File:A manual of elementary geometrical drawing, involving three dimensions. Designed for use in high schools, academies, engineering schools, etc. - and for the self-instruction of inventors,artizans, (14762650231).jpg

Identifier: manualofelementa01warr (find matches)
Title: A manual of elementary geometrical drawing, involving three dimensions. Designed for use in high schools, academies, engineering schools, etc. : and for the self-instruction of inventors,artizans, etc. ... In five divisions ..
Year: 1867 (1860s)
Authors: Warren, S. Edward (Samuel Edward), 1831-1909
Subjects: Geometrical drawing Mechanical drawing
Publisher: New York : J. Wiley and son
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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rge or complicatedstructures, as buildings or machines, when shown in isometricalprojection, causes this method to be confined, in its application, tosmall objects, details, &c. 205. It is often convenient to know in advance the extremeheight of the isometrical drawing of a given object, in order thatit may be better arranged upon the paper. See PI. X., Fig. 103,for example. Da being 10 inches—by scale—the distance of abelow a horizontal line through D, is the sine of SO* to a radius of10. Hence, as sin. 30°=^, that distance is 5 inches. In like man-ner aC being 4 inches, C is 2 inches below a ; and Cc being 3^inches, o is 10;- inches below D. 205a. As a final preliminary, it is to be noted, that, as no planesof projection are commonly employed in isometrical drawing, thedirection of the light is defined with respect to a cube as a standardbody of reference. Thus, Fig. 102, the ray entering at a is sup-posed to leave the cube at j!?, and all other rays are parallel to this. i
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The MajoriKnaiip Eni.HrviLith.Ca4« DmndwayHY. CHAPTER n. PROBLEMS IlSrVOLVING ONLY ISOMETRIC LINES. 206. Prob. 1. To make the isometrical drawing of a cube, froma given plan and elevation. \st Method. The plan and elevation, PL IX,, Fig. 98, repre-sents a cube, whose edge is one inch in length, seen in right pro-jection? To make the isometrical drawing of the same cube, Fig.101, take any point, C, as a centre, and describe a circle with oneinch radius, CD ; lay off the radius six times, commencing at eitherend of the vertical diameter; join the points thus formed, and drawaC, 5C, and cC. Then Ca and CJ, and all the lines parallel withthem, are drawn with the 30° triangle. 2nd Method. Draw the three axes, and lay off an inch on eachof them. The remaining lines, being equal and parallel to these,are drawn with the 30° triangle, placed in different positions, whichwill readily suggest themselves, on attempting the construction, 207. To complete the representation, certain lines are ma

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