Armenian bole is a red earth powder dusted on to the thin tissue pages, which separate the leaves of gold in a book of gold leaf, so that the gold leaf doesn't stick to the tissue. Research Armenian Bole
Budding is the art of multiplying plants by causing the leaf-bud of one species or variety to grow upon the branch of another. The operation consists in shaving off a leaf-bud, with a portion of the wood beneath it, which portion is afterwards removed by a sudden jerk of the operator's finger and thumb, aided by the budding-knife. An incision in the bark of the stock is then made in the form of a T; the two side lips are pushed aside, the bud is thrust between the bark and the wood, the upper end of its bark is cut to a level with the cross arm of the T, and the whole is bound up with worsted or other soft fastening, the point of the bud being left exposed.
In performing the operation, a knife with a thin flat handle and a blade with a peculiar edge is required. The bud must be fully formed; the bark of the stock must separate readily from the wood below it; and young branches should always be chosen, as having beneath the bark the largest quantity of cambium or viscid matter out of which tissue is formed. The maturer shoots of the year in which the operation is performed are the best. The autumn is the best time for budding, though it may also be practised in the spring. Research Budding
Chitin is a sort of transparent horny substance, the chief tissue-forming ingredient of the wing-cases of insects, and the shells of crabs and other crustaceans. Research Chitin
Engraving is the art of representing objects and depicting characters on metal, wood, precious stones, etc, by means of incisions made with instruments variously adapted to the substances operated upon and the description of work intended.
Impressions from metal plates are named engravings, prints, or plates those printed from wood being called indifferently wood engravings and wood-cuts. While, however, these impressions are not altogether dissimilar in appearance, the processes are distinct. In plates the lines intended to print are incised, and in order to take an impression the plate is daubed over with a thick ink which fills all the lines. The surface is then wiped perfectly clean, leaving only the incised lines filled with ink. A piece of damp paper is now laid on the face of the plate, and both are passed through the press, which causes the ink to pass from the plate to the paper. This operation needs to be repeated for every impression, for the wood block, on the contrary, the spaces between the lines of the drawing are cut out, leaving the lines standing up like type, the printing being from the inked surface of the raised lines, and effected much more rapidly than plate printing.
Engraving on wood, intended for printing or taking impressing from, long preceded engraving on metals. The art is of eastern origin, and at least as early as the 10th century engraving and printing from wood blocks was common in China. We first hear of wood engraving being cultivated in Europe by the Italians and Germans in the 13th century. For a hundred and fifty years, however, there is small indication of the practice of the art, which was at first confined to the production of block-books, playing cards, and religious prints. In the 15th century the art of printing from engraved plates was discovered in Florence by Maso Finiguerra.
Engraving had long been used as a means of decorating armour, metal vessels, etc, the engravers generally securing duplicates of their works before laying in the niello (a species of metallic enamel) by filling the lines with dark colour, and taking casts of them in sulphur. The discovery of the practicability of taking impressions upon paper led to engraving upon copper plates for the purpose of printing from.
The date of the earliest known niello proof upon paper is 1452. The work of the Florentine engravers, however, was almost at once surpassed in Venice and elsewhere in North Italy by Andrea Mantegna, Girolamo Mocetto, Giovanni Batista del Porto, and others. In Marc Antonio Raimondi, who wrought under the guidance of Raphael, and reproduced many of his works, the art reached its highest point of the earlier period, and Rome became the centre of a new school, which included Marco da Ravenna, Giulio Bonasone, and Agostino de Musis.
In the meantime, in Germany the progress of the art had been not less rapid. Of the oldest school the most important engraver is Martin Schongauer. He was, however, surpassed a generation later by Albert Durer who excelled both in copper and wood engraving, especially in the latter. Among his most famous contemporaries and successors were Burgkmair and Lucas Cranach. The Dutch and Flemish schools, of which Durer's contemporary Lucas van Leyden was the head, did much to enlarge the scope of the art, either by paying increased attention to the rendering of light and shade, and the expression of local colour, as in the case of Cornelius Cort and Bloemart; or by developing freedom and expression of line, as in the case of Goltzius and his pupils.
Rubens influenced engraving through the two Bolswerts, Vorstermann, Pontius, and de Jode, who engraved many of his works on a large size. Towards the end of the 17th century etching, which had before been rarely used, became more common, and was practised with great success by Rembrandt and other painters of that period. In France Noel Garnier founded a school of engraving about the middle of the 16th century; but it produced no work of any high distinction until the reign of Louis XIV, when Nanteuil's pupil Gerard Edelinck and Gerard Audran flourished. The former was skilled in using his graver to produce colour effects, the latter is famed for his engravings from Nicolas Poussin and Le Brun. But these were all surpassed about the middle of the 18th century by Wille, a German resident in Paris.
