tany, a nat. order of herbaceous Exogens, of which the Drosera, or Suu-dew, is the type.

Drosom'eter (Gr. drosos dew, and metron), in natural philosophy, an instrument for measuring the quantity of dew which collects on the surface of a body exposed to open air during the night.

Drug (Fr. drogue), in pharmacy, any substance, vegetable, animal, or mineral, which is used in the composition or preparation of medicines; the general name of substances used in medicine, and compounded by apothecaries and physicians.

Drum (Dutch trom), in architecture, the upright part of a cupola, either above or below a dome; also the solid part or base of the Corinthian and Composite columns. In mechanics, a sort of short cylinder revolving on an axis, generally for the purpose of turning several small wheels, by means of straps passing round its periphery. In anatomy, the drum of the ear is the tympanum, or barrel of the ear; the hollow part of the ear, behind the membrane of the tympanum. The latter is a tense membrane, which closes the external passage of the ear, and receives the vibrations of the air.

Drummond Light, (from the inventor, Lieut. Drummond), a very intense light, produced by throwing a stream of oxygen gas and another of hydrogen gas, brought into union, in an ignited state upon a ball of lime. Drupa'cee (Lat. drupa the seed of the olive), in botany, a nat. order of rosal exogenous plants, with polypetalous regular flowers, and a drupaceous fruit. (See Drupe.)

Drupe (Lat. drupa), in botany, a superior, indehiscent, one-celled fruit, consisting of a succulent rind, and containing a hard stone in the centre, as the cherry, plum, or peach.-Drupaceous, bearing fruit in the shape of a drupe. Drying Oil, in the arts, a term applied to linseed and other oils which have been heated with oxide of lead, and form the basis of many useful paints and varnishes.

Dry-pile, in electricity, a galvanic apparatus, in which the plates are separated by layers of farinaceous paste mixed with common salt.

Dry-rot, a disease which attacks wood, and destroys the cohesion of its parts, usually attributed to the attacks of fungi, especially the Polyporus destructor. Various scientific processes have been carried into operation for preserving timber from dry-rot, the most prominent of which is that of

kyanizing (so called from Kyan, the discoverer), by the application of corrosive sublimate, the perchloride of mercury. The timber is immersed in the solution thus prepared, when the primary element of fermentation is neutralized, and the fibre of the wood rendered imperishable.

Duct (Lat. ductus a canal or aqueduct), in anatomy and botany, a term of very extensive application, as signifying a tube or vessel for conveying a fluid, especially the arterial or venous blood, or the secretions of the animal system, or the juices of plants, &c. In the anatomical structure of man the following are the principal ducts:-D. arteriosus, a tube which, in the fœtus, joins the pulmonary artery with the aorta; -Ducts of Belini, the orifices of the uriniferous canals of the kidneys;-D.communis choledochus, the bile duct, formed by the junction of the cystic and hepatic; D. cysticus, the duct which leads from the neck of the gallbladder to join the hepatic;-D. hepaticus, the duct which results from the conjunction of the proper ducts of the liver; -D. incisorius, a continuation of the foramen incisivum between the palatine processes into the nose;--D. ejaculatorius, a duct within the prostate gland, opening into the urethra;-D. nasal, or lacrymal, a duct continued from the lachrymal sac, and opening into the nose;-D. pancreaticus, the pancreatic duct, which joins the gall duct at its entrance into the duodenum;-D. ef Steno, the excretory duct of the parotid gland; -D. thoracicus, the great trunk formed by the junction of the absorbent vessels;-D. venosus, a branch which in the fœtus joins the left vena hepatica with the umbilical vein.

Ductilim'eter (Gr.), an instrument for comparing the ductility of lead, tin, and other metals. Dudley Limestone, in geology, a calcareous deposit belonging to the silurian system, occurring near Dudley, equivalent to the Wenlock limestone. It contains about one hundred and twenty species of fossil shells, fourteen crustaceans, and one annelid.Penny Cyclop.

Dugong, in zoology, a large cetaceous herbivorous animal which inhabits the Indian Ocean, and is frequently confounded with the Manatus. It is the Halicore dugong of Cuvier, or the Sea-cow. Dulcama'ra (Lat.), the Bitter-sweet, or Solanum dulcamara of botanists.. The roots and stalks, on being

chewed, first produce a sensation of bitterness, which is soon succeeded by a degree of sweetness-hence the

name.

