Fig. 27.Fig. 27.
Framework.—As we now know the sizes, the first thing is to build the framework. The legs should be dressed square and smoothed down with the fore plane to make them perfectly straight. Now, lay out two mortises at the upper end of eachleg. Follow the illustrations to see how this is done.
Laying Out the Legs.—Fig. 27 shows a leg with square cross marks (A) at each end. These marks indicate the finished length of the leg. You will also see crosses on two sides. These indicate what is called the "work sides." The work sides are selected because they are the finest surfaces on the leg.
Fig. 28.Fig. 29.Fig. 28.Fig. 29.
Fig. 28.
Fig. 29.
The Length of the Mortises.—Then take a small try square (Fig. 28) and add two cross lines (B, C) on each of the inner surfaces, the second line (B) one-half inch from the finish line (A), and the other line (C) seven inches down from the line (A). The side facing boards, hereafter described, are seven inches wide.
When this has been done for all the legs, prepare your gage (Fig. 29) to make the mortise scribe, and, for convenience in illustrating, the legis reversed. If the facing boards are 1" thick, and the tenons are intended to be ½" thick, the first scribe line (E) should be ½" from the work side, because the shoulder on the facing board projects out ¼", and the outer surface of the facing board should not be flush with the outer surface of the leg. The second gage line (F) should be 1" from the work side.
Fig. 30.Fig. 30.
The Mortises.—When the mortises have been made they will appear as shown in the enlarged cross section of the leg (Fig. 30), the total depth of each mortise being 1½". The depth of this mortise determines for us the length of the tenons on the facing boards.
The Facing Boards.—These boards are each 1 inch thick and 7 inches wide. As the top of the table is 42 inches long, and we must provide an overhang, say of 2 inches, we will first take off 4 inches for the overhang and 4 inches for thelegs, so that the length of two of the facing boards, from shoulder to shoulder, must be 34 inches; and the other two facing boards 28 inches. Then, as we must add 1½ inches for each tenon, two of the boards will be 37 inches long and two of them 31 inches long.
Fig. 31.Fig. 31.
Fig. 32.Fig. 32.
The illustration (Fig. 31) shows a board marked with the cross lines (B) at each end for the end of the tenons, or the extreme ends of the boards.
The Tenons.—Do not neglect first to select the work side and the working edge of the board. The outer surface and the upper edges are the sides to work from. The cheekpiece (A) of the gage must always rest against the working side.
The cross marks (B, C) should be made with the point of a sharp knife, and before the small back saw is used on the cross-cuts the lines (B), which indicate the shoulders, should be scored with a sharp knife, as shown in Fig. 33. This furnishes a guide for the saw, and makes a neat finish for the shoulder.
Fig. 33.Fig. 33.
Fig. 34.Fig. 35.Fig. 34.Fig. 35.
Fig. 34.
Fig. 35.
Tools Used.—The back saw is used for cutting the tenon, and the end of the board appears asshown in the enlarged Fig. 34. Two things are now necessary to complete the tenons. On the upper or work edge of each board use the gage to mark off a half-inch slice, and then cut away the flat side of the tenon at the end, on its inner surface, so it will appear as shown in Fig. 35.
Fig. 36.Fig. 36.
Fig. 37.Fig. 37.
Chamfered Tenons.—The object of these chamfered or beveled tenons is to permit the ends to approach each other closely within the mortise, as shown in the assembled parts (Fig. 36).
The Frame Assembled.—The frame is now ready to assemble, but before doing so a drawer opening and supports should be made. The endsof the supports may be mortised into the side pieces or secured by means of gains.
Mortises and tenons are better.
The Drawer Supports.—Take one of the side-facing boards (Fig. 37) and cut a rectangular opening in it. This opening should be 4 inches wide and 18 inches long, so placed that there is 1 inch of stock at the upper margin and 2 inches of stock at the lower margin of the board. At each lower corner make a mortise (A), so that one side of the mortise is on a line with the margin of the opening, and so that it extends a half inch past the vertical margin of the opening.
Fig. 38.Fig. 38.
