instruct), the preliminary learning connected with any art or science. Prophylax'is (Gr. pro, and phylaxis a guarding), in pathology, the art of averting a disease. Prop'olis (Gr. pro, and polis a city), a glutinous substance, with which bees close the holes and crannies of their hives. the Proportion (Lat.), in arithmetic, a term applied to the rule by which any three of four numbers so circumstanced being given, the fourth may be found. In mathematics, equality of ratios; four numbers or quantities being said to be in proportion when the ratio of the first to the second is the same as that of the third to the fourth, as 2, 6, 3, 9, in which the equal ratios of 2 to 6 and 3 to 9 may be expressed = 3, and the proportion is written, 2:6:39.-In chemistry, definite proportions are the limited proportions in which elementary substances combine, so as to form compound bodies.-Proportional parts is name given in logarithmic and other tables to small tables which are annexed to the differences of the tabular number, and which consist merely in setting down the several tenths of the differences, or the nearest whole numbers to them.Proportional compasses are used in mechanical drawings for diminishing or enlarging. They have two pairs of points movable on a shifting centre, which slides in a groove, and thereby regulates the proportion that the opening at one end bears to that of the other. a Propyla'um (Lat. from Gr. pro, and pyle a portal), in architecture, the porch of a temple; the vestibule of a house. Prosen'chyma (Gr. a pouring upon), in botany, a cellular tissue, the cellules of which taper to each end, and consequently overlap each other at their extremities. It is the first approach on the part of cellular tissue to the condition of woody fibre. Prosenneahe'dral (Gr. pros, ennea nine, and hedra a side), in crystallography, having nine faces on two adjacent parts, as a crystal. Pros'erpine, in astronomy, one of the recently-discovered planets, first observed by Luther in 1853. Its mean distance from the sun is 253,260,000 miles, and its periodical revolution 4 years and 120 days. Prostate (Gr. situated before), in anatomy, the prostate gland is a gland situated before the vesiculæ seminales.-Prostate concretions, calculi of the prostate gland, consisting of phosphate of lime, tinged by the secretions of the gland. Prostyle (Gr.), in architecture, a range of columns before an edifice. Protea'cea (from the god Proteus), in botany, a nat. order of exogenous plants, consisting of small trees or shrubs, of which the Protea is the genus. Protégé (Fr.), one who is protected or patronized by another; a dependant. Pro'teine, the gelatinous semi-transparent substance obtained from albumen, fibrine, or caseine. Proto- (Gr. protos), a prefix to express priority; as, Protocol or Prototype, the original copy or rough draft of a treaty. Pro'toplasm (Gr.), in botany, the soft nitrogenous lining or contents of cells. Pro'tosalt, in chemistry, a term applied to oxysalts whose base is a prot oxide, as protosulphate of lead." Protosul'phate, in chemistry, a combination of sulphuric acid with a protoxide. Protox'ide, in chemistry, a substance combined with oxygen in the first degree; frequently used in chemical nomenclature. an Protozo'a (Gr. protos, and zoon animal), in zoology, a term applied to the lowest form of animal life, and corresponding with the true Infusoria. Protozo'ic (Gr.), in geology, noting the lowest system of rocks in which the traces of any organic structure have been discovered. Prunel'la (Lat.), in pathology, dryness of the throat in fevers.-In botany, a medicinal plant.