Dul'cimer (Lat. dulcis sweet), in music, an instrument the strings of which are made of brass, and struck with little sticks, which produce an agreeable and lively kind of music.

Dune (Sax. a low hill), in geology, a bank of drifted and movable sand, frequently met with on the sea-coast. Duodecimals (Lat. duodecim twelve), in the science of arithmetic, a method of ascertaining the number of square feet and square inches in a rectangular whose sides are given in feet and inches, called cross multiplication. Duodenum (Lat. twelve inches), in anatomy, the first division of the small intestine, immediately following the stomach, in man twelve fingerbreadths in length.-Duodenary, increasing in a twelve-fold proportion. Du'picho (Sp.), an elastic bitumen, obtained in Brazil fron the roots of the Siphonia elastica.

Du'plicable (Lat. duplex double), in geometry, Duplicate ratio is the ratio of the squares of two quantities, or the square of their ratio.-Duplication of the cube is the finding the side of a cube of twice the solid contents of a given cube.

Duplicature, in anatomy, is a term applied to the reflections of a membrane upon itself.

Dura Mater (Lat. hard mother), in anatomy, the exterior of the three membranes which envelop the encephalon, and which lines the vertebral canal and the cranial cavity.

Dura'men (Lat. stability), in botany, the central layers or heart-wood of exogenous trees. It is merely the sap-wood, solidified by the infusion of certain secretions into the interior of the cells and tubes of which such wood is composed.

Dutch, an epithet of frequent occurrence in botany, and the arts; as, Dutch elm, the Ulma tuberosa of botanical science;-Dutch myrtle, the plant Myrica gale of Linnæus; order Myricaceæ;-Dutch pink, a colour obtained from the plant Reseda luteola; order Resedaceæ;-Dutch rush, the Equisetum hymenale of botanists;Dutch drops, the balsam of turpentine; -Dutchman's laudanum, the name given to a tincture of the flowers of Passiflora rubra, or red passion-flower, formed by infusion of wine or spirits. Dutch gold, in metallurgy, an alloy of zinc and copper. In the arts, we have Dutch clinkers, long, narrow bricks im

ported from Holland; and Dutch tiles, ornamental tiles glazed and painted.

Dyke, in geology and mining, an intersection in the strata of rocks.

Dynam'eter (Gr. a power measurer), in optics, an instrument for determining the magnifying power of telescopes. Dynamics, the science of moving powers, or of matter in motion, or of the motion of bodies that mutually act upon one another.

Dys (Gr. bad or ill), is a prefix to numerous terms connected with pathology, expressive of an irregular or diseased state of the body; as, Dysarthritis, irregular gout;-Dysarthresis, faulty articulation of a joint; -Dyscataposis, difficulty of swallowing;-Dyscholia, a morbid condition or depravation of bile;-Dyschræa, a morbid alteration or change of the colour of the skin; - Dyschylia, a morbid condition of the chyle;-Dyschymia, a morbid condition of the chyme;-Dyscinesia, difficulty of motion from rheumatism or paralysis; - Dyscælia, habitual suffering in the bowels;Dyscopria, a bad condition of the fæces;-Dyscrasy, a bad admixture or depraved condition of the animal Auids; -Dysdacria, a morbid condition of the tears;-Dyseccrisis, deficient or defective excretion; Dysecoia, difficulty of hearing;Dysgenesia, lesion in the organs of generation;-Dysgeusia, depravation of the sense of taste;-Dyshaphia, lesion of the sense of touch; Dyshæmia, depraved condition of the blood;-Dyshydria, a morbid state of the perspiration;-Dyslalia, difficult articulation of words;-Dysmenia, difficult or retarded menstruation;-Dysodia, a disease characterized by fetid emanations; Dysopsy, dimness of sight; -Dysorexy, want of appetite;-Dysphagy, difficulty of digestion; -Dysphony, difficulty in speaking; -Dyspnea, difficulty of breathing;-Dysthetic, relating to a morbid state of the blood-vessels ;Dysthymia, depression of spirits;Dystonia, a morbid alteration of the tone of any structure or organ of the body;-Dysury, difficulty of voiding urine.