You can easily cut a gain (B) in a strip, or, as in Fig. 38, you may use two strips, one (C) an inch wide and a half inch thick, and on this nail a strip (D) along one margin. This forms the guide and rest for the drawer.
At the upper margin of the opening is a rebate or gain (E) at each corner, extending down to the top line of the drawer opening, into which are fitted the ends of the upper cross guides.
The Table Frame.—When the entire table frame is assembled it will have the appearance shown in Fig. 39, and it is now ready for the top.
The Top.—The top should be made of three boards, either tongued and grooved, or doweled and glued together. In order to give a massive appearance, and also to prevent the end grain of the boards from being exposed, beveled strips may be used to encase the edges. These marginal cleats are ¾ inch thick and 2 inches wide, and joined by beveled ends at the corners, as shown in Fig. 40.
Fig. 39.Fig. 39.
The Drawer.—The drawer (Fig. 41) shown in cross section, has its front (A) provided with an overlapping flange (B).
It is not our object in this chapter to show how each particular article is made, but simply to point out the underlying principles, and to illustrate how the fastening elements, the tenons and mortises, are formed, so that the boy will know the proper steps in their natural order.
Fig. 40.Fig. 40.
How Any Structure Is Built Up.—It should be observed that each structure, however small, is usually built from the base up. Just the same as the more pretentious buildings are erected: First, the sill, then the floor supports, then the posts and top plates, with their connecting girders, and, finally, the roof.
The chapter on House Building will give more detailed illustrations of large structures, and how they are framed and braced. At this point we are more concerned in knowing how to proceed in order to lay out the simple structural details, and if one subject of this kind is fully mastered the complicated character of the article will not be difficult to master.
Observations About a Box.—As simple a little article as a box frequently becomes a burden to a beginner. Try it. Simply keep in mind one thing; each box has six sides. Now, suppose you want a box with six equal sides—that is, a cubical form—it is necessary to make only three pairs of sides; two for the ends, two for the sides and two for the top and bottom. Each set has dimensions different from the other sets. Both pieces of the set, representing the ends, are square; the side pieces are of the same width as the end pieces, and slightly longer; and the top and bottom are longer and wider than the end pieces.
Fig. 41.Fig. 41.
A box equal in all its dimensions may be made out of six boards, properly cut. Make an attempt in order to see if you can get the right dimensions.
Joints.—For joining together boards at right angles to each other, such as box corners, drawers and like articles, tenons and mortises should never be resorted to. In order to make fine work the joints should be made by means of dovetails, rabbetsor rebates, or by beveling or mitering the ends.
Beveling and Mitering.—There is a difference in the terms "beveling" and "mitering," as used in the art. In Fig. 42 the joint A isbeveled, and in Fig. 43 the joint B ismitered, the difference being that a bevel is applied to an angle joint like a box corner, while a miter has reference to a joint such as is illustrated in Fig. 43, such as the corner of a picture frame.
Fig. 42.Fig. 43.Fig. 42.Fig. 43.
Fig. 42.
Fig. 43.
Proper Terms.—It is the application of the correct terms to things that lays the foundation for accurate thinking and proper expressions in describing work. A wise man once said that the basis of true science consists in correct definitions.
Picture Frames.—In picture frames the mitered corners may have a saw kerf (C) cut across the corners, as shown in Fig. 44, and a thin bladeof hard wood driven in, the whole being glued together.
Dovetail Joints.—It is in the laying out of the more complicated dovetail joints that the highest skill is required, because exactness is of more importance in this work than in any other article in joinery. In order to do this work accurately follow out the examples given, and you will soon be able to make a beautiful dovetail corner, and do it quickly.
Fig. 44.Fig. 44.
Preparing a Box Joint.—In order to match a box joint for the inner end of a table drawer, the first step is to select two work sides. One work side will be the edge of the board, and the other the side surface of the board, and on those surfaces we will put crosses, as heretofore suggested.
Fig. 45.Fig. 45.
Fig. 46.Fig. 46.
Fig. 47.Fig. 47.
