most advantageous posts, either for fight- round its diameter, generates a sphere, The office of a general is to regulate the march and encampment of the army; in the day of battle to choose out the most advantageous ground; to make the disposition of the army; to post the artillery; and, where there is occasion, to send his orders by his aids-de-camp. At a siege, he is to cause the place to be invested; to order the approaches and attacks ; to visit the works; and to send out detachments to secure his convoys. GENERAL issue, in law, is that plea which traverses and denies, at once, the whole declaration or indictment, without offering any special matter, whereby to evade it and it is called the general issue, because, by importing an absolute and general denial of what is alleged in the declaration, it amounts at once to an issue; that is, a fact affirmed on one side, and denied on the other. This is the ordinary plea upon which most causes are tried, and is now almost invariably used in all criminal cases. It puts every thing in issue, that is, denies every thing, and requires the party to prove all that he has stated. It is a frequent question, what can be given in evidence by the defendant upon this plea, and the difficulty is, to know when the matter of defence may be urged upon the general issue, or must be specially pleaded upon the record. In many cases, for the protection of justices, constables, excise officers, &c. they are by act of parliament enabled to plead the general issue, and give the special matter for their justification under the act in evidence. GENERATING line or figure, in geo. metry, is that by which its motion produces any other plane or solid figure. Thus, a right line moved any way parallel to itself generates a parallelogram; round a point in the same plane, with one end fastened in that point, it generates a circle. One entire revolution of a circle, in the same plane, generates the cycloid; and the revolution of a semi-circle GENERATION. See PHYSIOLOGY. GENERICAL name, in natural history, the word used to signify all species of na tural bodies, which agree in certain essential and peculiar characters, and therefore all of the same family or kind; so that the word used as the generical name equally expresses every one of them, and some other words, expressive of the peculiar qualities or figures of each, are added, in order to denote them singly, and make up what is called the specific name. Thus the word rosa, or rose, is the generical name of the whole series of flowers of that kind, which are distinguished by the specific names of the red-rose, the whiterose, the apple-rose, &c. GENEVA, gin, a hot fiery spirit, tou much used by the lower classes of people in this country as a dram, and is unquestionably most injurious to their constitution and morals. A liquid of this kind was formerly sold in the apothecaries' shops, drawn from the juniper-berry, but distillers have now completely supplanted the trade of the apothecary, who sell it under the name of Geneva, or gin, in which it is believed juniper-berries make no part of the composition. It is composed of oil of turpentine and malt spirits.A better sort is said to be drawn off by a slow fire from juniper berries, proof-spirits, and water, in the proportion of three pound of berries to four gallons of water and ten of spirit. The celebrated Hollands geneva is manufactured chiefly at a village near Rotterdam, from the same materials, making use of French brandy instead of malt-spirits. GENIOSTOMA, in botany, a genus of the Pentandria Monogynia class and order. Essential character: calyx turbinate, five-cleft; corolla one-petalled, with a villose throat, and a five-parted border; capsule oblong, two-celled, many seeded. There is but one species, a native of the isle of Tanna, in the South Seas. GENISTA, in botany, a genus of the Diadelphia Decandria class and order. Natural order of Papilionacea or Leguminosa. Essential character: calyx twolipped, two and three-toothed; banner oblong, reflex downwards from the pistil and stamens. There are seventeen species. GENIUS, in matters of literature, &c. a natural talent or disposition to do one thing more than another; or the aptitude a man has received from nature to per form well, and easily, that which others can do but indifferently, and with a great deal of pains. GENTIAN, in pharmacy, is to be found in many countries, but particularly in some parts of France, on the Aips, Py renees, and the mountainous districts of Germany. That used in this country is mostly brought from Germany. The roots are the only part of the plant made use of in medicine. Gentian stands at the head of the stomachic bitters. GENTIANA, in botany, a genus of the Pentandria Digynia class and order. Natural order of Ro aceæ. Gentianæ, Jussieu. Essential character: corolla monopetalous; capsule superior, twovalved, one-celled, with two longitudina! receptacles. There are fifty-three species. GENUS, among metaphysicians and logicians, denotes a number of beings, which agree in certain general properties, common to them all; so that a genus is an abstract idea, expressed by some general name or term. A genus is an assemblage of several species: that is, of several plants which resemble one another in their most essential parts. Hence it is aptly enough compared to a family, all the relations of which bear the same surname, although every individual is distinguished by a particular specific name. In botany the establishment of genera renders the subject more simple and easy, by abridging the number of names, and arranging under one denomination, termed the generic name, several plants, which, though different in many other respects, are found invariably to possess certain relations in those essential parts, the flower and fruit. Plants