In the preparation of mathematical diagrams for reproduction, it is often necessary to draw an ellipse or parabola with considerable accuracy. The methods described below need only a ruler, compasses and a set of French curves ; they produce very satisfactory results with a minimum of construction.

The process consists in setting out, by simple geometrical constructions, short circular arcs of curvature and then filling in the spaces between them with the aid of French curves. It is best to do the actual constructions in pencil and to ink the curves in afterwards with a drawing pen and French curves.