Gunpowder versus crossbow force, and a mirror drop test
Weighing bombard powder against a crossbow load; timing two falling weights with a mirror
On the recto Leonardo compares the driving power of bombard powder with the weight loaded onto a crossbow: weigh the powder a small gun (scoppietto) takes and the pull a crossbow takes, fire one and the same ball from each, and compare the two ranges and penetrations in a single material. He then gives a method for deciding which of two falling weights descends faster: stand with the ear at the point of impact and watch a flat mirror set three fall-heights away, reflecting the mid-point of the drop. If the greater weight's impact is heard just as the lesser is seen at mid-height, their velocities are as two to one. A large diagram shows a tall vertical scale with weights and a mirror at the left, lettered n, a, f, b, c, d.
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Comparing bombard powder to a crossbow load
To measure how much greater the power of bombard powder is than the weight loaded onto a crossbow, weigh the powder a small gun can hold and the pull a crossbow can hold, then fire the same ball from each and compare the two courses and penetrations in one material. From this Leonardo says one can make good judgment and rule.
A general rule for which weight falls faster
For two bodies released from equal height and of equal thickness but one of double weight, Leonardo devises a way to tell which descends faster. The ear judges the moment of impact while the eye watches a mirror; equal timing of sound and mid-height sighting reveals a doubled velocity.
A flat mirror set three fall-heights away
A flat mirror is placed as far off as three times the fall of the weights, arranged so that the mid-point of the drop is reflected in it. Watching that reflection while listening for the impact lets the observer catch both events at once.
The drop-scale with weights and mirror
A tall vertical scale runs up the right of the leaf with small weights hung along it, while a mirror disc sits at the left connected by long sight-lines. The figure carries the letters n, a, f, b, c, d.