Fig. 57 Fig. 58 Fig. 18
Although identified as a work for mariners, Sturmy's text was more wide-ranging in its mathematical coverage. Aside from navigation and trigonometry, the title page listed its contents as surveying, gauging, astronomy and dialling. Gunnery and 'artificial fireworks' were also included and the addition of Staynred's tract on fortification (catalogue no. 75) brought the book closer to a comprehensive survey. Sturmy nevertheless gave a nautical slant to his treatment of gunnery when he commented in the preface: 'I am ashamed to hear how senselesly many Sea Gunners will talk of the Art, and know little or nothing therein'.
One of Sturmy's remedies for the defects of contemporary gunners lay in the provision of instruments and he both illustrated and discussed an elaborate gunner's scale. This scale had a stepped edge to provide a gauge for the bore of guns. In use, the scale was inserted as far as possible into the barrel of a gun; the step that did not enter indicated the name of the artillery piece being measured. Each type of gun had an entry in a table giving numerical information on the gun, its powder, ladle and shot, as well as its point blank range. This scale, which was to be made of 'Silver, Brass, or Box, or any other fine-grained Wood, that will not warp', also carried a quadrant for elevating artillery.
Sturmy was concerned more with the practical procedures which a gunner had to master than with the mathematical analysis of ballistics. Just like Tartaglia almost 150 years earlier, he divided the path of artillery projectiles into three parts: an initial straight line of violent motion, then a curved section of 'mixt or crooked motion' and finally the vertical descent to the ground of natural motion.