could occasion. -Galvanometer, an instrument constructed for the purpose of detecting the presence of feeble electro-chemical currents.Galvanoscope, an apparatus for ascertaining the direction in which the pole of a magnetic needle is moved by a galvanic current. Galvanized iron, iron tinned by a peculiar patent process, by which it is rendered less liable to oxidation from moisture. -Galvano-plastic, same as electrometallurgic. Gamboge, a vegetable gum resin used in the arts as a bright yellow pigment, especially in miniature and water-colour paintings. It is also used in medicine as an emetic and purgative hydrogogue. Gammari'na (Gr. gammaron a lobster), in entomology, a family of amphipodous Crustaceans (the Sandhoppers), of which the genus Gammarus is the type. Gammarolite is a fossil lobster or crab. Gamut (Gr. gamma), in music, a scale on which musical notes are disposed in their several orders. Ganglion (Gr.), in anatomy, an enlargement in the course of a nerve -a small mass of nervous matter resembling a knot; a tumour in the sheath of a tendon. - In surgical pathology, a hard, indolent, globular swelling, situated in the course of an extensor tendon, and formed by viscid albuminous fluid, generally contained in a cyst. Gangrene (Fr.), in pathology, mortification of living flesh, or of some portion of a living animal;-Gangrenous, intimating mortification. Ganoceph'ala (Gr. bright-headed), in geology, an order of fossil reptiles, with polished horny plates covering the head. com Ganoi'dians (Gr. ganes splendour, and eidos appearance), in ichthyology and fossilology, an order of fishes which have angular scales posed of bony or horny plates, covered with a thick plate of enamel. This order contains about sixty genera, most of which are extinct. Garbe (Sax. garba), in heraldry, a sheaf of any kind of grain, borne in several coats of arms. Garganine, an extract of madder, prepared in France by means of sulphuric acid. Garnet (Ital. granato), a crystallized mineral of a reddish colour, of which there are many species. The precious garnet is found in dodecahedrons, in mica slate, amongst the oldest or primary rocks in many parts of the world. It is harder than quartz, and consists of nearly equal parts of silex, alumina, and oxide of iron, with traces of manganese. Common garnets are more opaque, of a duller colour, and less hard than the precious garnet, though harder than quartz. Garrot (Fr.), in surgery, a small cylinder of wood, employed to tighten the circular band by which the artery of a limb is compressed, for the purpose of suspending the blood in hæmorrhage from amputation or otherwise. Garruli'ne (Lat. garrulus chattering), in ornithology, the Jays, a sub-family of the Corvidæ, or Crows, of which the Garrulus is the type. Garrya'ceæ (from Nich. Garry), in botany, a nat. order of declinous Exogens, consisting of shrubs without stipules, of which the Garrya is the type. Gas, pl. Gases (Fr.), in chemistry, an aëriform fluid; a term applied to all permanently elastic fluids or airs differing from atmospheric air; a body, the constituent particles of which have so expanded by heat as to become aëriform. Of the different gases, four of them are simple substances - oxygen, hydrogen, nitrogen, and chlorine. The rest are more or less compound; as carbonic acid gas is a compound of oxygen and carbon. The gases which are inflammable are hydrogen and all its compounds, carbonous oxide, and cyanogen. Those which more or less support combustion are oxygen, protoxide of nitrogen, chlorine, and its oxides. Some gases emit an odour which is insupportable, and often characteristic. In Graham's "Elements of Chemistry" the following analyses of gases are given, which exhibit the distinctive properties of oxygen, nitrogen, protoxide of nitrogen, deutoxide of nitrogen, hydrogen, carbonic oxide, and carbonic acid : Gases soluble in water. - Carbonic acid: solution disturbs limewater;-Protoxide of nitrogen: does not disturb water. Gases which support combustion. -Oxygen;-Protoxide of nitrogen. -Carbonic oxide: product of combustion disturbs lime-water;-Hydrogen: does not disturb water. Gases which extinguish combustion. Deutoxide of nitrogen: forms brown fumes with oxygen;-Nitrogen: does not. Gas is applied in a variety of ways, and the word forms a compound allied to numerous words connected M with science and art.-Portable or coal gas, after its manufacture, is compressed by a condensing or forcepump into strong vessels prepared to receive it. These vesseis being portable, the gas may thus be used where required, at any distance from the gas-works.