be well worked in so as to exclude minute air-bubbles. | ing the cheaper into the most valuable woods, by platSome skill is required to produce a uniform effect, ing them with the latter, so that by cutting a tree into especially in large surfaces. The first coat of varnish thin slices, it may thus be sold several times over. is generally absorbed more or less by wood and porous surfaces, and the absorption raises the grain of the wood, so that a second and even a third coat may be required to fill up the pores uniformly. The work is then smoothed with fine glass-paper, and 2 or 3 coats of varnish are afterwards applied. As the absorption of the first layers produces a great expenditure of varnish, it is sometimes usual to substitute for the first layers size made of pale glue or parchment cuttings, or solutions of isinglass or tragacanth. | Turpentine and oil varnishes are applied generally in the same manner as spirit varnishes, but as they dry more slowly it is easier to produce a uniform effect on large surfaces with them than with spirit varnishes. Coloured works receive their coat of colour before being varnished.

In the cutting of veneers, it is of course desirable to economise the material as much as possible, and hence it is now usual to employ very accurate machinery for the purpose. They were formerly cut at the saw-pit, with very thin plates strained in the common pit-saw frame [see SAW], or they were cut with the smaller frame-saw, as is now done on the Continent. Skilful pit-sawyers would cut 6 veneers out of every inch of wood, and cabinet-makers 7 or 8 from smaller pieces, but as the veneers increased in size the difficulties of cutting them accurately were greatly increased. Small veneers for the backs of brushes, &c. were split or planed from small pieces squared to the required sizes. The scale-boards for making hat and bonnet boxes are cut by a PLANING-MACHINE, as noticed under that head. The method of producing continuous shavings of this kind is important where the material is costly, for the ordinary veneer-saw cuts on the average one-third of the material into sawdust. It is said to have originated in Russia, and by its means the veneers are cut spirally from a cylinder of wood with a knife of the same length as the cylinder. Ivory has been cut in this way into sheets of large dimensions. Pape, of Paris, some years ago, veneered a piano-forte entirely with ivory, and advertised to supply sheets as large as 30 by 150 inches. In the United States department of the Great Exhi bition was an ivory vencer 12 inches wide, and 40 feet long, cut out of a single tusk. In 1806, Mr. Brunel patented a method of splitting vencers of large size by means of a horizontal knife composed of several pieces of steel placed exactly in a line on their lower surfaces, but with their edges slightly rounded and very keen. A short reciprocating or sawing motion was imparted to this compound knife, and the block of wood to be cut up was carried slowly sideways beneath the knife by means of a screw-slide worked with a spoke-wheel. When one veneer had been cut off and the log restored to its first position, it was raised in exact parallelism by a system of two right-and-lefthanded screws at the four angles of the frame, and which were all moved together by means of one winchSee MINE handle. This machine answered the purpose when veneers were to be cut from straight-grained and pliant woods, such as Honduras mahogany: but with woods of irregular and brittle grain, such as rosewood, the veneer curled up or split. The circular saw, although so wasteful of the material, is therefore commonly used for cutting veneers; and in order to give the

The finest kinds of varnish-works, such as the wooded work of harps, is thus performed :- "The wood is covered with about 6 layers of the white hard varnish, and allowed thoroughly to dry between each; this entirely fills up the pores of the wood; the face is then rubbed quite smooth with fine glass-paper. The ornamental painting is then done, after which about 8 or 10 coats more of varnish are laid on, and at every third coat the surface is rubbed with fine glass-paper to remove the brush marks. When all the varnish is put on and has become hard, the surface is rubbed with fine pumice-stone powder and water on woollen rags; the work is allowed to stand for a day or two, and is then polished with yellow tripoli' and water, after which it is washed quite clean with a sponge and wiped dry with a clean wash-leather. The varnish is now touched at a few places with the finger smeared with fine rendered tallow, which is then thoroughly rubbed all over with the ends of the fingers; clean wheat flour is dusted over the work, and also well rubbed in with the fingers; and after the removal of the flour, the surface is slightly rubbed with a clean old silk handkerchief, which completes the splendid lustre given to these instruments."2

VAULT. See BRIDGE.
VEIN. See MINE-MINING.
VEINSTONE or GANGUE.

MINING.

