In 1711 John Davis, who had been boatswain on various ships for the last 30 years, published a book called 'The Seaman's Speculum, or Compleat Schoolmaster'. This has extensive rigging tables, and much other useful information. Unfortunately it now seems that no original copy exists, as none of the major repositories hold a copy. The only seeming survival is a volume which existed in 1945, and had been acquired by the library of the US Navy Department. Not sure if this copy still exists, and if