Force of a thick vs. thin axle, and a furnace
A rule on turning a rod a b, paired with a drawing of a labelled furnace
The sheet pairs a mechanical rule with the drawing of a furnace. In the transcribed note Leonardo argues that if two men each pull with 100 pounds on the ends of a rod a b, the one turning the thicker portion exerts four times the force of the one turning the thinner part, because the thin diameter fits four times into the thick one. Below, a cylindrical furnace is drawn and its parts named in the transcription: coals, a grate, smoke and air, and water. The mirror-script text at the top corresponds to the transcribed passage.
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Turning the thick versus the thin part of a rod a b
Leonardo takes a rod whose ends are labelled a and b as an example of thin and thick axles. If two men hold the ends and each exerts 100 pounds of force, the one turning the thick part produces four times the force of the one turning the thin part. The reason given is that the thin diameter is contained four times within the thick diameter.
Furnace with coals, grate, smoke and air, and water
A tall cylindrical furnace is drawn with a bed of fuel burning at its open top and a vertical shaft rising through its body. The transcription names its elements: coals, a grate, smoke and air, and water. The device is presented as a labelled figure rather than explained at length.