Bombard Breeches and the Casting of Culverins
Eight sketches of gun tails, with notes on breech length and bronze founding
A vertical column of eight small sketches shows the tails and breech chambers of bombards, drawn with circular and straight construction lines set inside the powder chamber. The accompanying notes argue that an over-long breech is merely a hindrance, wasting space dangerously and reducing the velocity of the shot. A grouped passage on founding holds that the hottest, most fluid bronze fills a mould best, so the chamber that receives the powder should always be cast before the muzzle. A final remark warns that when several culverins are poured in one casting the first comes out far better than the last.
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The long breech wastes space and reduces velocity
Leonardo objects that an over-long breech is a hindrance, an unnecessary and dangerous occupation of space, and a cause of lost velocity in the shot.
Cast the powder chamber before the muzzle
The most fluid bronze condenses best into the mould, and that bronze is the most fluid which is hottest, being the part that leaves the furnace first. Therefore the part of the culverin meant to receive the powder should always be cast before the mouth. He adds that when several culverins are cast from one pour the first is far better than the last.
Eight sketches of bombard tails
A column of eight small studies presents the tails and breech chambers of bombards, each with circular and straight construction lines drawn inside the inner chamber.