25. The goodness of joiners' work depends chiefly upon the care that has been bestowed in joining the materials. In carpentry, framing owes its strength to the form and position of its parts; but in joinery, the strength of a frame depends upon the strength of the joinings. The importance, therefore, of fitting the joints together as accurately as possible, is obvious. It is very desirable, that a joiner should be a quick workman; but it is still more so that he should be a good one; that he should join his materials with firmness and accuracy; that he should make surfaces even and smooth, mouldings true and regular, and the parts intended to move so that they may be used with ease and freedom.

Where dispatch is considered as the chief excellence of a workman, it is not probable that he will strive to improve himself in his art, further than to produce the greatest quantity of barely tolerable work with the least quantity of labour. In some articles of short duration, dispatch in the manufacture may be of greater importance; but in works that ought to remain firm for years, it certainly is bad economy to spare a few shillings' worth of labour at the risk of being annoyed with a piece of bad work as long as it will hold together.

We have seen, with no small degree of pleasure, the effect of encouraging good workmanship in the construction of machinery, and would recommend that a like encouragement should be given to superior workmen in other arts.

JOINING ANGLES.

26. When the length of a joint at an angle is not considerable, it is sufficient to cut the joint, so that when the parts are joined, the plane of the joint shall bisect the angle. This kind of joint is shown for two different angles, by fig. 16.

When an angle of considerable length is to be joined, and the kind of work does not require a jointing should be concealed, fig. 17 is often employed; the small bead renders the appearance of the joint less objectionable, because any irregularities, from shrinkage, are not seen in the shade of the quirk of the bead.

A bead upon an angle, where the nature of the thing does not determine it to be an arris, is attended with many advantages; it is less liable to be injured, and admits of a secure joint, without the appearance of one. Fig. 18 shows a joint of this description, which should always be used in passages.

Fig. 19 represents a very good joint for an exterior angle, whether it be a long or short one. Such a joint may be nailed both ways. But the joint represented by fig. 20 is superior to it; the parts being drawn together by the form of the joint itself, they can be fitted with more accuracy, and joined with certainty. The angles of pilasters are often joined, as fig. 20.

Interior angles are commonly joined, as shown by fig. 21.

If the upper or lower edge be visible, the joint is mitred, as in fig. 16, at the edge only, the other part of the joint being grooved, as in fig. 21. In this manner are put together the skirting and dado at the interior angles of rooms, the backs, and backlinings of windows, the jambs of door-ways, and various other parts of joiners' work.

FRAMING.

27. Frames in joinery are usually connected by mortise tenon joints, with grooves to receive panels. Doors, window-shutters, &c., are framed in this manner. The object in framing is, to reduce the wood into narrow pieces, so that the work may not be sensibly affected by its shrink- age; and, at the same time, it enables us to vary the surface without much labour.

From this view of the subject, the joiner will readily perceive, that neither the parts of the frame nor the pannels should be wide. And as the frame should be composed of narrow pieces, it follows, that the pannels should not be very long, otherwise the frame will want strength. The pannels of framing should not be more than 15 inches wide, and 4 feet long, and pannels so large as this should be avoided as much as possible. The width of the framing is commonly about one-third of the width of the panel.

It is of the utmost importance, in framing, that the tenons and mortises should be truly made. After a mortise has been made with the mortise chisel, it should be rendered perfectly even with a float; an instrument which differs from a single cut, or float file, only by having larger teeth. An inexperienced workman often makes his work fit too tight in one place, and too easy in another, hence the mortise is split by driving the parts together, and the work is never firm; whereas if the tenon fill the mortise equally, without using any considerable force in driving the work together, is is found to be firm and sound. The thickness of tenons should be about one-fourth of that of the framing, and the width of a tenon should never exceed about five times its thickness, otherwise, in wedging, the tenon will become bent, and bulge out of the sides of the mortise. If the rail be wide, two mortises should be made, with a space of solid wood between; fig. 22 shews the tenons for a wide rail.

In thick framing, the strength and firmness of the joint is much increased by putting a cross or feather tongue in on each side of the tenon; these tongues are about an inch in length, and are easily put in with a plough proper for such purposes. The projected figure of the end of a rail, fig. 22, shews these tongues put in, in the style there are grooves ploughed to receive them.

Sometimes, in thick framing, a double tenon in the thickness is made; but we give the preference to a single one, when tongues are put in the shoulders, as we have described; because a strong tenon is better than two weak ones, and there is less difficulty in fitting one than two.

The pannels of framing should be made to fill the grooves, so as not to rattle, and yet to allow the pannels to shrink without splitting.

28. When a frame consists of curved pieces, they are often joined by means of pieces of hard wood called keys. Fig 23 is the head of a Gothic window frame, joined with a key, with a plan of the joint below it. A cross tongue is put in on each side of the key, and the joint is tightened by means of the wedges a a.

