Composite Motions and the Course of Man
Dancing, fencing and rowing; the side over the supporting leg sinks; shoulder height and speed of movement
The text continues the classification of motion, naming composite motions such as dancing, fencing, juggling, sowing, ploughing, and rowing, and noting that rowing is purely actional because the man's motion mixes with local motion only through the movement of the boat. A chapter on the motion and course of man observes that the part of the body above the supporting leg always sits lower than the opposite part. A further rule links shoulder height to speed: the slower the whole moves, the greater the difference between the two shoulders; the faster it moves, the smaller the difference, proved by the ninth proposition of local motion. The leaf closes as an imagined adversary objects to the rule of ponderation. No diagram appears on this text page.
On this page
Composite motions, and why rowing is only actional
Composite motions are infinite, among them dancing, fencing, juggling, sowing, ploughing, and rowing. Rowing, however, is of the simple actional kind, because the actional motion the man makes in rowing is mixed with local motion not through the man's own movement but through the movement of the boat.
The side above the supporting leg drops lower
When a man or other animal moves, whether fast or slow, the part of the body directly above the leg that supports it always sits lower than the opposite part. This is the basic asymmetry the painter must render in a figure in motion.
Shoulder height varies inversely with speed of movement
The shoulders (or sides) of a body show the greatest difference in height when the whole moves most slowly, and the least difference when it moves most swiftly. This is proved by the ninth proposition of local motion: every heavy body weighs along the line of its motion, so a part joined to a moving whole follows the shortest line without shedding weight to the lateral parts.