-A preparation of purified nitre. Pruri'go (Lat.), in pathology, an itching of the skin with an eruption of pimples. Prus'siate, in chemistry, a salt formed of prussic acid and a base. Prussic, in chemistry, noting a very poisonous acid, called hydrocyanic, and forming the colouring matter of prussian blue. Psalte'rium (Gr. psallo to play on the harp), in anatomy, a part of the brain, consisting of lines impressed upon the under surface of the posterior part of the body of the fornix. Psammite (Gr. psammos sand), in geology, a species of micaceous sand stone. Psaria'næ, in ornithology, the Blackcaps, a sub-family of Muscicapidæ, or Fly-catchers, of which Psaris, or Black-cap, is the type. Pselaph'idæ, a family of minute coleopterous insects, of which the genus Pselaphus is the type. Pseudo- (Gr. pseudes), a prefix to numerous words, signifying false or counterfeit. Pseudoblep'sis (Gr. pseudes, and blepsis sight), in pathology, false vision, or imaginary vision of objects. Pseudo-bulb, in botany, the solid, aboveground tuber of some of the Orchidea. Pseudodip'teral (pseudes, dis twice, and pteron a wing), in architecture, applied to temples in which there were eight columns in front, and only one range round the cell. Pseudo-metallic, in mineralogy, affording a lustre only when held to the light, as a mineral. Pseu'doscope (Gr. false view), in optics, a name given to the stereoscope when employed to produce what are called conversions of relief. Pseudostel'la (Gr. false star), any kind of meteor or phenomenon appearing in the heavens, and resembling a star. Psilom'elane (Gr. psilos smooth, and melas black), in mineralogy, a massive, botryoidal, dark-coloured ore of manganese. Psittac'ida (Gr. psittakos a parrot), in ornithology, an extensive family of scansorial birds. Psoas, Psoe (Gr. psoai the loins), in anatomy, the name of a muscle in the loins. Psophi'ne (Gr.), in ornithology, the Trumpeters. Psora (Gr.), in pathology, the itch. Psoriasis (Gr.), a rough, scaly state of the cuticle. Pso'ries (Gr.), medicine for the itch. Psorophthalmia (Gr. psora the itch, and ophthalmia inflammation of the eye), in pathology, inflammation of the eyelids, with ulceration, &c. Psyche, one of the newly-discovered planets, first observed by De Gasparis in 1852. Its mean distance from the sun is 278,710,000 miles; and its periodical revolution 4 years 364 days. Psychiatry (Gr. psyche the soul), medical treatment of diseases of the mind. Psychology (Gr.), a treatise on the soul; mental philosophy. Psychopathy (Gr. psyche, and pathos suffering), in pathology, mental dis ease. Psychrom'eter (Gr. psychros cold, and metron a measure), an instrument for measuring the tension of aqueous vapour contained in the atmosphere. Psychrometry (Gr.), the science which treats of the measurement of the moisture in the atmosphere; hygrometry. Pterocephali'næ, a sub-family of the Raidæ, or Flat-fishes, of which Pterocephalus is the type. Pterodac'tyle (Gr. winged fingers), in geology, an extinct genus of flying reptiles, of the order of Saurians. Pterop'oda (Gr. winged feet), in zoology, a class of Molluscs which live in the open sea, and have a pair of flippers, or wings, by which they pass rapidly through the water. Pterosauria (Gr. winged reptiles), an order of fossil reptiles. Pterygo (Gr. pteryx a wing), in anatomy, a word used in composition, to denote muscles which are connected with the pterygoid processes. Ptisan (Gr.), in pharmacy, a decoction of barley with other ingredients. Ptolema'ic, relating to Ptolemy the astronomer, or his system of the universe, in which the earth is supposed to be the centre. Ptosis (Gr. a falling), in pathology, a falling of the upper eyelid, with a partial or complete want of power to elevate it. Ptyal'agogue (Gr. ptyalon spittle, and ago to excite), in pharmacy, any medicine which promotes salivation, or the discharge of saliva. Pty'aline (Gr. ptyalizo to spit), in chemistry, an organic principle constituting about one-third of the soluble solids of the saliva, and having the power of converting starch into dextrine and into sugar. Pty'alism (Gr.), in pathology, a flow of saliva; salivation. Pubes (Lat.), in anatomy, the middle part of the hypogastric region. Pubis (Lat.), in anatomy, the anterior part of one of the bones of the pelvis, corresponding with the genital or gans. Puccoon (Ind.), a red vegetable pigment obtained from a papaveraceous plant, the Sanguinaria Canadensis. Pu'ceron (Fr. from puce a flea), a tribe of small insects, which are found in great numbers on the bark and leaves of plants; the Aphides, or Plant-lice. Puerperal (Lat.), relating to or happening after childbirth. Pulmonary (Lat. pulmones the lungs), in anatomy, an epithet applied to the various arteries, veins, nerves, and other organs connected with the lungs; and, in pathology, to the morbid affections which are seated in, or directly implicate, the pulmonary Pulse (Lat. pulsus struck), the pulsation or motion of an artery.