Monophone
The monophone, which was as big as a footstool, was placed on the floor next to the conductor and operated by them. The device was used to tune the instruments in the orchestra. Here, a plate on the monophone was pressed down with the foot, whereby the pitch standard A sounded with 870 oscillations. The sound produced was strong, even and could be sustained as long as desired.
The tuning of the monophone was always the same and did not change after repeated use or under the influence of different temperatures. Thus, the monophone solved a fundamental problem that often occurred, especially with tuning forks.