10. Flange Screw.

11. Damper Lever Center Pin.

THE TRAP ACTION

consists of Pedals, Pedal Braces, Pedal Feet, Pedal Rods, Roller
Boards or Elbows, Studs, Plugs, Trap Springs, Wires and Lifter
Rods.

The cut is from the French action. Nearly all square pianos in
use at the present time are of this type.

The hammer rail in the square, in addition to serving its purpose as
a rest for the hammers, also serves the purpose of the regulating
rail, as you will see the regulating screw, with its button, attached
to it. This rail is stationary in the square, not moving toward the
strings and shortening the stroke as it does in the upright when the
soft pedal is used. The soft pedal in the square piano simply
interposes a piece of felt between each hammer and its corresponding
string or strings. This felt being much softer than that of the
hammers, the tone is greatly subdued.

The mechanical arrangement of the dampers is very different in the
square from that in the upright. The dampers are above the strings.
Instead of springs to hold them against the strings, they simply rest
upon them with their weight. In many old squares some of the dampers
fall upon nodal points, causing defective damping or harmonic
after-tones.