Practical engineering drawing and third angle projection, for students in scientific, technical and manual training schools and for ..draughtsmen .. . jection showing that it represents the side of the object farthest from theplane, making it the exact reverse of the third-angle sjstem. In tlic ordiiinri/ representation the same object -nould be reiDresented simply by its three views asin Fig. 280. In the elevations the short-dash Hnes indicate the in^^sible edges of the hole. The arcs show the rotation which carries the profile view into its proper place. 231. Fig. 3. r-e i Ac I 1. C Fig. 8.
Practical engineering drawing and third angle projection, for students in scientific, technical and manual training schools and for ..draughtsmen .. . jection showing that it represents the side of the object farthest from theplane, making it the exact reverse of the third-angle sjstem. In tlic ordiiinri/ representation the same object -nould be reiDresented simply by its three views asin Fig. 280. In the elevations the short-dash Hnes indicate the in^^sible edges of the hole. The arcs show the rotation which carries the profile view into its proper place. 231. Fig. 3. r-e i Ac I 1. C Fig. 8. t r^L. -i_ ?Ic: 386. For the sake of more readily contrasting the two methods a group of views is shown inFig. 231, all above G. L., illustrating an object by the First Angle system, while all below HKrepresents the same oliject by the Third Angle method. When looking at Figures 1, 2, 3 and 4 the observer queries: AVhat is the object, in space, whosefront is like Fig. 1, top is like Fig. 2, left side is Hke Fig. 3 and riciht side like Fig. 4? For the view of the left side he might imagine himself as having Ijeen at first between G andH. looking in the direction of arrow X, after which both himself and the object were turned, together 134 THEORETICAL AND PRACTICAL GRAPHICS. to the right, through a ninety-degree arc, when the same side would be presented to his viewin Fig. 3. Similarly, looking in the direction of the arrow M, an eqiial rotation to the left, asindicated by the arcs 1-2, 3-4, 5-6, etc., would give in Fig. 4 the view obtained from directionM. His mental querie
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Keywords: ., bookcentury1800, bookdecade1890, booksubjec, booksubjectlettering
