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again, for a similar reason to the preceding, lar position, that may be closed, or otherafter it is finished.

There are several tools used in finishing of dyes, which are gravers, chissels, and flatters, and many little punches for making ornamental borders and mouldings to coins and medals; the latter are always in greater relief than the former, and consequently more difficult to execute in perfection.

Engraving on precious Stones is accomplished with the diamond or emery. The diamond possesses the peculiar property of resisting every body in nature, and, though the hardest of all stones, it may be cut by a part of itself, and polished by its own particles. In order to render this splendid substance fit to perform the operations of the tool, two rough diamonds are cemented fast to the ends of the same number of sticks, and rubbed together till the form is obtain ed for which they are intended; the pow. der thus produced is preserved, and used for polishing them in a kind of mill furnished with a wheel of iron; the diamond is then secured in a brazen dish, and the dust mixed with olive oil applied, the wheel is set in motion, and the friction occasions the polished surface so necessary to give their lustre due effect. Other stones, as rubies, topazes, and sapphires, are cut into various angles on a wheel of copper, and the material for polishing those is tripoli diluted with

water.

A leaden wheel, cred with emery mixed with water, is preferred for the cutting of emeralds, amethysts, hyacinths, agates, granites, &c. &c. and they are polished on a pewter wheel with tripoli; opal, lapis lazuli, &c. are polished on a wheel made of wood.

Contrary to the method used by persons who turn metals, in which the substance to be wrought is fixed in the lathe, turned by it, and the tool held to the substance, the engraver of chrystal, lapis lazuli, &c. fixes his tools in the lathe and holds the precious stone to them, thus forming vases, or any other shape, by interposing diamond dust mixed with oil, or emery and water, between the tool and the substance as often as it is dispersed by the rotary motion of the former.

The engraving of armorial bearings, single figures, devices, &c. on any of the above stones after they are polished, is performed through the means of a small iron wheel, the ends of the axis of which are received within two pieces of iron, in a perpendicu

wise, as the operation requires; the tools are fixed to one end of the axis and screwed firm, the stone to be engraved is then held to the tool, the wheel set in motion by the foot, and the figure gradually formed. The materials of which the tools are made is generally iron, and sometimes brass, they are flat, like chissels, gouges, ferules, and others have circular heads. After the work is finished the polishing is done with hair brushes, fixed on wheels, and tripoli.

Engraving on Wood has been practised for several centuries, and originally with tolerable success, it languished for great part of the 18th century, but revived towards the close, and is still practised in a manner which reflects credit on the ingenuity of the age. Bewick will long be remembered by his works in this style of engraving, and his imitators have been numerous and successful. As it is entirely different from engraving on copper, the artist already acquainted with that mode would find himself at a loss how to proceed on wood, as the lines, instead of being cut into the substance, are raised like the letters of printing types, and printed in the same manner.

The wood used for this purpose is box, which is preferred for the hardness and closeness of its texture; the surface must be planed smooth and the design drawn on it with a black-lead pencil, the graver is then used, the finer excavations from which are intended for white interstices between the black lines produced by leaving the box untouched, and the greatest lights are made by cutting away the wood entirely of the intended form, length, and breadth; but the deepest shades require no engraving. Much of the beauty of this kind of engraving depends upon the printing, nor is it every artist who can excel in it, as expedition and freedom are not to be attained; in short, the best wooden cuts are evidently the products rather of perseverance and ingenuity than easy confidence in ability, observable in every line of fine etchings. There are some who succeed to admiration in representing foliage and plants, but unfortunately a few months practice will enable a pupil to etch them on copper with greater truth: drapery and architecture may be well done in wood, but the faces and limbs of figures never look well.

Such are the different descriptions of engraving which do not require the aid of

aqua fortis, of those made by the intervention of that liquid the principal is Etching, he that would excel in this branch of the arts must be thoroughly acquainted with drawing, otherwise his works will appear tasteless indeed. The ground used in etching is a combination of asphaltum, gummastick, and virgin wax, mixed in such proportions as will prevent the asphaltum from breaking the composition when under the aqua fortis, or the wax from making it so soft as to close the lines when cut through it by the needle. As every thing depends upon the stability of the ground, it should be purchased of those persons who are most celebrated for making it; or if the person wishing to use it prefers doing it himself, let him remember that he must keep every particle of grease or oil far from him and his materials, and that without the greatest care the inflammability of the asphaltum will ruin his operations in melting them. The proportions of the ingredients should be obtained by experiment.

