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A DICTIONARY

OF

OF

SCIENCE, LITERATURE, & ART,

COMPRISING

THE DEFINITIONS AND
DERIVATIONS OF THE SCIENTIFIC TERMS IN
GENERAL USE, TOGETHER WITH THE HISTORY AND DESCRIPTIONS OF THE
SCIENTIFIC PRINCIPLES OF NEARLY EVERY BRANCH

OF HUMAN KNOWLEDGE.

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AUTHOR OF
HISTORY OF GREECE,' "THE MYTHOLOGY OF THE ARYAN NATIONS, ETC.

NEW EDITION, REVISED.

IN THREE VOLUMES.

VOL. II.

LONDON:
LONGMANS, GREEN, AND CO.

198. e. 100

DICTIONARY

OF

SCIENCE, LITERATURE, AND ART.

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GADOLINITE G. The seventh letter of the English alpha-The distribution of this tax was most capricious bet, but the third in those of all the Oriental and arbitrary; and it may safely be affirmed that languages, and also of the Greek. The form the gabel was one of the greatest curses imof our Ğ is borrowed from the Roman alphabet. posed on France previously to the Revolution. G, in English, has two sounds; before a, 0, Gabian O11. A petroleum or mineral and 14, and occasionally before i and e, it is the naphtha exuding from the strata at Gabian, at medial letter of the guttural order; the other village in Languedoc. sound, which it possesses only before e and i, Gabions (Fr.; Ital. gabbione). In Fortiis one of the medials of the sibilant series. fication, cylinders, open at both ends, made The guttural G is liable to a variety of changes of twigs or bands of iron twisted round stakes. in different dialects and languages.

When filled with earth, they are used as a screen G, as a Roman abbreviation, is used for from the enemy's fire, and to revet parapets. gratis, gens, gaudium, &c. G.V. signifies genio Gable (Ger. giebel). In Architecture, the urbis, G.L. genio loci, and G.P.R. gloria populi vertical part of a wall at the end of a roof, Romani. As a numeral, it denoted 400. On from the level of the eaves to the summit. the French coins G indicates the city of Poi- Gaddy. [CESTRUM.] tiers; and in chronology it is the seventh Gadoids, Gadoidae (Gr. gados, cod). A Dominical letter.

family of soft-finned fishes, which belong to the G. In Music, a note of the scale correspond section Subbrachians, or those which have the ing to the sol of the French and Italians. | ventral fins below or in advance of the pec

Gabardine or Gabordine (Span. gabar-torals, and of which the cod-fish (Gadus mordina). A coarse frock or dress, mentioned by rhua, Linn.) may be regarded as the type. Shakspeare in the Tempest and Merchant of The general character of the Gadoid family Venice.

is as follows: Body moderately elongated, subGabbronite (gabbro, the Italian name of compressed, and corered with soft and very a rock composed of Diallage and Felspar). A numerous scales; head smooth; jaws and front mineral found in a vein of titaniferous iron of the vomer armed with pointed, unequal, near Arendal, in Norway. It is a silicate of moderate, or small teeth, disposed in several alumina, soda, and potash. It has also been rows, like a rasp; gill-openings large, and with termed Fuscite and Compact Scapolite, seven rays; most of the species with two or

Gabel (Fr. gabelle, said to be derived from three dorsal and one or two anal fins; stomach the Teutonic word geben, to give). Any impost strong and capacious; cæcal appendages very laid on commodities was originally thus termed numerous ; air-bladder large, with strong pain France: as, gabelle de vin, de draps, &c.; but rietes, often dentated laterally. The greater the word acquired in the course of time the number of the cod tribe inhabit the seas of cold peculiar signification of a duty on salt, which is or temperate latitudes; their flesh is white meant when the word gabelle is used simply. and well-flavoured; they are very prolific, The gabel was first established in the early and constitute the most important subject of part of the fourteenth century, during the reign fisheries. The great sand-bank of Newfoundof Philip of Valois, and with a brief interrup- land is the most famous of the cod fisheries. tion of five years, from 1340 to 1345, continued (FISHERY.) to be levied down to the reign of Louis XVI., Gadolinite. A silicate of yttria, found in at which time the revenue which it produced Sweden, chiefly near Fahlun, and at Ytterby, was estimated at thirty-eight millions of francs. near Stockholm, in imperfect green crystals, and

VOL II.

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Circle.

GADUS

GALAXY in amorphous masses, embedded in a coarse- | ecliptic is to planetary astronomy—a plane grained granite. It was named after the Rus- of ultimate reference, the ground-plane of the gian chemist Gadolin, who discovered in it a sidereal system. [GALAXY.) new earth, yttria.

Galactic Poles. The two opposite points Gadus (Gr. gyddos). [Ganoids.)

of the heavens, situated at 90° from the Galactic Gaelic or Gadholic. [ERSE.]

