Force-pyramids and the true centre of gravity
Weight given to the mover as a triangular load is lifted, with a small scissors sketch
Leonardo analyses a triangular 'pyramid' of load S r t raised on a cord, asking how many degrees of weight it delivers to its mover at each degree of motion, and observing that the final pyramid ceases to weigh once a line bisects it. A second study seeks the true centre of gravity of every pyramid, showing that pyramids sharing a base on line f l and meeting at point t are halved in weight by the line h K, because the squares are double one another. A small marginal sketch is labelled 'forbici' (scissors), and a geometric figure of a square with an inscribed circle and triangle accompanies the lower demonstration.
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Degrees of weight delivered by a raised force-pyramid
Leonardo wants to know, as he lifts the pyramid S r t up to the position v n o, how many degrees of weight it gives to its mover at every degree of its motion, when pulled at a right angle by its cord. He notes that the final pyramid v n r no longer weighs on its mover, because the line a n divides it perpendicularly into two equal parts.
Geometric bisection giving the centre of gravity of a pyramid
Seeking the mid-point of the true gravity of every pyramid, Leonardo states that all pyramids having their base on the line f l and terminating at the point t are divided into half of their weight by the line h K. This holds, he says, because the squares are double, one to the other.
Sketch labelled 'scissors'
A small drawing at the middle right of the sheet is annotated simply 'forbici' (scissors), showing a paired, hinged tool with U-shaped return. It sits apart from the mechanical demonstrations that fill the rest of the page.