A jointed rod worked by cords, and the speed of its tip
Why a jointed arm beats a sprung one, and how far its far points fall
The note explains a 'jointed rod' (aste disnodata) drawn across the top of the sheet and lettered p, o, n, r, K, q, h, g, m. It argues the jointed rod is safer than a sprung arm, since springs tire from repeated bending and no longer straighten: descending, it twists by the cord n g, and rising it straightens and twists upward by the cord h m, while the joint pivots can be bound in leather so they cannot come apart, with a spring optionally added and helped by the cord h m. A second paragraph on the velocity of the tip reasons that in a one-piece rod, when head q falls one braccio r falls 2 and K falls 4, whereas in the jointed rod bending at n g, q falls 1, r falls 3 and K falls 5 (making 9) in the same time the one-piece rod would fall 4. A further curved arm is sketched at the foot of the sheet.
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Jointed rod worked by cords n g and h m
The jointed rod (aste disnodata) is preferred over a sprung one because springs tire with repeated bending and fail to straighten. Descending, the rod twists by the cord n g; rising, it straightens and twists upward by the cord h m, and the joint pivots may be bound in leather so they cannot come apart, with a spring added if desired.
Velocity of the tip: jointed versus one-piece rod
In a one-piece rod, when head q falls one braccio, r falls 2 and K falls 4. But if the rod is jointed and bends at the cord n g while descending, q falls 1, r falls 3 and K falls 5 — which makes 9 — in the same time the one-piece rod would fall only 4.
Curved arm sketch at the foot of the sheet
Below the text a further curved arm is drawn, rising from a vertical post — a supplementary study of the same class of hinged, bending member.