It is, however, a better method to join such pieces by means of a screw bolt instead of a key, the cross tongues being used whichever method is adopted.

Joining with Glue.

29. It is seldom possible to procure boards sufficiently wide for pannels without a joint, on account of heart shakes, which open in drying. In cutting out pannels, for good Joinery work, shaken wood should be carefully avoided. That part near the pith is generally the most defective.

If the pannels be thick enough to admit of a cross or feather tongue in the joint, one should always be inserted, for then, if the joint should fail, the surfaces will be kept even, and it will prevent light passing through.

Sometimes plane surfaces of considerable width and length are introduced in joiners' work, as in dado, window backs, &c.; such surfaces are commonly formed of inch, or inch and quarter, boards joined with glue, and a cross or feather tongue ploughed into each joint. When the boards are glued together, and have become dry, tapering pieces of wood, called keys, are grooved in, across the back, with a dovetail groove. These keys preserve the surface straight, and also allow it to shrink and expand with the changes of the weather.

30. It would be an endless task to describe all the methods that have been employed to glue up bodies of such varied forms as occur in joinery; for every joiner forms work methods of his own, and merely from his being most familiar with his own process, he will perform his work, according to it, in a better manner than by another, which, to an unprejudiced mind, has manifestly the advantage over it. The end and aim of the joiner, in all these operations, is to avoid the peculiar imperfections and disadvantages of his materials, and to do this with least expense of labour or material. The straightness of the fibres of wood renders it unfit for curved surfaces, at least when the curvature is considerable. Hence short pieces are glued together as nearly in the form desired as can be, and the apparent surface is covered with a thin veneer; or the work is glued up in pieces that are thin enough to bend to the required form. Sometimes a thin piece of wood is bent to the required form upon a cylinder or saddle, and blocks are jointed and glued upon the back; when the whole is completely dry it will preserve the form that had been given to it by the cylinder.

The proper thickness for the pieces to be bent may be easily determined by an easy experiment on a piece of the same kind of wood. Thus, select a piece of wood, of the same kind as that to be used, and bend it as much as it will bear without injury; then ascertain the radius of curvature, and also the thickness of the piece, at the most curved part of it. From these data the proper thickness for any other curve will be determined by the following proportion:

As the radius of curvature, found by experiment, is to the thickness of the piece tried; so is the radius of any other curve to the thickness of the piece that may be bent into it.

For example, we have found that a piece of straight grained white deal, of an inch in thickness, may be bent, without injury, into a curve of which the radius is 120 inches, therefore, $120 : 1 :: \text{radius} : \text{thickness} = \frac{\text{radius}}{120}$. That is, a piece of deal of the same quality may be bent into any curve, of which the radius is not less than 120 times its thickness.

A piece of work glued up in thicknesses should be very well done; but it too often happens that the joints are visible, irregular, and in some places open; therefore other methods have been tried.

31. If a piece of wood be boiled in water for a certain time, then taken out and immediately bent into any particular form, and it be retained in that form till it be dry, a boiling... permanent change takes place in the mechanical relations of its parts; so that though, when relieved, it will spring back a little, yet it will not return to its natural form.

The same effect may be produced by steaming wood; but though both these methods have been long practised to a considerable extent in the art of ship-building, we are not aware that any general principles have been discovered, either by experiment or otherwise, that will enable us to apply it to an art like joinery, where so much precision is required. We are not aware that it has been tried; but, before it can be rendered extensively useful, the relation between the curvature to which it is bent, and that which it assumes, when relieved, should be determined, and also the degree of curvature which may be given to a piece of a given thickness.

The time that a piece of wood should be boiled, or steamed, in order that it may be in the best state for bending, should be made the subject of experiments; and this being determined, the relation between the time and the bulk of the piece should be ascertained.

For the joiner's purposes, we imagine, that the process might be greatly improved, by saturating the convex side of each piece with a strong solution of glue, immediately after bending it. By filling, in this manner, the extended pores, and allowing the glue to harden thoroughly before relieving the pieces, they would retain their shape better.

32. Large pieces of timber should never be used in joinery, because they cannot be procured sufficiently dry to prevent them splitting with the heat of a warm room. Therefore, the external part of columns, pilasters, and works of a like kind, should be formed of thin pieces of dry wood; and, if support be required, a post, or an iron pillar, may be placed within the exterior column. Thus, to form columns of wood, so that they shall not be liable to split, narrow pieces of wood are used, not exceeding five inches in width. These are jointed like the staves of a cask, and glued together, with short blocks glued along at each joint.

Fig. 24 is a plan of the lower end of a column glued up in staves; the bevel at A is used for forming the staves, that at B is used for adjusting them when they are glued together. A similar plan must be made for the upper end of the column, which will give the width of the upper end of the staves. The bevels taken from the plan, as at A and B, are not the true bevels; but they are those generally used, and are very nearly true, when the columns are not much diminished. To find the true bevels, the principle we have given in art. 19 should be applied. The same method may be adopted for forming large pillars for tables, &c.