of this kind are termed by botanists planta congeneres, that is, plants of the same genus. Linneus's genera contain a description of each particular part of fructification, its various relations and different modes with respect to number, figure, situation, and proportion. Thus, all the different species of calyx, corolla, nectarium, stamina, &c. furnish the observer with so many sensible and essential characters. These characters the author denominates the letters or alphabet of botany. By studying, comparing, and, as it were, spelling these letters, the student in botany comes, at length, to read and understand the generical characters which the great Creator has originally imprinted upon vegetables: for the genera and species, according to Linnæus, are solely the work of nature; whilst the classes and orders are a combination of nature and art Upon these principles, Linnæus, in his genera plantarum, determines the generical characters of all the plants there described. GENUS, in natural history, a sub-division of any class or order of natural beings, whether of the animal, vegetable, or mineral kingdoms, all agreeing in certain common characters. GEOCENTRIC latitude of a planet, is its distance from the echiptic as it is seen from the earth, which, even though the planet be in the same point of her orbit, is not constantly the same, but a ters according to the position of the earth in respect to the planet. GEOCENTRIC place of a planet, the place wherein it appears to us from the earth, supposing the eye there fixed: or it is a point in the ecliptic to which a planet seen from the earth is referred. GEODESIA, the same with surveying. See SURVEYING. GEOFFROYA, in botany, so named in honour of Monsieur Geoffroy, a member of the academy at Paris, a genus of the Diadelphia Decandria class and order. Natural order of Papilionacea or Legu minosa. Essential character: calyx fivecleft; drupe ovate; nut flatted. There are two species. GEOGRAPHY, is that science which exhibits the results of our investigations respecting the planet we inhabit, whether we consider its figure and the disposition of the lands and water upon its surface, or the subdivisions which the different nations who inhabit it have made, by which it is considered as forming kingdoms and states. The general curvature of the earth's surface is easily observable in the disappearance of distant objects; and, in particular, when the view is limited by the sea, the surface of which, from the common property of a fluid, becomes naturally smooth and horizontal; for it is well known that the sails and rigging of a ship come into view long before her hull, and that each part is the sooner seen as the eye is more elevated. On shore the frequent inequalities of the solid parts of the earth usually cause the prospect to be bounded by some irregular prominence, as a hill, a tree, or a building, so that the general curvature is the less observable. The surface of a lake, or sea, must be always perpendicular to the direction of a plumb line, which may be considered as the direction of the force of gravity; and by means either of a plumb line, or of a spirit level, we may ascertain the angular situation of any part of the earth's sur face with respect to a fixed star passing the meridian by going a little further north or south, and repeating the obser vation on the star, we may find the difference of the inclination of the surfaces at both points; of course, supposing the earth a sphere, this difference in latitude will be the angle, subtended at its centre by the given portion of the surface, whence the whole circumference may be determined, and on these princ ples the earliest measurements of the earth were conducted. The first of these which can be considered as accurate, was executed by Picart, in France, towards the end of the seventeenth century. But the spherical form is only an apIt was calcuproximation to the truth. lated by Newton, and ascertained experimentally by the French academicians, sent to the equator and to the polar circle, that, in order to represent the earth, the sphere must be flattened at the poles, and prominent at the equator. We may therefore consider the earth as an oblate elliptic spheroid; the curvature being greater, and consequently every degree shorter at the equator, than nearer the poles. If the density of the earth were uniform throughout, its ellipticity, or the difference of the length of its diameters, would be of the whole; on the other hand, if it consisted of matter of inconsiderable density, attracted by an infinite force in the centre, the ellipticity would be only; and whatever may be the internal structure of the earth, its form must be between these limits, since its internal parts must necessarily be denser than those parts which are nearer the surface. If, indeed, the earth consisted of water or ice, equally compressible with common water or ice, and following the same laws of compression with elastic fluids, its density would be several thousand times greater at the centre than at the surface; and even steel would be compressed into one-fourth of its bulk, and stone into one-eighth, if it were continued to the earth's centre: so that there can be no doubt but that the central parts of the earth must be much more dense than the superficial. Whatever this difference may be, it has been demonstrated by Clairaut, that the fractions expressing the ellipticity, and the apparent diminution of gravity at the equator, must always make toge ther; and it has been found, by the most accurate observations on the lengths of pendulums in different latitudes, that the force of gravity is less powerful by 1 320 at the equator than at the pole, whence the ellipticity is found to be of the equatorial diameter; the form being the same as would be produced, if