Dysæsthe'sia (Gr. dys), in pathology, impaired feeling, or a tendency to insensibility.

Dys'clasite (Gr. dys, and klasis imperfect fracture), a mineral which occurs in white masses, exhibiting considerable transparency, and having an opalescent appearance. It consists of potash, soda, silica, lime, water,

oxide of iron, and oxide of manganese: sp. gr. 2.362.

Dys'entery (Gr. dys, and enteron an intestine), in pathology, a painful disease, often epidemic, attended with fever, and with frequent mucous or bloody evacuations.

Dyspepsia, Dyspep'sy (Gr. indigestion), in pathology, a state of the stomach in which its functions are disordered.

Eagle Stone, in mineralogy, a variety of clay ironstone (ætites); so called from an old opinion that it had dropped from some eagle's nest. Eagle Wood, in botany, a highly fragrant Oriental wood.

Earth (Sax. eorth; Germ. erde), the name of the world or planet which we inhabit; the terraqueous globe; a region. In chemistry, any species of earthy matter; a body or substance composed of oxygen and a base of metallic oxide. By ancient philosophers earth was termed an element; and, in popular language, we still hear of the four elements-fire, air, earth, and water. In astronomy, the earth, as a planet, is the third in order from the sun, round which it performs a revolution once a year, or in 365 days, 6 hours, 9 minutes, 6.9 seconds, revolving at the same time on its axis every twenty-four hours. Its equatorial diameter is nearly 7,925 miles, and its polar diameter about 7,856. Its mean distance from the sun is about 95,000,000 miles.

Earth Fall, in geology, the name given to a natural phenomenon, from which a portion of the earth's surface is elevated by some subterraneous force, then cleft asunder, and the earth suddenly depressed, when the space becomes occupied with water.

Earth Flax, in mineralogy, a flexible, fibrous, and elastic mineral substance, consisting of long parallel filaments.

Earth Nut, in botany, a term applied to various underground productions, as the Conopodium flexuosum, the round tubes of Cyprus rotundus, the subterranean pods of Arachis hypogea, &c.

Earthquake, in cosmography, a shaking or violent agitation of the earth, and one of the most formidable phenomena of nature, sometimes producing immense rents that engulf large tracts of country, villages, and towns. Mounts Ætna and

-Dyspeptic, a person afflicted with bad digestion.

Dystom'ic (Gr. dys, and tome a section), in mineralogy, having an imperfect fracture or cleavage.

Dytis'cide (Gr. dytiskos diving), in entomology, a tribe of aquatic coleopterous insects, of which the genus Dytiscus is the type; the tribe comprehends eighteen genera.

Vesuvius are the most formidable in Europe, and their destructiveness often terrible.

Earthy Fracture applies to a mineral when the fracture is rough, with minute elevations and depressions. Ear Trumpet, in acoustics, an instrument or trumpet used to aid defective hearing by collecting and concentrating the waves of sound, so that they may strike upon the tympanum with increased force.

Easel (Germ. esel), in painting, the frame on which the artist rests his picture while at work.-Easel-pieces are the smaller pieces, either portraits or landscapes, which painted on the easel, as distinguished from those which are drawn on walls, ceilings, &c.

are

Eau de Cologne (Fr. Cologne water, in cosmetics and perfumery, a kind of liquid perfume originally prepared at Cologne. As a substitute for the original article, Di. Ure gives the following:-Alcohol, I pint; of the oils of bergamot, orange-peel, and rosemary, each drachm; bruised cardamom seeds, I drachm; orangeflower water, I pint; distil I pint from a water-bath. - In science, there are a variety of preparations which have received French names;as, Eau de Javelle, bleaching liquid, or the aqua alkalina oxymuriatica; -Eau de Luce, a compound of the essential oil of amber and the volatile alkali;-Eau de Rabel, one part of sulphuric acid to three of rectified spirit of wine.

Ebena'ceæ (Heb. ebn, and Gr. ebenos), in botany, a nat. order of exogenous trees and shrubs, the wood of which is as heavy and hard as ebony; so called from Diospyros ebenum,

the True Ebony. Ebony. (See Ebenacea.) Ebur'na (Lat. ebur ivory), in malacology, a genus of spiral univalve Mollusca, in which the shell is smooth, the body whorl ventricose, and the intestines grooved. It belongs to the

sub-family Eburninæ, of the family Turbinellidæ.

