A Balance Compared to a Bellows Crossbar
Statics of a lettered balance, above a large fan of geometric curves
At the top a lettered balance a n m o carries two equal four-pound weights, and Leonardo argues that the beam yields as much weight to remove the load at a as at n: because the point o lies twice as far from the fulcrum, two pounds at o balance four at a. He likens the action to the force exerted at a bellows by way of a crossbar. The lower half of the sheet is filled by a large untranscribed geometric construction -- a quarter-circle spanned by a dense fan of radiating and curved lines -- for which the bundle provides no text.
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A balance analysed like a bellows crossbar
With 4 pounds at n, removing a leaves 2 pounds in o and 2 in m; and because o is twice as far from the pole as a, 2 pounds at o stand equal with 4 at a. Leonardo compares this distribution of load to the force made at a bellows by way of a crossbar.
Untranscribed fan of curves
The lower half of the leaf carries a large geometric construction: a quarter-circle whose corner is crossed by a dense fan of straight radiating lines and nested arcs. The bundle supplies no transcription for this figure, which appears to explore a proportional or curve construction.