the room. The degree of temperature to which the air must be reduced for it to begin to deposit its moisture, is called the dew point. It varies with the greater or less quantity of moisture which the atmosphere happens to contain for its actual temperature. If it has just been deprived of a considerable proportion, and has acquired a higher temperature, it must be reduced to as great a degree of cold as before to part with any more moisture; but if already saturated with as much moisture as it can contain at its temperature, any chilliness being induced will cause its precipitation to commence. Dew is not therefore, as it has been generally described by poets, a shower "which falls like gentle rain from heaven." Almost universally its nature has been misconceived. Horace speaks of rores pluvii; Virgil says: rorantia vidimus astra; and Pliny: cum ros cecidisset; and our common form of expression at this day speaks of the dew drops. Aristotle alone appears to have conceived its true nature, when he describes it as the moisture separated from the cold air. Mysteriously appearing upon the blades of grass, and refreshing the vegetation in climates where rain rarely if ever falls, and gathering upon the herbage in sparkling beads, while it avoided the barren and rocky surface, the simple peasant might well look upon it as a special blessing sent like manna direct from heaven, and possessed of wonderful virtues, far transcending those of other crystal waters, however pure. Hence it came to be prescribed for restoring to the features the fresh charms of youth, and by the alchemists to be used in their processes as a solvent of subtle and mysterious powers. And when at the close of life the ancient patriarch confers his blessing in the words: "God give thee of the dew of heaven," the simple dew drop seems to typify all heaven's choicest gifts. The phenomena attending the

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 ætheriscope, 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 9o, 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

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 before 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 affection, he relinquished the practice of his profession, 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 Cuba, 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.