Bombards: the cortaldo and the Fulgorea
Loudness of bombards, a spherical-breech design with priming tube, and a recoil test
The sheet studies bombards. A note observes that the short bombard called cortaldo is louder than any other, while the longer piece is quieter. The main design is the Fulgorea, a bombard with a spherical breech pierced by a thin perforated iron priming-tube filled with fine powder, so the charge ignites all at once and the copper breech survives the blast. A final experiment proposes testing whether a bombard drives harder backward or forward by placing equal iron balls against lead buttresses front and rear.
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The cortaldo, loudest of bombards
The note states that the bombard called cortaldo makes a greater report than any other, while the longer piece is quieter. Its figure is drawn with a part labelled a, the box (scatola). The remark links barrel length to the loudness of the discharge.
Fulgorea: spherical breech with a perforated priming tube
The Fulgorea has a hollow spherical breech at whose centre sits a thin, finely perforated iron tube filled with fine powder. This is done so that the fire, reaching the centre, ignites all the packed powder at once, and so that the round copper cavity, made of fine copper, resists the violence of the charge and the bore is not consumed. The rest may be cast at four parts tin to a hundred of copper, and it is called the best machine that can be made.
Test of forward versus backward thrust
To learn true experience of whether a bombard drives harder backward or forward, Leonardo sets a lead buttress behind and a lead target in front. An iron ball equal to the one shot at the target is placed between the breech and the rear buttress. Whichever ball has pressed its obstacle more has been driven by the greater violence.