Air Resistance Subtracted from a Falling Weight's Motion
A five-row table sets each degree of a body's motion against what remains once the resisting air is deducted
This page treats the descent of a heavy body through air whose density increases toward the earth. A table in the outer column sets ten degrees of motion against the nine that remain once air resistance is subtracted, continuing to twenty/eighteen and on to fifty/forty-five, its columns keyed to the letters a, b, c and to n, m, S. The inner column argues that cloudless air grows rarer pyramidally with height (line n through a), while a falling weight gains a degree of velocity at every degree of motion, the degrees of motion being ten times stronger than the resisting air. Dense mirror-script fills both columns beneath the tabulated figures.
On this page
Table: air resistance deducted from each degree of motion
A three-column table headed a, b, c lists five degrees of motion (10, 20, 30, 40, 50) beside the reduced values that remain once the resisting air is taken away (9, 18, 27, 36, 45), and terminates in the letters n, m, S. Line c through S is the motion of the weight; b through m is that motion with the air resistance, a through n, subtracted from it.
Air grows rarer with height, pyramidally
When free of cloud or fog, the air is densest at its lowest level and acquires degrees of rarefaction with every degree of height, pyramidally, as line n through a demonstrates. A weight descending through it gains a degree of velocity at every degree of motion; Leonardo proposes the degrees of motion are ten times more powerful than the resisting air, so ten loses one to become nine and twenty loses two to become eighteen, as line b through m shows.