After being prepared in the above manner the ground is tied in a piece of lustring for use, and another piece of the same kind of silk must be made into a dabber by tying a quantity of cotton in it. The copper-plate, hammered to a considerable degree of hardness, polished as if intended for the graver, and perfectly cleansed with whiting, is then secured at one corner by a hand vice, heated over a charcoal fire, and the silk containing the ground rubbed over it till every part is covered by the melted composition; but before it cools the silk dabber must be applied in all directions, till the surface of the plate is thinly and equally varnished. After this part of the process is completed, several lengths of wax taper, twisted together, are to be lighted, the plate raised by the vice in the left hand, and the right holding the burning taper is to be moved gently backwards and forwards under the ground, carefully avoiding touching it with the wick, yet causing the flame to spread over the surface, which will render it perfectly black, smooth, and shining, in a short time; this is to be ascertained by turning the plate: if the copper appears through the ground, the taper must be applied again immediately; but if it is held too long beneath the plate, the ground will become opaque, and break when the aqua fortis is used.

the copper-plate printers' rolling press, who will accomplish it by laying the plate carefully on the board of his press, the pencilled paper slightly damped on it, and turning the press the lead will be conveyed firmly to the ground, which will appear in perfect outlines on removing the paper. Another method is to draw the design reversed from the original; rub the back with powdered white chalk, and laying it on the ground trace the lines through with a blunt point; this operation requires much precaution or the point will cut the ground; besides, if the paper is not securely fastened with wax at the corners it may slip, and either interrupt the true continuation of lines, or scratch the ground.

In working with the etching needle nothing more is required than to keep it upright, that the lines made by it through the ground may not slope, and thus make the aqua fortis corrode improperly; but it should be particularly observed, that the point, though taper, must be so rounded as to be free from a possibility of its tearing the surface of the copper, which would prevent the progress of the point, and ruin the plate when bitten; the necessary polish of the point may be accomplished by rubbing it on the sole of a shoe. The young artist must now be left to his own exertions, as directions for etching beyond those already given are useless, and he will acquire more knowledge and freedom from copying good prints in one week than a quarto volume of observations would afford. It seems almost needless to add, that every line must be kept distinct, at all events, throughout the plate, and that the most distant should be closer and more regular than those in the fore ground, as the greater the depth of shade the broader and deeper must the lines be made.

When the etching of the plate is completely finished, the edges of it must be surrounded by a high border of wax, so well secured that water will not penetrate between the plate and it. The best spirits of nitre fortis must then be diluted with water, in the proportion of one part of the former to four of the latter, which will be found to answer the first operations, if the weather is fine and the atmosphere free from moisture; but, if the contrary is the case, the spirits of nitre must be increased in proportion, to the humidity of The next object is to transfer the design the air; this, when poured on the plate, to the ground, which may be done by cannot be too attentively observed in order drawing it on thin white paper with a black to remove the bubbles of fixed air with lead pencil, and having it passed through a feather, and to ascertain the time for

stopping out the lightest parts; for it must be remembered the whole secret of biting or corroding any subject consists in the judicious manner in which the depth and breadth of the lines are varied, as by proper management they may be left scarcely perceptible, or increased very considerably. The composition used for the above purpose is, turpentine varnish mixed with lamp-black, and diluted so as to be used freely with a camel's hair pencil; this applied to the parts of the plate sufficiently corroded, will effectually prevent the aqua fortis from touching it again, and the remainder proceeds as if no such application had taken place: it will be necessary to strengthen the water as the work becomes nearer completion, but cautiously, lest the ground should be broken; and every time the aqua fortis is removed the plate must be washed with clean water and gradually dried, otherwise the varnish cannot be used, and the lines would be clogged with the decomposed metal. For taking the ground from the plate it is usual to cover the surface with olive oil, and heating it, wipe the plate with a soft piece of old linen and spirits of turpentine, will effectually remove all remain ing dirt.

Re-biting, is the art of strengthening those lines of an etching in a plate from which the original ground has been cleansed. This is done by applying the ground as at first directed, but with great care that the melted composition does not fill, or even partially fill the lines, to prevent which the cotton wrapt in silk, called the dabber, should be used exclusively by taking a small quantity of melted ground on it, and gently touching the parts between the lines till they are equally and completely covered; if the plate is considerably heated, the ground will spread with more facility over the various interrupted surfaces. Carelessness or inattention will instantly ruin this process, and the whole of the plate: a border of wax must surround the parts to be rebitten, and a channel made to carry off the aqua fortis without injuring those already completed. Supposing the operations of etching and biting the plate entirely finished, nothing more remains than to examine it attentively, and improve it with the graver and dry point.

Stipling, or engraving in the dotted manmer, was in a great measure introduced by Bartolozzi, whose works in this way are astonishingly numerous, exclusive of those to which his name is affixed and not the products of himself. Some pastoral scenes,

with figures, when printed in colours have a pleasing effect; and small portraits stipled will bear examination; but historical subjects, which have great breadth of shade, appear to no advantage engraved in this manner. Stipling is performed by etching the plate with dots and biting it, laying the shades with a tool for the purpose, using the graver and the dry point, and scraping off the roughness thus occasioned.

