Note 3 — MATHEMATICS AND ASTRONOMY

In the case of the parabola, the base (as distinct from the ‘erect side’) of the rectangle is what is called the abscissa (Gk. αποτεμνομενη, ‘cut off’) of the ordinate, and the rectangle itself is equal to the square on the ordinate. In the case of the central conics, the base of the rectangle is ‘the transverse side of the figure’ or the transverse diameter (the diameter of reference), and the rectangle is equal to the square on the diameter conjugate to the diameter of reference.