Motion through right and obtuse angles: load on suspending cords
Weight shared among perpendicular cords, and the proportion b c : b a
A tall rectangular figure is filled with a fan of lines radiating from its lower-right corner across quarter-circle arcs, illustrating how a load's share changes with the angle of pull — 'motion made through right and obtuse angles.' Leonardo states that the proportion b c : b a equals the ratio of weight a to weight b, less what is lost to the beam's obliquity, and asks the reader to take 'beam' to mean a uniform body of equal length, weight and thickness. A lower figure labelled l K i h g f – a – b – c – d – e – n m gives the general rule that a beam hung by its ends from perpendicular cords gives an equal weight to each cord.
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A beam on perpendicular cords loads each cord equally
General rule: every beam suspended by its ends from perpendicular cords gives of itself an equal weight to each cord. The lower figure is laid out along the points l K i h g f – a – b – c – d – e – n m.
Share of weight follows the proportion b c : b a
The proportion that b c bears to b a is the same as that of weight a to weight b, once the part naturally lost through the beam's obliquity is set aside. Leonardo asks the reader to take 'beam' to mean a body of uniform length, weight and thickness.