Young, George, jr, Baxter, Hubert Eugene, joint author · New York, The Macmillan Co. · leaf 167
thehand rail on a spiral stair,etc. Another type of helix canbe generatedby a pointmoving on thesurface of acone, follow-ing the samelaws as above.Such a curve is called a conical helix. Its hori-zontal projection is a spiral of Archimedes.(See § 136.) EXERCISE SHEET XLIX [Note. Each of the… … ■ ffiy ^///^y/ Br VII, § 137] CURVED LINES 151 When the dooi is opened, the point h moves outward and upward asindicated by the arrow h, while the roller moves directly upward, incontact with the wall, as shown by the arrow r. Determine the exactlimits of the space not interfered with by the…
Geometry, Descriptive
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