These improvements have made the piano second only to the orchestra for all around usefulness and expressiveness. The size of the instrument and the high tension of the strings made its tone sufficient for the largest concert hall, and permitted a keyboard range almost double that of the harpsichord. The individual dampers responsive to the pressure of the key made a quasi-legato and true melody playing possible. The rebounding hammer directly controlled by the key made possible all varieties of soft and loud tone. And the sustaining or damper, incorrectly called the loud pedal, made possible the sustaining of chords in great richness. The usefulness of this last device is still not half stated in saying that chords can be sustained; for, when all the strings are left open, there occurs a sympathetic vibration in the strings which are not struck by the hammers but are in tune with the overtones of the strings that are struck. This fact increases to an astonishing extent the resonance and sonority of any chords sounded with the help of the sustaining pedal. It makes the instrument almost orchestral in quality, opening to it an amazing range and variety of effect which Chopin, Liszt, and many piano writers after them, used with supreme and magical skill. The soft pedal opens another range of effects. On the grand piano it shifts the hammers so that they hit but one of the three strings proper to each note in the middle and upper registers. Hence the direction _una corda_, written in the pianoforte works of all great masters, including Beethoven. The piano thus became an ideal sounding board for the romantic movement. It was capable of luscious expressive melody. It could obtain effects of great delicacy and intimate character. It could be loud, astonishing and orchestral. Its tone was in itself a thing of sensuous beauty. Its freedom in harmony was no less than its freedom in melody, and enharmonic changes, beloved of all the romanticists, became easy. It allowed the greatest liberty in the disposition of notes, and harmonic accompaniment, with broken chords and arpeggios, could take on an absolute beauty of its own. This sufficiently explains the complete change in the method of writing clavier music in the nineteenth century. One example of the way in which Mozart and Chopin obtained harmonic sonority in accompaniments will show how far-reaching the change was. [Illustration: Music score: Mozart: Sonata in F major] [Illustration: Music score: Chopin: Nocturne Op. 27, No. 2] By the use of the damper pedal the Chopin formula gives the effect of a sustained chord. On the harpsichord it would have sounded like a few notes too widely scattered to be united in sonority.