It covers the sector (a form of calculator that predates the slide rule), the gunner's calipers, the proportional compasses, and a variety of lesser instruments.

Examples show how to use all of the instruments, with extensive details on architectural drawing, plane geoemtry, spherical trigonometry, unit conversion, surveying, perspective drawing, and ship's guns (cannons and mortars). 12 plates of figures illustrate and clarify the text.