The earliest form of the modern piano action was invented by Bartolomeo Cristofori of Florence, Italy in 1709. He was a repairer and tuner of the harpsichord collection of Prince Fernando de Medici. The invention of the modern piano action came mainly from the desire to overcome the harpsichord's inability to express subtle dynamic contrasts at will, and to eliminate the need of the harpsichord's use of manual "stops". The limitations of the clavichord action also figured into it.
The harpsichord and the clavichord were two of the more popular stringed keyboard instruments of the time. The harpsichord key lifted a string plucking device called a plectrum, and the clavichord key raised a small piece of metal up to hit the string called a tangent. But the harpsichord volume could not be controlled by the key pressure, and the clavichord's tangent remained in contact with the string until the key was released. Some usable elements of the harpsichord and clavichord remained . They had the same simple "see saw", up/down levers of the keyboard used on the yet-to-be invented piano. The cabinet and stringing of the harpsichord were used in the new instrument, as well has the concept of striking the string with a device coming from the clavichord.
But in the new hybrid, instead of the plucked stings of the harpsichord, Cristofori invented a system of levers that propelled a small hammer toward the string, where the downward key pressure effected the pressure of the hammer hitting the string. The action worked like a miniature, controlled catapult. A system of levers zig-zagged from the back of the simple see-saw of the key up to the the hinged hammer, slinging it toward the string. And in contrast to the clavichord, Cristofori invented a way for the hammer to become independent of the key once the string is hit. This ability is referred to as the hammer's "escapement". The hammer could now fall back into its ready-to-play position, while the key is still being held down, allowing the string to keep ringing until the key is released.
His first keyboard of this type was called gravicembalo col piano e forte (harpsichord with soft and loud). This name was soon condensed to pianoforte, and eventually just piano. Although many advances have been made since then to give the piano more even more volume, dynamic range, and tuning stability, the essential elements of Cristofori's first action are still present.
by Robert Callaghan, RPT
References: The History of Musical Instruments by Curt Sachs and The History of the Piano by Ernest Closson
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