-Gas apparatus consists of the furnaces, retorts, pipes, valves, purifying machine, lime machine, gasometers, gas meters, governors, &c., used in the manufacture, the purifying, and the supply of gases, particularly of coal gas.Gas-burner is the jet or contrivance fixed to the end of a gas-pipe for the purpose of separating and diffusing the flame. The Gas hydraulic main is the large pipe or tube into which the tubes leading from the various retorts are fixed, and which conveys the gas to the tar vessel or cistern in which it is cooled and purified from any undecomposed tar.Gas main consists of the principal pipes which conduct the gas from the gas-works to the places where it is to be consumed.-Gas-light is the light afforded by the combustion of carburetted hydrogen gas, as procured by the distillation of coal, oil, tar, &c.; it is therefore called coal gas, oil gas, &c.-Gas-meter, a simple but ingenious mechanical contrivance, the design of which is to measure and record the quantity of gas passing through a pipe in any given time.Gas-works. The manufactory at which coal gas is made for public purposes, together with the whole machinery and apparatus, is included under this term. Gas'alier, a gas-burner for containing several lights; answering the same purpose as a chandelier for candles. Gas'elier, an apparatus for making aërated waters. Gasometry (gas, and Gr. metron a measure), the art and science of measuring gas. Gasometer is a reservoir in gas-works, into which the purified gas is received; also an instrument for measuring gas;-sometimes termed a gas-meter. Gas'oscope (gas, and Gr. skopeo to view). an apparatus for indicating the presence of carburetted or hydrogen gas in mines, buildings, &c. Gasteromycetes (Gr. gaster the belly, and mykos a mushroom), in botany, an order or tribe of Fungi, in which the hymenium is closed in a pericardium. Gasterop'oda, or Gas'teropods (Gr.gaster, and podes feet), in zoology, the third class of Mollusca, that crawl upon a fleshy disc situated under the belly, which serves them as feet. The Limax, or Slug, is an example of the class. The Gasteropods are divided by Cuvier into nine orders, viz.: the Pulmonea, the Nudibranchiata, the Inferobranchiata, the Tectibranchiata, the Heteropoda, the Pectinibranchiata, the Tubulibranchiata, the Scutibranchiata, and the Cyclobranchiata. Gastric (Gr. gaster the belly), in physiology, an epithet applying to the stomach or belly.-Gastric juice is the thin pellucid liquid which for the dilution of food) distils from certain glands in the stomach. Gaster, or gastro, in medical science, is a prefix much used in the composition of terms connected with that important organ of the animal economy, the stomach, or the region of the belly--as shown by the following list:-Gastrocele, hernia in the stomach; gastro-cephalitis, co-existent inflammation of the stomach and the substance or membranes of the brain; gastro-cholecystitis, inflammation of the stomach and gallbladder; gastro-colic, an epithet applied to designate organs and blood-vessels which are alike connected with, and distributed upon, the stomach and colon; gastrocolititis, inflammation of the large intestine; gastro-cystitis, inflammation of the stomach and urinary bladder; gastro-dermitis, inflammation of the stomach and skin; gastroduodenalis, pertaining to vessels which belong to, or are distributed over, the stomach and duodenum; gastro-duodentitis, co-existent inflammation of the stomach and duodenum; gastro-dynia, pain in the stomach, same as gasteralgia; gastroencephalitis, inflammation of the stomach and the brain; gastro-enteritis, simultaneous inflammation of the stomach and small intestines; gastro-piploric, pertaining alike to the stomach and omentum; gastroepiploitis, simultaneousinflammation of the stomach and omentum; gastrohypatic, belonging to, or connected with, the stomach and the liver; gastro-hepatitis, simultaneous inflammation of the stomach and the liver; gastro-hysterotomia, the abdominal Cæsarian operation; gastro-inflammatory, an epithet applied to a combination of inflammatory and gastric fever; gastro-intestinal, applied to diseases simultaneously implicating the stomach and intestines; gastro-metritis, complicated inflammation of the stomach and womb; gastromucosus, applied to fevers in which gastric irritation is complicated with i inordinate secretion of mucus; gastro-nephritis, a complication of gastritis with nephritis; gastro-æsophagitis, simultaneous