The viola organista: a spring-return bow mechanism
Pen-and-red-chalk study of the drive that draws the bow back by itself
An inverted study in pen and red chalk of part of Leonardo's 'viola organista', the bowed keyboard instrument. Wheels and discs are mounted within a tapering frame, with a companion detail at right marked B, and a short annotation beside the mechanism explains the point marked a. There a spring is arranged so that the motion of the little bow returns backwards of its own accord, and a further detail carries the figures 8 to 81.
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Spring that returns the bow by itself
At the point labelled a, a spring is set so that the motion of the little bow (archetto) returns backwards on its own. The surrounding drawing shows the stacked wheels and discs of the viola organista's drive within a tapering frame, with a related detail at the right lettered B.
Numbered detail of the same
A further detail of the same mechanism is marked with the figures 8 - 81, keying the small enlargement to the main assembly. It records the self-returning bow drive as a problem of spring-restored motion.