VELLUM. See PARCHMENT. VELVET. See WEAVING. VENEER-VENEERING. The art of covering a cheap and inferior wood with a thin layer of wood of a more ornamental and costly character is not a modern invention. The elder Pliny refers to it as a recent invention in his time, suggested doubtless by the large sums which the luxurious Romans were accustomed to pay for solid tables of rare and costly woods. Pliny speaks of the ingenious art of convert(1) Tripoli and rottenstone for such works as these are prepared for use by grinding very fine with a stone muller.

(2) Holtzapffel, Mechanical Manipulation, vol. iii. There is a long and instructive chapter in this volume on Varnishing, Lackering, Japanning, Bronzing, &c.

(3) The most costly wood in the time of Cicero, was pro

cured from a tree named citrus, a native of Mauritania, near

Mount Atlas. In leaf, trunk, and odour it resembles the female

wild cypress; the most valuable part is a tuber or warty excre

scence, which when found on the root and underground is more esteemed than when growing on the branches. When cut and polished, it presents various figures, such as curling veins, or concentric eye-like spots; the former have procured for the wood the name of tiger-wood, the latter panther-wood. A table of this kind is said to have cost Cicero a million of sesterces, or £8,072 sterling. Even higher prices are quoted for the solid tables. See Mr. Aikin's paper on "Ornamental Woods," in the Transactions of the Society of Arts, vol. 1.

means of a freeing-stick applied beneath the timber during the action of the saw.

As the veneers are cut they are rough on both sides, in which condition they are used by cabinetmakers for veneering articles of furniture. The operations of veneering consist in glueing the veneer to the prepared surface, and cleaning and polishing it when so fixed. Suppose the top of a table or of a sideboard is to be veneered. The workman first cuts out his veneers a little larger than the required size to allow for waste; he also cuts out a caul or board to prevent the clamp screws from leaving marks, and he next proceeds to scratch over the surface of the table or sideboard, and both surfaces of the veneer, with an iron toothing-plane, which gives to the surfaces the required roughness, or tooth, or key, as it is called, for holding the glue. The clamps consist of strong wooden bars somewhat rounded on their inner edges, and connected by iron screw-bolts and nuts. surface of the table being warmed, and the veneer and caul made hot, the table is brushed over with thin glue; the veneer is also glued and placed on the table: upon the veneer is put the heated caul, and the clamping bars are next quickly screwed down 3 or 4 inches apart. The heat of the caul retains the glue in a fluid state during the screwing down, which operation brings every part of the veneer into contact with the table, and forces out most of the glue. The table is generally left all night before the screws are removed. For curved work the cauls are also curved, and the clamp screws are numerous, in order to multiply the points of pressure.

The

saw sufficient strength, it is made thick towards the centre, and towards the edge it is thinned away almost to a feather edge. The solid block of wood or The number of veneers cut out of each solid inch ivory is conducted along a parallel guide across the of wood varies with the width of the veneers, and the flat face of the saw, while the thin pliant veneer purpose to which they are to be applied. In general, separates and forms an opening for the wedge-shaped when the width of the wood is 6, 12, 18, 24, 30, 36, edge of the blade, the veneer passing uninterruptedly | 48, 60 inches, each inch of wood is cut into 15, 14, along the conical back of the saw. For cutting large | 13, 12, 11, 10, 9, 8 veneers. veneers, the saw is composed of a number of segments or plates of steel screwed to the edge of a metal disk, cast-iron wheel, or chuck, and is sometimes as much as 18 feet in diameter. In all veneer saws the edge must run very true, and the teeth must be sharp and very faintly set. [See SAW.] If the segment veneer-saw exceeds about 4 feet in diameter, the horizontal platform or table is not used for guiding the wood, but a contrivance called the drag. In saw-mills where veneers are cut, the arrangement of the segment saw is called a veneer-mill. The axis of the saw runs in massive brasses, fixed on brick or stone piers; and if the saw be large, its edge is made to dip into a pit below the ground. The axis of the saw is connected or disconnected with the moving power by means of a fast-and-loose pulley. The log of wood is usually adzed over to remove sand and dirt, and is then partially levelled to adapt it to the vertical face of the drag. The log is held by iron fastenings or dogs, while its surface is levelled by the saw; it is then glued to a wooden frame containing transverse and oblique bars, which have also been levelled with the saw. By this arrangement, the whole log can be cut into veneers without interruption from the joint. The timber is carried across the face of the saw by means of a rack and pinion acting on the drag, which is supported on a railway extending across the face of the saw. The axis of the pinion is furnished with a double train of toothed wheels, and a clutch-box, the latter capable of being adjusted to 3 positions, by which the drag may be at rest or be carried slowly past the saw, or returned quickly back preparatory to another cut. The lever by which these motions are given is placed just behind the stool on which the workman is seated. Between every two veneers, the block requires to be advanced sideways through a small space equal to the thickness of the intended veneer. This is accomplished by means of adjusting screws, which act upon the standards which support the frame or wooden bars to which the wood is attached. The adjusting screws have worm-wheels at one end, and are simultaneously moved by a winchhandle, 50 or 60 turns of which are required to advance the log 1 inch, so that the veneers can by this adjustment be cut to any desired thickness. The thin veneer as it is cut is guided away from or in front of the saw by a feather-edged brass guide-plate, fixed almost in contact with the blade of the saw. As the veneer is being cut, the workman leads it on to the guide by means of a thin blunt chisel or spud; and it passes over the guide through a curved wooden trough, and when fully detached, it is removed and placed in a heap of veneers already cut from the same log. The teeth of the saw are cleared of saw-dust by

