Young, George, jr, Baxter, Hubert Eugene, joint author · New York, Macmillan · leaf 200
from the surface by any horizontal plane, is aninvolute of the circle (§ 134) which the plane cuts from thecylinder. These facts may be visualized without formal proof. VIII. § 159] CURVED SURFACES 181 159. To Draw the Projections of a Developable Helicoid ofTwo Nappes. Let the directing cylinder… … Fig. 173 the base circle, and extending to the involutes, as 1*6*2/*, 2*c*x*,etc. These lines are the H projections of elements of therequired surface (corresponding to fg in Fig. 172 (2)). TheV projections of 1, 2, 3, 4 are in HA, and those of w, x, y, zare in the plane of the upper base, HA. The…
Geometry, Descriptive
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