Before the middle of the 17th century England produced little noteworthy work, availing herself principally of the work of foreign engravers, of whom many took up temporary and even permanent residence. The first English engraver of marked importance was William Hogarth, whose works are distinguished for character and expression. Vivares, a Frenchman by birth, laid the foundation of the English school of landscape-engraving, which was still further developed by William Woollet, who was also an excellent engraver of the human figure.
In historical engraving a not less remarkable advance was made by Sir Robert Strange, and Richard Earlom produced some admirable works in mezzotint. In succession to these came William Sharp, James Bazire, Bartolozzi, James Heath, Bromley, Raimbach, and others.
The substitution of steel for copper plates around 1820 to 1830 gave the power of producing a much larger number of fine impressions, and opened new possibilities for highly-finished work.
During the closing years of the 18th century line engraving attained a depth of colour and fulness of tone in which earlier works generally are deficient, and during the following century it reached a perfectness of finish which it had not previously attained. A picture, whether figure or Landscuape, may be translated by line engraving with all its depth of colour, delicacy of tone, and effect of light and shade; the various textures, whether of naked flesh, silk, satin, woollen, or velvet, all successfully rendered by ingenious modes of laying the lines and combinations of lines of varying strength, width, and depth. Among engraverswho have produced historical works of large size and in the line manner the names of Raphael Mrghen, Longhi, Anderloni, Garavaglia, and Toschi, in Italy; of Forster, Henriquel-Dupont, Bridoux, and Blanchard, in France; of John Burnet, J H Robinson, Doo, J H Watt, and Lumb Stocks, in England, stand pre-eminent.
Among historical and portrait engravers in the stipple or dotted manner the names of H T Ryall, Henry Robinson, William Holl and Francis Holl, may well be mentioned.
In the period 1820 to 1860 landscape engraving attained a perfection in Great Britain which it had not attained in any other country, or at any other time. Among landscape engravers the names of George Gooke, William Miller, E Goodall, J Cousen, K Brandard, and William Forrest hold the foremost places. In mezzotinto engraving Samuel Cousins is unrivalled.
In the period 1830 to 1845 various publications called Annuals, composed of light literature in prose and verse, and illustrated by highly-finished engravings in steel, were very popular. The engravings were necessarily of small size, and are generally of great excellence. A number of them both figure and landscape are executed with such finish and completeness as to be esteemed perfect works. The unrivalled illustrations of Rogers' Poems and Rogers' Italy after Turner and Stothard belong to this period. Many of the originals of the engravings in the Annuals were finished pictures of large size.
A great part of the difficulty in engraving on a small scale from a large picture, consists in determining what details can be left out, and still preserve the full effect and character of the original. The most noted engravers for work of small size are Charles Heath, Charles Bolls, W Finden, E Finden, E. Portbury, J Goodyear, F Engleheart, Henry Le Keux, E Goodall, and W Miller.
After 1870 many plates were produced by a combination of etching and dry point, a comparatively cheap and rapid process. Such works were fashionable and very popular with collectors. But while some of them have been excellent of their kind, the process is of limited resource, and the best works in this manner will not stand comparison with the masterpieces of line engraving. Through lack of encouragement, change of fashion, and the adoption of other methods of reproduction such as photography, line engraving rapidly becoming a lost art in Great Britain. The men who made line engraving famous died, and there was no sufficient inducement for younger men to pursue that art. In France and in Germany some able line engravers were still in practice at the start of the 20th century.
Line Engraving, as implied by the term, is executed entirely in lines. The tools are few and simple. They consist of the graver or burin, the point, the scraper, and the burnisher; an oil-stone or hone, dividers, a parallel square, a magnifying lens; a bridge on which to rest the hand; a blind or shade of tissue paper, to make the light fall equally on the plate, callipers for levelling important erasures, a small steelanvil, a small pointed hammer, and punches. In etching, the following articles are required: a resinous mixture called etching-ground, capable, when spread very thinly over the plate, of resisting the action of the acids used; a dauber for laying the ground equally; a hand-vice; some hair-pencils of different sizes, and bordering wax, made of burgundy-pitch, bees'-wax, and a little oil.
