... tangents at Q and Qdraw F T Fparallel to QQ and terminated at F and F by the diameters through Q and Q.Let the tangent at P meet TQ, T Qin E and E, and QF , QFin G and G.Then ... , and if theline bisecting the P SPmeet the curve in q and q, F q and F qwill be thetangents at q and q.Taking the figure of Art. 7, the line SQ meets the curve in q and q, and, since ... of orthogonal projection, and anotherto the harmonic properties of curves, and to the relations of poles and polars,GEORGE BELL & SONSLONDON: YORK STREET, COVENT GARDEN AND NEW YORK, 66,...