inflammation of the stomach and gullet; gastro-pericarditis, inflammation of the stomach and pericardium; gastroperitoneum, inflammation of the stomach and peritoneum; gastropharyngitis, inflammation of the stomach and pharynx; gastro-pleuritis, a complication of gastritis with pleurisy; gastro-pneumonia, a complication of gastritis and pneumonia; gastro-pyloric, belonging to the pyloric artery; gastro-splenic, pertaining to the stomach and spleen; gastro-splenitis, gastric irritation with painful tumefaction of the spleen; gastro-adynamic, applied to a fever in which the gastric are complicated with adynamic symptoms; gastro-ataxic, applied to a fever in which the gastric are complicated with the ataxic symptoms; gastroarachnoiditis, co-existent inflammation of the stomach and the arachnoid membrane of the brain; gastro-bronchitis, inflammation of the stomach and bronchia. Craig. Gastriloquist (Gr. gaster, and Lat. loquor to speak), one who speaks from his belly orstomach, or who so modifies his voice as to appear to come from another person;-a ventriloquist Gastritis (Gr.), inflammation of the intestines, or more especially the stomach. Gastroraphy (Gr. gaster, and rapto to sew), in surgery, the sewing up of wounds of the abdomen. Gastrorrhagia (Gr. gaster, and regnymi to burst out), gastric hæmorrhage; exudation of blood from the internal surface of the stomach. Gastrot'omy (Gr. gaster, and tomeincision), in surgery, the operation of cutting open the belly; an incision of the stomach for extracting some foreign body introduced into it through the esophagus; also an incision of the abdominal parietes for the purpose of extracting a fœtus. Gauge (Fr.), a standard of measure; a term of frequent application in the arts and sciences; as, gauge-of-way is the width between the rails on a railway; the broad gauge being 7 feet, and the narrow gauge 4 feet 71⁄2 inches. - Gauge-cock, a cock commonly attached to steam-boilers, for the purpose of ascertaining the height of water in them. Pressuregauge, an instrument to determine the pressure exerted in hydrostatic or pneumatic machines, as the hydrostatic press, the airpump, steam-engine, &c. - Gaugepoint, in gauging, the diameter of a cylinder, whose altitude is I r inch, and its contents equal to those of a given measure. Rain-gauge, an instrument for measuring the quantity of water which falls from the clouds at any given place. Sea-gauge, an instrument for finding the depth of the sea. Gauge-point of a solid is used to denote the diameter of that circle, or the diagonal of that square, whose area is expressed by the same number as is equal to the number of cubic inches in the solid.-Siphongauge, a name given to any gauge which is made in the form of a siphon, that is, with two legs bent upon each other, such as that of the steam-gauge, the condenser-gauge, &c.-Among letter-founders, gauge is a piece of hard wood variously notched, used to adjust the dimensions, slopes, &c., of the various sorts of letters. Gauging, in practical science, the art of measuring the capacities of vessels of any shape or form. - The gauging rod, or gauging rule, is adopted for the purpose of measuring the contents of any vessel. The latter is a kind of sliding rule about 12 inches long, particularly adapted for the purposes of gauging: it has four faces or sides, which are furnished with sliding picces running in grooves. The lines upon them are mostly logarithmic ones, or distances which are proportional to the logarithms of the numbers placed at the head. - Gauger is an officer whose business it is to measure and ascertain the contents of vessels or casks, generally for revenue pur poses. or Gault, in geology, a stiff marl black clay; an intermediate deposit, which divides the upper from the lower members of the greensand formation, and contains numerous organic remains. Gay'lussite (from Gay-Lussac, the French chemist), a white crystallized mineral disseminated in clay, and consisting of carbonic acid, soda, lime, water, and alumina: sp. gr. 1'92; H=20-3.0. Gazon (Fr.), in fortification, a turf or piece of earth covered with grass, for lining the faces of parapets. Geat (Dutch), in metallurgy, the orifice through which the metal runs into the mould. Geckotide (from gecko, the Indian name), a family of platydactile or broad-toed Saurians, the Geckos, divided by Cuvier into eight subgenera. Gelatine (Ital.), an animal substance of the consistence of jelly, obtained by boiling with water the soft and solid parts, as the muscles, cartilages, bones, tendons, &c. The