In engraving, the plate, which is highly polished and must be free from all scratches, is first prepared by spreading over it a thin layer of ground. The surface is then smoked, and the outline of the picture transferred to it by pressure from the paper on which it has been drawn in fine outlines by a black-lead pencil. The picture is then drawn on the ground with the etching-needle, which removes the ground in every form produced by it, and leaves the bright metal exposed. A bank of wax is then put round the plate and diluted acid poured on it, which eats out the metal from the lines from which the ground has been removed, but leaves the rest of the plate untouched. The plate is then gone over with the graver, the etched lines clearly defuned, broken lines connected, new lines added, etc. Sometimes the plate is rebitten more than once, those parts which are sufficiently bitten in the first treatment being stopped with varnish, and only the selected parts exposed to after-biting. Finally the burnisher is brought into play alternately with the graver and point to give perfectness and finish.
Such is the process for landscape engraving. In historical and portrait engraving of the highest class, the lines are first drawn on the metal with a fine point and then cut in by the graver, first making a fine line and afterwards entering and re-entering till the desired width and depth of lines is attained. Much of the excellence of such engravings depends on the mode in which the lines are laid, their relative thickness, and the manner in which they cross each other. In historical engraving etching is but little used, and then only for accessories and the less important parts.
In Soft-ground Etching the ground, made by mixing lard with common etching-ground, is laid on the plate and smoked as before, but its extreme softness renders it very liable to injury. The outline of the subject is drawn on a piece of rough paper larger than the plate. The paper is then damped, and laid gently over the ground face upwards, and the margins folded over and pasted down on the back of the plate. When the paper is dry and tightly stretched the bridge is laid across, and with a hardish pencil and firm pressure the drawing is completed in the usual manner. The pressure makes the ground adhere to the back of the paper at all parts touched by the pencil, and on. the paper being lifted carefully off, these parts of the ground are lifted with it, and the corresponding parts of the plate thus left bare are exposed to the subsequent action of the acid. The granulated surface of the paper, causing similar granulations in the touches on the ground, gives the character of a chalk-drawing. The biting-in is effected in the same manner as already described, and the subject is finished by re-biting and dotting with the graver.
Stipple, or Chalk Engraving, in its pure state, is exclusively composed of dots, varying in size and form as the nature of the subject demands, but few stipple plates are now produced without a large admixture of line in all parts, flesh excepted. A great advance, however, was made in stipple engraving by the introduction of large and varied forms of dotting in the draperies, the results almost rivalling line engraving in richness and power.
The Mixed Style is based on mezzotinto, which, still forming the great mass of shading, is in this method combined with etching in the darker, and stipple in the more delicate parts. By this combination a plate will produce a larger number of good impressions than were it done entirely in mezzotinto.
The wood best adapted for engraving is box. It is cut across the grain in thicknesses equal to the height of type, these slices being subjected to a lengthened process of seasoning, and then smoothed for use. Every wood engraving is the representative of a finished drawing previously made on the block; the unshaded parts being cut away, and the lines giving form, shading, texture, etc, left standing in relief by excavations of varied size and character, made between them by gravers of different forms. Drawings on wood are made either with black-lead pencil alone or with pencil and indian ink, the latter being employed for the broader and darker masses. It is now much the practice to photograph drawings made in black and white upon the wood instead of making the drawing on the wood block. When the drawing is put on the wood by washes or by photography instead of being entirely done by pencil lines, the engraver has to devise the width and style of lines to be employed instead of cutting in facsimile, as is the case when the drawing is made entirely in lines. The tools required for wood engraving are similar but more numerous than those of the engraver on copper or steel. Research Engraving
An animal is an organized and sentient living being. Life in the earlier periods of natural history was attributed almost exclusively to animals. With the progress of science, however, it was extended to plants. In the case of the higher animals and plants there is no difficulty in assigning the individual to one of the two great kingdoms of organic nature, but in their lowest manifestations, the vegetable and animal kingdoms are brought into such immediate contact that it becomes almost impossible to assign them precise limits, and to say with certainty where the one begins and the other ends. From form no absolute distinction can be fixed between animals and plants. Many animals, such as the sea-shrubs, sea-mats, etc, so resemble plants in external appearance that they were looked upon as such. With regard to internal structure no line of demarcation can be laid down, all plants and animals being, in this respect, fundamentally similar; that is, alike composed of molecular, cellular, and fibrous tissues. Neither are the chemical characters of animal and vegetable substances more distinct. Animals contain in their tissues and fluids a larger proportion of nitrogen than plants, whilst plants are richer in carbonaceous compounds than the former. In some animals, moreover, substances almost exclusively confined to plants are found. Thus the outer wall of Sea-squirts contains cellulose, a substance largely found in plant-tissues; whilst chlorophyll, the colouring-matter of plants, occurs in Hydra and many other lower animals.
