16. .... sans elle on ne parviendroit jamais à bien dresser la petite face du poinçon, sur laquelle la lettre doit être pour ainsi dire découpée. The point is that the face carrying the letter in relief must be absolutely perpendicular to the sides of the shank of the punch which must also be parallel to each other so that they will lie squarely against the jig or ‘square’( l'équerre ) that holds the punch as it is ground on the oilstone.