First Steps.—Now lap together the inner surfaces of these boards (Y, Z), so the ends are toward you, as shown in Fig. 45. Then, after measuringthe thickness of the boards to be joined (the thinnest, if they are of different thicknesses), set your compasses, or dividers, for ¼ inch, providing the boards are ½ inch thick, and, commencing at the work edge of the board, step off and point, as at A, the whole width of the board, and with a square make the two cross marks (B), usingthe two first compass points (A), then skipping one, using the next two, and so on.
Fig. 48.Fig. 48.
Fig. 49.Fig. 49.
Fig. 50.Fig. 50.
When this is done, turn up the board Z (Fig. 46), so that it is at right angles to the board Y, and so the outer surface of the board Z is flush with the end of the board X, and with a sharp knife point extend the lines B along with the grain of the wood on board Z,up to the cross mark C. This cross mark should have been previously madeand is located as far from the end of the board Z as the thickness of the board Y.
We now have the marks for the outer surface of the board Z, and the end marks of board Y. For the purpose of getting the angles of the end of the board Z and the outer side of board Y, a cross line (D, Fig. 47) is drawn across the board X near the end, this line being as far from the end as the thickness of the board Z, and a vertical line (E) is drawn midway between the two first cross marks (A).
Now, with your compass, which, in the meantime, has not been changed, make a mark (F), and draw down the line (G), which will give you the working angle at which you may set the bevel gage. Then draw down an angle from each alternate cross line (A), and turn the bevel and draw down the lines (H). These lines should all be produced on the opposite side of the board, so as to assure accuracy, and to this end the edges of the board also should be scribed.
Cutting Out the Spaces.—In cutting out the intervening spaces, which should be done with a sharp chisel, care should be observed not to cut over the shoulder lines. To prevent mistakes you should put some distinctive mark on each part to be cut away. In this instance E, H show the partsto be removed, and in Fig. 48 two of the cutaway portions are indicated.
When the end of the board Z is turned up (Fig. 49), it has merely the longitudinal parallel lines B. The bevel square may now be used in the same manner as on the side of the board Y, and the fitting angles will then be accurately true.
This is shown in Fig. 50, in which, also, two of the cutaway parts are removed.
Tools Used in Laying Out Tenons and Mortises.—A sharp-pointed knife must always be used for making all marks. Never employ an awl for this work, as the fiber of the wood will be torn up by it. A small try square should always be used (not the large iron square), and this with a sharp-pointed compass and bevel square will enable you to turn out a satisfactory piece of work.
The foregoing examples, carefully studied, will enable you to gather the principles involved in laying off any work. If you can once make a presentable box joint, so that all the dovetails will accurately fit together, you will have accomplished one of the most difficult phases of the work, and it is an exercise which will amply repay you, because you will learn to appreciate what accuracy means.
The Square.—The square is, probably, the oldest of all tools, and that, together with the compass, or dividers, with which the square is always associated, has constituted the craftsman's emblem from the earliest historical times. So far as we now know, the plain flat form, which has at least one right angle and two or more straight edges, was the only form of square used by the workman. But modern uses, and the development of joinery and cabinet making, as well as the more advanced forms of machinery practice, necessitated new structural forms in the square, so that the bevel square, in which there is an adjustable blade set in a handle, was found necessary.
The Try Square.—In the use of the ordinary large metal square it is necessary to lay the short limb of the square on the face of the work, and the long limb must, therefore, rest against the work side or edge of the timber, so that the scribing edge of the short limb does not rest flat against the work. As such a tool is defective in work requiring accuracy, it brought into existencewhat is called the try square, which has a rectangular handle, usually of wood, into which is fitted at one end a metal blade, which is at right angles to the edge of the handle. The handle, therefore, always serves as a guide for the blade in scribing work, because it lies flat down on the work.
The T-Squareis another modification of the try square, its principal use being for draughting purposes.
The Compass.—The compass is one of the original carpenter's tools. The difference betweencompassanddividersis that compasses have adjustable pen or pencil points, whereas dividers are without adjustable points. Modern work has brought refinements in the character of the compass and dividers, so that we now have the bow-compass, which is, usually, a small tool, one leg of which carries a pen or pencil point, the two legs being secured together, usually, by a spring bow, or by a hinged joint with a spring attachment.