If a column have flutes, with fillets, the joints should be in the fillets, in order to make the column as strong as possible; also, if a column be intended to have a swell in the middle, proper thickness of wood should be allowed for it.

When columns or pillars are small, they may be made of dry wood; and to secure them against splitting, a hole may be bored down the axis of each column.

Fixing Joiners' Work.

33. We have hitherto confined our remarks to that part of joinery which is performed at the bench; but by far the most important part remains to be considered. For, however well a piece of work may have been prepared, if it be not properly fixed, it cannot fulfil its intended purpose. As in the preceding part, we shall state the general principles that ought to be made the basis of practice, and illustrate those principles by particular examples.

If the part to be fixed consist of boards jointed together, but not framed, it should be fixed so that it may shrink, or swell without splitting. The nature of the work will generally determine how this may be effected. Let us suppose that a plain back of a window is to be fixed.

Fig. 25 is a section shewing B the back of the window, A the window-sill, D the floor, and C the skirting. The back is supposed to be prepared, as we have stated in art. 29, and that it is kept straight by a dovetailed key a. Now, let the back be firmly nailed to the window-sill A, and let a narrow piece d, with a groove, and cross tongue, in its upper edge, be fixed to bond timbers or plugs in the wall; the tongue being inserted also into a corresponding groove in the lower edge of the back of B. It is obvious, that the tongue being loose, the back B may contract or expand, as a panel in a frame. The dado of a room should be fixed in the same manner. In the principal rooms of a house, the skirting C is usually grooved skirting into the floor D, and fixed only to the narrow piece d, for rooms which is called a ground. By fixing, in this manner, the skirting covers, the joint, which would otherwise soon be open by the shrinking of the back, and from the skirting being grooved into the floor, but not fastened to it, there cannot be an open joint between the skirting and floor. When it is considered, that an open joint, in such a situation, must become a receptacle for dust, and a harbour for insects, the importance of adopting this method of fixing skirting will be apparent.

In fixing any board above five or six inches wide, similar precautions are necessary; otherwise it is certain to split when the house becomes inhabited. We may, in general, either fix one edge, and groove the other, so as to leave it at liberty, or fix it in the middle, and leave both edges at liberty.

Sometimes a wide board, or a piece consisting of several Fixing boards, may be fixed by means of buttons, screwed to the landing of back, which turn into grooves in the framing, bearers, or stairs, joists, to which it is to be fixed. If any shrinking takes place the buttons slide in the grooves. In this manner the landing of stairs are fixed, and it is much the best mode of fixing the top of a table to its frame.

34. The extension of the principle of ploughing and Forming tonguing work together is one of the most important of archi- the improvements that have been introduced by modern traves, &c. joiners. It is an easy, simple, and effectual method of combination, and one that provides against the greatest defect of timber work, its shrinkage. By means of this method, the bold mouldings of Gothic architecture can be executed with a comparatively small quantity of material; and even in the mouldings of modern architecture it saves much labour. For example, the moulded part of an architrave may be joined with the plain part, as shewn by fig. 26. If this method be compared with the old method of glueing one piece upon another, its advantage will be more evident.

33. The architraves, skirtings, and subbase mouldings, Fixing are fixed to pieces of wool called grounds; and as the grounds' straightness and accuracy of these mouldings must depend upon the care that has been taken to fix the grounds truly; it will appear, that fixing grounds, which is a part often left to inferior workmen, in reality requires much skill and attention; besides, they are almost always the guide for the plasterer. Where the plasterer's work joins the grounds, they should have a small groove ploughed in the edge to form a key for the plaster.

36. In our remarks on construction, we must not omit Laying to say a few words on laying floors, because it will give us floors. JOINERY.

Joinery, an opportunity of pointing out a defect which might be easily remedied. The advice of Evelyn, to tack the boards down only the first year, and nail them down for good the next, is certainly the best, when it is convenient to adopt it; but, as this is very seldom the case, we must expect the joints to open more or less. Now these joints always admit a considerable current of cold air, and also, in an upper room, unless there be a counter floor, the ceiling below may be spoiled by spilling a little water, or even by washing the floor. To avoid this, we would recommend a tongue to be ploughed into each joint, according to the old practice. When the boards are narrow, they might be laid without any appearance of nails, in the same way as a dowelled floor is laid, the tongue serving the same purpose as the dowels. In this case we would use cross or feather tongues for the joints.

There is a method sometimes used in laying floors, which workmen call folding; according to this method, two boards are laid, and nailed at such a distance apart, that the space is a little less than the aggregate width of the boards intended for it; these boards are then put to their places, and, on account of the narrowness of the space left for them, they rise like an arch between its abutments. The workmen force them down by jumping upon them. Accordingly, the boards are never soundly fixed to the joists, nor can the floor be laid with any kind of evenness or accuracy. We merely notice this method here, in order that it may be avoided.

