On impact: a rule for the powder charge of projectiles
Match the powder to iron, lead or stone shot, with calculations
Under the heading 'On impact' the note calls for a rule governing every kind of projectile, whether of iron, lead or stone, and how its charge of gunpowder must be increased or diminished accordingly. Around the text are columns of figures worked by multiplication, with 2592 and the recurring total 1855. The page joins a memorandum on gunnery and percussion to supporting arithmetic.
On this page
Matching the powder charge to the shot
Leonardo resolves to establish a general rule for artillery: for every quality of ball, whether iron, lead or stone, one must know how much to increase or decrease the powder charge. The note treats the loading of guns as a matter to be regulated systematically.
The heading 'On impact'
The entry opens with the title 'On impact' (De percussione), placing the gunnery rule under Leonardo's wider study of percussion, the force of a striking or falling body. The differing weights of iron, lead and stone are what make the charge vary.
Supporting columns of figures
Numerals surround the note as worked calculations, including 81, 162, 243 and the repeated product 2592, with 1855 once more standing as a total. They form the computation behind the rule.