Marc (Fr.), the refuse or cake 'after expressing the oil or juice from fruits or seeds, as of apples, olives, &c., mostly used for manure.

Marcasite, in mineralogy, a variety of iron pyrites; a term applied to a substance having metallic particles in it, called by the Cornish miners mundic.

Marceline (from St. Marcel, in Piedmont), a mineral of a greenish-black colour and vitreous lustre, consisting of silica, oxide of manganese, oxide of iron, and alumina.

Marcgravia'cese (in honour of Marcgrave, the German naturalist), in botany, a nat. order of exogenous plants, of which the Marcgravia is the type.

Marchantia'cese (in honour of Marchant, of Paris), a nat. order of plants, of which the Marchantia, or Liverwort, is the type.

Mar'garamide, a substance obtained from ammonial soap.

Margarate, a salt formed of margaric acid and a base.

Margaric, Margaritic, in chemistry, noting a fatty acid prepared from hog's lard and potash.

Margarite (Gr. a pearl), in mineralogy, pearl mica, a thinly laminated mineral of a greyish, reddish, or yellowish-white colour: sp. gr. 3.0; H = 3.5-4.5.

Margaron, in chemistry, a solid fatty matter, obtained by distilling margaric acid with excess of lime.

Marginate, Marginated (Lat. marginatus), in conchology, denoting a prominent margin or border.-In entomology, an epithet used when the sharp edge is marginated on the outside, and surrounds the surface with a narrow border.

Marine Chair, a machine contrived for enabling the spectator to view the satellites of Jupiter in the open sea. -Marine engine, a steam-engine for use in ships at sea.

Mark (Sp. marco), a term applied to a money of account in Hamburg, Lubeck, Denmark, and Norway; also to a weight, used chiefly for gold and silver, in different parts of the Continent, varying from about 3,500 to 3,700 troy grains.

Marking Ink, an indelible ink for marking linen, usually made by dissolving a drachm of fused nitrate of silver in half an ounce of distilled water.

Marl, in mineralogy, a sort of calcareous earth compounded of carbonate of lime and clay.

Marline, in nautology, a small line used for winding round ropes.-Mar

line-spike, a piece of iron used in splicing small ropes.

Marlstone, in geology, a calcareous and irony stratum. Marmite, in mineralogy, a black sulphuret of zinc.

Marmolite, in mineralogy, the silicate of magnesia, consisting of silica, magnesia, lime, and water: sp. gr. 247; H = 3.5.

Marquetry (Fr.), inlaid work, consisting of different pieces of divers coloured woods; parquetry.

Mars (Lat.), in astronomy, the fourth planet in the order of distance from the sun. Its mean diameter is 4,398 miles; distance from the sun 142,000,000 miles; period of revolution round the sun, 686 days, 23 hours, 30 min., 39 sec.

Marsupialia, in zoology, a class of animals, the females of which are furnished with a marsupium or pouch for carrying their young, as in the Opossum or Kangaroo.-Marsupial, in anatomy, is a term applied to the obturator internus, from its purselike shape.

Martel'lo (Ital.), an epithet applied to circular towers, some of which may still be seen on different parts of the British coast.

Martial (Lat. Mars), in mineralogy, martial ethiops is the protoxide of iron, obtained by moistening iron filings slightly with water and exposing them for a day or two in the air, when a quantity of black or protoxide is formed upon the surface. Mascag'nin, in mineralogy, native sulphate of ammonia, found in volcanic districts.

Mascle, in heraldry, a bearing in the form of a lozenge perforated.

Massil'ia, in astronomy, the name of one of the newly-discovered planets, first observed by De Gasparis in 1852. Its mean distance from the sun is 229,598,000 miles, and the time of its periodical revolution 3 years and 269 days.