As boards can seldom be got long enough to do without joints, it is usual, except in very inferior work, to join the ends with a tongued joint, as shewn in fig. 27, where B is the joist. The etched board is first laid, and nailed to the joist.

In oak floors, the ends are forked together sometimes, as shewn at A, fig. 28, in order to render the joints less conspicuous.

The joints should be kept as distant from one another as possible.

Hinging.

It requires a considerable degree of care to hang a door, a shutter, or any other piece of work in the best manner. In the hinge, the pin should be perfectly straight, and truly cylindrical, and the parts accurately fitted together.

The hinges should be placed so that their axes may be in the same straight line, as any defect in this respect will produce a considerable strain upon the hinges every time the hanging part is moved, which prevents it from moving freely, and is injurious to the hinges.

In hanging doors, centres are often used instead of hinges; but, on account of the small quantity of friction in centres, a door moves too easily, or so that a slight draft of air accelerates it so much in falling to, that it shakes the building, and is disagreeable. We have seen this in some degree remedied by placing a small spring to receive the shock of the door.

The greatest difficulty, in hanging doors, is to make them to clear a carpet, and be close at the bottom when shut. To do this, that part of the floor which is under the door, when shut, may be made to rise above a quarter of an inch above the general level of the floor; which, with placing the hinges so as to cause the door to rise as it opens, will be sufficient, unless the carpet should be a very thick one. Several mechanical contrivances have been used for either raising the door, or adding a part to spring close to the floor as the door shuts. The latter is much the better method. The reader who may be desirous of examining this method, may consult the Transactions of the Society of Arts, (vol. xxvi. p. 196.)

Various kinds of hinges are in use. Sometimes they are concealed, as in the kind of joints called rule joints; others project, and are intended to let a door fold back over projecting mouldings, as in pulpit doors. When hinges project, the weight of the door acts with an increased leverage upon them, and they soon get out of order, unless they be strong and well fixed.

The door of a room should be hung so that, in opening the door, the interior of the room cannot be seen through the joint. This may be done by making the joint according to fig. 29. The bead should be continued round the door, and a common butt-hinge answers for it.

The proper bevel for the edge of a door or sash may be found by drawing a line from the centre of motion C, fig. 30, to e, the interior angle of the rebate, draw ed perpendicular to C e, which gives the bevel required. In practice, the bevel is usually made less, leaving an open space in the joint when the door is shut; this is done on account of the interior angle of the rebate often being filled with paint.

Stairs.

The construction of stairs is generally considered the highest department of the art of joinery, therefore we treat of it under a distinct head.

The principal object to be attended to in stairs is, that they afford a safe and easy communication between floors of different levels. The strength of a stair ought to be apparent as well as real, in order that those who ascend it may feel conscious of safety. In order to make the communication safe, it should be guarded by a railing of proper height and strength; in order that it may be easy, the rise and width, or tread, of the steps should be regular and justly proportioned to each other, with convenient landings; there should be no winding steps, and the top of the rail should be of a convenient height for the hand.

The first person that attempted to fix the relation between the height and width of a step, upon correct principles, was, we believe, Blondel, in his Cours d'Architecture. If a person walking upon a level plane move over a space P, at each step, and the height which the same person could ascend vertically, with equal ease, were H; then, if h be the height of a step, and p its width; the relation between p and h must be such, that when p = P, h = o; and when H = h, p = o. These conditions are satisfied by an equation of the form $h = H \left(1 - \frac{p}{P}\right)$. Blondel assumes 24 inches for the value of P, and 12 inches for that of H; substituting these values in our equation, it becomes $h = \frac{1}{2} (24 - p)$, which is precisely Blondel's rule. We do not think these the true values of P and H; indeed, it would be difficult to ascertain them; but they are so near, and agree so well with our observations on stairs of easy ascent, that they may be taken for the elements of a practical rule. Hence, according as h or p is given, we have $h = \frac{1}{2} (24 - p)$, or $p = 24 - 2h$.

Thus, if the height of a step be six inches, then $24 - 12 = 12$, the width or tread for a step that rises six inches.

The forms of staircases are various. In towns, where space cannot be allowed for convenient forms, they are often made triangular, circular, or elliptical, with winding steps, or of a mixed form, with straight sides and circular ends. In large mansions, and in other situations, where convenience and beauty are the chief objects of attention, winding steps are never introduced when it is possible to avoid them. Good stairs, therefore, require less geometrical skill than those of an inferior character.

The best architectural effect is produced by rectangular staircases, with ornamented railing and newels. In Gothic structures scarcely any other kind can be adopted, with propriety, for a principal staircase. Modern architecture admits of greater latitude in this respect; the end of the staircase being sometimes circular, and the hand-rail continued, beginning either from a scroll or a newel.

