Many keyboard instruments dating from before the nineteenth century, such as harpsichords and pipe organs, have a keyboard with the colours of the keys reversed: the white notes are made of ebony and the black notes are covered with softer white bone. The arrangement of longer keys for C major with intervening, shorter keys for the intermediate semitones dates to the 15th century. The pattern repeats at the interval of an octave.
Because these keys receive less wear, they are often made of black colored wood and called the black notes or black keys.
The keys for the remaining five notes-which are not part of the C major scale-(i.e., C ♯/D ♭, D ♯/E ♭, F ♯/G ♭, G ♯/A ♭, A ♯/B ♭) (see Sharp and Flat) are raised and shorter. Because these keys were traditionally covered in ivory they are often called the white notes or white keys. The twelve notes of the Western musical scale are laid out with the lowest note on the left The longer keys (for the seven 'natural' notes of the C major scale: C, D, E, F, G, A, B) jut forward. Harpsichord with black keys for the C major scale