Eburna'tion (Lat.), in pathology, the excessive deposition of compact osseous matter which sometimes takes place in the diseased state of bones.

Eburnifica'tion (Lat. ebur), the conversion of substances in objects which have the appearance or characters of ivory, arising from an inordinate accumulation of the phosphate of lime. Eccentric (Lat. deviating from a centre), in geometry, a term applied to a circle not having the same centre with another circle, and consequently not parallel, in opposition to concentric, having a common centre. Eccentricity, in astronomy, is the distance of the centre of a planet's orbit from the centre of the

sun.

Ecchymo'sis (Gr. ekcheo to pour out), extravasation of blood, causing livid spots or blotches, generally the result of blows or bruises.

Eccoprot'is (Gr. ex, and kopron excrement), having the quality of promoting alvine discharges; a medicine which purges gently; a mild cathartic,

Eccre'sis (Gr.), in pathology, the excretion of perspirable matter from the lungs and fæces.

Eccrinology (Gr. ekkrino to separate from, and logos a discourse), in anatomy and physiology, a treatise on the secretions of the animal body.

Ecdysis (Gr. expiation), in natural history, a casting off of the old skin, unaccompanied by any variation of form, or by the development of any new members.

Ech'elon (Fr. by steps), in military science, the position of an army in the form of steps, or with one division more advanced than another.

Echid'na (Gr. echinos a hedgehog), in zoology, a genus of spring quadrupeds, the Porcupine Ant-eaters, natives of Australia; order Edentata. Echim'ys (Gr. echinos, and mys a rat), in zoology, the Spring rats, which have strong spines mixed with the hair on the back; order Rodentia. Echin'idæ (Gr. echinos), in zoology, a family of radiated animals, comprehending those known under the name of Sea-urchins, Sea-eggs, &c., of which there are various genera and species.

Echinodermata, or Echinoderms (Gr. echinos, and derma skin), in zoology, a class of Radiata which are armed with movable or articulated spines. The class is divided into two orders: the first constitutes the Pedicellata,

and embraces the Star-fishes, the Sea-urchins, the Holothuriæ, &c.; the second order, Apoda, are without the vesicular feet of the other, and are allied to the Holothuriæ.

Echinus (Gr. a hedgehog or seaurchin), a genus of the Echinodermata, which have the body invested by a shell composed of angular pieces that join each other exactly, and are perforated by innumerable holes, for the transmission of the membranous feet. - Echinus forms a prefix to numerous compound words connected with botany and zoology, signifying spiny, lamellar, or prickly. - In architecture, a term equivalent to the ovalo or quarter-round; but it is only properly so named when carved with eggs. In botany, Echinus is applied to a genus of plants, of the order Euphorbiaceæ.

Echo (Gr. sound), in acoustics, the repercussion of sound. -Echometry is the art of measuring the duration of sounds. Echometer is an instrument for measuring the duration of sounds; also the art of constructing vaults to produce echoes.

Eclamp'sy (Gr. vivid light), in pathology, a flashing of light symptomatic of epilepsy; the epilepsy of a child. Eclipsa'reon (Lat. eclipsis), in astronomy, an instrument for showing the phenomena of eclipses.

Eclipse (Lat.), obscuration of the light of a heavenly body by the intervention of another body. An eclipse of the sun is caused by the intervention of the moon, which totally or partially hides the sun's disc; an eclipse of the moon is occasioned by the shadow of the earth, which falls on it, and obscures it in whole or in part. Ecliptic (Lat.), in astronomy, an imaginary great circle of the heavens, in which the sun appears to perform his annual revolution.-Ecliptic limits are the greatest distances at which the moon can be from her nodes, in order that an eclipse of the sun or moon may happen. Econom'ics, or Econ'omy (Lat.economia, from Gr.oikos a dwelling, and nomos law), the science of household affairs, or of domestic management. - In physiology, the laws which govern the organization of plants and animals; the order and connection of the phenomena exhibited by organized bodies, as, "animal economy," "vegetable economy," &c.-Political economy is the science which investigates the circumstances most favourable to the production of national wealth, and the laws which determine its distribution among the dif

K

ferent ranks and orders of society.Maude.

Ecos'sines, a sort of grey limestone. Ecos'tate, in botany, having no nerves on the leaf.