Power of motion, again, though broadly distinctive of animals, cannot be said to be absolutely characteristic of them. Thus many animals, as oysters, sponges, corals, etc, in their mature condition are rooted or fixed, while the embryos of many plants, together with numerous fully developed forms, are endowed with locomotive power by means of vibratile, hair-like processes called cilia. The distinctive points between animals and plants which are most to be relied on are those derived from the nature and mode of assimilation of the food. Plants feed on inorganic matters, consisting of water, ammonia, carbonic acid, and mineral matters. They can only take in food which is presented to them in a liquid or gaseous state. The exceptions to these rules are found chiefly in the case of plants which live parasitically on other plants or on animals, in which cases the plant may be said to feed on organic matters, represented by the juices of their hosts. Animals, on the contrary, require organized matters for food. They feed either upon plants or upon other animals. But even carnivorous animals can be shown to be dependent upon plants for subsistence; since the animals upon which Carnivora prey are in their turn supported by plants. Animals, further, can subsist on solid food in addition to liquids and gases; but many animals (such as the Tapeworms) live by the mere imbibition of fluids which are absorbed by their tissues, such forms possessing no distinct digestive system.
Animals require a due supply of oxygen gas for their sustenance, this gas being used in respiration. Plants, on the contrary, require carbon dioxide. The animal exhales or gives out carbon dioxide as the part result of its tissue-waste, whilst the plant taking in this gas is enabled to decompose it into its constituent carbon and oxygen. The plant retains the former for the uses of its economy, and liberates the oxygen, which is thus restored to the atmosphere for the use of the animal. Animals receive their food into the interior of their bodies, and assimilation takes place in their internal surfaces. Plants, on the other hand, receive their food into their external surfaces, and assimilation is effected in the external parts, as are exemplified in the leaf-surfaces under the influence of sunlight. All animals possess a certain amount of heat or temperature which is necessary for the performance of vital action. The only classes of animals in which a constantly-elevated temperature is kept up are birds and mammals. The bodily heat of the former varies from 100 degrees Fahrenheit to 112 degrees Fahrenheit and of the latter from 96 degrees to 104 degrees. The mean or average heat of the human body is about 99 degrees Fahrenheit, and it never falls much below this in health. Below birds animals are named cold-blooded, this term meaning in its strictly physiological sense that their temperature is usually that of the medium in which they live, and that it varies with that of the surrounding medium, Warm-blooded animals, on the contrary, do not exhibit such variations, but mostly retain their normal temperature in any atmosphere. The cause of the evolution of heat in the animal body is referred to the union (by a process resembling ordinary combustion) of the carbon and hydrogen of the system with the oxygen taken in from the air in the process of respiration. Research Animal
Baleen plates are sheets of stiff fibrous tissue derived from the upper palate in some whales, that shred as they are worn to form a filter plate for plankton. The whales catch the plankton on the straining-hairs and suck them off with their tongues. Research Baleen Plates
Cellulose is the cellular tissue of plants. It is a member of the carbohydrate family and is allied to starch. In plants, cellulose is normally combined with woody, fatty, or gummy substances. With some exceptions among insects, true cellulose is not found in animal tissues. Microorganisms in the digestive tracts of herbivorous animals break down the cellulose into products that can then be absorbed.
Cellulose is insoluble in all ordinary solvents and may be readily separated from the other constituents of plants. Depending on its concentration, sulphuric acid acts on cellulose to produce glucose, soluble starch, or amyloid; the last is a form of starch used for the coating of parchment paper. When cellulose is treated with an alkali and then exposed to the fumes of carbon disulphide, the solution yields films and threads. Rayon and cellophane are cellulose regenerated from such solutions.
