« AnteriorContinuar »
A TABLE of the Segment of a Circle, whose Area is Unity,
By such simple means we may ascertain the dimensions of most vessels in common use. We may, indeed, ordinarily estimate the diameters of casks to be in the proportion of 7 at the chine for 10 at the bung, which gives a medium of 8.5.
But gaugersare, in general, provided with a neat, compact instrument, in form of it folding rule, whereby the measurement of a cask's interior may be taken with sufficient accuracy. This instrument consists of four pieces, each a foot long, and about three-eights of an inch square. It has three brass joints, for the purpose of folding. On one face is a double line of diagonals, one appropriated to wine, the other to beer measure. By inserting the lower end of the rod at the bung of acask, and directing it obliquely so as to touch the junction of the head and stave, and noting the figures which stand opposite the centre of the interior of the bung-hole, the measurement is taken : in this process care must be taken to measure towards both chimes, because it cask has not always the bung truly centrical: when any difference appears, the medium of the two measurements serves as a standard. Open vessels may be measured
in the same way, by measuring the oblique line from the surface, or one side to the bottom of the other side; but only half the quantity shewn on the scale is to be taken for the contents. There is also a scale for _ cylindrical vessels, which shows the contents of one inch deep in any given area or diameter.
We must remark, that complete accuracy is not to be expected from this rod, however justly it may have been graduated, because the curves of staves, as has been shewn, vary so much, as to render some exclusive attention to that circumstance absolutely necessary; it being a point which cannot be determined by the rod or rule. 1 he gaugers in excise offices usually understand, at sight, if any unusual curve exists, and fail not to make allowance for such anomalies. The wine merchants, however, for many years, got the start of them, by causing the staves to be hollowed out considerably, indeed as far as could be done with safety, leaving the bnugholes and the ends of the staves of their ordinary thickness. By this device many gallons escaped paying duty, while the vendor, selling by the gallon, lost nothing, though he saved freight in proportion to the quantity of wood scooped from the interior face.
GAULTHERIA, in botany, a genus of the Decandria Monogynia class and order. Natural order, of Bicornes. Erica-, Jussien. Essential character: calyx, outer twoleaved, inner fire-cleft; corolla ovate; nectary with ten-dagger points; capsule fivecelled, covered with the inner calyx, now become a berry. There are two species.
GAURA, in botany, a genus of the Octandria Monogynia class and order. Natural order of Calycanthems. Onagrae, Jussieu. Essential character: calyx four-cleft, tubulous; corolla four-petalled, rising towards the upper side; nut inferior, oneseeded, four-cornered. There is but one species.
GAUZE, in commerce, a thin transparent stuff, sometimes woven with silk, and sometimes only of thread. In preparing the silk for making gauze it is wound round a wooden machine six feet high, in the middle of which an axis is placed perpendicularly, with six large wings: on these the silk is wound on bobbins by the revolution of the axis; and, when it is thus placed round the mill it is taken off by means of another instrument, and wound on two beams. This is then passed through as many small beads as it has threads, and is thus rolled on another beam in order to supply the loom. Gauzes are either plain or figured; the latter are worked with flowers of silver or gold, on a silk ground; and are chiefly imported from China. Gauzes of excellent quality have, of late years, been manufactured at Paisley.
GAZELLA. See Antelope.
GAZETTE, a newspaper, or printed account of the transactions of all the countries in the known world, in a loose sheet, or half sheet. This name is with us confined to that paper of news published by authority.
The first gazette in England was published at Oxford, the court being there, Nov. 7, 1665. On the removal of the court to London the gazette was published there. In this work are recorded all commissions and promotions in the army; all state appointments of consequence, with a variety of matters interesting to men of business and others.
GAZONS, in fortification, pieces of fresh earth, covered with grass, and cut in form of a wedge, about a foot long, and half a foot thick, to line the outsides of works made of earth, as ramparts, parapets, &c.
GELATINE, in chemistry, is one of the
constituent parts of animal substances, Glue, well known in many of the mechanical and other arts, is gelatine in a state of impurity, and may be obtained by repeatedly washing the fresh skin of an animal in cold water, afterwards boiling it, and reducing it to a small quantity by slow evaporation, and allowing it to cool. It then assumes the form of jelly, and becomes hard and semi-transparent. Gelatine has neither taste nor smell; it is soluble in hot acids and alkalies; but there is no action between any of the earths and this substance. Some of the metallic oxides and salts form precipitates with gelatine in its solution in water, and the compound thus formed is insoluble. Gelatine forms a copious white precipitate with tan, which is brittle and insoluble in water, and is not changed by exposure to the air. It is composed of carbon, hydrogen, azote, and oxygen, with small portions of phosphate of lime and of soda. It is a principal part both of the solid and fluid parts of animals, and is employed in the state of glue, size, and isinglass. Sec Glue;
GELD, in our old customs, a Saxon word, signifying money, or tribute: also a compensation for some crime committed. See Gild.
