it any bigger, in the equatrial diameter gg, fig. 11, he lays the pipe on a hook driven in the side of the stool, and turns it round very quickly, the centrifugal force soon enlarges it in the equator. If on the other hand he wishes to lengthen its polar diameter, he holds the pipe perpendicular, the glass hanging downwards, its weight lengthening it, and to shorten the polar diameter he holds the pipe upright, the glass at the top; by blowing through the pipe the capacity is increased, and the thickness of the glass of the vessel diminished. bees-wax, the cold of these plicrs, instantly cracks the glass all round, and a very slight jerk struck upon the rod 8, breaks it off. A hole is now made in the end of the glass, which is enlarged by the pliers while the glass is turned, as in fig. 13, until the neck is brought to the proper size and length to fit the brass cap as before described, and the inferior half of the lamp is brought to its shape and size in the same manner. In order to form the upper half, the third workman has in the mean time being preparing a round lump of glass K, fig. 14, on the end of one of the rods fig. 8, this he applies hot to the end of the neck, it being guided by the principal workman, and it immediately holds tight, he then breaks off the other neck at 7, by the cold pliers, and thus separates it from the blowing pipe. We now suppose that by a very dexterous application of the above methods, the workmen has brought it to the shape of fig. 11, he now carries it to the mouth of the furInace, and holds it in to get a fresh heat, (for by this time it is become too stiff to work easily,) taking care to turn it round slowly, that it may not alter its figure. The vessels in this stage is delivered to the second, or principal workman, the other two being only assistants, he is seated upon the stool, figs. 1 and 2, and lays the blowing pipe with the glass at its end across its arm ab, and with his left hand rolls the pipe along the arms, turning the glass and pipe round at the same time; in his right hand he holds the pliers, fig. 3, whose blades are rubbed over with a small piece of beeswax, and as the glass turns round presses the blade of the shears against it, following it with the shears as it rolls, at the end or side as occasion requires, until he has brought it to the proper size which he determines by the compasses, fig. 4, though not materially altering its figure, the first workman kneeling on the ground and blow-cooled gradually, and is fit for sale. ing with his mouth at the end of the pipe, which hangs over the arm b when directed by his principal. The third workman now produces the small rod, fig. 8, which is dip ped into the melting pot to take up a small piece of metal to serve as cement, the end of this rod he applies to the centre of the glass just opposite the blowing pipe, the principal workman directing it, by holding its end between his pliers, the rod by the small piece of glass on its end immediately sticks to the glass vessel, and the third workman draws it away, both workmen turning their rods round, but in contrary directions; this operation forms a short tube on the end, as in fig. 12. The principal workman then takes the short tube at i, between the blades of a pair of pliers, exactly like the others, but which are not covered with The glass is now heated a third time, and brought from the furnace in the state, fig. 15, to the principal workman, who enlarges the small orifice at the end by turning it round, and holding the pliers against it, until he enlarges it, as in fig. 16, to the shape of fig. 10, it is now finished, and the third workman takes it to a stool strewed over with small coals, he rests the rod upon the edge of the stool, and with the file, fig. 6, files the joint at the bottom neck and soon breaks off, and the lamp falls upon the coals, the distance being so very small, as to be in no danger of breaking; a boy now puts the end of a long stick into the open mouth of the glass, and thus carries it up the steps before described, places it in the annealling oven, where it remains some hours, when taken out it must be In the history of glass there is a fact deserving record; it is related by Pliny, that the discovery was owing to the following accident. Some merchants with soda as part of their freight, had cast anchor at the mouth of the river Belus, in Phoenicia, and were dressing their dinner on the sand, making use of large lumps of the soda as supports for their kettles. The heat of the fire melted the soda, and the siliceous earth together; the result was glass. The hint was not lost, and a manufacture in that trading country was instantly established, and to this place it was for a long time confined. Glass was undoubtedly made in great perfection among the ancients. In their accounts we read of drinking glasses, glass prisms, and coloured glasses of various kinds. Glass was first used for windows in the third century of the Christian æra, but it did not come into common use till very long after this. GLASS, painting on. See ENAMELling. GLASS, in sea affairs, the usual appellation for a telescope. A night-glass is a lelescope made for viewing objects at night. Half-hour glass, called also the watch-glass, is used to measure the time which each watch has to stay upon deck. Half and quarter-minute glasses are used to ascertain the rate of the ship's velocity, measured by the log; these glasses should be frequently compared with a good stop-watch, to determine exactly how many seconds they run. GLAUBER (JOHN RUDOLPH), an industrious chemist, was born in Germany, After passing a considerable time in travel, he settled at Amsterdam, about