Proportional Dividers.—A useful tool is called the proportional dividers, the legs of which are hinged together intermediate the ends, so that the pivotal joint is adjustable. By means of this tool the scale of work may be changed, although its widest field of usefulness is work laid off on ascale which you intend to reduce or enlarge proportionally.
Determining Angles.—Now, in order to lay out work the boy should know quickly and accurately how to determine various angles used or required in his work. The quickest way in which to learn this is to become familiar with the degree in its various relations.
Fig. 51.Fig. 51.
Definition of Degree.—A degree is not a measure, as we would designate a foot or a pound to determine distance or quantity. It is used to denote a division, space, interval or position. To illustrate, look at the circle, Fig. 51. The four cardinal points are formed by the cross lines (A, B), and in each one of the quadrants thus formed the circle is divided into 90 degrees. Look at the radial lines (C, D), and you will find that the distance between these lines is different along thecurved line (E) than along the curved line (F). The degree is, therefore, to indicate only the space, division or interval in the circle.
The Most Important Angle.—Most important for one to know at a glance is that of 45 degrees, because the one can the more readily calculate the other degrees, approximately, by having 45 degrees once fixed in the mind, and impressed on the visual image. With a square and a compass it is a comparatively easy matter accurately to step off 45 degrees, as it is the line C, midway between A and B, and the other degrees may be calculated from the line C and the cardinal lines A or B.
Degrees Without a Compass.—But in the absence of a compass and when you do not wish to step off a circle, you will in such case lay down the square, and mark off at the outer margin of the limbs two equal dimensions. Suppose we take 2 inches on each limb of the square. The angle thus formed by the angle square blade is 45 degrees. To find 30 degrees allow the blade of the angle square to run from 2 inches on one limb to 3½ inches on the other limb, and it will be found that for 15 degrees the blade runs from 2 inches on one limb to 7½ inches on the other limb. It would be well to fix firmly these three points, at least, in your mind, as they will be of the utmost value to you. It is a comparatively easy matter now tofind 10 degrees or 25 degrees, or any intermediate line.
What Degrees Are Calculated From.—The question that now arises is what line one may use from which to calculate degrees, or at what point in the circle zero is placed. Degrees may be calculated either from the horizontal or from the vertical line. Examine Fig. 53. The working margin indicated by the cross mark is your base line, and in specifying an angle you calculate it from the work edge. Thus, the line A indicates an angle of 30 degrees. The dotted line is 45 degrees.
Fig. 52.Fig. 52.
Fig. 53.Fig. 54.Fig. 53.Fig. 54.
Fig. 53.
Fig. 54.
The Dividers.—The dividers are used not only for scribing circles, but also for stepping and dividing spaces equally. There is a knack in the use of the dividers, where accuracy is wanted, and where the surface is of wood. Unless the utmost care is observed, the spaces will be unequal, for the reason that the point of the dividers will sink more deeply into the wood at some places than at others, due to the uneven texture of the wood grain. It will be better to make a line lengthwise, and a cross line (A) for starting (see Fig. 54). You may then insert one point of the dividers at the initial mark (B), and describe a small arc (C). Then move the dividers over to the intersection of the arc (C) on the line, and make the next mark, and so on.
Some useful hints along this same line will be found under the chapter on Drawing, which should be carefully studied.
The Right Name for Everything.—Always make it a point to apply the right term to each article or portion of a structure. Your explanation, to those who do know the proper technical terms, will render much easier a thorough understanding; and to those who do not know, your language will be in the nature of an education.
Proper Designations.—Every part in mechanism, every point, curve and angle has its peculiar designation. A knowledge of terms is an indication of thoroughness in education, and, as heretofore stated, becomes really the basis of art, as well as of the sciences. When you wish to impart information to another you must do it in terms understood by both.
Furthermore, and for this very reason, you should study to find out how to explain or to define the terms. You may have a mental picture of the structure in your mind, but when asked to explain it you are lost.
Learning Mechanical Forms.—Suppose, for example, we take the wordssegmentandsector.Without a thorough understanding in your own mind you are likely to confuse these terms by taking one for the other. But let us assume you are to be called upon to explain a sector to some one who has no idea of terms and their definitions. How would you describe it? While it is true it is wedge-shaped, you will see by examining the drawing that it is not like a wedge. The sector has two sides running from a point like a wedge, but the large end of the sector is curved.