Mast (Sax. mast), a long piece of timber raised nearly perpendicularly to the keel of a vessel, to support the yards or gaffs on which the sails are extended. In ship-building there are three principal masts:-(1) the mainmast, the largest mast in a ship, standing nearly in midships between stem and stern; (2) the foremast, the next in size to the mainmast, which stands near the stem of a ship, and carries the foresail and foretopsailyard;-(3) the mizen-mast, the smallest mast, which stands about halfway between the mainmast and the stern. Jury-mast is a yard set up instead of a mast which has been broken down by a storm. There are different names applied to different parts of the mast; as, lower mast, the lowest part of the mast;-topmast, that which is raised at the head or top of the lower mast;topgallant mast is a smaller mast than the preceding, to which it is raised;-topgallant-royal mast is smaller than the preceding, and is usually elevated through irons at the head of the topgallant mast.

Mas'tacine, a soft, elastic substance, which has all the characteristics of caoutchouc when moist.

Mastic (Fr.), a gum or peculiar resin which exudes from the lentisk tree, used in plastering walls, and in varnishing. In architecture, a kind of mortar or cement.

Mastitis (Gr. mastos the breast), in pathology, inflammation of the breast in women.

Mas'todon (Gr. mastos, and odontes teeth, from the mammillated projections of the teeth), a huge, mammiferous, pachydermatous, extinct quadruped, allied to the elephant, and exceeding it in size, known only by its fossil remains. - Mastodonsaurus, a gigantic extinct saurian.

Mater (Lat. mother), in anatomy, a term applied to the membranes of the brain, as the dura mater and the pia mater.

Mate'ria Medica (Lat.), in medical science, that branch which treats of the articles employed in the practice of medicine, and explains the nature and mode of action of those substances which are had recourse to for the restoration of health.

Materialism, the theory that the material universe is self-existent and self-directed, and that the functions of life, sensation, and thought arise out of modifications of matter; a doctrine which denies the existence of a spiritual or unnatural principle in man, as distinct from matter. Mathematics (Gr. mathesis learning), that science which treats of agnitude and number, or of whatever can be measured or numbered. - Pure mathematics is where geometrical magnitude or numbers are the subject of investigation. -Mixed mathematics is where the deductions thus made are from relations obtained by observation and experiment, and constitute what is called physical

science.

Mattock, in military art, an implement used by the pioneers of an army, which resembles a pickaxe, but has two broad edges instead of points.

Mausoleum (Lat.), a magnificent tomb or monument, so called from Mausolus, King of Caria, to whose memory it was raised by his wife Artemisia, 353 B.c. Hence all sepulchral structures of importance are called mausoleums.

Maxil'læ (Lat.), in entomology, a name applied to the lower jaw of insects. Maximilia'na, in astronomy, one of the newly discovered plants. Max'imum (Lat.), the greatest quantity or degree attainable. Maxima et minima, in geometry, are the greatest and the least quantities of a variable quantity, the method of finding which is by what is termed methodus de maximis et minimis. Mazology (Gr. mazos the breast, and logos a discourse), the science of mammiferous animals.

Mean (Sax. mane), an epithet of frequent occurrence in scientific phraseology. In mathematics, mean is that quantity which has an intermediate value between several others, formed according to any assigned law of succession: the arithmetical mean is formed by dividing all the quantities, by their number; the geometrical mean is the middle term of a duplicate ratio, or continued proportion, and three terms. In astronomy, mean distance of a planet from the sun is an arithmetical mean between the planet's greatest and least distance; mean motion is that by which a planet is supposed to move equably in its orbit; mean time, that. which is measured by an equable motion; mean conjunction, or opposition, is when the mean place of the sun is in conjunction or opposition. Meandri'na, a genus of hemispherical, lamelliferous corals, the Brain Coral, so named from the labyrinthine form of the cavities and ridges, which resemble the convolutions of the brain.

Measles, in pathology, the Rubeola, a contagious disease, usually characterized by small red spots; also a disease in swine and trees.

Measure (Fr.), the entire extent or dimensions of an object, including length, breadth, and thickness. The measure of a line is its length compared with some determinate line, such as a mile, foot, inch, &c.-The measure of a surface is the number of square miles, feet, inches, &c., contained on it. The measure of a solid is the number of cubic inches, feet, &c., it contains. The measure of an angle is the number of degrees, minutes, &c., contained in the arc arc of a circle comprised between the two legs which form the angle, the angular point being the centre.-Measure of velocity, the space uniformly passed over by a moving body in a given time.