about three-eighths of the whole force of gravity were directed towards a central particle, the density of the rest of the earth being uniform. This method of determining the general form of the earth is much less liable to error and irregularity, than the measurement of the lengths of degrees in various parts, since the accidental variations of curvature produced by local differences of density, and even by superficial elevations, may often produce considerable errors in the inferences which might be deduced from these measurements. For example, a degree measured at the Cape of Good Hope, in latitude 330 south, was found to be longer than a degree in France, in latitude 56 north, and the measurements in Austria, in North America, and in England, have all exhibited signs of similar irregularities. There appears also to be some difference in the length of degrees under the saine latitude, and in different longitudes. We may, however, imagine a regular elliptic spheroid to coincide very nearly with any small portion of the earth's surface, although its form must be somewhat dif ferent for different parts: thus for the greater part of Europe, that is, for England, France, Italy, and Austria, if the measurements have been correct, this oscillating spheroid must have an ellipticty of 130 The earth is astronomically divided into zones and into climates. The torrid zone is limited by the tropics, at the distance of 23° 23' on each side of the equator, containing all such places as have the sun sometimes vertical, or imme. diately over them: the frigid zones are within the polar circles, at the same distance from the poles, including all places which remain annually within the limit of light and darkness, for a whole diurnal rotation of the earth, or longer: the temperate zones between these, have an uninterrupted alternation of day and night, but are never subjected to the sun's vertical rays. At the equator, therefore, the sun is vertical at the equinoxes, his least meridian altitude is at the solstices, when it is 66° 32', that is, more than with us at midsummer; and this happens once on the north, and once on the south side of the hemisphere. Between the equator and the tropics he is vertical twice in the year, when his declination is equal to the latitude of the place, and his least meridian altitudes, which are unequal between themselves, are at the solstices. At the tropics, the meridian sun is vertical once only in the year, and at the opposite solstice, or the time of midwinter, his meridian altitude is 43° 4′, as with us in April and the beginning of September. At the polar circles the sun describes, on midsummerday, a complete circle, touching the north or south point of the horizon; and in midwinter he shews only half his disc above it, for a few minutes, in the opposite point; that is, neglecting the elevation produced by refraction, which, in these climates especially, is by no means inconsiderable. At either pole, the corresponding pole of the heavens being vertical, the sun must annually describe a spiral, of which each coil is nearly horizontal, half of the spiral being above the horizon, and half below; the coils being much more open in the middle than near the end. The climates, in the astronomical sense of the word, are determined by the duration of the longest day in different parts of the earth's surface; but this division is of no practical utility, nor does it furnish any criterion for judging of the climate in a meteorological sense. The natural division of the surface of the globe is into sea and land; about three-fourths of the whole being occupied by water, although probably no where to a depth comparatively very considerable, at most of a few miles on an average. The remaining fourth consists of lands, elevated more or less above the level of the sea, interspersed, in some parts, with smaller collections of water, at various heights, and in a few instances, some what lower than the general surface of the main ocean. Thus the Caspian Sea is said to be about three hundred feet lower than the ocean; and in the interior parts of Africa there is probably a lake equally depressed. We cannot observe any general symmetry in this distribution of the earth's surface, excepting that the two large comanents of Africa and South America have some slight resemblance in their forms, and that each of them is terminated to the eastward by a collection of numerous islands. The large capes projecting to the southward have also a similarity with respect to their form, and the islands near them; to the west the continents are excavated into large bays, and the islands are to the east: thus Cape Horn has the Falkland Islands; the Cape of Good Hope, Madagascar; and Cape Comorin, Ceylon, to the east. The great continent, composed of Europe, Asia, and Africa, constitutes about a seventh of the whole surface of the earth: America about a sixteenth; and Australasia, or New South Wales, about a fiftieth; or in hundreth parts of the whole, Europe contains two; Asia, seven; Africa, six; America, six; and Australasia, two: the remaining seventy-seven being sea; although some authors assign seventy-two parts only out of one hundred to the sea, and twenty-eight to the land. These proportions may be ascertained with tolerable accuracy by weighing the paper made for covering a globe, first entire, and then cut out according to the terminations of the different countries; or, if still greater precision were required, the greater part of the continents might be divided into known portions of the whole spherical surface, and the remaining irregular portions only weighed. The general inclinations and levels of the continents are discovered by the courses of their rivers. Of these the principal are, the river of Amazons, the Senegal, the Nile, the