laft velocity acquired by the direct defcent, is to the latt velocity acquired in the fame time by the oblique defcent, as the abfolute gravity is to the relative gravity of the defcending body. 4. The line defcribed by the direct defcent, is to the line defcribed in the fame time by the oblique defcent, as the length of the oblique plane is to its height. 5. If the line defcribed by the direct defcent be to the line defcribed by the oblique defcent, as the height of the inclined plane to its length, then the times of defcent fhall also be in the fame proportion, and the laft velocities equal. 6. The last velocities acquired upon feveral inclined planes of the fame height, however different in length, are equal. 7. The time of oblique descent thro' any chord of a circle, drawn from its lowest point, is equal to the time of a direct defcent thro' the diameter of that circle. 8. The last acquired velocities of a body, defcending to the lowest point of a given circle, through different chords, are as thofe chords. 9. The time of the defcent of a body in any arch of a femi cycloid, is equal to the time of its defcent through any other arch, whether longer or fhorter, of the fame curve. Io. A body will defcend fooner along an arch of a cycloid, than along that of any other curve, drawn between the fame points.

II.

If water runs out through a hole made in the bottom of a parabolic conoid, the furface of the water will defcend equal fpaces in equal times. 12. A body defcends in a refifting medium with a force only equal to the excess of its gravity above that of an equal bulk of the medium. 13. If a body be thrown downwards, in a refifting medium, with fuch a force as fhall make the relillance of the medium equal to the acceleration of gravity, it will afterwards defcend with an uniform motion. 14. If a body defcends through any number of inclined planes, it will acquire the fame velocity at the end of its fall, as though it had fallen through a plane equal in height to the whole, and of the fame inclination with the laft of them.

DESCENT, or DISCENT, in law, an order

or method whereby lands or tenements are derived to any man from his ancestors, It is either by the common law, cuitom, or flatute. By the common law, as where a perfon has lands of inheritance in fee, and dies without having made any dif polal thercof: wherefore the land defcends

and goes in courfe to the eldest son and heir. By cuftom, as where the lands fometimes defcend to all the fons; or to all the brothers, where one brother dies without iffue, as in gavel-kind, &c. And defcent by ftatute is a descent in feetail, as directed by the manner of the limitation or fettlement, purfuant to stat. Weftm. 2. and 13 Ed. I.

Defcent, at common law, is either lineal or collateral.

Lineal defcent is that conveyed down in a right line from the grand-father to the father, from the father to the son, and from the fon to the grand-fon. Collateral defcent is that fpringing out of the fide of the line, or blood, as from a man to his brother, nephew, or the like. DESCENT, in genealogy, the order or fucceffion of defcendants in a line or family; or their distance from a common progeni tor: thus we fay, one defcent, two defcents, &c. See EXTRACTION. DESCENT, in heraldry, is used to exprefs the coming down of any thing from above; as, a lion en defcent, is a lion with his head towards the base points, and his heels towards one of the corners of the chief, as if he were leaping down from fome high place.

DESCENT, in fortification, are the holes, vaults, and hollow places made by undermining the ground.

The defcent into the moat or ditch is a deep paffage made through the efplanade and covert-way, in form of a trench, whereof the upper part is covered with madriers and clays, to fecure the befiegers from the enemy's fire. In wet ditches this trench is on a level with the furface of the water, but in dry ones it is funk as deep as the bottom of the ditch. DESCRIBENT, in geometry, a line or furface, which, by its motion, describes a furface or folid.