Meat Biscuit, in the culinary art, a concentrated preparation of meat pounded and dried, then mixed with meal, and baked.

Mecca Balsam, a fine oleo-resin, obtained from the Balsamodendron Gileadensis.

Mechanics (Gr. and Lat. machina, a machine), that science in natural philosophy which treats of forces and powers, and their actions on bodies by the intervention of machinery; the science of the laws of matter and motion, as applied to the construction of machines. The term mechanics of late years has been extended to the motion and equilibrium of all bodies, whether solid, fluid, or aëriform, and has been employed to comprehend the sciences of hydrodynamics and pneumatics.-Mechanical philosophy is the science of mechanics applied to physical inquiries, or, on the other hand, the application of the laws of general science to the improvement and construction of machinery. The six mechanical powers are the lever, wheel and axle, pulley, inclined plane, wedge, and screw. -Mechanical force is the power of any machine or mechanical contrivance. It is, in fact, the measure of all other force, as it bears reference to the effect produced: thus steam, water, man, and horse power are all represented by the amount of mechanical force they can exert.

Mechlo'ic, in chemistry, noting an acid formed by passing chlorine gas over fused meconine.

Mec'onate, a salt formed of meconic acid and a base.

Mec'onine, a white, fusible substance obtained from opium. Meco'nium (Gr. mekon a poppy), the juice of the white poppy; opium; the first fæces of children.

Me'dian (Lat. medius), in anatomy, situated in the middle of the body. Me'diant (Lat. medius), in music, the chord which is a major or minor third higher than the key-note.

Mediastinum (Lat.), in anatomy, the duplicature of the pleura, which divides the cavity of the thorax into two parts.

Med'icament (Lat.), anything used in healing; a topical application. Med'icate (Lat.), to tincture or impregnate with anything medicinal. Med'icine (Lat.), that branch of physic

which relates to the healing of diseases; the science of the preservation of health, and the cure of diseases. It is divided into practical, theoretical, and forensic. Practical medicine is divided into four branches -surgery, physic, midwifery, and therapeutics. Theoretical medicine is divided into anatomy, pathology, and physiology. Forensic medicine consists in the application of the principles of medical science to the administration of justice and the preservation of the public health. Medium (Lat.), that through which a body not in contact with another must pass to reach it. In optics, any substance through which light is transmitted. In logic, the medium or mean term of a syllogism. In fencing, the preparatory guard of the broadsword or sabre, which consists in presenting the sword in a perpendicular line with the centre of the

object opposed.

Medulla (Lat.), in anatomy, the marrow in the cavities of the bones. -In botany, the pith of plants. -Medullary rays, in botany, are the vertical plates of cellular tissue which radiate from the stem of exogenous plants through the wood to the bark. Medu'sidæ, a family of Acalephans, known commonly by the name of Sea-nettles or Sea-blubbers. Medu'sidans, gelatinous radiate animals, which float or swim in the sea, of which the Medusa is the genus. Meer'schaum, (Germ. foam of the sea), a silicated, soft, magnesian mineral, used in manufacturing tobacco-pipes. Mega- (Gr. megas), a prefix in compound words, denoting largeness of

size.

Mega'ceros (Gr. large-horned), in geology, the fossil Deer of the British Isles; the Irish Elk.

Meg'acosm (Gr. megas, and kosmos world), the great world, as distinguished from microcosm. Megalodon'tes (Gr. large-toothed), a family of coleopterous insects. Meg'alonyx (Gr. megas, and onyx a claw), in geology, a large extinct Mammal.

Megalop'tera (Gr.), a family of neuropterous insects.

Megalosau'rus (Gr.), in geology, a fossil gigantic amphibious animal of the

Saurian tribe.

Meg'amètre (Gr.), an instrument for determining longitude by measurement of the stars.

Meganyc'terans (Gr. megas, and nycteris a bat), a tribe of the order Cheiroptera, including the largest species of Bats.

Megapodi'idæ, in ornithology, a family of rasorial birds, the Great-foots, with the feet very large.

