HOW THE DIFFERENT STRUCTURAL PARTS ARE DESIGNATED
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 words segment and sector. 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.
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.See King 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.
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.
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 beam at 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.
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.
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.
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.