Gaff. The boom or yard extending the Galactin (Gr. gyára, milk). A substance upper edge of what are called fore and aft sails. yielding gelatin found in milk by Morin. (JourThe gaff turns on the mast against which its nal für Pharmacie [3] xxv. 423.) thicker end rests; the mast, as an axis, occupy- / Galactite (Gr. ydra). A fossil substance, ing a semicircular cavity in the end of the not unlike French chalk. When immersed in gaff. This cavity is known as the gaff's jaws. water, it has the colour of milk. It is supported by two independent ropes; the Galactodendron (Gr. gara, milk; 8évdpov, throat halliards at the mast, and the peak hal-a tree). [BROSIMUM; COW-TREE ; GALACTINE.) liards at the outer end. It is steadied, when Galactopoiotic (Gr. yára, milk, and morew, the sail is not set, by ropes at the extremity 1 make). A term applied by some medical called vangs.

writers to diet and medicine supposed to proGage or Gauge (Fr. jauge). In Architec- mote the secretion of milk. ture, the length of a slate, or tile, exposed Galangal. A dried root brought from beyond the lap; also the measure to which China; it has an aromatic smell, and a pungent anything is confined. Plasterers use the word bitter flavour, and was formerly used in medito signify the greater or less quantity of plaster cine. The greater galangal is the produce of of Paris used with the common lime and hair the Kæmpferia Galanga, and the lesser of the to accelerate the setting; bricklayers use it to Maranta Galanga. express the state of mortar: thus, they say a Galanthus (Gr. yara, milk, and ávdos, a mortar is gauged stiff, or thin, as it partakes flower). The Snowdrop genus, especially inof one or other of those qualities. Engineers teresting in gardens as being the first pale use the word to express the distance between blossom of the unripened year. The common rails, the thickness of boiler plate, wire, copper, Snowdrop is G. nivalis ; a larger and finer speand other materials.

cies, G. plicata, is a native of the Crimea. GAGE or GAUGE. In Physics, any apparatus Galatea. [Acts.) for measuring pressure, force, height, depth or | Galathæa. A genus of long-tailed (masize. Thus the gage of an air-pump indicates crourous) Crustacea, including some very beauthe extent to which the rarefaction in the re- tiful species (G, rugosa, strigosa et squamifera), ceiver has been carried. [AIR-PUMP.] The occasionally found on the British coasts. The steam gage measures the pressure of steam in true Galathea have the thorax oblong or ovoid, any vessel; the wind gage, the force of the the median antennæ produced, and the pincers wind; the tide gage, the height of the tide, &c. elongated. This term is derived from the name [ANEMOMETER; HYDROMETER.] .

of the nymph Galatea. Gahnite. A native aluminate of zinc, called Galaxy (Gr. o yanatlas KÚKAOS). The Via also Automolite. Named after Gahn, who first Lactea or Milky Way. This luminous zone, so described it.

remarkable in a clear night, must have attracted Galllarde. The name of a lively dance the notice of the first observers of the heavens, peculiar to Italy, and supposed to have been and its true nature seems to have been surmised practised by the ancient Romans, whence it is at an early period. Manilius, in his Astronosometimes designated Romanesque.

micon, after alluding to the well-known mythoGainage. In old English writers, this word logical fable of its origin, asks— signifies the draught oxen, horses and their

Anne magis densi stellarum turba corona furniture, which were left free when a villein Contexit flammas, et crasso lumine candet, was amerced, that agriculture might not be Et fulgore nitet collato clarior orbis ? interrupted.

The explanation of the phenomenon here sug Gaining Twist. In rifled arms, a twist or gested, namely, the condensed light of countless spiral inclination of the grooves, which becomes multitudes of small stars so crowded together more rapid towards the muzzle.

as to be individually undistinguishable, is asGalactic Circle (Gr. galaktikos, milky). cribed to Democritus, and its truth was conA term first used by Sir John Herschel to de- firmed, or at least rendered much more pronote that great circle of the heavens to which bable, immediately on the discovery of the the course of the Milky Way, as traced by the telescope, Galileo himself enumerating among unaided eye, most nearly conforms. It is in the advantages resulting from his instrument, clined, at an angle of about 63°, to the equator, that of putting an end to the disputes about the and cuts that circle in two points, whose right nature of the Milky Way. About the middle of ascensions are respectively about Oh. 47 m. the last century, Wright of Durham, and Kant and 12 h. 47 m., so that its northern and south- and Lambert in Germany, speculated on the ern poles respectively are situated in R.A. connection of the phenomenon with the general 12 h. 47 m., N.P.D. 63°, and R.A. 0 h. 47 m., arrangement of the stars in space; but the X.P.D. 1170. This circle, Sir John Herschel first who undertook a systematic examination observes, is to sidereal what the invariable of the galaxy with telescopes of adequate power was Sir William Herschel, and to the indefa- of contrast with the luminosity of the Milky tigable labours of this great astronomer, and Way, which surrounds it on all sides, and which to those of Sir John F. W. Herschel (who, in this region is remarkably brilliant. during his memorable residence at the Cape, It is to be remarked that the great increase with the same telescope which had been used by in the number of stars observed in the neighhis father, and by a similar process of exami- bourhood of tho galaxy is occasioned chiefly by dation, explored those regions of the sky which the greater abundance of telescopic stars, i.e. are invisible in our latitudes), astronomers are of those below the sixth order of magnitude. mainly indebted for the facts upon which any Stars of the first magnitude are distributed sound speculation respecting the constitution of over the sphere with tolorable uniformity. If, the heavens can as yet be founded.