41. When a rectangular staircase has a continued rail, it is necessary that it should be curved so as to change gradually from a level to an inclined direction. This curvature is called the ramp of the rail. The plan of a staircase of this kind is represented by ABCD, fig. 31, and fig. 32 shews a section of it, supposing it to be cut through at ab, on the plan.

The hand-rail is supposed to begin with a newel at the bottom, and the form of the cap of the newel ought to be determined, so that it will mitre with the hand-rail. Let H, fig. 33, be the section of the hand-rail, and ab the radius of the newel; then the form of the cap may be traced at C by the method we have already described. (Art. 9 and 10.)

The sections of hand-rails are of various shapes; some of the most common ones are too small; a hand-rail should never be less than would require a square, of which the side is 2½ inches, to circumscribe it.

For the level landings of a staircase the height of the top of the hand-rail should be about 40 inches, and in any part of the inclined rail the height of its upper side above the middle of the width of the step should be 40 inches less the rise of one step, when measured in a vertical direction.

To describe the ramps, let rs be a vertical line drawn through the middle of the width of the step, fig. 32; set ru equal to rs, and draw ut at right angles with the back of the rail, cutting the horizontal line st in t. From the point t, as a centre, describe the curve of the rail. When there is a contrary flexure, as in the case before us, the method of describing the lesser curve is the same.

42. The hand-rail of a stair often begins from a scroll; and that kind of spiral which is called the logarithmic spiral, has been proposed as the best for the purpose. It is shewn by writers on curve lines, that any radial lines drawn from the centre will be cut by the logarithmic spiral in one and the same angle. By means of this property of the curve, it may be described as follows:

Let C be the centre, fig. 34, and draw AB perpendicular to DE, crossing it in C. Bisect the angles by the lines ab, cd. Draw eBb to cut CB at the angle proposed for the curve, and to meet Cb in b; draw eb perpendicular to be, cutting Ce in c; draw ca perpendicular to eb cutting Ca in a; and proceed round with as many revolutions as may be required in the same manner. Then B, E, A, D, F, G, &c. are points in the curve, and the lines eb, eb, ea, ad, &c. are tangents to the curves at these points. Therefore, the curve may be either drawn by hand, or by means of circular arcs. Also, any number of interior or exterior spirals may be drawn by drawing lines parallel to the tangents, as xy, yz, &c.

If eb were to cross BC at a right angle, the curve would be a circle.

43. The scrolls and volutes used in architecture are allways made to terminate in a circle at the centre; consequently none of the curves described by mathematicians are adapted for these purposes. But the construction we have employed for the logarithmic spiral readily leads to a species of spiral that appears well suited for scrolls or volutes. In the logarithmic spiral the angle of the curve is constant; but imagine the angle to change regularly, and to become a right angle at the point where the circle called the eye begins. This would afford us a regular and pleasing curve, unfolding itself from a circle in the centre. This curve might be called the Architectural Spiral.

Let C be the centre, fig. 35, and round this centre describe a circle for the eye of the scroll, or volute. Divide this circle into eight equal parts, and draw lines from the centre through the points of division.

With any radius ac, and C as a centre, describe the arc ac, and upon this arc set off any number of equal divisions. The extent of a division must be regulated by the quantity the curve may unfold at each revolution, and the number depends on the number of revolutions.

Then, beginning at A, draw Ab perpendicular to Ca; db parallel to C; de perpendicular to C2; ef parallel to C3; and so on for any number of revolutions. The points A, B, D, E, F, G, and H, in the curve, and the tangents to these points, are found; therefore the curve may be described by hand, or by means of circular arcs.

The tangents to any interior or exterior spiral will be parallel to the ones first found, and, therefore, any number may be drawn with the greatest facility. Neither the logarithmic nor the architectural spiral can be drawn truly by circular arcs; but we shall here point out the principle by which such spirals may be drawn. When a spiral is drawn by means of circular arcs only, the centres of the adjoining arcs must always be upon the same straight line; and the regularity of the curve will depend on the number of arcs employed to describe one revolution. Let the proposed distance between the revolutions be divided into as many equal parts as there are to be circular arcs in one revolution; and, on the eye as a centre, construct a regular polygon of the same number of sides as the number of divisions, and on each side equal to one division. Then the angles of the polygon will be the centres for describing the spiral, as shewn by the figures below, where the triangle, square, and hexagon, are given as examples:

Fig. 36. Fig. 37.

Fig. 38. Fig. 39.

If a spiral be drawn to begin from a circle at the centre, let the arcs be described from the angles of a rectangular fret, as in fig. 39, the sides of which may increase in any regular proportion. Or, a figure may be drawn in the same manner as the tangents of the spiral, fig. 35, and the arcs described in the angle, as in fig. 40. By either of these methods a pleasing curve may be obtained.