-In botany, leguminous plants or their seeds, as Peas and Beans. Pulsim'eter (Lat. pulsus, and Gr. metron a measure), in pathology, an instrument for measuring the quickness or force of the pulse. Pulvil'lus (Lat.), in entomology, a membrane capable of being inflated, which covers the feet of insects, and by which they can create a vacuum, and thus suspend themselves or walk against gravity. Pumice (Lat. pumex), a porous substance ejected from volcanoes.Pumice-stone, a slag or cinder of some fossil. Pump (Fr.), an engine or machine by which water is drawn up from wells. -The forcing pump, a pump which is capable of driving a stream of water above the pump-barrel by means of compressed air. - Chain-pump, a pump used in ships-of-war. Pupip'ara (Lat. pupa, and pario to bring forth), in entomology, a family of dipterous insects distinguished by the larvæ issuing from the mother in the form of a soft white egg, the skin of which hardens and becomes a firm shell, from which, in time, the perfect insect emerges. Purbeck, in geology, a fresh-water de posit, consisting of marl and lime stone.-Purbeck beds constitute the lowest members of the Wealden group, lying below the Hastings sands, and immediately above the Portland beds. The Purbeck limestone abounds in organic remains. Purlin, in architecture, a horizontal piece of timber lying on the main rafters. Purple Wood, in botany, the wood of the of the tinctures used in blazonry, represented in engraving by diagonal lines from the sinister to the dexter side of the escutcheon.-In pathology, the scorbutus, or scurvy; an eruption of small, distinct, purple specks and patches, attended with languor, general debility, and pain in the limbs. The varieties are P. simplex, petechial scurvy; P. hæmorrhagica, land scurvy; P. urticans, nettle-rash scurvy; P. senilis, scurvy of old age; P. contagiosa, contagious scurvy. Pursuivant (Fr.), in heraldry, a kind of probationer in the Heralds' College. Pus (Lat.), in pathology, a peculiar fluid yielded from the blood in consequence of inflammation Pustule (Lat.), in pathology, a cuticular elevation with an inflamed purulent base. Puzzola'na(from Puzzuoli, whence it was brought), a substance formed of volcanic ashes more or less compacted together, and valuable for the foundation of lighthouses and other marine erections. Pye'mia (Gr. pyos pus, and haima blood), in pathology, a dangerous disease, consisting of a peculiar alteration of the blood, and the formation of numerous abscesses in various parts of the body. Pycnite (Gr. pyknos thick), a prismatic mineral, a variety of topaz, the constituents of which are alumina, silica, and fluoric acid: sp. gr. 3'57: Pyc'nodonts (Gr. thick-toothed), in geology, an extinct family of fishes which prevailed extensively during the middle period of geological history. Pycnogonidae (Gr. pyknos, and gonon race), a family of Entomostraca, consisting of spider-looking creatures, with eight very long unguiculated legs, of which the Pycnogonon is the type and genus. Pyc'nostyle (Gr. thick-columned), in architecture, an arrangement of columns, in which the intercolumniations are equal to one diameter and a half. Pycnoti'næ, in ornithology, a sub family of dentirostral birds, of the order Passeres. Pylo'rus (Gr.), in anatomy, the lower orifice of the stomach, through which the food passes into the intestines. Pyophthal'mia (Gr. pyon pus, and ophthalmia inflammation of the eye), purulent ophthalmia. Pyorrhoea (Gr. pyon, and rheo to flow), a continued purulent discharge, especially from the genital organs, lungs, and other parts. Pyr-, or Pyro- (Gr.), a prefix to numerous scientific words, denoting fire, or the idea of fever or heat. Thus, in chemistry, the products which are obtained by subjecting certain organic acids to heat are termed pyroacids, as pyro-citric, pyro-gallic, pyro-kinic, pyro-maric, pyro-meconic, and pyro-sorbic acids. Pyral'lolite (Gr. pyr, allos another, and lithos a stone), a mineral which changes its colour by heat. Pyramid (Gr.), a solid figure standing on a polygonal square or triangular base, and terminating in a point at the top. In anatomy, an eminence in the tympanum, enclosing the stapedius muscle.