Young, George, jr, Baxter, Hubert Eugene, joint author · New York, The Macmillan Co. · leaf 24
e called the datum planes for locating the light. These datum planes, or planes of reference, may be chosenat will. Ordinarily, however, each plane is taken perpendicularto the other two (as in the cases cited above), one being hori-zontal, and the other two vertical. This will be done in this I,… … ff=the horizontal plane of projection V^=the vertical planeof projection P=the profile planeof projection a=horizontal projection of aa=vertical projection of oFig. 8 a=profile projection of a aa^=horizontal projecting lineaa=vertical projecting lineaa=profile projecting line on each plane by means…
Geometry, Descriptive
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