[Piano] The Digitorium - Finger-Strengthening Device for PianistsA rare "Digitorium" apparatus manufactured by Metzler & Co. of London, ca. 1880, as a practice device for pianists to strengthen their fingers. With five spring loaded keys and an adjustable wrist support, the tool was patented in 1866 by Myer Marks. In fine condition with expected wear, measuring 7. 5 x 6. 5 x 2. 25 inches (19 x 16. 5 x 5. 7 centimeters). The 1900 edition of the Grove Dictionary of Music and Musicians describes the device as "An