-In surgery, the pivot or centre-pin attached to the crown of the trephine. Osseous Pyrar gillite (Gr. pyr, and argillos clay), a mineral consisting of potash, soda, silica, alumina, oxide of iron, magnesia, and water: sp. gr. 2'50; H 3'5. Pyrene'ite, in mineralogy, a black variety of garnet, found in the Pyrenees, embedded in primitive limestone. Pyret'ics (Gr.), medicine for fevers. Pyretology (Gr.), a discourse on fevers. Pyri'tes (Gr.), fire-stone; a sulphuret of iron or other metal.-Pyretology, a treatise on pyrites. Pyro-acetic Spirit, in chemistry, a limpid, colourless, inflammable liquid, of an agreeable ethereal odour and pungent taste. Pyro-acid, in chemistry, an acid made by subjecting another acid to heat. Pyrochlore (Gr. pyr, and chloros greenish yellow), a reddish-brown or black mineral, consisting of titanic acid, lime, protoxide of uranium, peroxide of cerium, protoxide of manganese, peroxide of iron, peroxide of tin, and water sp. gr. 4'20; H=5. Pyrocitric, in chemistry, noting an acid obtained by distilling citric acid. Pyro-electric'ity, electricity developed by heat, as in certain crystals. Pyrolig'neous, Pyrolig'nous (Gr. and Lat.), noting an acid obtained from wood. Pyrolignite (Gr.), a salt formed by the union of pyroligneous acid with a base. Pyrolith'ic (Gr.), noting an acid obtained from uric acid. Pyrol'ogy (Gr.), a treatise on heat or fire. Pyrolu'site (Gr. pyr, and louo to loosen), in mineralogy, common black manganese. It is the most important and most abundant of all the ores of manganese, and, according to Thomson, consists of binoxide of manganese, silica, and peroxide of iron: sp. gr. 4'97; H =2—2.8. Pyroma'lic Acid (Gr. pyr, and Lat. malum an apple), in chemistry, a volatile substance obtained by heating malic acid in close vessels. Pyrom'etry (Gr. pyr, and metron a measure), the measurement of heat, or the expansion of bodies by heat.Pyrometer is an instrument for the measurement of expansion caused by heat. Pyromorphite (Gr.), in mineralogy, native phosphate of lead. Pyromu'cous (Gr. pyr, and mucous), in chemistry, noting an acid obtained from sugar, gum, and mucilage.Pyromucite, a salt formed of pyromucous acid and a base. Pyron'omy (Gr.), the laws of igneous action in chemical processes. Pyrope (Gr.), in mineralogy, a fiery, brilliant red garnet, a gem highly prized. Pyrophane (Gr. appearance of fire), a mineral said to change its colour by heat. Pyroph'orus (Gr. bearing fire), a substance which spontaneously takes fire when exposed to air. Pyrophosphate (Gr.), in chemistry, a compound of pyrophosphoric acid with a base. Pyrophosphor'ic (Gr.), in chemistry, an acid procured by exposing phosphoric acid to heat. Pyrophyllite (Gr. pyr, phyllon a leaf, and lithos a stone), a foliated mineral of a light green colour. Pyrophy salite (Gr. pyr, and physa a bladder), in mineralogy, a variety of topaz. Pyropneumatic (Gr.), noting a kind of lamp for producing instantaneous light by the action of inflammable air upon a metallic substance. Pyr'oscope (Gr. viewing the fire), an instrument for measuring the intensity of heat radiating from a fire. Pyrosid'erite (Gr. fire-steel), in mineralogy, a mineral composed of peroxide of iron and water. Pyro'sis (Gr. inflammation), in pathology, a burning redness in the face. Pyros'klerite (Gr. pyr, and skleros hard), an emerald-green mineral, consisting of silica, alumina, magnesia, protoxide of iron, oxide of chromium, and water. Pyros'malite (Gr. pyr, osme smell, and lithos a stone), a native submuriate of iron. Pyr'osome (Gr.), in entomology, a sort of compound Ascidian, which is remarkable for emitting phosphoric light. Pyrotartar'ic, noting an acid obtained by distilling pure tartrate of potassa. Pyrotar'trate, in chemistry, a salt formed by pyrotartaric acid and a base. Pyr'otechny, or Pyrotechnics (Gr. pyr, and techne art), the art or science of managing fire, particularly as applied to the art of war, and more especially the making of ornamental fireworks for amusement. Pyrotic (Gr.), in pathology, a caustic medicine. Pyrou'ric (Gr.), in chemistry, noting an acid obtained from uric acid. Pyroxene (Gr.), in mineralogy, the augite; a crystallized mineral. Pyrox'yle (Gr. pyr, and xylon wood), a term embracing all explosive substances obtained by immersing vegetable fibre in nitric or sulphuric acid. -Pyroxylic, in chemistry, applied to a spirit produced by the destructive distillation of wood.