44. Fig. 41 represents the plan of a staircase, beginning with a scroll, and having steps winding round the circular part of the well-hole.

In the first place, let the end of the steps be developed according to the method we have given in Art. 13. Fig. 43 shows this development. Now, the hand-rail ought to follow the inclination of a line drawn to touch the nosings of the steps, except where there is an abrupt transition from the rake of the winding to that of the other steps; at such places it must be curved; the curve may be drawn by the help of intersecting lines, as in fig. 44, if the workman cannot trust to his eye.

The part which is shaded in fig. 43, represents the hand-rail and ends of the steps, when spread out, and the hand-rail is only drawn close to the steps for convenience, as it would require too much space to raise it to its proper position. This development of the rail is called the falling mould.

The wood used for hand-rails being of an expensive kind, it becomes of some importance to consider how the plank may be cut so as to require the least quantity of material for the curved part of the rail. Now, if we were to suppose the rail executed, and a plain board laid upon the upper side of it, the board would touch the rail at three points; and a plank laid in the same position as the board would be that out of which the rail could be cut with the least waste of material.

Let it be required to find the moulds for the part ab of the rail, fig. 41, and to avoid confusing the lines in our small figure, the part ab has been drawn to a larger scale, moulds in fig. 42. The plain board, mentioned above, would touch the rail at the points marked C and B in the plan; draw the line CB, and draw a line parallel to CB, so as to touch the curve at the point E. Then E is the other point on the plan; and a', e', and b', are the heights of these points in the development, fig. 43.

Erect perpendiculars to CB, from the points C, E, and B, fig. 42, and set off Ca, on fig. 42, equal to ae, fig. 43; Ee equal to de', and Bb equal to fb'. Through the points C and E, draw the dotted line Ch; through ae draw a line to meet CE in h; and through the points ab, draw a line to meet CB in g; then join hg, and make Ci perpendicular to hg.

Now, if Cd be equal to Ca, and perpendicular to Ci; and di be joined, it will be the angle which the plank makes with the horizontal plane, or plan. Therefore, draw FD parallel to Ci, and find the section by the process described in Art. 10. This section is the same thing as would be obtained by projecting vertical lines from each point in the hand-rail against the surface of a board, laid to touch it in three points. The inexperienced workman will be much assisted in applying the moulds if he acquires a clear notion of the position when executed.

To find the thickness of the plank, take the height to the under side of the rail cr in the development, fig. 43, thick and set it off from s, in the line Ci, to r, in fig. 42; from the pl... The point r draw a line parallel to di, and the distance between those parallel lines will be the thickness of the plank.

The mould, fig. 42, which is traced from the plan, is called the face mould. It is applied to the upper surface of the plank, which being marked, a bevel should be set to the angle idC, and this bevel being applied to the edge will give the points to which the mould must be placed to mark out the under side. It is then to be sawn out, and wrought true to the mould. In applying the bevel, care should be taken to let its stock be parallel to the line di, if the plank should not be sufficiently wide for di to be its arris.

After the rail is truly wrought to the face mould, the falling mould, fig. 43, being applied to its convex side, will give the edge of the upper surface, and the surface itself will be formed by squaring from the convex side, holding the stock of the square always so that it would be vertical if the rail were in its proper situation. The lower surface is to be parallel to the upper one.

The sudden change of the width of the ends of the steps causes the soffit line to have a broken or irregular appearance; to avoid it, the steps are made begin to wind before the curved part begins. Different methods of proportioning the ends of the steps are given by Nicholson, Roubo, Rondelet, and Krafft. We cannot in this place enter into a detail of these methods, but for the reader's information a list of the principal writers on staircases is subjoined.

Price, in his British Carpenter, 4to, 1735; Langley, Builders' Complete Assistant, 8vo, 1738; Frezier, Coupe des Pierres des Bois, 4to, 1739; Roubo, L'Art du Menuisier, folio, 1771; Skaife, Key to Civil Architecture, 8vo, 1774; Nicholson, Carpenters' New Guide, 4to, 1792; Carpenters' and Joiners' Assistant, 4to, 1792; Architectural Dictionary, 4to; Transactions Society of Arts, &c., for 1814; Treatise on the Construction of Staircases and Handrails, 4to, 1820; Rondelet, Traité de l'Art de Bâtir, tome iv. 4to, 1814; and Krafft, Traité sur l'Art de la Charpente, part ii. folio, 1820.

Sect. III.—On Materials.

There is no art in which it is required that the structure and properties of wood should be so thoroughly understood as in joinery. The practical joiner, who has made the nature of timber his study, has always a most decided advantage over those who have neglected this most important part of the art.

In the article Anatomy, Vegetable (vol. iii. p. 61 and 82), the structure of wood is described; in this place, therefore, we shall only show how the joiner may, in a great measure, avoid the warping caused by its irregular texture.