the middle of the seventeenth century. He wrote a rumber of works, mostly infected with the enigmatical jargon and unintelligible theory of the hermetic philosophy, yet containing some useful facts in true chemistry, and some processes of his own invention. His name is perpetuated in the purgative neutral salt called Glauber's, composed of the sulphurc acid and soda; a valuable remedy, but, together with others of his invention, extolled by himself to an extravagant degree. He kept several of his medicines secret, and made advantage of them as nostrums. Of his works an abridged collection was made in German, which was translated into English in 1689; but they are now consigned to oblivion. GLAUBER'S salt. See SODA, sulphate of. It is found native; and, according to Bergman, it contains sulphuric acid, soda, and water, in the proportions of 27.15.58; that is, when saturated with water of crystallization. When efflorescent, the native Glauber's salt contains, beside pure sulphate of soda, some oxide of iron, and portions of muriate and carbonate of soda. It is found in old salt-mines, on the borders of the salt lakes in different parts of the world, and on the surface of peat-mosses in France. It is also held in solution in the Natronlakes of Egypt, and the mineral springs of Carlsbad. Glauber's salt easily dissolves in water, and shoots into long and beautiful crystals, which contain a large quantity of water; in consequence of which they undergo the aqueous fusion, when exposed to heat. This salt, on account of its efficacy as a purgative, was formerly held in the highest esteem, and was denominated sal mirabile Glauberi. It has been used in VOL. III. some countries as a substitute for soda, in the manufacture of white glass. GLAUCOPIS, or the wattle-bird, in natural history, a genus of birds of the order Picæ. Generic character: bill incurvate and arched; lower mandible shorter than the upper, and carunculate beneath at the base; nostrils depressed, half covered with a cartilaginous membrane; tongue cartilaginous, split and ciliated at the end; legs carinated at the back; feet formed for walking. The G. cinerea, or cinereous wattle-bird, is about the size of a jay; it is found in every part of New Zealand: berries, and insects of almost every kind, constitute its food; it rarely perches on trees; but is often seen walking on the ground; its notes are said at different times to resemble whistlings and murmurings, and its flesh is good for the table. GLAUX, in botany, a genus of the Pen tandria Monogynia class and order. Natural order of Calycanthemæ. Salicariæ, Jussieu. Essential character: calyx one-leafed, bell-shaped ; corolla none; capsule onecelled, five-valved, five-seeded. There is only one species, viz. G. maritima, sea milkwort, or black salt wort. It is common on the sea-coast, and on salt marshes at a distance from the sea; it is a beautiful little plant, enlivening large tracts of the dreary situations where it is found; the whole plant is succulent, and salt to the taste. GLAZING, in the arts, is the polishing or crusting over earthen ware. When earthen ware is properly baked, it is dipped into a composition called a glaze, made by mixing together in water, till it becomes as thick as cream; fifty-six parts of white lead, twelve of ground flints, and three of ground flint glass. The ware, by being baked, acquires a strong property of imbibing moisture, and in this state, it is called biscuit; when dipped into the glaze, it at tracts it into its pores, and the ware be comes presently dry; it is then exposed a second time to the fire, by which means the glaze it has imbibed is melted, and a thin, glassy coat is formed upon the surface. The colour is more or less yellow, according as a greater or less proportion of lead has been used. The lead promotes also the vitrification; the flint serves to give a con, sistency to the lead during the time of its vitrification, and to prevent its becoming too fluid, and running down the sides of the ware, and thereby leaving them unglazed. This kind of glazing by lead, is Z liable to be attacked by acids, and of acting in some degree as a poison; a substitute has therefore been recommended, which consists of equal parts of white glass and soda finely pulverized, and exposed to a strong heat till quite dry, and with this the vessels are varnished or glazed. See POTTERY. GLEANING, in law. It hath been said, that by the common law and custom of England, the poor are allowed to enter and glean upon another's ground, after the harvest, without being guilty of trespass; and that this humane provision seems borrowed from the Mosaical law; but it is now positively settled, by a solemn judgment of the court of Common Pleas, that a right to glean in the harvest field cannot be claimed as a general right by every person at common law; nor as a custom by the poor of a parish, legally settled. GLEBE, or Glebe-land, is a portion of land, meadow or pasture, belonging to, or parcel of the parsonage or vicarage, over and above the tithes. Glebe lands, in the hands of the parson, shall not pay tithes to the vicar; nor, being in the hands of the vicar, shall they pay tithes to the parson. By statute 28 Henry VIII. c. 11, every successor, on a month's warning after induction, shall have the mansion-house, and the glebe belonging thereto, not sown at the time of the predecessor's death. He that is instituted, may enter into the glebe-land before induction, and has right to have it against any strangers. GLECHOMA, in botany, English groundivy, a genus of the Didynamia Gymnospermia class and order. Natural order of Verticillatæ. Labiatæ, Jussien. Essential character: calyx five cleft; each pair of an thers converging in form of a cross. There is but one species, viz. G. hederacea, ground-ivy. GLEDITSIA, in botany, a genus of the Polygamia Dioecia class and order. Natural order of Lomentaceæ. Leguminosa, Jussieu. Essential character: hermaphrodite; calyx four-cleft; corolla four-petalled; stamens six; pistil one, legume. There is only one species, with several varieties. GLEE, in music, a vocal composition in three or more parts, generally consisting of more than one movement, the subject of which may be either gay, tender, or grave; bachanalian, amatory, or pathetic. GLEET, in medicine, the flux of a thin, limpid humour from the urethra. GLINUS, in botany, a genus of the Dodecandria Pentagynia class and order. Na tural order of Coryophyllei. Ficoideæ, Jussieu. Essential character: calyx five-leaved; corolla none; nectaries cloven-bristles; capsule five-cornered, five-celled, five-valved, containing numerous seeds. There are three species. GLOBBA, in botany, a genus of the Diandria Monogynia class and order. Natural order of Scitamineæ. Cannæ, Jussieu. Essential character: calyx superior, trifid; corolla equal, trifid; capsule threecelled; seeds very many. There are four species. GLOBE, a round or spherical body, more usually called a sphere, bounded by one uniform convex surface, every point of which is equally distant from a point within called its centre. Euclid defines the globe or sphere, to be a solid figure described by the revolution of a semi-circle about its diameter, which remains unmoved. Also, its axis is the fixed line or diameter about which the semi-circle revolves; and its centre is the same with that of the revolving semi-circle, a diameter of it being any right line that passes through the centre, and terminated both ways by the superficies of the sphere. Euclid, at the end of the twelfth book, shews that spheres are to one another in the triplicate ratio of their diameters, that is, their solidities are to one another as the cubes of their diameters. And Archimedes determines the real magnitudes and measures of the surfaces and solidities of spheres and their segments, in his treatise "De Sphæra et Cylindro:" viz. 1. That the su perfices of any globe is equal to four times a great circle of it. 2. That any sphere is equal to two-thirds of its circumscribing cylinder, or of the cylinder of the same diameter and altitude. 3. That the curve surface of the segment of a globe, is equal to the circle whose radius is the line drawn from the vertex of the segment to the circumference of the base. 4. That the content of a solid sector of the globe, is equal to a cone whose altitude is the radius of the globe, and its base equal to the curve superficies or the base of the sector, with many other properties. And from hence are ea sily deduced these practical rules for the surfaces and solidities of globes and their segments; viz. 1. "For the Surface of a Globe," multiply the square of the diameter by 3.1416; or multiply the diameter by the circumference. 2. "For the Soli dity of a Globe," multiply the cube of the diameter by .5236 (viz. one-sixth of 3.1416); or multiply the surface by one-sixth of the diameter. 3." For the Surface of a Segment," multiply the diameter of the globe by the altitude of the segment and the product again by 3.1416. 4. "For the Solidity of a Segment," multiply the square of the diameter of the globe by the difference between three times that diameter and twice the altitude of the segment, and the product again by .5236, or one-sixth of GLOBE, in practical mathematics, an artificial spherical body, on the convex surface of which are represented the countries, seas, &c. of our earth; or the face of the heavens, the circles of the sphere, &c. That with the parts of the earth delineated upon its surface, is called the terrestrial globe; and that with the constellations, &c. the celestial globe. These globes are placed in frames, with other appurtenances. Their principal use, besides serving as maps to distinguish the ontward parts of the earth, and the situation of the fixed stars, is to illustrate and explain the phenomena arising from the diurnal motion of the earth. The globes commonly used are composed of plaster and paper in the following manner: A wooden axis is provided, somewhat less than the intended diameter of the globe, and into the extremes two iron wires are driven for poles: this axis is to be the beam or basis of the whole structure. On the axis are applied two spherical or rather hemispherical caps, formed on a kind of wooden mould or block. These caps consist of pasteboard or paper, laid one lay after another on the mould, to the thickness of a crown-piece; after which, having stood to dry and embody, making an incision along the middle, the two caps thus parted are slipped off the mould. They remain now to be applied on the poles of the axis, as before they were on those of the mould; and to fix them in their new place, the two edges are sewed together with pack thread, &c. The rudiments of the globe thus laid, they proceed to strengthen and make it smooth and regular. In order to this, the two poles are hasped in a metalline semicircle of the size intended; and a kind of plaster made of whiting, water, and glue, heated, melted, and incorporated together, is daubed all over the paper surface. In proportion as the plaster is applied, the ball is turned round in the semicircle, the edge of which pares off whatever is superfluous, and beyond the due dimension, leaving the rest adhering in places that are short of it. After such application of plaster, the ball stands to dry; which done it is put again in the