Meg'ascope (Gr.), an optical instrument for examining large bodies. Megathe'rioid (Gr.), one of a family of extinct mammiferous quadrupeds. Megathe'rium (Gr.a great beast), in geology, a large extinct animal found in S. America.

Megrim (Fr.), in pathology, a violent intermitting pain affecting one side of the head; vertigo.

Meibo'mian, in anatomy, noting glands situated at the edge of the eyelids. Mei'onite (Gr.), in mineralogy, a greyishwhite felspar.

Melæ'na (Gr.), a discharge of black blood, in consequence of the presence of acid.

Melain (Gr. melas black), the colouring matter of the ink of the cuttle-fish. Melam, a substance consisting of carbon, nitrogen, and hydrogen. Melam'pyrine, a substance containing neutral crystals.

Melan'agogue (Gr. melas, and ago to drive), a medicine for expelling black bile, choler, or melancholy.

Melania'næ, a sub-family of the Turbidæ, the Black Snails, in which the shells are spiral.

Mel'anite, in mineralogy, a species of black garnet. Melanoch'roite, a Siberian mineral of a hyacinthine or orange-red colour, nearly opaque. It consists of oxide of lead and chromic acid: sp. gr. 5.75. Melano'sis (Gr.), in pathology, a malignant disease, characterized by deposition of black matter.

Melan'terite, a native sulphate of iron. Melantha'ceæ, an order of liliaceous Endogens.

Melaphyre, a variety of black porphyry.

Melasma (Gr.), a disease of aged persons, in which a black spot appears upon the skin, and forms a foul ulcer. Melaso'ma (Gr. melas, and soma a body), the name of a family of heteromerous Coleoptera, consisting of black or cinerous-coloured Beetles, mostly apterous, and frequently with soldered elytra.

Melastoma'cese, a nat. order of exogenous plants, of which the Melastoma is the type.

Melia'ceæ, in botany, a nat. order of exogenous plants.

Melice'ris (Gr. meli honey, and keros wax), in pathology, an encysted tumour, the contents of which resemble honey and wax.

Meliphag'idæ (Meliphaga one of the genera), a genus of tenuirostral birds, Honey-suckers.

Melo'sis (Gr.), in surgery, the art of probing a wound.

Melpom'ene, the name of one of the newly-discovered planets, first observed by Hind in 1852. Its mean distance from the sun is 218,930,000 miles. Membrane (Lat.), in physiology, the expansion of any of the tissues of the body into a thin layer. Membranes are of different kinds; as, Membrana pupillaris, the membrane which covers the pupil of the eye of the fœtus before the sixth month;-Membrana nictitans, a thin membrane which serves to defend the eyes of birds and beasts from dust, &c.;Membrana tympani, the drum of the ear; the membrane which separates the internal from the external ear;Membrana urinaria, the urinary coat belonging to the fœtus in the womb; - Membrana adiposa, the membrane which contains the fat, and serves as one of the integuments of the body. Membranology is that branch of anatomy which treats of the membranes of the body. Memo'ria Tech'nica (Lat.), artificial or technical memory. Men'achanite (from Menachan, in Cornwall), the ferruginous oxide of titanium.

Mengite, a mineral of a hyacinth or brick-red colour and vitreous lustre, found at Miask, in Siberia. Its constituents are phosphoric acid, peroxide of cerium, oxide of lanthanium, thorina, peroxide of tin, protoxide of manganese, and lime: sp. gr. 4.92; H =

5.0. Men'ilite, a kind of semi-opal found at Menil Montant, near Paris. Menin'ges (Gr.), in anatomy, two membranes that envelop the brain, called the pia mater and dura mater.Meningitis is inflammation of the membranes of the brain.

Menin'go-phalanx, in surgery, an instrument for the protection of the cerebral membranes during the operation of the trephine on a diseased or fractured skull.

Meningorrhœ'a (Gr. menigx the membrane of the brain, and rheo to flow), extravasation of the blood on or between the cerebral membranes. Meningo'sis (Gr.), in anatomy, the union of osseous pieces by the intervention of membrane, as exhibited in the cranial bones of the fœtus.