Engraving in Aquatinta. The print from an aqua-tinted plate resembles a neatly finished drawing in Indian ink; this effect is produced by corroding the plate between the particles of a material entirely different from the etching ground. The first step in this process is to prepare a plate exactly in the way already described, and etch the outlines of the subject to be aqua-tinted, which are to be slightly bitten, and the plate thoroughly cleansed. The substance used to form the grains of the subject (which may be common resin, burgundy-pitch, ásphaltum, gum-mastich, or gum-copal, either separate or mixed) should be reduced to a fine powder and sifted, put into a piece of muslin, and holding it high above the plate it must be struck against any substance held in the left hand till the shower of dust thus produced has covered the plate equally throughout, preserving it carefully in this situation, the plate is to be heated sufficiently to melt the powder, which will make the grains assume a circular form, and contract, leaving, when cold, a beautiful sur. face fit for the aqua fortis. Common resin is generally preferred for this part of the operation, but gum-copal is less liable to be broken loose from the plate during the process of biting.

The drawing to be copied must serve as the future basis of proceeding, which is to be imitated in the following manner: the perfectly white parts of the intended print are to be covered on the plate, with the varnish mentioned in etching, by the use of a camel's-hair pencil; a border of wax must then be raised, and the aqua fortis diluted poured on; the same method is afterwards practised in the stopping out before recommended, except that the depth of the corroding cannot be so great as in the line

manner.

In order to obviate any difficulties which occur in procuring sufficient depths of shade, a method has been invented that enables the artist to produce an effect almost equal to the decisive touches of a brush filled with colour in drawing, which is the use of a liquid made with water, treacle,

or sugar, and fine washed whiting, exactly of the consistence of Indian ink, and laid on the granulated surface with a pencil, in the same free manner adopted on paper; after the above composition is thoroughly dry, the whole plate must be covered with a thin, weak, varnish of mastich, turpentine, or asphaltum, and when dried a second time, the aqua fortis is to be applied, which immediately breaking the varnish and whiting, will corrode the plate precisely in the marks of the pencil. The border of wax may be removed by heating the plate gently, and the ground varnish, &c. by oil of turpentine; a little fine whiting and a clean rag will then render the plate fit for the printer.

As the manner of procuring the grain by heating the powdered substance scattered over the plate is liable to objections, on account of the difficulty of making the particles assume the desired coarseness, or the reverse, and the engraving so produced rapidly wearing out in the printing, another has been contrived far more certain and satisfactory. In this mode, common resin, mastich, or Burgundy pitch, is dissolved in highly rectified spirits of wine of the best quality, each of which produce different descriptions of grains; but these substances may be mixed in such proportions as the artist prefers, and he must recollect that the resin makes the coarsest: to satisfy himself in this particular, the grain of every proportion should be tried on useless pieces of copper. Having a solution to his mind, it must remain undisturbed till every impure particle has subsided. The plate, polished and cleansed with whiting, is then placed to receive the liquid, which being poured on it, is held slanting till the most fluid parts has run off; it is afterwards laid to dry, in the progress of which the resin granulates, and adheres firmly to the surface. The greatest precaution must be used in going through this process, as the interposition of dust, grease, hairs, or fibres of linen, will cause total derangement, and even then it is subject to most vexatious uncertainty, often compelling the experienced artist to renew it to obtain a good grain; in short, the weather and untoward accidents frequently ruin his labours, though guarded against by every method his invention suggests. There is one advantage attending the pouring the liquid off, which is, that the heaviest particles of the resin will float to the lower side, and consequently leave a coarser grain there than above, much better suited to the deep shades of a

landscape than if the granulations had been equally fine; in large subjects the grain is sometimes laid coarse purposely in the parts requiring it.

Although a fine grain has a very pleasing effect, and will bear close examination, it has several disadvantages; for this reason a medium description of granulation is preferable, which admitting the aqua fortis freely to the copper, it bites deeper, and is less apt by acting laterally to force off the resin, besides, the plate will of course afford a greater number of impressions.

Some hints have been given already for biting the plate; but however useful those may be found in particular instances, there are others which can only be extracted from close application and experiment, and those are often varied in their results: as an illustration, we may suppose an artist provided with several pieces of copper granulated, and trying each successively by his watch with spirits of nitre diluted to the state of the air at the commencement of his operations, how many minutes is necessary to produce one tint, how many for a second, &c. granting him two hours for his experiment; during this interval a violent shower of rain may occur, which will immediately affect the acid by weakening its properties in the same proportion as salt is observed to be dissolved by a humid atmosphere: thus it appears, a result obtained on a clear dry day will not suit a rainy one, and vice versa.