Veneers are sometimes laid with a veneering hammer, which is a hammer with a very wide and thin pane; or simply a piece of wood 3 or 4 inches square, with a round handle projecting from the centre: one edge of the head is sawn down for the reception of a piece of sheet-iron or steel, which is made to project

inch, with a straight, smooth, round edge, and the opposite side of the square head is rounded to make it fit the hand better. The table and both sides of the veneer are toothed, the surface of the table is warmed, and the outer face of the veneer and the surface of the table are wetted with thin glue or stiff size. The inner face of the veneer is next glued, and the veneer is held for a very short time before a blazing fire to make the glue very fluid; the veneer is then turned down upon the table and rubbed down by hand, several men being employed if the veneer be of large size. The greater part of the glue is then forced out with the edge of the veneering hammer, which is placed in the centre of the table, and gradually worked to the edge. A number of men are employed on this at once, and in order to keep the glue fluid, as also to relieve the friction of the hammers, hot size is occasionally applied to the surface of the veneer.

When

VENEER-VENEERING-VERATRINE-VICE.

901

the work is judged to be complete, it is tapped all | with the pane of the hammer, after which the work is over with the back of the hammer; if the sound be laid aside to dry. When thoroughly dry, it only reanywhere hollow or tacky, the contact is imperfect, mains to scrape the bottom with the toothing-plane, and the hot size and the work of the hammer must or, when the work is small, with its iron alone, and be repeated; or if the glue be well set, the inner then the bull is ready to be glued on the box or furvessel of the glue-pot, or a hot iron, must be applied niture in the manner of an ordinary veneer, as already to the spot to melt it. Should the glue be in excess explained; when the work is again dry, it is scraped at one spot, the hot iron must be slowly moved to- and polished. Exactly the same routine is pursued wards the edge, so as to form a kind of channel along in combining the holly-ground and the ebony honeywhich the glue is pressed by the edge of the veneer- suckle, and these constitute the counter, or counterpart ing hammer. buhl, in which the pattern is the same, but the colours are reversed. It is obvious that precisely the same general method would be pursued to make 4 satinwood honeysuckles at the respective angles of a rosewood box; the veneers for which would then be selected of the full size, and glued together with paper interposed. To ensure the exact similitude of the several honeysuckles, one of them having been cut out would be printed from, by sticking it slightly to the table, dabbing it with printing-ink, and then taking impressions to be glued on the other angles of the box at their exact places. The counter would have, in this case, a satin-wood ground, with the

saw,

3 thicknesses of wood may be glued together, as rosewood, mahogany, and satin-wood, and a centre ornament added to the group of 4 honeysuckles. The 3 thicknesses, when cut through, split asunder, and re-combined, would produce 3 pieces of buhl-work, the grounds of which would be of rose-wood, mahogany, and satin-wood, with the honeysuckle and centre of the two other colours respectively. Such are technically known as 'works in three woods,' and constitute the general limit of the thicknesses, but the patterus consist of many more parts than are here supposed." See MARQUETRY.

