Meshing lantern-pinion teeth; right and left motion
Teeth set on alternate intervals, oblique like a screw, as in the Chiaravalle clock
Headed 'right and left motion', the folio studies how gear teeth engage in clockwork: two lantern-pinions, a drum of pins, a spiral spring, a grooved wheel and a scatter of small balls. Leonardo insists that the spindles (fusi) of two stacked lantern-pinions must sit over each other's gaps, so the driving tooth catches the next spindle as it leaves the last. He follows the tooth m as it leaves the pinion and the tooth g runs to the centre line of the two poles, notes that the teeth of wheel a are cut oblique like a screw and sharp on top, and cites the clock 'at Chiaravalle' as a model of poles running in poles.
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Stacking two lantern-pinions on alternate intervals
The spindles (fusi) of the two lantern-pinions must not sit one directly above the other; those of the upper pinion should stand over the gaps of the lower. Otherwise, as the driving tooth leaves the last lower spindle, it would fail to catch a spindle of the upper pinion.
Tooth g running to the centre line of the two poles
When the tooth m leaves the tooth of the lantern-pinion, the tooth g by itself runs to meet the central line of the two poles, and r has little effort in moving it until it releases it. A companion note explains this drawing shows only the motion the moving body follows after leaving its mover.
Teeth of wheel a cut oblique like a screw
The teeth of the wheel a are set oblique, in the manner of a screw, and should be cutting on top, that is, at the entry of the teeth of its lantern-pinion. The detail governs how the wheel engages its pinion.
Poles in poles, as at Chiaravalle
A note cites 'poles in poles, as at Chiaravalle' as a working model for how the pivots should run within one another. It grounds the pinion arrangement in an existing clock mechanism.