Ecoutes (Fr.), in fortification, small galleries made at equal distances in front of the glacis.

Ecplex'is (Gr.), in pathology, a kind of stupor arising from a blow, or from sudden consternation.

Ec'ptome (Gr. a fall or dislocation), in pathology, a term synonymous with luxation; also the elimination of gangrenous parts, expulsion of the placenta, prolapsus of the womb, and descent of the intestine or omentum in hernia.

Ecpyreu'ma (Gr.), in surgery, a state of perfect suppuration, or suppuration itself.

Ecsarco'ma (Gr.), in surgery, a fleshy

excrescence or sarcoma.

Ecstasy (Gr. ekstasis), in pathology, a species of catalepsy, when the patient remembers the ideas he had during the paroxysms when the fit is over.Ecstatic is an epithet applied to a state of ecstasy

Ecthy'ma (Gr.), in pathology, a cutaneous eruption, characterized by pimples or large round pustules upon an indurated and highly-inflamed base.-Dunglison.

Ecto, a Greek prefix to compound words, signifying outside. Ectopia (Gr.), in pathology, the morbid change of the situation of a part. Ectrim'ma (Gr.), in pathology, ulceration of the skin in those parts of the body in contact with the blood. Ectropium (Gr. ektrepo), an unnatural eversion of the eyelids. Ectrot'ic (Gr.), producing abortion. Ectylot'ic (Gr.), in medicine, having a tendency to remove callosities or indurations of the skin.

Eczema (Gr. a boiling out), in pathology, an eruption of the skin, consisting of small vesicles, sometimes mistaken for the itch.

Eden'tates (Lat. without teeth), in zoology, an extensive order of the class Mammalia, comprehending those unguicolated quadrupeds which have no front teeth. They are divided into three tribes, the Tardigrada, the ordinary Edentata, and the Monotremata: the Sloths, Ant-eaters, and the Ornithorhynchus are examples.Edentates is also a name given to a sub-order of the Cetacea, including the two genera Balæna and Balænoptera, the Toothless or Whalebone whales.

Ed'ingtonite, the name of a mineral found in the Kilpatrick hills of Dum

bartonshire a variety of felspar; so named in honour of Mr. T. Edington, of Glasgow. It occurs in small greyish-white crystals, and consists of silica, alumina, lime, water, and alkali: sp. gr. 2.7-2.75. Educ'tion Pipe, the pipe from the exhaust passage of the cylinder to the condenser.

Edulcorant (Lat. making sweet), in pharmacy, a medicine which purifies the fluids of the system by depriving them of their acidities or other disagreeable qualities. - Edulcoration, in chemistry, is the science of rendering substances more mild by freeing them from salts, acids, or other impurities.

Effection (Lat.), in geometry, an effect of a general proposition. The term is also used in reference to problems which, when they are deducible from or founded upon some general propositions, are called the geometrical effections of them. Efflorescence (Lat. production of flowers), the pulverization of minerals or crystals on exposure to the air.-In chemistry, the formation of a mealy powder on the surface of certain bodies, occasioned either by decomposition or drying, often the result of the formation of minute spicular crystals. In pathology, an eruption or redness of the skin.

Effluvium, pl. Efflu'via (Lat. effluo to flow out), in physics, the minute and often invisible particles which exude from terrestrial or putrefying bodies, as the odour or smell of plants, or the noxious exhalations from diseased bodies, or putrefying animal or vegetable substances.

Effodien'tia (Lat. effodio to dig), in zoology, a family of edentate animals, so called from their digging habits. Effracture (Lat. a breaking open), in surgery, a fracture, with depression of the cranial bones. Effu'sion (Lat. a pouring out), in pathology, the pouring out or extravasation of a fluid into a visceral cavity, or into the areolæ of the cellular tissue.

Eft, an old Saxon word, applied, in natural history, to the different species of batrachian lizards found in Great Britain; as, Lacerta palustris, or Warty Eft; L. aquaticus, or Water Eft; and L. vulgaris, or Brown Eft.

Eg'eran, in mineralogy, a variety of garnet found at Egeran, in Bohemia. Ege'ria, in astronomy, the name of one of the newly-discovered planets, first observed by De Gasparin in 1850. Its mean distance from the sun is