In opposition to this discouraging uncertainty, and in opposition to the judgment and preference of all true connoisseurs, aquatinted prints seem to increase in value in the estimation of many persons, who forget that national taste should be improved by works of superior execution, and not vitiated by being constantly familiarized to those produced by means which set genius at defiance.

ENNEAGON, in geometry, a polygon with nine sides. If each side be 1, the area will be 6, 18, &c.

ENNEANDRIA, the name of the ninth class in Linnæus's sexual system, consisting of plants which have hermaphrodite flowers, with nine stamina or male organs. The orders, or secondary divisions, in this class are three, being founded on the number of the styles, seed buds, or female organs. Laurus, tinus, and cassytha, have one style; rhubarb (rheum), has a triple stigma or summit, but scarce any style; flowering rush has six styles. The genera just enumerated are all that belong to the

class Enneandria. The first genus, laurus, is very extensive; comprehending the bay. tree, cinnamon tree, camphor tree, benjamin tree, sassafras tree, and the avocado or avogato pear.

ENS martis, an old name given by chemists to sal ammoniac sublimed with iron filings, and therefore consisting of muriate of ammonia mixed with a little muriate of iron.

ENS veneris, a similar preparation, in which copper filings are substituted for those of iron.

ENSATE, (from enses, a sword), the name of the sixth order in Linnæus's Fragments of a Natural Method, consisting of plants with sword-shaped leaves.

ENSIFORM, in general, something resembling a sword, ensis: thus we find mention of ensiform leaves, ensiform cartilage, &c.

ENSIGN, in the military art, a banner under which the soldiers are ranged according to the different companies or parties they belong to. The European ensigns are pieces of taffety with various figures, arms, and devices painted on them in different I colours: the Turkish ensigns are horses' tails.

ENSIGN is also the officer that carries the colours, being the lowest commissioned of ficer in a company of foot, subordinate to the captain and lieutenant. It is a very honourable and proper post for a young gentleman at his first coming into the army; he is to carry the colours both in assault, day of battle, &c., and should not quit them but with his life; he is always to carry them himself on his left shoulder, only on a march he may have them carried by a soldier. If the ensign is killed, then the captain is to carry the colours in his stead.

ENTABLATURE, in architecture, is that part of an order of a column, which is over the capital, and comprehends the architrave, frieze, and cornice.

ENTAIL, in law, signifies fee-tail, or fee-intailed. See ESTATE.

ENTIERTIE denotes the whole, in contradistinction to moiety, which denotes the half; and a bond, damages, &c. are said to be entire when they cannot be apportioned.

ENTIRE tenancy, signifies a sole possession in one man.

ENTOMOLOGY is that branch of natural history that treats of insects. The study of insects has sometimes been ridiculed as unworthy the attention of men of science; for this, however, there is no just reason; though inferior in point of magni

tude, yet they surpass, in variety of struc ture and singularity of appearance, all the larger branches of the animal world. No one can examine with an attentive eye the subjects of this branch of science without surprise; the great variety of forms, the nice adaptation of their parts to the situation in which each happens to be placed, may excite the amazement of the curious and intelligent mind. The same power and wisdom which are manifested in the order, harmony, and beauty of the heavenly bodies, are equally shewn in the formation of the minutest insect; each has received that mechanism of body, those peculiar instincts, and is made to undergo those different changes, which fit it for its destined situation, and enable it to perform its proper functions. The utility of many insects, either in their living or dead state, as the bee, the crab, the silk-worm, cochineal insect, (see Apis, Coccus, &c.) renders them interesting and important; besides, though diminutive in point of size, they are, in regard to numbers, unquestionably the most distinguished of the works of nature; they are to be found in every situation, in water, in air, and in the bowels of the earth; they live in wood, upon animals, decayed vegetables, and all kinds of flesh, and in every state of its existence down to the most putrid.

The general characters by which insects are distinguished are the following: they are furnished with several, six or more, feet; the muscles are affixed to the internal surface of the skin, which is a substance more or less strong, and sometimes very hard and horny; they do not breathe like larger animals, by lungs or gills situated in the upper part of the body; but by a sort of spiracles, distributed in a series or row on each side the whole length of the abdomen; these are supposed to communicate with a continued chain, as it were, of lungs, or something analogous to them, distributed throughout the whole length of the body; the head is furnished with a pair of what are termed antennæ, or horns, which are extremely different in different tribes, and which, by their structure, &c., form a leading character in the institution of the genera into which insects are divided.

Writers on natural history formerly included snails, worms, and the smaller animals, or animalcules, in general, among insects: these are now more properly placed among the tribe vermes, or worm-like animals. Insects have also been denominated

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