If you were called upon to define a segment you might say it had one straight line and one curve, but this would not define it very lucidly. Therefore, in going over the designations given, not only fix in your mind the particular form, but try to remember some particular manner in which you can clearly express the form, the shape or the relation of the parts.
For your guidance, therefore, I have given, as far as possible, simple figures to aid you in becoming acquainted with structures and their designations, without repeating the more simple forms which I have used in the preceding chapters.
Fig. 55.-Fig. 65.
55.Arcade.—A series of arches with the columns or piers which support them, the spandrels above, and other parts.
56.Arch.—A curved member made up, usually, of separate wedge-shaped solids, A. K, Keystone; S, Springers; C, Chord, or span.
57.Buttress.—A projecting mass of masonry. A, used for resisting the thrust of an arch, or for ornamentation; B, a flying buttress.
58.Chamfer.—The surface A formed by cutting away the arris or angle formed by two faces, B, C, of material.
59.Cotter or Cotter Pin.—A pin, A, either flat, square or round, driven through a projecting tongue to hold it in position.
60.Crenelated.—A form of molding indented or notched, either regularly or irregularly.
61.Crosses.—1. Latin cross, in the Church of Rome carried before Bishops. 2. Double cross, carried before Cardinals and Bishops. 3. Triple or Papal cross. 4. St. Andrew's and St. Peter's cross. 5. Maltese cross. 6. St. Anthony or Egyptian cross. 7. Cross of Jerusalem. 8. A cross patté or fermé (head or first). 9. A cross patonce (that is, growing larger at the ends). 10. Greek cross.
62.Curb Roof.—A roof having a double slope, or composed on each side of two parts which have unequal inclinations; a gambrel roof.
63.Cupola.—So called on account of its resemblance to a cup. A roof having a rounded form. When on a large scale it is called a dome.
Crown Post.—SeeKing Post.
64.Console.—A bracket with a projection not more than half its height.
65.Corbels.—A mass of brackets to support a shelf or structure. Largely employed in Gothic architecture.
Fig. 66.-Fig. 79.
66. Dormer.—A window pierced in a roof and so set as to be vertical, while the roof slopes away from it. Also called a Gablet.
67. Dowel.—A pin or stud in one block, or body, designed to engage with holes in another body to hold them together in alignment.
68. Drip.—That part of a cornice or sill course A, or other horizontal member which projects beyond the rest, so as to divert water.
69. Detents.—Recesses to lock or to serve as a stop or holding place.
70. Extrados.—The exterior curve of an arch, especially the upper curved face A. B is the Intrados or Soffit.
71. Engrailed.—Indented with small concave curves, as the edge of a bordure, bend, or the like.
72. Facet.—The narrow plain surface, as A, between the fluting of a column.
73. Fret, Fretwork.—Ornamental work consisting of small fillets, or slats, intersecting each other or bent at right angles. Openwork in relief, when elaborated and minute in all its parts. Hence any minute play of light and shade. A, Japanese fretwork. B, Green fret.
74. Frontal, also called Pediment.—The triangular space, A, above a door or window.
75. Frustums.—That part of a solid next the base, formed by cutting off the top; or the part of any solid, as of a cone, pyramid, etc., between two planes, which may either be parallel or inclined to each other.
76. Fylfat.—A rebated cross used as a secret emblem and worn as an ornament. It is also called Gammadium, and more commonly known as Swastika.
77. Gambrel Roof.—A curb roof having the same section in all its parts, with a lower, steeper and longer part. See Curb Roof and distinguish difference.
78. Gargoyle.—A spout projecting from the roof gutter of a building, often carved grotesquely.
79. Gudgeon.—A wooden shaft, A, with a socket, B, into which is fitted a casting, C. The casting has a gudgeon, D.
Fig. 80.-Fig. 93.
