Practical plane and solid geometry for advanced students, including graphic statics, adapted to the requirements of the South Kensington syllabus (1899)
Harrison, Joseph, Baxandall, George Albert · London Macmillan · leaf 98
eellipse. For, bisect ab in O and join CO. ThenCO = Ob = \ab = constantand angle OCb = angle ObC. Hence CO, OP, two lines of constant length, move roundC, and in all positions are symmetrically inclined to a fixedline CA ; therefore by Theorem 4, Art. 82, the locus of Pis an ellipse of which the… … If Pa and Pb had been set off opposite ways along the edge of the trammel, the same ellipse would have been described. CO would then have been the longer of the two cranks. Xotc.—Tracing-paper may with advantage be used for the trammel,in which case the points /*, a, b need not be on its edge. 84…
