Draw the straight line A B - about three inches long - as the axis, or abscissa of the parabola. At A and B draw the lines EF and C D perpendicular to A B, and with the T-square draw E C and F D, 1 1/2 inches above and below A B, respectively. Let A be the vertex of the parabola. Divide A E and E C into the same number of equal parts. Through R, S, T, U, and V, draw horizontal lines and connect L, M, N, O, and P, with A. The intersections of the horizontal lines with the oblique lines are points on the curve. For instance, the intersection of A L and the line V is one point and the intersection of A M and the line U is another.
The lower part of the curve A D is drawn in a similar manner.