It is well known that wood contracts less in proportion, in diameter, than it does in circumference; hence a whole tree always splits in drying. Mr Knight has shown that, in consequence of this irregular contraction, a board form may be cut from a tree that can scarcely be made, by any means, to retain the same form and position when subjected to various degrees of heat and moisture. From the ash and the beech he cut some thin boards, in different directions relatively to their transverse septa, so that the septa crossed the middle of some of the boards at right angles, and lay nearly parallel with the surfaces of others. Both kinds were placed in a warm room, under perfectly similar circumstances. Those which had been formed by cutting across the transverse septa, as at A in fig. 44, soon changed their form very considerably, the one side becoming hollow, and the other round; and in drying, they contracted nearly 14 per cent. in width.

The other kind, in which the septa were nearly parallel to the surfaces of the boards, as at B in fig. 44, retained, in shrinking with very little variation, their primary form, and did not contract in drying more than three and a half per cent. in width.

As Mr Knight had not tried resinous woods, two specimens were cut from a piece of Memel timber; and, to render the result of our observation more clear, conceive fig. 45 to represent the section of a tree, the annual rings being shewn by circles. BD represents the manner in which one of our pieces was cut, and AC the other. The board AC contracted 3-75 per cent. in width, and became hollow on the side marked b. The board BD retained its original straightness, and contracted only 0-7 per cent. The difference in the quantity of contraction is still greater than in hard woods.

From these experiments, the advantages to be obtained merely by a proper attention in cutting out boards for panels, &c. will be obvious; and it will also be found that panels cut so that the septa are nearly parallel to their faces, will appear of a finer and more even grain, and require less labour to make their surfaces even and smooth.

The results of these experiments are not less interesting to cabinet-makers, particularly in the construction of billiard-tables, card-tables, and indeed every kind of table in use. For such purposes, the planks should be cut so as to cross the rings as nearly in the direction BD as possible. We have no doubt that it is the knowledge of this property of wood that renders the billiard-tables of some makers so far superior to those of others.

In wood that has the larger transverse septa, as the oak, for example, boards cut as BD will be figured, while those cut as AC will be plain.

There is another kind of contraction in wood whilst Cause of drying, which causes it to become curved in the direction pieces of its length. In the long styles of framing we have often observed it; indeed, on this account, it is difficult to prevent the style of a door, hung with centres, from curving, length so as to rub against the jamb. A very satisfactory reason for this kind of curving has been given by Mr Knight, which also points out the manner of cutting out wood, so as to be less subject to this defect, which it is most desirable to avoid. The interior layers of wood, being older, are more compact and solid than the exterior layers of the same tree; consequently, in drying, the latter contract more in length than the former. This irregularity of contraction causes the wood to curve in the direction of its length, and it may be avoided by cutting the wood so that the parts of each piece shall be as nearly of the same age as possible.

Besides the contraction which takes place in drying, Changes wood undergoes a considerable change in bulk with the variations of the atmosphere. In straight-grained woods the change in length is nearly insensible; hence they are sometimes employed for pendulum rods; but the lateral dimensions vary so much, that a wide piece of wood will serve as a rude hygrometer. The extent of variation de-

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1 Philosophical Transactions, part ii. for 1817, or Philosophical Magazine, vol. i. p. 437. 2 Ibid. 3 Mr Ramsden and General Roy made some experiments on the expansion in length. See Account of the Trig. Survey, vol i. p. 46 and 49. 4 See Phil. Trans. Lowthorpe's Abridg. vol. ii. p. 37. creases in a few seasons, but it is of some importance to the joiner to be aware, that even in very old wood, when the surface is removed, the extent of variation is nearly the same as in new wood.

It appears, from Rondelet's experiments, that in wood of a mean degree of dryness, the extent of contraction and expansion, produced by the usual changes in the state of the atmosphere, was,

in fir wood, from $\frac{1}{360}$ to $\frac{1}{75}$ part of its width;

and, in oak, from $\frac{1}{412}$ to $\frac{1}{84}$ part of its width.

Consequently, the mean extent of variation in fir is $\frac{1}{124}$,

and in oak, $\frac{1}{140}$; and, at this mean rate, in a fir board about $12\frac{1}{2}$ inches wide, the difference in width would be $\frac{1}{8}$th of an inch. This will show the importance of attending to the maxims of construction we have already laid before the reader; for, if a board of that width should be fixed at both edges, it must unavoidably split from one end to the other.

49. The kinds of wood commonly employed in joinery are, the oak, the different species of pine, mahogany, lime-tree, and poplar.

