A very rare, if somewhat macabre looking French device used by musicians (often pianists) to exercise their fingers. . .
It is known as THE OCHYDACTYL
It was a patented apparatus that was to increase the nimbleness of musician’s fingers, and give them independent action and strength. It was called “L’assouplisseur Ochydactyl” (The Finger Softener), and invented by the Frenchman Georges Rétif in 1922.
The device gained a U.S. patent in 1929, and the description reads, “Skill in playing musical instruments is acquired only after prolonged practice, which endows the performer’s fingers with nimbleness, independent action, and strength. The objective of the musical exercises performed by the student is to develop certain muscles of the fingers and to render their action independent, since naturally these muscles have a tendency to act in pairs. The objective of the present invention [The Ochydactyl] is to replace this long, arduous study, which in the case of students of no great talent sometimes without success, by an adaptation of the muscles acquired mechanically. The part of the operator is reduced to a simple, passive resistance or contraction opposed to the forced movements.” 
To use the operator would insert 4 fingers into the adjustable, rubber padded clamps and tighten while the wrist rested on the seat. The other hand would crank the device in either direction making the fingers travel up and down supposedly making them more nimble. The lever could be swapped to either left or right hand. 
The advertising for this machine, named dozens of prominent musicians, but it still had very little success. 
It was found to be not good for the fingers and production stopped.