VENTILATION. See WARMING AND VENTILA

INLAYING is a species of veneering in patterns which are cut with the buhl-saw, or piercing-saw, Fig. 381. [See BUHL-WORK.] As an example of buhl-work in wood we take the liberty of quoting Mr. Holtzapffel's excellent description of the mode of forming the honey-suckle ornament. "To make this, two pieces of veneer of equal size, say of ebony and holly, are scraped evenly on both sides with the toothing-plane, and glued together with a piece of paper between, for the convenience of their afterseparation. Another piece of paper is glued outside the one or other veneer, and on which the design is sketched; a minute hole is then made with a sharp-honeysuckles in rose-wood. To advance another stage, pointed awl or scriber, for the introduction of the that spot being selected in which the puncture will escape observation. The buhl-cutter being seated on the horse, the saw is inserted in the hole in the veneers, and then fixed in its frame; the work, held in the left hand, is placed in the vice, which is under control of the foot, and the saw is grasped in the right hand, with the fore-finger extended to support and guide the frame; the medium and usual position | of which is nearly horizontal and at right angles to the path of the saw. The several lines of the work are now followed by short quick strokes of the saw, the blade of which is always horizontal; but the frame and work are rapidly twisted about at all angles, to place the saw in the direction of the several lines. Considerable art is required in designing and sawing these ornaments, so that the saw may continue to ramble uninterruptedly through the pattern, whilst the position of the work is as constantly shifted about in the vice, with that which appears to be a strange and perplexing restlessness. When the sawing is completed, the several parts are laid flat on a table, and any removed pieces are replaced. The entire work is then pressed down with the hand, the holly is stripped off in one layer with a painter's paletteknife, which splits the paper, and the layer of holly is laid on the table with the paper downwards, or without being inverted. The honeysuckle is now pushed out of the ebony with the end of the scriber, and any minute pieces are picked out with the moistened finger; these are all laid aside; the cavity thus produced in the ebony is now entirely filled up with the honeysuckle of holly, and a piece of paper smeared with thick glue is rubbed on the two to retain them in contact. They are immediately turned over, and the toothings, or fine dust of the ebony, are rubbed in to fill up the interstices; a little thick glue is then applied, and rubbed in, first with the finger, and then

TION.

VERATRINE or VERATRIA, an alkaloid contained in the seeds of Veratrum sabadilla, and in the roots of V. alba, or white hellebore. It is a white or yellowish-white powder, with a sharp burning taste; it is poisonous; and is remarkable for occasioning violent sneezing. It is insoluble in water, but dissolves in hot alcohol, in ether, and in acids: and the solution has an alkaline reaction. Veratria is said to contain C3H2O6N.

VERDIGRIS. See COPPER.
VERDITER. See COPPER.

VERMICELLI. See MACARONI.
VERMILION. See MERCURY.

VIADUCT. See BRIDGE-ROADS AND RAIL-
ROADS-AQUEDUCT.

VICE, a well-known contrivance for fixing work during the filing or otherwise shaping thereof.

(1) "Mechanical Manipulation," vol. ii. As an example of complex inlaying, Mr. Holtzapffel gives an engraving of a border of flowers on a black ground of ebony, with instructions for

making it. The green leaves are of holly, stained green, notched

and engraved. The petals are of holly stained blue, or scorched; white holly, yellow Zante, and red Brazil wood are also used.

(2) A large number of vices are described and figured in Holtzapffel's "Mechanical Manipulation," chap. xxviii. sec. 3.

902

WACKE-WADDING-WAFERS-WARMING AND VENTILATION.

down, whereby the paste is formed into a thin layer

VINEGAR. See ACETIC ACID. VITRIFIABLE COLOURS. See GLASS, Sec. ix. of equal thickness, the superfluous portion being -POTTERY AND PORCELAIN, Sec. viii. ix.

VITRIFICATION. See GLASS-POTTERY AND

PORCELAIN.

squeezed out. The instrument is then held in the fire for a few seconds, when it is perfectly baked, and by exposure to the air it soon becomes dry and brittle. A number of these plates of paste being collected into a heap, the wafers are cut out by means of hollow punches of various sizes. Some of the mineral colours employed to colour wafers being poisonous, the refuse is sold for the purpose of destroying rats and other vermin.

