Sighting a crossbow with a mirror; ties and struts
A longer, steadier stock shoots straighter; shooting at an unseen target; why a rod should pull, not push
The upper part of the sheet treats a crossbow: one held more steady over the man, with a longer stock, shoots straighter, and by resting it on a stool at eye height and fixing a flat mirror at its foot the shooter sees almost twice the weapon's length. Leonardo also heads a note "to shoot at a place not seen by you." Below, mechanical problems follow: a balance where the weights are in inverse proportion to the arms a b and b c, and a structural study of a ship's rod showing that member a c serves well when it pulls but rod n o fails when made to push, since pushing would bend it.
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A steadier, longer-stocked crossbow shoots straighter
The crossbow held more steady over the man and with the longer stock shoots straighter. Leonardo gives it a stool so that, resting on the shoulder to draw backward, its tiller stands as high as the eye.
A flat mirror at the crossbow's foot doubles the sighting line
A flat mirror is fastened at the foot of the crossbow; looking into it the archer sees almost twice the length of the weapon, aiding a straight aim.
Shooting at a place not seen by you
A mid-page heading opens the problem of how to shoot at a place that is not seen by the marksman.
Balance: weights inverse to the arms a b and b c
At a balance figure lettered a, b, c with weights 1 and 2, the proportion that a b has with b c is the same that the weight c has with the weight a.
A rod should pull, not push (a c good, n o bad)
In a figure marked "ship," the rod a c is good and resists well because its office is to pull, not to push; if it pushed it would tend to bend. Conversely rod n o does its office badly, because its office is to push not to pull, and pushing would make it bend.