John Broadwood & Sons, grand piano, London, 1827. New York, Metropolitan Museum of Art. Via Wikimedia Commons (public domain).
Augsburg, 17 October 1777. Mozart is twenty-one, on his way to Mannheim and Paris, and writes to his father a letter full of enthusiasm for the pianos of Johann Andreas Stein. He praises the escapement, which lets the hammer fall back without making the string tremble. Then he adds a line that today reads like a marginal note and is in fact the birth certificate of a sound: the machine that is pressed with the knee, too, Stein makes better than anyone else, you only have to brush it and it works.
The machine is a wooden lever mounted under the keyboard. The pianist pushes it upward with the knee and the lever lifts all the dampers at once, the little pads that rest on the strings and silence them as soon as the finger leaves the key. With the dampers gone, every note keeps vibrating after it has been played, and above all the strings nobody has touched vibrate: they answer sympathetically to the harmonics of the others, and the whole instrument begins to resonate like a sounding box thrown open. Before Stein, similar devices already existed, but they were operated by hand, which had to be taken off the keyboard. With the knee lever, the hands stay where they are.
For Mozart it nonetheless remains an effect, to be used in certain passages, like a harpsichord stop. The next leap happens in London, where makers move the control from the knee to the foot. The grand piano that Americus Backers builds in 1772, now at Apsley House, is the oldest known example with a forte and a piano pedal; around 1783 John Broadwood fits them as well. German and Viennese makers get there more slowly, and for a few decades knee levers and pedals live together under the same keyboards.
In scores the pedal already appears in the 1790s: in the Sonata in C major that Haydn writes in London one reads “open Pedal”. Beethoven makes it the condition of an entire movement. In 1801, at the head of the first movement of the Sonata in C-sharp minor op. 27 no. 2, the one the world calls the Moonlight, he writes: “Si deve suonare tutto questo pezzo delicatissimamente e senza sordino”, this whole piece must be played most delicately and without damper. Senza sordino means with the dampers raised, from beginning to end. On a Viennese piano of 1801, with thin strings and a sound that dies away quickly, the harmonies overlap in a light veil. On a modern concert grand, which sustains the sound much longer, the same marking performed to the letter produces a fog in which the lines are lost: this is why pianists have argued for two centuries over how far to obey. Beethoven meanwhile changes instrument. The Érard he receives from Paris in 1803 has four pedals; the Broadwood that reaches him from London in 1818 has the sustain pedal split in two, one for the bass and one for the treble.
The rest of the nineteenth century turns the special effect into a permanent condition. The Romantic piano is played with the right foot almost always down and lifted at each change of harmony, and the sound we associate with that century, basses that hold a chord while the right hand sings three octaves higher, is largely the sound of strings left free. In 1844, at the Exposition of the Products of Industry in Paris, the firm of Boisselot of Marseille presents a third pedal able to hold up only the dampers of the notes already pressed; Albert Steinway perfects it and patents it in 1874. It is the middle pedal of modern grand pianos. The one on the right still does today exactly what Stein’s lever did at Augsburg: it lifts all the felts together.