coarser forms of gelatine, obtained from hoofs, hides, &c., are called glue; that from the skin and finer membranes, size; and when obtained from air-bladders and other membranes of fish, isinglass. Gelatino'si, the name of the gelatinous Polypi, whose bodies are gelatinous, and more or less conical. Gem (Lat.gemma), in mineralogy, a precious stone cut by the lapidary, and used for ornamental purposes. The principal gems are the diamond, ruby, emerald, amethyst, onyx, calcedony, jasper, rock crystal, topaz, cornelian, and blood-stones. These are the natural or real gems; but there are others of an inferior character artificially produced; and these are called artificial gems, which are usually made of a very fusible, transparent, and dense glass or paste, containing a large proportion of oxide of lead, the colours being given by a skilful admixture of the metallic oxides. In botany, gems are the leaf-buds, or frondous germination of a plant, to distinguish it from flower-buds. Gemina'tion (Lat. doubling), in botany, a term applied to the parts or organs of plants which are disposed in pairs from the same point. Gem'ini (Lat.), in astronomy, the twins, Castor and Pollux; the third sign in the zodiac, into which the sun enters on the 21st of May. Gemme (Lat.), in botany, leaf-buds, as distinguished from the flowerbuds. Gemmip'ares (Lat. gemma a bud, and pario to bring forth), animals which propagate as vegetables by buds, as the fresh-water Polypi. Gen'erant (Lat. producing), in physics, the power or principle that produces; thus, a circle which revolves rapidly on any diameter generates a sphere; a line moved steadily along forms asurface; the circle and line are there fore generants. In mathematics, a line is generated by a point, a solid by a surface, and so on. In the fluxional analysis, all kinds of quantities are supposed to be generated by the motion of other quantities. Generation (Lat.), in geometry, generation, or genesis, is the production of a geometrical figure or quantity.-In physiology, it is the collective name of all those vital operations engaged in the production of an organized being. In the Mammifera, it comprehends conception, pregnancy, parturition, and lactation. Genera'tor (Lat.), in music, the principal sound or sounds by which others are produced. Generic (Lat. genus a kind), in natural history, pertaining to a genus; distinguishing a genus from a species. Genesiology (Gr. genesis first production, and logos a discourse), in physiology, a treatise on the origin and first production of animals. Gen'esis (Gr. generation), in geometry, the formation of a line, plane, or solid by the motion or flux of another. -Genetic, pertaining to the origin of a thing, or its mode of production. Ge'nia (Gr. geneion the chin), in anatomy, a word used in the composition of terms to indicate the muscles, &c., connected with the chin. Gen'itals (Lat.), in physiology, the sexual organs. In botany, the stamens and styles of generation. Gen'ouillère (Fr.), in fortification, that part of the parapet of a battery which remains above the platform, and under the gun, after the opening of the embrasure has been made. Gentiana'cese (Lat.), in botany, a nat. order of corollifloral herbaceous Exogens, of which the Gentian, a pretty flowering plant, is the type and genus.-Gentianin is the bitter principle of gentian. Genus, pl. Gen'era (Lat.), in natural history, a distinct class of beings, or group of animals or plants, which exhibit a certain degree of analogy, and are each connected by peculiarities of structure. Each genus is subdivided into different species or varieties; and whenever any natural object cannot be referred to a known species, it is made to constitute a genus. All species connected with the genus have the same name preceding the specific or distinguishing term; as, Equus caballus, the horse; Equus asinus, the ass.