80. Guilloche.—An ornament in the form of two or more bands or strings twisted together or over or through each other.
81. Half Timbered.—Constructed of a timber frame, having the spaces filled in with masonry.
82. Hammer Beam.—A member of one description of roof truss, called hammer-beam truss, which is so framed as not to have a tie beamat the top of the wall. A is the hammer beam, and C the pendant post.
83. Haunches.—The parts A, A, on each side of the crown of an arch. Each haunch is from one-half to two-thirds of the half arch.
84. Header.—A piece of timber, A, fitted between two trimmers, B, B, to hold the ends of the tail beams, C, C.
85. Hip Roof.—The external angle formed by the meeting of two sloping sides or skirts of a roof which have their wall plates running in different directions.
86. Hood Molding.—A projecting molding over the head of an arch, as at A, forming the outer-most member of the archivolt.
87. Inclave.—The border, or borders, having a series of dovetails. One variation of molding or ornamentation.
88. Interlacing Arch.—Arches, usually circular, so constructed that their archivolts, A, intersect and seem to be interlaced.
89. Invected.—Having a border or outline composed of semicircles or arches, with the convexity outward. The opposite of engrailed.
90. Inverted Arch.—An arch placed with the crown downward; used in foundation work.
91. Keystone.—The central or topmost stone, A, of an arch, sometimes decorated with a carving.
92. King Post.—A member, A, of a common form of truss for roofs. It is strictly a tie intended to prevent the sagging of the tie beam, B, in the middle. If there are struts, C, supporting the rafters, D, they extend down to the foot of the King Post.
93. Label.—The name given to the projecting molding, A, around the top of the door opening. A form of mediæval architecture.
Fig. 94.-Fig. 104.
94. Louver.—The sloping boards, A, set to shed rain water outward in an opening of a frame, as in belfry windows.
95. Lintel.—A horizontal member. A spanning or opening of a frame, and designed to carry the wall above it.
96. Lug.—A. projecting piece, as A, to which anything is attached, or against which another part, like B, is held.
97. M-Roof.—A kind of roof formed by the junction of two common roofs with a valley between them, so the section resembles the letter M.
98. Mansard Roof.—A hipped curb roof, that is, a roof having on all sides two slopes, the lower one, A, being steeper than the upper portion or deck.
99. Newel Post.—The upright post at the foot of a stairway, to which the railing is attached.
100. Parquetry.—A species of joinery or cabinet work, consisting of an inlay of geometric or other patterns, generally of different colored woods, used particularly for floors.
101. Peen. also Pein.—The round, round-edged or hemispherical end, as at A, of a hammer.
102. Pendant.—A hanging ornament on roofs, ceilings, etc., and much used in the later styles of Gothic architecture where it is of stone. Imitated largely in wood and plaster work.
103. Pentastyle.—A pillar. A portico having five pillars, A, is called the Pentastyle in temples of classical construction.
104. Pedestal.—An upright architectural member, A, right-angled in plan, constructionally a pier, but resembling a column, having a capital, shaft and base to agree with the columns in the structure.
Fig. 105.-Fig. 117.
105. Pintle.—An upright pivot pin, or the pin of a hinge; A represents the pintle of a rudder.
106. Portico.—A colonnade or covered structure, especially in classical style, of architecture, and usually at the entrance of a building.
107. Plate.—A horizontal timber, A, used as a top or header for supporting timbers, roofs and the like.
108. Queen Post.—One of two suspending posts in a roof truss, or other framed truss of simple form. Compare with King Post. A, B, tie beam; C, C, queen posts; D, straining piece; E, principal rafter; F, rafter.
109. Quirk Molding.—A small channel, deeply recessed, in proportion to its width, used to insulate and give relief to a convex rounded molding. An excellent corner post for furniture.
110. Re-entering.—The figure shows an irregular polygon (that is, many-sided figure) and is a re-entering polygon. The recess A is a re-entering angle.
111. Rafter.—Originally any rough and heavy piece of timber, but in modern carpentry used to designate the main roof support, as at A. See Queen Post.
112. Scarfing.—Cutting timber at an angle along its length, as the line A. Scarfing joints are variously made. The overlapping joints may be straight or recessed and provided with a key block B. When fitted together they are securely held by plates and bolts.
