Square pianos often came with various accessories that modified the tone or volume, sometimes added by the maker, and occasionally as after market additions by specialty firms and individuals. This page will review these as information develops from the community.
We begin with a discussion of the wooden covers occasionally found inside the piano over the action, and sometime covering almost the entire interior.
Next we take up the lid swell mechanism, and a few embodiments.
The following PDF gives a basic overview of Janissary Music pedals