Given that it is an engraving, it might also be a plan for sharpening a burin. There are many kinds of burins -- for a general impression of what I am after, s

Given that it is an engraving, it might also be a plan for sharpening a burin. There are many kinds of burins -- for a general impression of what I am after, see http://www.google.com/patents/US7032586 http://www.google.com/patents/US7032586