Known by some historians as the "Manuscrito Ignoto" (Unknown Manuscript), this anonymously written book is essential to understanding Spanish shipbuilding in the 18th century. Written in 1733, it covers the time between Antonio de Gaztañeta and Jorge Juan—a period with scant documentary evidence relating to Spanish naval shipbuilding.
The book is bound in parchment and contains more than 70 pages of text, along with over 50 ships' plans, some of which are made up of as many as 6 folded pages.