|  In the Middles Ages, the masons who built cathedrals used a particular tool made of 5 articulated lengths.  Each length corresponded to a unit of measurement :  'coudee', 'paume', 'palme', 'empan', 'pied'.  The lengths were measured in 'ligne'.  One 'ligne' measures 2.247 mm, the width of a grain of barley.   |