DESCRIPTION is fuch a ftrong and beautiful reprefentation of a thing, as gives the reader a distinct view and satisfactory notion of it,

Defcriptions are almoft peculiar to poetry hiftorians indeed defcribe things, places, and perfons; but not fo much for the fake of ornament, as of neceffity. Orators likewise attempt defcriptions when they have a mind to work upon the paffions; but neither the one nor the other ufe them as decorations to their writings, which poets generally do, very fuccessfully, not only with a defign to

move

move the paffions, but to please the fancy. Great judgment is required in the due exercise of this art. A judicious author will omit low and vulgar circumftances, and chiefly beftow his pains to complete all the effential and masterly ftrokes, cutting off all fuperfluities, and rejecting the most pleafing thought and florid lines, when foreign to his fubject: many things must be left to the imagination of the reader, and feasonable filence has its emphasis; thus Virgil tells us, Georg. iv. 457. that Eurydice was killed by a monstrous ferpent, lurking in a bank; but says nothing more of that venemous creature. A poetafter would probably have spent as many lines in the defcription of it, as compofed that admirable poem. The description of a perfon is called a character, in drawing which the true proof of art and judgment is to hit a beautiful likeness, and, with a delicate touch, to give thofe features and colours which are peculiar to the person, and distinguish him from the reft of mankind. In every good and lively defcription, a man must come to an enumeration of the chief particulars; for generals are often obfcure and faint. A judicious author, by fetting every thing in full view, makes a strong and lafting im preffion on the reader.

DESEADA, or DESIDERADA, one of the Caribbee-iflands, lying eastward of Guadaloupe.

DESERTER, in a military fenfe, a foldier who, by running away from his regiment or company, abandons the service

A deferter is, by the articles of war, punishable by death, and, after conviction, is hanged at the head of the regiment he formerly belonged to, with his crime writ on his breast, and suffered to hang till the army leave that camp, for a terror to others.

DESHACHE', in heraldry, is where a beaft has its limbs feparated from its body, fo that they ftill remain on the efcutcheon, with only a small feparation from their natural places DESIDERATUM is used to fignify the defirable perfections in any art or fcience: thus, it is a defideratum with the blacksmith, to render iron fufible by a gentle heat, and yet preferve it hard enough for ordinary uses; with the glassman and looking-glafs maker, to render glafs malleable, with the clock-maker,

to bring pendulums to be useful, where there are irregular motions; with the brafier and copperfinith, to make malleable folder; with the fhipwright, to build veffels that will fail under water; with the diver, to procure manageable inftruments for conveying fresh air to the bottom of the fea, fufficient for refpiration and the burning of lights; with the allaymafter, to melt or copel ores or metals immediately, without the use of bellows or furnaces; and with the carvers and joiners, to fashion wood in moulds like plaifter of paris, or burnt alabafter, &c. And though, as Mr. Boyle obferves, the obtaining of thefe defiderata may be thought chimeral, yet it is proper they fhould be propofed; for, although perfection may not be attainable, yet approaches to it may be made, and arts thereby improved. To this may be added, that the making of iron malleable, with pit-coal was once looked upon as chimerical, yet it is now put in practice, to the great advantage of the owners of feveral mines in this kingdom.

All arts have their defects; and it is not at first to be gueffed, for how many of thefe remedies may be found, by means of chemical researches, properly directed. Chemistry itfelt is greatly defective in many particulars, as in an experimental history of general fermentation, feparatory and combinatory; in fubjects of the animal, vegetable, and mineral kingdoms. The schemes for new trades will rife occafionally in profecuting many of the subjects; thus it is natural for the common operations of brewing and fugarbaking, to fuggeft that fugar may be procured from malt and other vegetables. That nurseries of peculiar ferments, both native and foreign, may be raifed on the common principles; and it is evident that the introduction of fuch new trades would greatly improve the bufinefs of brewing, fugar baking, and the like. DESIGN, in a general fenfe, the plan, order, reprefentation, or conftruction of a building, book, painting, &c.

In building, the term ichnography may be used, when by defign is only meant the plan of a building, or a flat figure drawn on paper: when fome fide or face of the building is raifed from the ground, we may use the term orthography; and when both front and fides are feen, in perspective, we may call it fcenography. See

ICHNO.

ICHNOGRAPHY, ORTHOGRAPHY, and SCENOGRAPHY.