GELLIBRAND, (henr\) an industrious English mathematician and astronomer, was born at London in the year 1597. When he was eighteen years of age he was admitted a commoner of Trinity College, in the university of Oxford, where, in the year 1619, he took his degree of B.A. At that time, Anthony Wood says, "He was esteemed to have no great matter in him;" but afterwards he conceived a strong inclination for the mathematics, upon accidentally hearing one of Sir Henry Saville's lectures in that science, and applied to it with considerable diligence and success. Having taken orders, he settled for some time as a curate at Cliiddingstone in Kent; but his passion for mathematical studies determined him to quit that situation, and to return to the University, where he might uninterruptedly pursue the bent of his mind, supported by the moderate private patrimony which descended to him on the death of his father. His sole attention was now devoted to the mathematics, in which he made such proficiency, at the time of his taking his degree of M.A. in 1623, that he attracted the notice and friendship of several able mathematicians who flourished at that time, particularly of the celebrated Henry Briggs, then Savtliian professor of geometry at Oxford.
While he continued in the pursuit of these v studies, the professorship of astronomy in Gresham College, London, becoming vacant by the death of the ingenious Edmund Gunter, Mr. Briggs encouraged Mr. Gellibrand to become a candidate for that chair. Accordingly he proceeded to London, with strong testimonials in his favour from the President,Vice President, and Fellows of his College, and other active friends, and was chosen to fill that post by the electors, in the month of January, 1626. From that time he lived, as he had done before, in a close intimacy with Mr. Briggs, who took great pleasure in communicating to him his mathematical opinions and discoveries, and at the time of his death confided to him the task of completing his " British Trigonometry,'' which he did not live to finish. While Mr. Gellibrand was preparing that work for the press, Lee was cited, together with his servant William Beale, into the High Commission Court, by Doctor Laud, then Bishop of London, on account of an almanac for the year 1631, which Beale had published with the approbation of his master. In this almanac, the Popish saints usually put into the calendar were omitted, and the names of other saints and martyrs, mentioned in "Fox's Acts and Monuments of the Church," were inserted, as they stood in Fox's calendar. This circumstance gave great offence to the haughty prelate, and determined him to prosecute them for a measure which he considered to be an unequivocal evidence of their Puritanism. But when their cause came to a hearing, by shewing that what they had done was no innovation, and pleading that they had no ill intention, they were acquitted by Archbishop Abbot, and the whole court, Laud only excepted , which was made an article of accusation against the last-mentioned prelate at his own trial. This prosecution proved the means of retarding the publication of Mr. Briggs'* work; but when Mr. Gellibrand had escaped from the vengeance of Laud, he again applied to the completion of his friend's design, and having added to it the preface and the application of the logarithms to plane and spherical trigonometry, &c. constituting the second book of the work; the whole was printed at Gouda in Holland, under the care of Adrian Vlacq, in 1656. It was entitled, "Trigonometria Britannica, sive de Doctrina Triangulorum, Libri duo, &c." folio.
Mr. Gellibrand, however, though an industrious mathematician, had not sufficient
comprehension of mind to admit the evidence, which Galileo had lately produced, in support of the Copemican system. This appears from the account which he has given of a conversation which be had, when he went over to Holland on the business of printing the Trigonometry, with Lansberg, an eminent astronomer in Zealand, who insisted on the truth of that system. "This, which he was pleased to style a truth," says our author, "I should readily receive as an hypothesis, and so be easily led on to the consideration of the imbecility of man's apprehension, as not able rightly to conceive of this admirable opifice of God, or frame of the world, without falling foul of so great an absurdity. Yet, sure I am, it is a probable inducement to shake a wavering understanding."
