Betty Cooper describes this beautifully-penned manuscript as a "fair copy of working instructions as used by master ship-wrights of the period. The contents deal mainly with mathematical propositions worked out in diagrams. There are also details of 'Proportions for gallies, borde measure, timber measure, guaging of vessels, and a table of synes.'" It precedes the first work on shipbuilding, to be printed in English, by at least several decades, and is very little older than Diego Garcia de Palacio's Instrucion Nauthica (Mexico, 1587) which is the first known work dealing with naval architecture.