DESIGN, in the manufactories, expreffes the figures wherewith the workman enriches his ftuff, or filk, and which he copies after fome painter, or eminent draughts-man, as in diaper, damask, and other flowered filk and tapestry, and the like.

In undertaking of fuch kinds of figured ftuffs, it is neceffary, fays Monf. Savary, that, before the firft ftroke of the fhuttle, the whole defign be reprefented on the threads of the warp; we do not mean in colours, but with an infinite number of little packthreads, which, being difpofed fo as to raife the threads of the warp, let the workmen fee, from time to time, what kind of filk is to be put in the eye of the fhuttle, for woof. This method of preparing the work is called reading the defign, and reading the figure, which is performed in the following manner: a paper is provided, confiderably broader than the ftuff, and of a length proportionate to what is intended to be reprefented thereon. This they divide lengthwife, by as many black lines as there are intended threads in the warp; and crofs thefe lines, by others drawn breadthwife, which, with the former, make little equal fquares: on the paper thus fquared, the draughts-man defigas his figures, and heightens them with colours, as he fees fit. When the defign is finished, a workman reads it, while another lays it on the fimblot.

To read the defign, is to tell the perfon who manages the loom, the number of fquares, or threads, comprifed in the fpace he is reading, intimating at the fame time whether it is ground or figure. To put what is read on the fimblot, is to faften little ftrings to the feveral packthreads, which are to raise the threads named; and thus they continue to do till the whole defign is read.

Every piece being compofed of feveral repetitions of the fame defign, when the whole defign is drawn, the drawer, to rebegin the defign afresh, has nothing to do but to raise the little ftrings, with flipknots, to the top of the fimblot, which he had let down to the bottom: this he is to repeat as often as is neceffary till the whole be manufactured.

The ribbon-weavers have likewife a design, but far more fimple than that now

defcribed. It is drawn on paper with lines and fquares, reprefenting the threads of the warp and woof. But instead of lines, whereof the figures of the former confift, these are conftituted of points only, or dots, placed in certain of the little fquares, formed by the interfection of the lines. Thefe points mark the threads of the warp that are to be raised, and the fpaces left blank denote the threads that are to keep their fituation: the reft is managed as in the former.

DESIGN is alfo ufed, in painting, for the first idea of a large work, drawn rough. ly, and in little, with an intention to be executed and finished in large. The art of painting has been by fome of the greatest mafters divided into the defign, or draught, the proportion, the expreffion, the claro-obfcuro, the ordonnance, the colouring, and the perspective. Defign, in painting, is the fimple contour, or outlines of the figures intended to be reprefented, or the lines that terminate and circumfcribe them: fuch defign is fometimes drawn in crayons, or ink, without any fhadows at all; fometimes. it is hatched, that is, the fhadows are expreffed by fenfible outlines, usually drawn acrofs each other with the pen, crayon, or graver. Sometimes, again, the fhadows are done with the crayon rubbed fo as that there do not appear any lines: at other times, the grains or ftrokes of the crayon appear, as not being rubbed: fometimes the defign is washed, that is, the fhadows are done with a pencil in indian ink, or fome other liquor; and fometimes the defign is coloured, that is, colours are laid on much like thofe intended for the grand work.

The eflential requifites of a defign are correctnefs, good tafte, elegance, character, diverfity, expreffion, and perfpective. Correctnefs depends on the juftness of the proportions, and knowledge of anatomy. Tafte is a certain manner of correctnefs peculiar to one's felf, derived either from nature, mafters, or studies, or all of them united. Elegance gives a delicacy that not only ftrikes perfons of judgment, but communicates an agree ablenefs that pleafes univerfally. The character is what is peculiar to each thing, wherein there must be diverfity, infomuch that every thing has its peculiar character to diftinguish it. The expreffion is the représentation of an object, ac

cording

as mace-bearers before magiftrates. DESIGNING, the art of delineating or drawing the appearance of natural objects, by lines, on a plane.

