Force, Weight, Motion and the Blow
Force infinite with time, weight finite; the natural, accidental and participating varieties of motion, and a plan of study
A theoretical note on dynamics. Leonardo finds force to be infinite together with time, while weight is finite, bounded by the weight of the whole globe of the earthly machine, and holds the blow to occupy an indivisible instant of time and motion. He distinguishes three kinds of motion, natural, accidental and participating, noting where each is strongest: the participating spends its greatest power at the middle of its course where it turns from accidental into natural, the natural is most powerful at the end, the accidental strongest in its first third and weakest at the end. He closes with an order of treatment: first weight, then motion which begets force, then force, and lastly the blow. Fainter offset lines and further writing show on the lower sheet.
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Force infinite with time; weight finite
Force is infinite together with time, whereas weight is finite, bounded by the weight of the whole earthly globe. The blow, by contrast, occupies an indivisible instant of both time and motion. These opening claims frame force, weight and the blow as the terms Leonardo will analyze.
The three kinds of motion and the order of treatment
Motion is of many varieties: natural, accidental and participating. The participating motion spends its greatest power at the middle of its course, where it changes from accidental into natural; the natural is strongest at the end, the accidental strongest in its first third and weakest at the end. Leonardo sets out to treat first weight, then the motion that begets force, then force, and finally the blow.