From Mr. Gellibrand's situation at Gresham College, and his intercourse with the lovers of mathematical studies, he had an opportunity of contributing some pieces, mentioned below, to the improvement of navigation, which science would probably have been farther benefited by him had he uot been immaturely carried off by a fever in 1636, when in the fortieth year of his age. That his mathematical knowledge was considerable, and usefully applied, is sufficiently apparent from the treatises which he left behind him, and the estimation in which he was held by the most respectable men of science among his contemporaries, both at Oxford and London. But he is entitled more to the praise of close and unwearied industry than of invention or genius. Besides his part of the "Trigonometria Britannica," he was the author of "An Appendix concerning Longitude," subjoined to Captain Thomas James's Voyage for the Discovery of the North West Passage,
1633, quarto; "A Discourse, mathematical, on the variation of the Magnetic Needle, together with the admirable diminution lately discovered," annexed to Wright's "Errors in Navigation Detected, &c" 1635, quartp; "A Preface to the Sciographia of John Wells, of Brembridgc, Esq." 1635, 8vo; "An Institution, trigonometrical, explaining the doctrine of plane and spherical Triangles, after the most exact and compendious way, by Tables of Sines, Tangents, NC. with the application thereof to questions of Astronomy and Navigation,"
1634, octavo; and afterwards republished with enlargements by William Ley bourn, 165f, octavo: "An Epitome of Navigatiop, v, Ask the necessary tables, &c. and "An Appendix concerning the Use of the Quadrant, Fore-staff, and Nocturnal," octavo; "Oratio in Lundem Gassendi Astrononiiae, babita in Aula .Edis Christi, Oxon," and of several unpublished MSS. on the Doctrine of Eclipses, Lunar Astronomy, Ship Building, Sec.
GEMINI, the Twins, in astronomy, one of the twelve signs of the zodiac, the third in order, beginning with aries. See AstroNomy.
GEMMA (reinier), a learned Dutch physician and mathematician in the sixteenth century, was born at Dockum, in Friesland, in the year 1608. He was educated to the medical science, of which he became a professor in the university of I«uvain. But he was particularly eminent for his proficiency in mathematics and astronomy, which he taught with distinguished reputation, and the character of being one of the best astronomers of his time. The fame of his great scientific knowledge, and of the excellent instruments which he made use of in the illustration of it, occasioned his being frequently invited to the court of the Emperor Charles V.; but lie always modestly declined the overtures made to him, preferring the tranquillity of his literary retreat to the honours which he might expect from princely favour. He died at Louvain, in 1555, when only forty-seven years of age. He has sometimes bad the surname of Friscitis given him, from the country in which he was born. The most celebrated of his works were " Methodus Arithmetics ;* "De usu Annuli Astronomici;" "Dc Locorom dew cribendomm Ratione, deque Distantiis eornm inveniendis;" "Libellus de Principais Astronomic et Cosuio-;rapliia," Sec. "Demonstrationes Geometries de usu Radii Astronomici," Sec.; and "De Asrrolabio Catholico Liber."
The author had a son, named Cornelius, who was born at Lonvain, in 1535, and died in 1579. He was a poet, philosopher, and physician, and taught the mathematical sciences at Lonvain with considerable reputation. He was the author of "De Arte Cycloguomicir," Sec.; " De Naturae divinis Characterisrais, sea Cosmocritico;" and "De Prodigio$a Specie Naturaque Comets," occasioned by the extraordinary new star in the constellation Cassiopeia, in 1572, vvVich disappeared after being visible for eighteen months ; and other pieces.
Gut Ma, in botany, a bud, a compendium of a plant seated upon the stem and branches ,
and covered with scales, in order to defend the tender rudiments inclosed, from cold and other external injuries, till their parts being unfolded, they acquire strength, and render any further protection unnecessary. Buds, together with bulbs, which are a species of buds generally seated upon or near the root ; constitute that part of the herb by Linnxus called hybernacula; that is, the winter quarters of the future vegetable, as it is during that severe season that the tender rudiments are protected in the manner just mentioned. Plants considered in analogy to animals, may properly enough be reckoned both viviparous and oviparous. Seeds are the vegetable eggs; buds, living fetuses, or infant plants, which renew the species as certainly as the seed. In general, we may distinguish three kinds of buds: that containing the flower, that containing the leaves, and that containing both flower and leaves. The first, contains the rudiments of one or several flowers folded over one another, and surrounded with scale. In several trees, this kind of bud is commonly found at the extremity of certain small branches which are shorter, tougher, and less garnished with leaves than the rest. The external scales of this species of bud are harder than the internal • both are furnished with hairs, and in general more swelled than those of the second sort. The bud containing the flower, too, is commonly thicker, shorter, almost square, less uniform, and less pointed, being generally terminated obtusely. The second species of bud, contains the rudiments of several leaves which are variously folded over one another, and outwardly surrounded by scales, from which the small stipulx that are seated at the foot of the young branches, are chiefly produced. These buds are commonly more pointed than the former sort. In the hazel-nut, however, they are perfectly round; and in horse-chesnut very thick. The third sort of bud is smaller than either of the preceding, and produces both flowers and leaves, though not always in the same manner. Sometimes the flowers and leaves are unfolded at the same time. This mode of the flower and leaf-bud admits of the following distinctions from the sex of the flowers so produced with the leaves; male flower and leaf-buds as in the pine and fir-tree ; female flower and leaf-buds, as in hazel-nut and horn-beam; hermaphrodite flower and leaf-buds, as in the elm-tree, cornel-tree, mezereon, and almond tree. GEMS, certain stones, which, on account
of their hardness, transparency, and beauty, when cut and polished, are highly esteemed, aud tiom their small size and scarcity, are valued at very considerable price. The gems have been placed an.1,11. the siliceous fossils, as in sonic measure allied with them in external characters; and silcx was supposed to be their principal ingredient. Bergman first shewed the error of this opinion, and proved, by analysis, that in the emerald, sapphire, topaz, ruby, and hyacinth, argil predominates; their other constituent principles, as discovered by his analysis, being silex, lime, and oxide of iron. Still, however, the old prejudice prevailed, and they have been generally ranked by mineralogists under the siliceous genus.