Medallion wafers, containing a classic design on a ground of a deeper colour, were in fashion some years ago. They were formed in the following manner :-Pure glue was dissolved in water, and the colouring matter added. A gem, seal, or medallion was next moistened with a weak solution of gum, in which an opaque white, or other colour had been dissolved; this coloured gum water was carefully wiped off the smooth uncut surface of the seal, and a small quantity of the coloured glue was poured over the seal, and left to dry at a gentle heat. In drying, the

VITRIOL. See SULPHUR, page 800, note. WACKE, or GRAU or GREYWACKE, a term adopted from the German geologists, and applied to some of the ancient stratified rocks. When the term is applied to particular rocks, it bears nearly the same relation to clay slates that argillaceous sandstones and conglomerates bear to common clays; "for argillaceous slate," as Mr. Phillips remarks, "by including rolled fragments or minute grains of quartz sand, with or without mica, becomes the grauwacke, and grauwackeslate of Werner and his followers. When the sand or gravel predominates, so as nearly to exclude the argillaceous cement, the distinction between grauwacke and sandstone is almost imaginary, just as, on the other hand, indurated shale and soft clay-slate are not always certainly distinguishable." The grauwacke rocks lie amidst the primary argillaceous strata, and form part of the transition series of continental geolo-glue and gum contracted, and were thus easily sepagists. The grauwacke group of De la Beche includes the Silurian rocks of Murchison, and a portion of the older strata called the Cambrian rocks by Sedgwick. WAD, a term applied by miners to a soft black mineral, the hydrate of the peroxide of manganese.

rated from the seal, thus forming a wafer not thicker than writing paper, and affording a beautiful imitation of the device, the coloured gum giving the figure, and the glue the ground. On wetting the back of the wafer, it adhered to and secured a letter just like an ordinary seal.

The French isinglass wafer was prepared by dissolv

WADDING, a spongy material used for lining ladies' dresses; it is made with a lap of cotton prepared by the carding-engine, or lap-machine, [seeing isinglass in water, and pouring it upon glass plates COTTON, Fig. 637]; and is attached to tissue paper by means of size.

WAFERS. The invention of wafers is attributed to the Genoese; but long before their application to the sealing of letters, they were made by the pastrycook in the form of a thin curled-up cake. Indeed, a pastry cook was formerly called a wafirer. According to Beckmann, the oldest seal with a red wafer is on a letter written by D. Krapf, at Spires, in the year 1624, to the government at Bayreuth. It appears that wafers were not used during the seventeenth century in the chancery of Brandenburg, "because people were fonder of Spanish wax." By an order dated 1716, the use of wafers in law matters was forbidden in the duchy of Weimar; but this order was abolished in 1742. See SEALING-WAX.

The French term for wafers, pains à cacheter, indicates the materials of which they are made. Wafers are small disks of dried wheaten paste, to which an adhesive property is instantly communicated on the addition of moisture. In the manufacture of wafers fine wheaten flour is formed into a smooth paste, with the addition of colouring matter and sometimes of a small quantity of white of egg and isinglass. This paste is baked in thin layers, between two plates of iron attached to handles, which are hinged together like snuffers or curling-tongs. The lower plate, which is furnished with a slightly raised ledge, forms a mould for the paste. The plates are warmed, and slightly greased, and a portion of the paste being poured into the lower plate, the top plate is shut

with raised borders, previously smearing the plates
with ox-gall, to prevent the isinglass from adhering.
Various colouring matters, and even perfumes, were
mixed with the fluid isinglass. When the film on the
plate was evenly distributed, a plate of glass was
placed upon it, and the film was thus moulded into a
fine delicate sheet: before it was quite dry, it was cut
along the edges, and separated, and afterwards cut
into wafers in the usual manner. These wafers were
exceedingly thin, and far more adhesive than common
wafers. Gelatine wafers are now largely manufactured
in a similar manner. See GELATINE.

WALKING WHEEL. See PEDOMETER.
WALL. See BRICKLAYING-MASONRY-BRIDGE
-ROADS AND RAILROADS.

WARP. See WEAVING.

The art

WARMING AND VENTILATION. of warming or of ventilating a building is not a difficult one; but the art of warming and ventilating is extremely difficult, and cannot be said to have attained to anything like perfection. And yet there is no art of greater importance, for on it depend the health, the comfort, and much of the prosperity of man, and of the animals which he domesticates for his use and profit.

In order to arrive at satisfactory results in the practice of this art, it is necessary to be well acquainted with the chemical conditions of the problem which is to be solved. Now it is well known that the combustion of fuel and the respiration of animals are processes almost chemically identical; they require