however, we take the whole number visible to The Milky Way, as seen by the naked eye, the naked eye, a rapid increase is perceptible presents the appearance of a succession of as we approach the limits of the galaxy; with luminous patches of varying intensity. Its respect to those of smaller magnitudes, the acbreadth is very unequal, in some parts hardly cumulation along that circle and its branches exceeding 5o, in others extending to 16°; and almost exceeds imagination. The minuteness there is a part between Serpentarius and An- of the stars indicates their enormous remotetinous where the two branches into which it is ness. As far as number is concerned it is there divided occupy together a breadth of 22o. estimated that of 20,000,000 visible in powerful Its course through the heavens is nearly that of telescopes 18,000,000 are in the Milky Way. a great circle inclined at an angle of about 630 From the relatively greater abundance of to the equator, and cutting that circle in two stars in the plane of the Galactic Circle than points whose right ascensions are, respectively, in the regions on either side of it, and from 0 h. 47 m. and 12 h. 47 m. Struve remarks the indication of some preponderance on the that the most condensed stratum does not lie southern side, Sir W. Herschel drew the conexactly in one plane, but appears rather to be clusion that the galaxy is composed of a contained in two different planes inclined at an stratum of stars of which the thickness is inangle of 10', and intersecting in the plane of considerable in comparison with its length and the celestial equator, the sun being at a little breadth, and that the sun is placed not far from distance from the line of intersection. This the middle of the stratum, somewhat nearer to slight deviation from a great circle had been its northern than to its southern surface, and remarked at an earlier period, and Lambert near tho point where it subdivides into two supposed it might be occasioned by the place principal laminæ inclined at a small angle to of the sun being not exactly in the middle of each other. Assuming the real magnitudes of the zone, but a little on one side. It is con- stars to be the same, on the average, through venient, however, in speaking generally of the the whole sidereal system, he determined by a system of the galaxy, to refer it to a great series of photometrical experiments that stars circle of the sphere; and the great circle to of the sixth magnitude (the least visible to the which it most nearly conforms has been named naked eye) are twelve times more remote than by Sir John Herschel the Galactic Circle. those of the first, and that the penetrating power

At several parts of its course the Milky Way of his twenty-foot telescope was seventy-five throws off streams or branches. In Perseus times greater than that of the naked eye, so a branch is sent off which is traceable to that the smallest stars visible in the telea considerable distance. Another proceeds scope are at a distance equal to 900 times the from a point near the star m Puppis, Dearly distance of Sirius. Now, as the arerage appaon the southern tropic. In Argo it opens rent breadth of the Milky Way is about 50, out into a wide fan-like expanse, nearly 200 in its thickness at that great distance must be breadth, which terminates abruptly, and at 900 x sin 5°, or equal to seventy-eight times this part its continuity is interrupted by a wide the distance of Sirius, or more than six times gap. At a Centauri it again subdivides. At the distance of the stars of the sixth magnitude. 9 Sagittarii it suddenly collects into a virid Therefore the Milky Way, even in the direction oral mass, about 6° in length and 4° in breadth, of its poles, extends to three times the distance So exceedingly rich in stars that a moderate of the smallest stars visible to the unaided eye, calculation gives upwards of 100,000. On the the sun being supposed at the centre of the other hand, spaces occur in the very middle of stratum. Hence it follows that not only our its course, which appear, to the naked eye, solar system, but all the stars in the firmament, entirely devoid of stars, and perfectly black. visible to the naked eye, are plunged to a great The most remarkable of these is situated in depth in the stratum of stars composing the the Southern Cross, where the Milky Way galaxy, and form an integral part of it. approaches the nearest to the south pole, and I: must be kept in mind that the above so striking is its appearance that the early conclusions are based on two hypotheses which navigators designated it by the name of the are, at best, very precarious; and in fact both coal sack. This space is of an irregular pear of them appear to have been abandoned by Sir shaped form; it is about 8° in length and 5° W. Herschel himself in his later years. With in breadth, and was described and figured by respect to the first, namely, the distribution of the Abbé Feuillée in 1710. Lacaille correctly the stars in space at nearly equal distances attributed its striking blackness to the effect from each other, he remarks, in a paper pub

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