-In music, the general name for any scale, as the diatonic genus and chromatic ge nus. Geocen'tric (Gr. ge the eartlı, and kentron a centre), in astronomy, having the earth for a centre; but the planets moving round the sun as a centre are not geocentric; yet we speak of their geocentric places, latitudes, longitudes, &c., meaning thereby as they appear when viewed from the earth's centre. Geoc'ronite (Gr.), a mineral containing lead, sulphur, antimony, arsenic, &c. Geocyclic (Gr. ge, and kyklos a circle), encircling the earth periodically. Geode (Gr.), earthstone; a nodule of ironstone with internal cavities. Geode'sia, or Geodesy (Gr. ge, and daio to divide), the division or geometry of the earth; land-surveying. Geog'nosy (Gr. ge, and gnosis knowledge), a knowledge of the substances that compose the earth or its crust. Geog'ony (Gr. ge, and gone birth), the doctrine of the formation of the earth; geology. Geography (Gr.ge, and graphe description), a description of the earth, according to the divisions of its surface, natural or artificial, together with its productions and inhabitants; a book containing a description of the earth. Geology (Gr.ge, and logos a discourse), that part of natural philosophy which treats of the formation and structure of the earth beneath its surface, and the changes it has undergone. Geology is the history of the primeval conditions of our planet, as illustrated in the monuments of change which exhibit themselves on and beneath the surface of the earth. It is, in fact, the great history of Nature, which classifies, by means of existing monuments, the various rocks and strata of the earth's crust, according to their comparative ages, and treats of the different races of animals and plants which characterise the mundane formations or systems deposited by water during the lapse of countless ages. Geologists have reduced the grand divisions, in which the aqueous systems have been classed, into a perfectly intelligible form, of which the annexed is a summarycommencing with the unstratified rocks, the primary formations of the great globe itself :-1. PRIMARY FORMATIONS, consisting of schists of various kinds, limestones, graywacke, mica slate, gneiss, &c.; a few organic remains in the newest beds only. Igneous rocks of many sorts, such as granite, porphyry, greenstone, basalt, and traps of various kinds, produced at different eras, occur in each system;-2. The Silurian System, the upper and lower consisting of sandstones (often micaceous), limestones (abounding in the oldest types of organic life), and slates; -3. The Devonian or Old Red Sandstone System, consisting of sandstones (often red), cornstones, and shales, with extinct fishes, &c.;-4. Carboniferous System, consisting of the coal formation, carboniferous or mountain limestone-organic remains-all extinct. -5. SECONDARY FORMATIONS, consist ing of the chalk, greensand, oolite, lias, new red sandstone, with their subordinate beds, all abounding in organic remains, chiefly marine-all extinct. 6. TERTIARY or SUPRACRETACEOUS FORMATIONS, composed chiefly of clays, sands, gravels, and limestones, containing a mixture of extinct and recent animal remains, and distinguished by the presence of those of numerous Mammalia, extinct and recent; -7. Recent deposits of clay, sand, gravel, limestones, &c., from existing rivers, lakes, &c., formed during the historical era, and sometimes containing the remains of man or of his works. Geometry (Gr. ge, and metron a measure), the science which treats of and explains the properties of figured space, and the proportions, properties, and measurement of lines and surfaces. In architecture, Geometrical elevation is a design for any part of a building drawn according to the rules of geometry, as opposed to the perspective or natural elevation.Geometrical staircase is a term applied to a staircase when the stairs are supported only by being inserted in the wall at one end, with a continued range of balusters at the other. -In arithmetic, Geometrical progression is when a series of numbers are in geometrical proportion, and have a common ratio or multiplier; thus, multiply 1 by 2, and the number produced by 2 again, and the second result by 2, the numbers resulting will consequently be in geometrical progression. The series will, of course, be 1, 2, 4, 8, 16, 32. Geon'omy (Gr. ge, and nomos law), the science of physical laws. Geopon'ics (Gr. ge, and ponos labour), the science or art of cultivating the earth; agriculture, or rural economy. Geora'ma (Gr. ge, and orao to see), a hollow sphere which interiorly exhibits a complete geographical view of the earth's surface. Geoscopy (Gr. ge, and skopeo to view), a knowledge of the nature and qualities of soil gained by viewing it.. Geosele'nic (Gr.), relating to the earth and moon. Geothermometer (Gr. ge, and therma warmth), an instrument for measuring the warmth of the earth, or ascertaining the degree of heat contained in the earth at different places, especially in artesian wells, mines, &c. German Silver, in metallurgy, an alloy or mixture of copper, zinc, and other metal.-German steel, a metal made of pig or white plate iron, in forges where charcoal is used for fuel. |