Perspective and geometrical drawing adapted to the use of candidates for second and third-class teachers' certificates . 78 DRAWING. Ttie Pyramid. We now come to consider solids, which are not wholly rec-tangular; they are cones and pyramids and their frusta. In speaking of the height of a pyramid or cone, we meanthe distance from the vertex perpendicularly to the base,yhis is important, especially in frusta, where the slant heightmight be mistaken for the real height of the solid. Example 1.—Draw a pyramid, 8 high with square base,each side of which is 4, and touches 4 to right. H = 6,L.
Perspective and geometrical drawing adapted to the use of candidates for second and third-class teachers' certificates . 78 DRAWING. Ttie Pyramid. We now come to consider solids, which are not wholly rec-tangular; they are cones and pyramids and their frusta. In speaking of the height of a pyramid or cone, we meanthe distance from the vertex perpendicularly to the base,yhis is important, especially in frusta, where the slant heightmight be mistaken for the real height of the solid. Example 1.—Draw a pyramid, 8 high with square base,each side of which is 4, and touches 4 to right. H = 6, = 4^ scale 1 = ; K L M. Fig. 47. Take A, 4 to right and B, 4 to right of A; complete thesquare ABDC; draw diagonals intersecting in O; join O with THE PYRAMID. 79 and produce it backward to meet base line in E; at Eerect perpendicular, 8 in height to M; join M ; throughO, draw OX, parallel to EM; join XA, XB, XC, completingthe pyramid. ^Now, OX = EM = 8, and this represents thevertical height. (Fig. 47.) It is not absolutely necessary to join O with Wemay draw it to any point on the , as K or S., and pro-duce it backward to F or A, and erect a perpendicular fromeither of these points; but it must be carefully remembered,that the so-found point K or L, must be joined to S or Krespectively. Such lines, KS, LN, M , etc., will all passthrough same point X, which may be considered as a locusfor all such lines. For convenience, however, the line O be used, unless the solid be directly in front. 80 DRAWING. TTbie Cone. The drawing of the cone does not differ materially fromthat of t
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