Force and distance in the crossbow's discharge
How lightening the missile lengthens the distance the power drives it
Leonardo works out the relation between the weight that draws a crossbow's cord and the distance a shot is driven. If four hundred pounds draws the cord one-third of a braccio, then two hundred pounds is shot two-thirds and one hundred pounds one and one-third braccia; the lighter the missile, the farther the power carries it, always in the same proportion, if the air does not impede. A small drawing of the crossbow's lock, with its lever and cord, sits among the lines of writing.
On this page
Drawing-weight against distance shot
The motion of the cord and the motion of the thing moved keep the same proportion as the weight that drew the cord to the weight it drives. So four hundred pounds drawing the cord one-third braccio shoots two hundred pounds two-thirds braccio, and one hundred pounds one and one-third braccia.
The qualification 'if the air does not impede'
Leonardo adds a condition to the rule: the more the weight of the mobile object is diminished, the farther the power sends it, provided the air offers no resistance. Setting aside air drag lets the proportion be stated cleanly.
The crossbow lock drawn among the text
A small pen drawing of the crossbow's lock, its nut, lever and cord, is set into the writing at the upper centre of the page. It pictures the very mechanism whose releasing force is being analysed.