French curves

These are made in many different shapes, normally come in sets of 6,12,16 etc. French curves are best suited to draw smooth curves/ arcs (which cannot be drawn by a compass) with ease. To draw a smooth curve using french curve first set it by trial against a part of the line to be drawn, then shift it to the next portions. Each new portion should fit atleast three points on the curve just drawn. It should be seen that the curve (radius) is increasing or decreasing smoothly and no corner should be formed on the curve

show how to use the french curve and draw a smooth curves. They are made of transparent celluloid (no bevel edge).