A very unusual design by Mathushek. This piano came with the original Patent Office model which inventors often brought along to get their designs patented. The back of the piano has large diameter wires used to counterbalance the piano string tension.
The action is a little like a square grand and in fact the hammers strike nearly from below since the plate and strings lean forward at a severe angle making it necessary to make an angle joint in the keys.
adopted and then adapted his counterbalance thought, using large diameter steel rods rather than the heavy wire Mathushek used.