Spanton, J. Humphrey (John Humphrey) · London, Macmillan and Co., Limited; New York, The Macmillan Company · leaf 128
are. Takea piece of string equal inlength to CD, fix one end atD and the other at E, whichis the focus of the curve. Ifa pencil be held against thestring so as to keep it tightagainst the tee-square whenthe tee-square is moved up-wards, the pencil will tracehalf a parabola. AB is thedirectrix, and… … CONIC SECTIONS. 5 166. To draw an oval by arcs of circles, its transverse diameter ABand its conjug-ate CD being given. Set off on AB the distance AE equal to half the conjugatediameter. Through E draw the line FG perpendicular to A AB (Prob. 7). With Eas centre and EA asradius, draw the…
Geometrical drawing · Design · Drawing
Internet Archive · Wellesley College Library · Public Domain Mark 1.0. Free to use for anything.
