One such device is pictured above. Known as the Ochydactyl, it was patented in 1929. Part of the description reads as follows: "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.”
You can learn more by reading an article posted here.