113. Scotia Molding.—A sunken molding in the base of a pillar, so called from the dark shadow which it casts.
114. Sill.—In carpentry the base piece, or pieces, A, on which the posts of a structure are set.
115. Skew-Back.—The course of masonry, such as a stone, A, with an inclined face, which forms the abutment for the voussoirs, B, or wedge-shaped stones comprising the arch.
116. Spandrel.—The irregular, triangular space, A, between the curve of an arch and the enclosing right angle.
117. Strut.—In general, any piece of a frame, such as a timber A, or a brace B, which resists pressure or thrust in the direction of its length.
Fig. 118.-Fig. 123.
118. Stud, Studding.—The vertical timber or scantling, A, which is one of the small uprights of a building to which the boarding or plastering lath are nailed.
119. Stile.—The main uprights of a door, as A, A; B, B, B, rails; C, C, mullions; D, D, panels.
Tie Beam.—See Queen Post.
120. Trammel.—A very useful tool for drawing ellipses. It comprises a cross, A, with grooves and a bar, B, with pins, C, attached to sliding blocks in the grooves, and a pen or stylus, D, at the projecting end of the bar to scribe the ellipse.
121. Turret.—A little tower, frequently only an ornamental structure at one of the angles of a larger structure.
122. Transom.—A horizontal cross-bar, A, above a door or window or between a door and a window above it. Transom is the horizontal member, and if there is a vertical, like the dotted line B, it is called a Mullion. See Stile.
123. Valley Roof.—A place of meeting of two slopes of a roof which have their sides running in different directions and formed on the plan of a re-entrant angle.
A knowledge of drawing, at least so far as the fundamentals are concerned, is of great service to the beginner. All work, after being conceived in the brain, should be transferred to paper. A habit of this kind becomes a pleasure, and, if carried out persistently, will prove a source of profit. The boy with a bow pen can easily draw circles, and with a drawing or ruling pen he can make straight lines.
Representing Objects.—But let him try to represent some object, and the pens become useless. There is a vast difference in the use of drawing tools and free-hand drawing. While the boy who is able to execute free-hand sketches may become the better artist, still that art would not be of much service to him as a carpenter. First, because the use of tools gives precision, and this is necessary to the builder; and, second, because the artist deals wholly with perspectives, whereas the builder must execute from plane surfaces or elevations.
Forming Lines and Shadows.—It is not my intention to furnish a complete treatise on this subject,but to do two things, one of which will be to show, among other features, how simple lines form objects; how shading becomes an effective aid; how proportions are formed; and, second, how to make irregular forms, and how they may readily be executed so that the boy may be able to grasp the ideas for all shapes and structural devices.
Fig. 125.Fig. 125.
Fig. 126.Fig. 127.Fig. 126.Fig. 127.
Fig. 126.
Fig. 127.
Analysis of Line Shading.—In the demonstration of this work I shall give an analysis of the simple lines formed, showing the terms used to designate the lines, curves, and formations, so that when any work is laid out the beginner will be able, with this glossary before him, to describe architecturally, as well as mathematically, the angles and curves with which he is working.
How to Characterize Surface.—Suppose we commence simply with straight lines. How shallwe determine the character of the surface of the material between the two straight lines shown in Fig. 125? Is it flat, rounded, or concaved? Let us see how we may treat the surface by simple lines so as to indicate the configuration.
Fig. 128.Fig. 129.Fig. 128.Fig. 129.Fig. 130.Fig. 131.Fig. 130.Fig. 131.
Fig. 128.
Fig. 129.
Fig. 130.
Fig. 131.
Concave Surfaces.—In Fig. 126 the shading lines commence at the upper margin, and are heaviest there, the lines gradually growing thinner and farther apart.
Convex Surfaces.—In Fig. 127 the shading is very light along the upper margin, and heavy at the lower margin. The first shaded figure, therefore, represents a concaved surface, and the secondfigure a convex surface. But why? Simply for the reason that in drawings, as well as in nature, light is projected downwardly, hence when a beam of light moves past the margin of an object, the contrast at the upper part, where the light is most intense, is strongest.
The shading of the S-shaped surface (Fig. 128) is a compound of Figs. 126 and 127.