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Another mode is to plane the edge of a board as straightas can be done by the eye, then plane the edge of anotherboard until it coincide with the former; plane the edge of athird board in like manner, to coincide with the edge of thefirst, and apply their edges together; then, if they coincide,the operation is at an end, but if not, repeat till they do.

By any of these methods, the superficies of the boards to beshot are supposed to be parallel planes, not very distant fromeach other ; for if the faces be not parallel, or if the thicknessbe considerable, the operation will be more liable to error.

To reduce the rough surface of a body to a plane. —Thiswill not be very difficult, when it is known that a plane willeverywhere coincide with a straight line.

The most practical methods are the following :—Providetwo winding-sticks, and apply them as before directed, makingthe ends out of winding, if they are not found to be so ; then,if all the parts of the surface on which the edges of thewinding-sticks were placed are straight, it is evident that thewhole surface must be plane. If the surface is hollowbetween the said lines, one of the ends, or both, must beplaned lower, until the surface acquires a small convexity inthe length ; and then, if straightened between the straightlines at the ends, it will be a perfect plane.

Another mode of forming a plain, supposing the surface tobe of a quadrilateral form. Apply a ruler along the diago-nals, then, if they are straight, they are in a plane ; but ifthey are both hollow, or both round, the surface to be reducedis either concave or convex, and must be straightened in thesedirections accordingly.

Lastly, if, by trying across the diagonals with the straightedge, it be found that the one is hollow and the other round,the surface of the board winds. In this case, bring downthe protuberant part of the convex diagonal, so as to bestraight with the two extremities; then straighten the con-cave diagonal, by planing either of the two ends, or both ofthem, according as the thickness of the board may require.Both diagonals being now straight, traverse the wood—thatis, plane it across the fibres, until all the protuberant partsbetween the diagonals are removed ; then smooth it byworking in the direction of the fibres.

To join any number of planks together , so as to form a boardo) a determinate breadth , the fibres of each running longitudinali to those of any other. —Shoot the two edges that are to be| joined; turn the sides of the boards towards each other, sothat the edges that are shot may be both uppermost; spread| these edges over with strong glue of a proper consistence,

! made very hot ; one of the boards being fixed, turn the otherupon it, so that the two edges may coincide, and that the facesI may be both in the same plane : rub the upper one to and froI in the direction of the fibres, till the glue is almost out of the! joint; let these dry for a few hours : then proceed to make! another joint; continue to join as many boards or planks ini the same manner, till the whole intended breadth be madeout. If the boards, or planks of which the board is to becomposed, be very long, the edges that are to be united willI require to be warmed before a fire ; and, for rubbing andkeeping the joints fair to each other, three men will be foundnecessary, one at each extremity, and one at the middle.

• Boards glued together with this kind of cement will stand aslong as the substance of the deals or planks composing them,if not exposed to rain or intense heat, provided the wood has, been well seasoned beforehand, and the grain be free andstraight, and interrupted with few or no knots. When aboard which is to be exposed to the weather is to be made ofseveral pieces, the cement to be used for uniting them shouldnot be of skin glue, but of white-lead ground up with linseed-oil, so thin that the colour may be sensibly changed into a

whitish cast ; this kind of glue will require a much greatertime to dry than skin glue. Boards to be exposed to theweather, when their thickness will admit, are frequently jtongued together : that is, the edges of both boards aregrooved to an equal distance from the faces, and to an equal |depth ; and a slip of wood is made to fit the cavity made in jboth : this slip should be made to fill the grooves, but not 1so tight as to prevent the joint from being rubbed with proper Icement.

To glue any two boards together forming a given angle. — jThis may be accomplished, either by shooting the edge of oneboard to the whole of the given angle, keeping the face of the ,other straight ; and then, by applying the two surfacestogether, and rubbing as before, they will form the anglerequired ; or, if the two edges, being shot to half the given jangle, be applied together, and rubbed and set as before, their ;faces will form the angle required. In both these methods, jwhen only one side of the board is to be exposed to sight,which is most commonly the case, pieces of wood, calledblocks, are fitted to the inside of the angle, and the sides gluedacross the joint or legs of the angle, being previously planed jfor that purpose. |

To form wooden architraves for apertures, by givng longi - 'jtudinal pieces together. —Architraves are sometimes formed !of solid pieces, but a better and more economical mode is that 'of gluing longitudinal pieces together. See Architrave.Architraves of the Grecian form, for doors and windows, :generally consist of one or two faces in parallel planes, one of !which recedes only in a small degree from the other, whilethe outer edge is terminated with one or several mouldings, iwhich have a very prominent projection. In this case, make ;a board of sufficient thickness, and in breadth equal to thebreadth of the architrave: prepare a slip of wood of a suffi-cient thickness and breadth for the mouldings on the outertermination of the architrave, and glue it upon the face, close ,to the edge of the board, with the outer edge flush therewith, j ,In this operation, two men, at least, will be required to rub ; \the slip to a joint with the board ; and as it often happens ' \that the side of the slip, which is to comply with the surface iof the board, is considerably bent, it must be nailed down to |the board ; previously to this, small square pieces of wood,called buttons must be bored with holes, one in each, and a i \nail put through the hole to the head; then the slip is also 'to be bored with a bradawl, and the nails, with the pieces ,thus described, are entered and driven home as far as the ,!buttons will permit. These buttons may be about three-quarters of an inch thick, and the other two dimensions each ;equal to, or something more than the breadth of the slip- ;Sometimes the slip is grooved ; and the edge of the board ;tongued, glued, and inserted into the groove, instead of theabove method. Or, the two faces may be made of differentboards, tongued together at their joining, and the whole after' :wards stuck into mouldings. j

To form the surface of a cylinder with wood, whose fibre 1 1are in planes perpendicular to the axis of the cylinder, suchas may be used in a circular dado, or the soffits of wisdom.

Method I.—When the dimension of the cylindric surface,parallel to the axis, is not broader than a plank or board. |This may be done by bending and gluing several veneers 'together ; the first upon a mould, or upon brackets, with their ■ !edges in the surface of the proposed cylinder, parallel to i ts -axis.

This may be accomplished by means of two sets of brackets,fixed upon a board, with a hollow cylindric space between . jthem, of sufficient thickness for taking in the veneers, with j idouble wedges for confining them. If this operation be care- |:fully done, and the glue properly dried, the wedges may 1)0 i j