The profile of the talon is formed by two arcs of a circle united at their end, and "whose centres are on different sides of a right line, which joins their extremi- ties. This line, which is dotted in the figure, is cut in the middle by the arcs, and each half being taken for the base of an equilateral triangle, the summit or apex of the triangle is the centre of the arc. The right line which joins these two summits or centres of the arcs, passes through the point where the two arcs touch at the middle of the first right line.
9. The monitor must now require the pupil to draw the eight preceding figures, turned towards the left*
Here the arcs, end to end, belong one to an ellipse, and the other to a circle. The centres and axes are marked.