river St. Lawrence, the Hoangho, the river La Plata, the Jenisei, the Mississippi, the Volga, the Oby, the Amur, the Oronooka, the Ganges, the Euphrates, the Danube, the Don, the Indus, the Dnieper, and the Dwina; and this is said to be nearly the order of their magnitudes. But if we class them according to the length of country through which they run, the order will, according to Major Rennel's calculation, be somewhat different; taking the length of the Thames for unity, he estimates that of the River Amazons at 15; the Kian Kew, in China, 15; the Hoangho, 13; the Nile, 12; the Lena, 114; the Amur, 11; the Oby, 10; the Jenisei, 10; the Ganges, its companion the Burampooter, the river of Ava, and the Volga, each 94; the Euphrates, 8; the Mississippi, 8; the Danube 7; the Indus, 5; and the Rhine, 54 We may form a tolerable accurate idea of the levels of the ancient continent, by tracing a line across it in such a direction as to pass no river, which will obviously indicate a tract of country higher than most of the neighbouring parts. Begin ning at Cape Finisterre, we soon arrive at the Pyrenees, keeping to the south of the Garronne and the Loire. After taking a long turn northwards, to avoid the Rhine, we come to Swisserland, and we may approach very near to the Mediterranean, in the state of Genoa, taking care not to cross the branches of the Po. We make a circuit in SwisserJand, and pass between the sources of the Danube, and of the branches of the Rhine, in Swabia. Crossing Franconia, we leave Bohemia to the north, in order to avoid the Elbe; and coming near to the borders of Austria, follow those of Hungary to the south of the Vistula. The Dnieper then obliges us to go northwards through Lithuania, leaving the Don wholly to the right; and the Volga, to pass still further north, between Petersburg and Moscow, a little above Bjelosero. We may then go eastwards to the boundary of Asia, and thence northwards to Nova Zembla. Hence we descend to the west of the Oby, and then to the east of the branches of the Volga, and the other inland rivers flowing into the lake Aral and the Caspian Sea. Here we are situated on the widely extended elevation of India, in the neighbourhood of the sources of the Indus; and, lastly, in our way from hence towards Kamschatka, we leave the Jenisei and Lena on the left, and the Ganges, the Kiang Kew, the Hoangho, and the Amur, to the right. The direction of the most conspicuous mountains is, however, a little different from this; the principal chain first constitutes the Pyrenees,and divides Spain from France; then passes through Vivarais and Auvergne, to join the Alps, and through the south of Germany to Dalinatia, Albania and Macedonia; it is found again beyond the Euxine, under the names of Taurus, Caucasus, and Imaus, and goes on to Tartary and to Kamschatka. The peninsula of India is divided from north to south by the mountains of Gate, extending from the extremity of Caucasus to Cape Comorin. In Africa, Mount Atlas stretches from Fez to Egypt, and the mountains of the Moon run nearly in the same direction: there is also a considerable elevation between the Nile and the Red Sea. In the new world, the neigh. bourhood of the western coast is, in general, the most elevated; in North America, the Blue Mountains, or Stony Mountains, are the most conisderable; and the mountains of Mexico join the Andes or Cordeliers, which are continued along the whole of the west coast of South America. There are several points, in both hemispheres, from which we may observe rivers separating to run to different seas; such are, Swisserland, Bjelosero, Tartary, Little Tibet,Nigritia or Guinea, and Quito. The highest mountains are, Chimboracao, and some others of the Cordeliers in Peru, or perhaps Descabesado, in Chili, Mont Blanc, and the Peak of Teneriffe. Chimboracao is about seven thousand yards, or nearly four miles, above the level of the sea; Mont Blanc, five thou sand, or nearly three miles; the Peak of Teneriffe, about four thousand, or two miles and a quarter; Ophir, in Sumatra, is said to be five or six hundred feet higher It has, however, been asserted, that some of the snowy mountains to the north of Bengal are higher than any of those of South America. The plains of Quito, in Peru, are so much elevated, that the barometer stands at the height of fifteen inches only, and the air is reduced to half its usual density. But none of these heights is equal to a thousandth part of the earth's semi-diameter, and the greatest of them might be represented, on a six-inch globe, by a single additional thickness of the paper with which it is covered. Mount Sinai, in Japan, Mount Caucasus, Etna, the Southern Pyrenees, St. George among the Azores, Mount Adam, in Ceylon, Atlas, Olympus, and Taurus, are also high mountains; and there are some very considerable elevations in the island of Owyhee. Ben Nevis, in Scotland, is the loftiest of the British hills, but its height is considerably less than a mile. The most elevated mountains, excepting the summit of volcanos, consist of rocks, more or less mixed, without regular order, and commonly of granite or porphyry. These are called primary mountains; they run generally from east to west in the old world, and from north to south in the new; and many of them are observed to be of easier ascent on the east than the west side. The secondary mountains accompany them in the saine direction; they consist of strata, mostly calcareous and argillaceous, that is, of the nature of lime-stone and clay, with a few animal and vegetable remains, in an obscure form, together with salt, coals, and sulphur. The tertiary mountains are still smaller; and in these, animal and vegetable remains are very abundant; they consist chiefly of lime-stone, marble, alabaster, building-stone, mill-stone, and |