Motive power and distance; a bisecting transversal
Halving the power halves the distance; pulleys, a balance, and a geometric proof
The leaf sets out a law of motive power illustrated by pulleys and a balance: if a power moves a body a given distance in a given time, half that power moves the same body half that distance in the same time. The proportion is argued through the mobiles of movers a and b and the levers of their turning wheels. A separate geometric proposition shows that a line dropped from the foot of one outer parallel to the head of the other bisects a line set midway between the two parallels; small figures rotated on the sheet carry braccia measurements.
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Half the power moves the body half the distance
If a power moves a body a certain distance in a certain time, half that power moves the whole body half that distance in the same time. Mover b drives its mobile through the whole figured line in two harmonic beats, while mover a, being half of b, drives its mobile half as far in the same time; the same proportion holds between the levers of the turning wheels of a and b.
A transversal bisects a line set between two parallels
A straight line b n a - o - d m c is placed at equal distance between two parallel lines, its upper ends level and its lower ends level. A line drawn from the lowest point of one outer line to the top of the other outer line cuts that interposed line into two equal parts.