To defign, according to the rules of mathematics, makes the object of perspec tive. See the article PERSPECTIVE. To defign by the camera obfcura. See the article CAMERA OBSCURA. Mechanical method of DESIGNING. There are feveral methods of defigning mechanically. The following is the method of the learned Sir Chriftopher Wren, and may be put in practice with great ease. A is a fmall fight, with a fhort arm B (plate LXIX. fig. 5.) which may be turned round about, and moved up and down the final cylinder CD, which is fcrewed into the piece ED, at D; this piece E D moving round about the center E, by which means the fight may be removed either towards E or F.

sording to the circumftances it is fuppofed to be in. Perfpective is the reprefentation of the parts of a painting, or a figure, according to the fituation they are in with regard to the point of fight, The defign or draught, is a part of the greatest import and extent in painting. It is acquired chiefly by genius and application, rules being of lefs avail here iban in any other branches of the art, as colouring, &c. The principal rules that regard defign are, that novices accustom themfelves to copy good criginals at first fight; not to ufe fquares in drawing, left they stint and confine their judgment; to design well from life, before they prac tise perspective; to learn to adjust the fize of their figures to the visual angle, and the distance of the eye from the model or object; to mark out all the parts of their design before they begin to shade; to make their contours in great pieces, without taking notice of the little mufcles, and other breaks; to make themfelves mafters of the rules of perspective; to obferve the perpendicular, parallel, and distance of every stroke; to compare and oppose the parts that meet and traverfe the perpendicular, fo as to form a kind of square in the mind, which is the great and almoft the only rule of defigning juftly; to have a regard not only to the model, but to the parts already defigned, there being no fuch thing as defigning with ftri&t juftness, but by comparing and proportioning every part to the firft. All the other rules relate to perspective. See PERSPECTIVE. DESIGNATION, the act of marking or indicating, and making a thing known. There were defignations of the confuls and other magiftrates among the Romans fome time before their election. DESIGNATOR, in roman antiquity, a fort of petty mafter of the ceremonies, who affigned every body their places in the theatres, and other public fhews. The Romans had officers of this nature attending all their folemn fhews and proceffions, for directing precedencies. The defignator was one of the goddess Libitina's principal fervants, the shews of the funerals of perfons of quality being marshalled by the defignator. When he went to raise the corps, he was attended with a train of funeral officers called libitinarii, fubdivided into pellinatores, vefpiliones, uftores, &c. All thefe, habited in black, walked before the defignator, VOL. II.

EF is a ruler faftened on the two rulers GG, which rulers ferve both to keep the fquare frame S S S S perpendicular, and, by their fliding through the fquare holes TT, they ferve to ftay the fight, either farther from, or nearer, to the faid frame; on which frame is ftuck, with a little wax, the paper 0000, whereon the picture is to be drawn by the pen I. The pen I is, by a small brass handle V, so fixed to the ruler H H, that the point I may be kept very firm, so as always to touch the paper. H H is a ruler that is conftantly, by means of the small strings aaa, bbb, moved horizontally, or parallel to itself; at the end of which is ftuck a small pin, whofe head P is the fight, which is to he moved up and down on the out-lines of any object.

The contrivance of the ftrings is this: the two ftrings à a a, b bb, are exactly of an equal length. Two ends of them are faftened into a small leaden weight, which is employed in a focket on the backfide of the frame, and ferves exactly to counterpoife the ruler H H, being of an equal weight with it. The other two ends of them are fastened to two fmall pins H H, after they have rolled about the small pullies M M, LL, KK; by means of which pullies, if the pen I be taken hold of, and moved up and down the paper, the ftring moving very eafily, the ruler will always remain in an horizontal po fition.