semicircle, and fresh matter applied: thus they continue alternately to apply the composition, and dry it, till the ball every where accurately touches the semicircle; in which state it is perfectly smooth, regular, and complete. The ball thus finished, it remains to paste the map or description on it. In order to this, the map is projected in several gores or gussets, all which join accurately on the spherical surface, and cover the whole ball. To direct the application of these gores, lines are drawn by a semicircle on the surface of the ball, dividing it into a number of equal parts corresponding to those of the gores, and subdividing those again answerably to the lines and divisions of the gores. The papers thus pasted on, there remains nothing but to colour and illuminate the globe, and to varnish it, the better to resist dust, moisture, &c. The globe itself thus finished, they hang it in a brass meridian, with an hour-circle and a quadrant of altitude, and thus fit it into a wooden hori circles are the horizon, with its parallels shall now give some problems on both the and secondaries. The horizon is that broad wooden circle surrounding the globe, and dividing it into two equal parts, called the upper and lower hemispheres. It has two notches, to let the brazen meridian slip up and down, according to the different heights of the pole. On the flat side of this circle are described the twelve signs, the months of the year, the points of the compass, &c. The brazen meridian is an annulus or ring of brass, divided into degrees, viz. each quadrant in 90 degrees. It divides the globe into two equal parts, called the eastern and western lemispheres. The quadrant of altitude is a thin pliable plate of brass, auswering exactly to a quadrant of the meridian. It is divided into 90°, and has a notch, nut, and screw, to fix to the brazen meridian in the zenith of any place; where it turns round a pivot, and supplies the room of verticle circles. The hour-circle is a flat ring of brass, divided into twenty-four equal parts, or hour distances; and on the pole of the globe is fixed an index, that turns round with the globe, and points out the hours upon the hour-circle. Lastly, there is generally added a compass and needle upon the pediment of the frame. The surface of the celestial globe may be esteemed a just representation of the concave expanse of the heavens, notwithstanding its convexity; for it is easy to conceive the eye placed in the centre of the globe, and viewing the stars on its surface; supposing it made of glass, as some globes are: also that if holes were made in the centre of each star, the eye in the centre of the globe, properly placed, would view through each of the holes the very stars in the hea vens represented by them. As it would be impossible to have any distinct notion of the stars, in respect of their number, order, and distances, without arranging them in certain forms, called constellations, this the first observers of the heavens took care to do; and these, like kingdoms and countries upon the terrestrial globe, serve to distinguish the different parts of the superficies of the celestial globe. The stars, therefore, are all disposed in constellations under the forms of various animals, whose names and figures are represented on the celestial globe; which were first invented by the ancient astronomers and poets, and are still retained for the better distinction of these luminaries. We globes, beginning with the terrestrial globe. TERRESTRIAL GLOBE. PROB. 1. "To find the latitude and longitude of any place." Bring the place to the graduated side of the first meridian : then the degree of the meridian it cuts is the latitude sought; and the degree of the equator then under the meridian is the longitude. 2. "To find a place, having a given latitude and longitude.” Find the degree of longitude on the equator, and bring it to the brass meridian; then find the degree of latitude on the meridian, either north or south of the equator, as the given latitude is north or south; and the point of the globe just under that degree of latitude is the place required. S. "To find all the places on the globe that have the same latitude, and the same longitude, or hour, with a given place, as suppose London." Bring the given place, London, to the meridian, and observe what places are just under the edge of it, from north to south; and all those places have the same longitude and hour with it. Then turn the globe round; and all those places which pass just under the given degree of latitude on the meridian, have the same latitude with the given place. 4. "To find the antoci, periœci and antipodes, of any given place, suppose London." Bring the given place, London, to the meridian, then count 514 the same degree of latitude southward, or towards the other pole, and the point thus arrived at will be the antoci, or where the hour of the day or night is always the same at both places at the same time, and where the seasons and lengths of days and nights are also equal, but at half a year distance from each other, because their seasons are opposite or contrary. Loudon being still under the meridian, set the hour index to twelve at noon, or pointing towards Loudon; then turn the globe just half round, or till the index point to the opposite hour, or twelve at night; and the place that comes under the same degree of the meridian where London was, shews where the pericci dwell, or those people that have the same seasons and at the same time as London, as also the same length of days and nights, &c. at that time, but only their time or hour is just opposite, or twelve hours distant, being day with one when |