The specific distinctions of these fossils were not less obscure; they were perplexed by the distinctions of the jewellers, drawn from very vague notions: the colour, in particular, being the property in which the gems differ most obviously, and which frequently gives them their mercantile value, served as a ground of distinction: hence the ruby, the sapphire, and the topaz were considered as different, though essentially the same. Another circumstance added to the confusion thus introduced, was that, other fossils, bearing a resemblance to these gems, had been classed with them; but, being inferior in lustre, transparency, and hardness, in order to distinguish between them, the epithet oriental was applied to those which were most perfect; and, by this contrivance, fossils were classed under one name, and regarded only as varieties of one species, which were totally different. The Oriental and the Saxon topaz, for example, were regarded under this point of view, or as varieties of one species, to which the common name of topaz belonged, though they are fossils altogether distinct. From these two circumstances, fossils were separated which ought to have been associated, and others were connected, which were specifically different; and it has required much mine'ralogical discussion to disentangle the perplexity, and establish the proper species.
Romi de l'lsle threw the first ray of light on this subject, by disregarding the colour, and attending rather to the form of crystallization; in consequence of which he arranged together the principal gems named oriental, under the title of the oriental ruby. Werner also has placed them under one species, to which he gives the name of sapphire. Hauy has adopted the same ar
rangement, distinguishing the species by the name of telesie; and, more lately, Bournon has still farther extended the relations of these fossils, by connecting them with the corundum, a fossil which had been brought from India, and which, analysed by Klaproth, was found to he composed principally of argillaceous earth. This, having in general little transparency or lustre, Bouinon names imperfect corundum; while the other variety, possessing these qualities, and comprising the oriental gems, is distinguished by the appellation of perfect corundum : these arrangements have received the sanction of chemical analysis. The skill of Klaproth, of Vauquelin, and Chenevix, has been exerted in investigating the composition of these fossils, and they have proved to be argil nearly pure. See Diamond, Corundum, Telesie, Ruby, Sapphire, Topaz, Amethyst, Emerald, Emery, Beryl, Ciirysolyte, Chrysoberyll.
GENDARMES, or Gens D'armes, in the French armies, a denomination given to a select body of horse, on account of their succeeding the ancient gendarmes, who were thus called from their being completely clothed in armour.
GENDER, among grammarians, a division of nouns, or names, to distinguish the two sexes.
GENEALOGICA arbor, or tree of consanguinity, signifies a genealogy or lineage drawn out under the figure of a tree, with its root, stock, branches, Me. The genealogical degrees are usually represented in circles, ranged over, under, and aside each other.
GENEALOGY, an enumeration of a series of ancestors; or a summary account of the relations and alliances of a person or family, both in the direct and collateral line. GENEKALo/'unarmy.in the art of war, he who commands in chief.
A general ought to be a man of great courage and conduct, to have great experience, and to be of good quality. His conduct appears in establishing his magazines in convenient places; in examining the country, that he may not engage his troops too far, while he is ignorant of the means of bringing them off; in subsisting them ; and in knowing how to take the most advantageous posts, either for fighting or shunning a battle. His experience inspires his army with confidence, and an assurance of victory; and his quality, by creating respect, augments his authority. By his liberality he gets intelligence of the