Doubling the Time Doubles a Body's Descent and Speed
A triangular array of dots, ten columns wide, shows time, motion and velocity holding the same proportion
For air of uniform density, Leonardo states that a descending body gains one more degree of motion in each degree of time than in the one before, and likewise one more degree of velocity, so that doubling the time doubles both the length of the fall and the speed. A triangular array of small circles and dots, ten columns wide and headed 1 through 10, is drawn across the lower page to demonstrate the rule. The figure shows that whatever proportion holds between any two quantities of time, the same proportion holds between the corresponding quantities of motion and of velocity.
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Doubling the time doubles the descent and the velocity
In air of uniform density, a descending heavy body acquires in every degree of time one degree of motion more than in the previous degree of time, and one degree of velocity more than in the previous degree of motion. Therefore in every doubled quantity of time it doubles both the length of the descent and the velocity of the motion.
A triangular array of dots proving equal proportions (columns 1-10)
A staircase array of circles and points, ten columns wide and numbered 1 to 10, is set out to demonstrate the rule. It shows that whatever proportion one quantity of time bears to another, the same proportion holds between the corresponding quantities of motion and of velocity.