Of the oak, there are two species common in this island; that which Linnæus has named Quercus Robur is the most valuable for joiners' work; it is of a finer grain, less tough, and not so subject to twist as the other kind. Oak is also imported from the Baltic ports, from Germany, and from America. These foreign kinds being free from knots, of a straighter grain, and less difficult to work, they are used in preference to our home species. Foreign oak is also much used for cabinet-work; and lately, the fine curled oak that is got from excrescences produced by pollard, and other old trees, has been used with success in furniture. When well managed, it is very beautiful, and makes a pleasing variety. It is relieved by inlaid borders of black or white wood, but these should be sparingly used. Borders of inlaid brass, with small black lines, give a rich effect to the darker coloured kinds.

The greater part of joiners' work is executed in yellow fir, imported from the north of Europe. White fir is often used for internal work, and American pine is much used for mouldings.

The forest of Braemar, in Aberdeenshire, furnishes yellow fir of an excellent quality, little inferior to the best foreign kinds.

For the general purpose of joinery, the wood of the larch tree seems to be the best; this useful tree thrives well on our native hills. We have seen some fine specimens of this wood from Blair-Athol. It makes excellent steps for stairs, floors, framing, and most other articles.

Mahogany, in joinery, is only used where painted work Mahogany is improper, as for the hand-rails of stairs, or for the doors and windows of principal rooms. For doors it is not now so often used as it was formerly; its colour is found to be too gloomy to be employed in large masses. In cabinet-work it is almost the only kind used for ornamental work.

Lime-tree, and the different species of poplar, make very good floors for inferior rooms, and may often be used for other purposes, in places where the carriage of foreign timber would render it more expensive. Lime-tree is valuable for carved work, and does not worm-eat; but carving is at present seldom used in joinery.

For farther information on wood, in addition to the works referred to, the reader may consult Evelyn's Silva, Dr Hunter's edition; Duhamel, Du Transport, de la Conservation, et de la Force des Bois, Paris, 1767; Barlow's Essay on the Strength and Stress of Timber, 1817; Tredgold's Elementary Principles of Carpentry, sect. x. 1820; and the article Dry-Rot.

JOINT, in general, denotes the juncture of two or more things. The joints of the human body are called by anatomists articulations. See Anatomy.

JOINTURE, in Scotch Law, signifies generally a settlement of lands and tenements, made on a woman in consideration of marriage.

JOINVILLE, a city of the department of the Upper Marne, in France, in the arrondissement of Vassy. It stands on the left bank of the Marne, at the foot of a lofty hill, on which there remains an ancient castle, where the association of the League was formed in 1584. It contains 845 houses, and 3100 inhabitants. There are manufactures of woollen cloths and stockings. Long. 5.1. E. Lat. 48. 26. N.

JOISTS, or JOISTS, in Architecture, those pieces of timber framed into the girders and summers, upon which the boards of the floor are laid.

JOKAGUR, a town of Hindustan, in the Mahratta territories, in the province of Khandesh, seventy-four miles south-east from Oojain. Long. 76. 46. E. Lat. 22. 31. N.

JOKES. See JESTING.

JOLLOXOCHITL, an Indian word, signifying "flower of the heart," is the name of a plant, bearing a large, beautiful flower, which grows in Mexico, where it is much esteemed for its beauty and odour; the latter being so powerful, that a single flower is sufficient to fill a house with the most pleasing fragrance.

JONAH, or the Prophecy of JONAH, a canonical book of the Old Testament, in which it is related, that Jonah, about 771 before Christ, was ordered to go and prophecy the destruction of Nineveh, on account of the wickedness of its inhabitants. But the prophet, instead of obeying the divine command, embarked for Tarshish, when, a tempest arising, the marines threw him into the sea. He was swallowed by a great fish, and after being three days and nights in its belly, was cast upon the land. The prophet, sensible of his past danger and surprising deliverance, now betook himself to the journey and embassy to which he was appointed; and arriving at Nineveh, the metropolis of Assyria, he, according to his commission, boldly laid open the sins of the Ninevites, and proclaimed their sudden overthrow; upon which the whole city, by prayer, fasting, and speedy repentance, happily averted the divine vengeance, and escaped the threatened ruin. Upon this, Jonah, fearing that he would pass for a false prophet, retired to a hill at some distance from the city, where God, by a miracle, condescended to show him the unreasonableness of his discontent.

JONATHAN, the son of Saul, celebrated in sacred history for his valour, and his friendship for David against

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1 Traité Théorétique et Pratique de l'Art de Bâtir, article Menuiserie, tome iv. p. 425, 1814. 2 When the roof of Westminster Hall was under repair, an opportunity was taken to examine the wood of which it is constructed; and it was found to be of oak, and not of chestnut, as stated in the Article Dry-Rot, vol. viii. p. 233. The oak has been of an excellent kind, but is now much worm-eaten. Jonathan, or Jonas, Maccabaeus, brother of Judas, a renowned general of the Jews. He forced Bacchides, the Syrian general, who made war with the Jews, to accept a peace, conquered Demetrius Soter, and afterwards defeated Apollonius, general of that prince; but, being ensnared by Tryphon, he was put to death, 144 before Christ.