General Method for the Center of Gravity of Weights on a Rod
Combining weights a, b, c, d, m pair by pair to find the center of the whole load
The upper part of the leaf shows a long rod hung by cords and carrying five weights lettered a, b, c, d and m. In a detailed note Leonardo sets out a general method for finding the center of gravity of any set of weights hung at random along a uniform rod. He works the weights in pairs, combining a and b (4 against 5, total 9) and then d and m together with c (total 6), and finally locates the center of the whole load between the two partial centers 9 and 6 by dividing the interval into 15 parts. Further lines of Leonardo's mirror-script continue down the leaf beyond this passage.
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Center of gravity of weights hung at random on a uniform rod
Leonardo poses the problem of a rod of uniform quality from which any number of weights may be hung at will, seeking the center of the whole suspended load. He resolves it by finding partial centers for groups of weights and then balancing those partial centers against one another.
Dividing the interval by the summed weights
For weights a and b, 4 against 5, the span between their cords is divided into 9 equal parts, giving 5 spaces against 4 weights so the center falls between 4 and 5. The weights d, m and c are combined to a center of 6, and the whole center is then set between 9 and 6 by dividing the interval into 15.