The manner of using it is this: fet the inftrument upon a table, and fix the fight SY

A

A at what height above the table, and at what diftance from the frame SSSS, you pleafe. Then looking through the fight A, holding the pen I in your hand, move the head of the pin P up and down the out-lines of the object, and the point of the pen I will describe on the paper 0000 the fhape of the object fo traced. DESISE, a town of France, fituated on the river Loire, fifteen miles fouth-eaft of Nevers eait longitude 3° 32', north latitude 46° 48'.

:

DE SON TORT DEMESN, in law, a formula used, in an action of trespass, by way of reply to the defendant's plea; fignifying that the trefpafs was his own voluntary and free act.

DESPOTE, a term fometimes used for an abfolute prince. See the next article. Under the emperors of Conftantinople, defpote was a title of honour given to the emperor's fons, or fons in law; as alfo to their colleagues, and partners in the imperial dignity, in the fame manner as Cæfar was at Rome. See the article CESAR. DESPOTICAL, in general, denotes any thing that is uncontrouled and absolute; but is particularly used for an arbitrary government, where the power of the prince is unlimited, and his will a law to his fubjects: fuch are those of Turky, Perfia, and most of the eastern governinents; and even thofe of Europe, if we except the republics, our own, and the fwedish government.

DESPOUILLE', in heraldry, the whole cafe, skin, or flough of a beaft, with the head, feet, tail, and all appurtenances, fo that being filled and stuffed, it looks like the intire creature. DESPUMATION, a term fometimes used for the clarifying a liquor, by the skimming off its froth. See CLARIFICATION. DESQUAMATION, the fame with exfoliation. See EXFOLIATION. DESSAW, a city of upper Saxony, in Germany, fituated on the river Elbe, fixty miles north-west of Drefden, and fubject to the prince of Anhalt Deffaw : eaft long. 12° 40', north lat. 51° 50′. DESSERT, or DESART, a fervice of fruits and fweet-meats, usually served up laft to table.

DESSICCATIVE, or DESICCATIVE, in pharmacy, an epithet applied to fuch topical medicines as dry up the humours flowing to a wound or ulcer. See the article WOUND. DESTILLATION, or DISTILLATION,

See the article DISTILLATION. DESTINIES, in mythology, the fame with parcæ. See the article PARCÆ. DESTINY, among philofophers and divines, the fame with fate. See FATE. DESTRUCTION, in general, an alteration of any thing from its natural state to one contrary to nature; whereby it is deemed the fame with corruption. See the article CORRUPTION.

A chemical deftruction, or corruption, is nothing but a refolution of the whole naturally mixt body into its parts. DESUDATION, in medicine, a profufe and inordinate fweat, fucceeded by an eruption of pustules, called fudamina, or heat-pimples. See the article SUDAMINA. DESULTOR, in antiquity, a vaulter, or Jeaper, who, leading one horfe by the bridle, and riding another, jumped from the back of one to the other, as the cuf tom was after they had run several courses, or heats.

This practice required great dexterity, being performed before the ufe of either faddles or ftirrups. The custom was practised in the army, when necessity required it; but chiefly among the Numidians, who always carried two horfes, at leaft, with them for that purpofe, changing them as they tired. The Greeks and Romans borrowed the practice from them, but only used it at races, games, &c. The Sarmata were great masters of this exercife, and huffars have still fome remains of it; but now we fee the most dexterous feats of this kind that perhaps were ever known in any age or nation performed by our countryman, Mr. Johnson.

DETACHED PIECES, in fortification, are fuch out-works as are detached, or at a distance from the body of the place; as demilunes, ravelines, baftions, &c. In painting, the figures are faid to be well detached, when they ftand free and difengaged from each other. DETACHMENT, in military affairs, a certain number of foldiers drawn out from feveral regiments or companies equally, to be employed as the general thinks proper, whether on an attack, at a fiege, or in parties to fcour the country.

A detachment of two or three thousand men, is a command for a brigadier; eight hundred, for a colonel; four or five hundred for a lieutenant-colonel. A captain never marches on a detach ment with less than fifty men, a lieute nant, an enfign, and two ferjeants. A

lieu