Weight of a bar suspended by two cords
How shifting a cord toward the centre redistributes the load
Three columns of mirror-script, with small diagrams of a rod hung from two cords in the left margin, analyse how a suspended bar shares its weight. A bar hung by its ends divides its weight equally between the two cords; moving one cord toward the centre changes the weight it carries in proportion to its displacement, so that every degree of motion produces a degree of weight. Leonardo frames the shift in scholastic terms of motion 'in actuality' and 'in potentiality', and records trial weights such as 2, 4 and 6 in red chalk.
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A bar hung by its ends shares weight equally
The bar suspended by its ends from two cords distributes its weight equally to those cords. This is the base case from which the following variations depart.
Moving one cord toward the centre alters its load
If one cord is moved toward the centre of the bar while the other stays at its end, every degree of motion gives it a variety of weight. The change in weight of the moving cord has the same proportion to the original as its motion has to the rest of the bar, so the more it moves inward the more weight it takes from the other.
Motion in actuality and in potentiality
If one of the cords stays fixed and the other moves toward it, weight is moved from the fixed cord and joins the weight of the movable one. If one cord moves toward the other in actuality, the other, opposite to it, moves in potentiality.
Every degree of motion makes a degree of weight
The weight of the rising end of the bar has to its original the same proportion that the space of the perpendiculars at the ends, as they become oblique, has to the length of the bar. In short, every degree of motion makes a degree of weight, tallied by figures such as 1, 2 and 4.
