figure having four sides, and
consequently four angles. Any figure formed by four lines.

177. _Rhomb._--An equilateral parallelogram or a quadrilateral figure
whose sides are equal and the opposite sides, B, B, parallel.

178. _Sector._--A part, A, of a circle formed by two radial lines, B, B,
and bounded at the end by a curve.

179. _Segment._--A part, A, cut from a circle by a straight line, B. The
straight line, B, is the chord or the _segmental line_.

180. _Sinusoid._--A wave-like form. It may be regular or irregular.

181. _Tangent._--A line, A, running out from the curve at right angles
from a radial line.

182. _Tetrahedron._--A solid figure enclosed or bounded by four
triangles, like A or B. A plain pyramid is bounded by five triangles.

183. _Vertex._--The meeting point, A, of two or more lines.

184. _Volute._--A spiral scroll, used largely in architecture, which
forms one of the chief features of the Ionic capital.

CHAPTER IX

MOLDINGS, WITH PRACTICAL ILLUSTRATIONS IN EMBELLISHING WORK

MOLDINGS.--The use of moldings was early resorted to by the nations of
antiquity, and we marvel to-day at many of the beautiful designs which
the Ph[oe]necians, the Greeks and the Romans produced. If you analyze
the lines used you will be surprised to learn how few are the designs
which go to make up the wonderful columns, spires, minarets and domes
which are represented in the various types of architecture.

THE BASIS OF MOLDINGS.--Suppose we take the base type of moldings, and
see how simple they are and then, by using these forms, try to build up
or ornament some article of furniture, as an example of their utility.

THE SIMPLEST MOLDING.--In Fig. 185 we show a molding of the most
elementary character known, being simply in the form of a band (A)
placed below the cap. Such a molding gives to the article on which it is
placed three distinct lines, C, D and E. If you stop to consider you
will note that the molding, while it may add to the strength of the
article, is primarily of service because the lines and surfaces produce
shadows, and therefore become valuable in an artistic sense.

THE ASTRAGAL.--Fig. 186 shows the ankle-bone molding, technically called
the _Astragal_. This form is round, and properly placed produces a good
effect, as it throws the darkest shadow of any form of molding.

[Illustration: _Fig. 185. Band._]

[Illustration: _Fig. 186. Astragal or Ankle Bone._]

[Illustration: _F