Draw E F about 3 inches long and mark the point X, 1 inch from E and the point Y, 1 inch from X. With the triangle and T-square, draw the rectangles A B D C and O P Q R such that A B is 1 inch in length and A C, 3 inches in length. Divide A E and A B into the same number of equal parts. Connect Y with the points T, U, and V, on A E, and connect X with L, M, and N, on A B. The first point on the curve is at A; the next is at the intersection of T Y and L X; the third is at the intersection of U Y and M X. The remaining points are found in the same manner. Repeat the process for X C and the right-hand curve P Y Q.
In inking the figures on this plate, use the French or irregular curve and make full lines for the curves and their axes. Dot the construction lines as usual. Ink in all the construction lines used in finding one-half of a curve, and in Problems 19, 20, 23, and 24 leave all construction lines in pencil except those inked. In Problems 21 and 22 erase all construction lines not inked. The trammel used in Problem 21 may be drawn in the position shown, or outside of the ellipse in any convenient place.