-Pyroxyline, a substance found in pyroxylic spirit. Pyrr'hite (Gr. pyrrhos flame-coloured), a mineral of a deep orange yellow, and vitreous lustre. Pyrrhocoraci'næ, or Pyrrhuli'næ, in ornithology, a sub-family of conirostral birds, of the order Passeres and family Corvida; Choughs. Q. In mathematical problems Q.E.D. | stands for quod erat demonstrandum, which was to be demonstrated; and, in chemistry, Q.S. stands for quantum sufficit. Quadra (Lat. quatuor four), in architecture, a square moulding, border, or frame encompassing a bas-relief, &c.; a term applied to the plinth or lower member of the podium.-A prefix to compound words, signifying four. Quad'rangle (Lat.), a plane figure with four angles. In geometry, the fourth part of a circle; an arc of 90°. Quadrant (Lat. the fourth part), a mathematical instrument for taking altitudes; an instrument used in gunnery for elevating and pointing cannon, &c.-Quadrant of altitude is an appendix to an artificial globe, consisting of a slip of brass graduated into 90°, of the same length as those on one of the great circles of the globe, and used as a scale for measuring the distance between places in degrees. Quadrat (Lat. quadratus squared), a mathematical instrument for measuring altitudes, called also a geometrical square and line of shadow.-In printing, a square piece of metal to fill up a void space between words and letters. Quad'ratrix (Lat.), in geometry, a mechanical line, by means of which right lines are found equal to the circumferences of circles. Quad'rature (Lat. quadratio act of squaring), in mathematics, the determination of the area of a curve.In astronomy, the position of the moon when she is 90° from the sun. -The quadrature of the circle is a problem of great celebrity in the history of mathematical science.-In anatomy, quadratus lumborum, a muscle arising from the crest of the ilium.-Quadratus femoris, a muscle arising from the tuber ischii. Quad'ricorns (Lat. quatuor, and cornua horns), in entomology, a family of insects having four antennæ.-In zoology, a four-horned antelope. Quadrifurcate (Lat. quatuor, and furca a fork), doubly forked. Quadrino'mial (Lat. quatuor, and nomina names), in algebra, having four terms. Quadripartite (Lat.), divided into four parts. Quadrisul'cate (Lat.), in zoology, an unguiculate quadruped, having the hoof divided into four parts. Quadrox'alate, in chemistry, a salt composed of four equivalents of oxalic acid and one of base. Quadru'mana (Lat. four-handed), in zoology, the second order of mammiferous animals in Cuvier's system, as the Apes, Monkeys, &c. Quadrune, in mineralogy, a kind of grit-stone with a calcareous cement. Quaquaver'sal (Lat. quaquà and versus, inclined on every side), in geology, noting the dip of beds to all points of the compass around a centre, as in the case of beds of lava around the crater of a volcano. Quartan (Lat. quartus fourth), in pathology, applied to a form of ague; occurring every fourth day. Quarta'tion (Lat. art of quartering), in metallurgy, the separation of silver from gold by the agency of nitric acid. In chemistry, a process by which the quantity of one thing is made equal to the fourth part of another. Quartersil'icate, a mineral in which four atoms of silica are combined with one atom of some other substance. Quartet (Ital.), in music, a piece arranged for four voices or four in struments. Quartz (Germ.), a transparent mineral, composed of pure silex; rock-crystal; one of the ingredients of granite, found under every variety of form: sp. gr. 2'5-27; H = 7'0. Quartzite (Germ.), in mineralogy, an aggregate of grains of quartz; quartz rock. Quartz'sinter, in mineralogy, a substance found in the form of siliceous concretions. Quaver (Welsh), in music, a note or |