Cellulose acetates are spun into fine filaments for the manufacture of some fabrics and are also used for photographic safety film, as a substitute for glass, for the manufacture of safety glass, and as a moulding material. Cellulose ethers are used in paper sizings, adhesives, soaps, and synthetic resins. With mixtures of nitric and sulphuric acids, cellulose forms a series of flammable and explosive compounds known as cellulose nitrates, or nitrocelluloses. Pyroxylin, also called collodion cotton, is a nitrate used in various lacquers and plastics; another, collodion, is used in medicine, photography, and the manufacture of artificial leather and some lacquers. A third nitrate, guncotton, is a high explosive. Research Cellulose
The cherry gall wasp (Cynips quercusfolii) is a hymenopterous insect of the family Cynipidae widespread throughout Europe and Asia Minor, that produces spherical leaf galls on various species of oak. The galls are mostly to be seen between July and October and are attached to either the main leaf vein or one of the stronger side veins by a very short stem. The gall is at first green-yellow in colour later turning yellow and then red on the side facing the sun before becoming brown and wrinkled. The larvae develops within the gall, feeding upon the galltissue and pupates within the gall. Two generations appear within a year, the first all female that reproduce parthenogenetically the second male and female. Research Cherry Gall Wasp
In an organism, circulation is the flowing of sap or blood through the veins or channels, by means of which the perpetual and simultaneous movements of composition and decomposition manifested in organic life are carried on. Although Galen, who had observed the opposite directions of the blood in the arteries and veins, may be said to have been upon the very point of discovering the circulation, the discovery was reserved for William Harvey, who in 1628 pointed out the continuity of the connections between the heart, arteries, and veins, the reverse directions taken by the blood in the different vessels, the arrangements of valves in the heart and veins so that the blood could flow only in one direction, and the necessity of the return of a large proportion of blood to the heart to maintain the supply.
In 1661 Malpighi exhibited microscopically the circulation in the web of a frog's foot, and showed that the blood passed from arteries to veins by capillaries or intermediate vessels. This finally established the theory with regard to animals, but the movements of sap in vegetables were only traced with difficulty and after numerous experiments.
Many physiologists were reluctant to ascribe the term 'circulation' to this portion of the economy of plants; but though sap, unlike the blood, does not exhibit movements in determinate vessels to and from a common centre, a definite course is observable. In the stem of a dicotyledonous tree, for example, the sap describes a sort of circle, passing upwards from the roots through the newer woody tissue to the leaves, where it is elaborated under the action of air and light; and thence descending through the bark towards the root, where what remains of it is either excreted or mixed with the new fluid, entering from the soil for a new period of circulation.
In infusorial animalcules the movement of the fluids of the body is maintained by that of the animal itself and by the disturbing influence of nutritive absorption. In the Coelentera (zoophytes, etc) the movement receives aid besides from the action of cilia on the inner walls of the body. The Annelids, as the earth-worm, possess contractile vessels traversing the length of the body. The Insects, Crustaceans, Myriapods, and Spiders have a dorsal tube, a portion of which may be specially developed as a heart. The blood is driven to the tissues, in some cases along arterial trunks, being distributed not in special vessels, but simply through the interstices of the tissues. From the tissues it is conveyed, it may be by special venous trunks to a venous sinus which surrounds the heart and opens into it by valvular apertures. The Mollusca have the heart provided with an auricle and a ventricle, as in the snail and whelk; two auricles, one on either side of the ventricle, as in the fresh-water mussel; or two auricles and two ventricles, as in the ark-shells. Among the ascidians, which stand low in that division of animals to which the molluscs belong, the remarkable phenomenon is encountered of an alternating current, which is rhythmically propelled for equal periods in opposite directions.
All vertebrated animals (except Amphioxus) have a heart, which in most fishes consists of an auricle and ventricle, but in the mud-fishes (Lepidosiren) there are two auricles and one ventricle; and this trilocular heart is found in the amphibians, and in most reptiles except the crocodiles, which, like birds and mammals, have a four-chambered organ consisting of two auricles and two ventricles. In these two last-named classes the venous and arterial blood are kept apart; in the trilocular hearts the two currents are mixed in the ventricle. Research Circulation
The Dodo (Didus ineptus) was a huge, flightless bird of the pigeon order, Columbidae, formerly found in abundance only on the island of Mauritius. The Dodo had rudimentary wings, short, stout legs and a tail of soft plumage. The beak was strongly arched towards the end, and the upper mandible had a hooked point like that of a bird of prey. In 1644 when the island was first colonised by the Dutch the dodo was present in great numbers, but within forty years a combination of the loss of natural habitat to cyltivation and hunting for food led to the Dodo's extinction in the first and most famous ecological tragedy committed by Man.
In 2002 scientists at Oxford university, England extracted DNA from the only remaining Dodo tissue in existence and claimed to have discovered that the Dodo was a pigeon. However, this had already been known for at least 100 years, as evidenced by Lloyd'sEncyclopaediaDictionary, published in 1895 by Edward Lloyd Limited of London describes the dodo as 'A large bird, belonging to the order Columbidae, or Pigeons'. Research Dodo
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Armenian Bole
