File:Descriptive geometry (1909) (14802312363).jpg

Identifier: descriptivegeome00anth (find matches)
Title: Descriptive geometry
Year: 1909 (1900s)
Authors: Anthony, Gardner Chace, 1856- (from old catalog) Ashley, George Francis, (from old catalog) joint author
Subjects: Geometry, Descriptive
Publisher: Boston, D. C. Heath & co.
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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he elements will be per-pendicular to it. The ends of these perpen-diculars will be at a distance from the lineequal to the true distances of the ends of theelements from the right section. A smoothcurve may then be drawn through the ends ofthe perpendiculars. Method. 1. Draw a right line equal inlength to the periphery of the right section.2. Upon this right line lay off the true dis-tances between the elements. 3. Throughthe points thus obtained draw perpendicularsto the right line. 4. On these perpendicularslay off the true lengths of the correspondingelements, both above and below the right line.5. Trace a smooth curve through the ends ofthe perpendiculars. CoxsTRUCTiON. Figs. 162 and 163. Thesecant plane JSF ol Fig. 162 has been so chosenas to cut a right section from the cylinder,that is, the traces of the plane are perpen-dicular to the projections of the axis of thecylinder (Art. 62, page 44). Element 1) hasbeen revolved parallel to V to obtain its true 90 DESCRIPTIVE GEOMETRY
Text Appearing After Image:
1 Fig. 163. DEVELOPMENT OF CYLINDER 91 length Dj, and d is projected to c?^, thus ob-taining the true lengths of each portion of D.Since all the elements of a cylinder are ofthe same length, D^ represents the true lengthof each element, and their segments are ob-tained by projecting the various points of thecut section upon it, as at 5^, (?j, etc. Upon theright line dd^ Fig. 163, the true distancesbetween the elements, de^ ch^ etc., have beenlaid off equal to the rectified distances dc\ch\ etc. Through points c?, e, 5, etc., perpen-diculars to line dd have been drawn equal tothe true length of the elements. The portionsabove and below dd are iequal to the lengthsof the elements above and below the cutsection. 126. If the axis of the cylinder be parallelto a coordinate plane, the development may beobtained without the use of a right section. Fig. 164 represents an oblique cylinderwith its axis parallel to V and its basesparallel to H. The elements are representedin vertical projection

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