Cannon diagram and tables, from a 17th century maritime manual. At top, a cannon is thoroughly labelled, with the figure at upper left stating that the illustration includes: 'Ye names of ye members of a pece [sic] of Ordnance'. A cannonball is at upper right (being measured with calipers), with ram rods at upper left. The tables at bottom allow calculations to be carried out according to the type of cannon and shot used. The diagram at centre left shows the diameter of various parts of a cannon. This is a page from Mariner's Magazine (1669), a compendium of maritime information compiled by the English writer Samuel Sturmy (1633-1669).