Suspended Model Bird for Studying Tail Movements
A feather hung to study how a bird's tail steers, and how weight leads motion
Leonardo proposes suspending a body shaped like a bird and twisting its tail through various angles, so as to derive general rules for how birds steer by bending the tail. A second, briefer note states that in every kind of movement the heaviest part of a moving body becomes the guide of the motion. The page, written upside down relative to the sheet, shows a large feather drawn in perspective with a small feather sketched at the lower left.
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Suspending a model bird to study tail-twisting
A body made in the likeness of a bird is to be hung up and its tail twisted through various obliquities. From this Leonardo hopes to draw up general rules for the different twistings of birds' movements produced by bending the tail.
The heaviest part guides the motion
In all the varieties of movement, Leonardo notes, the heaviest part of the moving body makes itself the guide of the motion. The observation underpins his account of how a suspended feather or bird settles as it swings.
Feather drawn in perspective
A single large feather is drawn in foreshortened perspective, its barbs rendered as fine parallel strokes, with a much smaller feather sketched below at the left. The drawing accompanies the note on a suspended, oscillating feather.