Menis'cus (Gr. meniskos a crescent), in optics, a lens convex on one side, and concave on the other.

Menisperma'ceæ (Gr. mene the moon, and sperma seed), a nat. order of exogenous plants, of which Menispermum is the genus.

Menispermate, a compound of menispermic acid and a salifiable base. -The menispermic acid is obtained from the seeds of the Cocculus Indicus.

Menisper'mina, a vegetable alkali extracted from the Cocculus Indicus. tasteless, white,

Menispermine,

a

opaque, crystalline, alkaloid. Menses (Gr. menos a month), in physiology, the monthly flow of blood which takes place in women, and in others of the female Mammifera, by the organs of generation.

Men'struum (Lat.), a fluid substance which dissolves a solid body; a solvent.

Mensura'tion (Lat.), in geometry, the art or act of ascertaining the extension, solidity, and capacity of bodies by measuring lines and angles. Mentag'ra (Lat.), an herpetic eruption of the skin.

Mephi'tis (Lat.), a noxious exhalation, particularly applied to carbonic acid

gas.

Mercap'tan, in chemistry, a liquid composed of sulphur, carbon, and hydrogen.

Merca'tor's Chart, in geography, a projection of the globe of the earth in plano. In navigation, Mercator's sailing is the science of finding upon a plane the way of a ship on a course assigned, the meridians being all parallel, and the parallels of latitudes being straight lines.

Mercury, in astronomy, the planet nearest the sun, from which he is distant about 36,000,000 miles. His mean sidereal revolution is performed in 78.969258 mean solar days. His diameter is about 3,140 miles. He revolves on his axis in 24 hours, 5 min., 28 sec. In mineralogy, a white metal which is fluid at common temperatures; quicksilver. Its specific gravity is 13'5; its equivalent is 200. Formula, Hg, from the Latin hydrargyrum.

Merid'ian (Lat. mid-day), in astronomy and geography, an imaginary great circle of the sphere, passing through the earth's axis and the zenith of the spectator, dividing the sphere into two hemispheres, eastern and western, and crossing the equinoctial at right angles. In geography, the meridians are as numerous as the places on the earth, and the first

meridian is that from which the reckoning commences. This is fixed differently by different nations, the capital of each country being mostly chosen as the first meridian for their respective globes. In all our English maps and globes, the meridian of England is that circle which passes through London and the poles of the earth, and from which our longitude is reckoned.-Meridional distance is the difference of the longitude between the meridian under which the ship is at present, and any other she was under before.

Meri'no (Sp.), a species of sheep noted for the fineness of their wool. Merismatic (Gr. merizo to divide), in zoology, multiplying by division. Merlin, in military phraseology, a handspike.

Merlon (Fr.), in fortification, the part of a parapet included between two embrasures.

Merop'idans, a family of insessorial birds, of which the Merops, or Beeeater, is the type.

Meros (Gr.), in architecture, the plane face between the channels in the triglyphs of the Doric order. Mes'entery (Gr. mesos middle, and enteron intestine), in anatomy, a membrane by which the intestines are attached to the vertebræ.

Me'sial (Gr.), in anatomy, applied to a longitudinal line dividing the body

into two equal parts. Mesmerism (in honour of Ant. Mesmer, of Vienna) another term for animal magnetism; an agent (as taught by its advocates) by which one person can communicate certain influences at will to the mind of the person mesmerized, or put into a state of sleep, in which questions are answered.-Mesmerization is the act of producing the mesmeric state. Mes'ocarp (Gr.), in botany, the middle of the three layers in fruit. Mesoco'lon (Gr.), in anatomy, the mesentery of the colon. Mesogastric (Gr. mesos, and gaster the belly), in anatomy, occupying the umbilical region.

Mesole (Gr.), a mineral which occurs massive, globular, or reniform. Mesoleu'cos (Gr.), a precious stone, black, with a streak of white in the middle.

Mes'olite (Gr.), in mineralogy, a hydrated silicate of alumina, lime, and

soda.

Mesolog'arithm (Gr.), a logarithm of the cotangent, or differential logarithm. Mesom'elas (Gr.), a precious stone with a black vein parting every colour in the midst.