There are 36 black keys and 52 white keys on a standard piano, with a total of 88 keys.
Have you ever wondered how the piano came to have both black and white keys?
Why should there be two different groups of keys? Why not just have an unending row of white keys?
The answer lies in both the physics of acoustics and the construction of the human hand.
The first keyboards were derived from an ancient Greek water organ called the Hydraulis. This organ-like instrument had a uniform group of levers (think "all white") that you pushed to make the sounds on the organ, probably much like a bell tower carillon.
Although it was not always true, the keys on a Hydraulis were generally organized in groups of seven keys, corresponding to the seven white keys of the modern major scale. (A scale is the rationale that governs how much higher each key will be in pitch than the previous key.)
But soon, composers wanted to go beyond the limitations of the seven (white) keys, and began to add another key, which usually was colored differently from the others and set apart slightly to distinguish it. This single "black" key opened up a world of sound poassibilities that were not possible with just the seven "white" keys.
Starting with one black key, composers eventually discovered that there were five (black) keys that could be added to the original seven (white) keys, making a total of seven white keys, and five black keys. This process took thousands of years, coming to its final, modern form during the Renaissance.
The $64,000 question, though, is how the black keys came to be grouped in twos and threes.
The answer lies in the construction of the human hand, but to understand that we must first examine the keyboard itself.
Imagine, if you will, an imaginary piano keyboard that has alternating white and black keys across the entire 5-foot length.
You can visualize this if you take a piece of paper or cardboard and hold it perpendicular to the keys, masking your view of the black keys. What do you see? A mass of white keys with no way of distinguishing exactly which white key is which.
Now imagine again the keyboard as described above, an imaginary piano keyboard that has alternating white and black keys across the entire 5 foot length.
Even with black keys, one is still lost, as there is no pattern in the white-black arrangement that will allow you to consistently pick out any particular black or white key. All the eye can see is white-black-white-black endlessly, with no way of finding any pattern to the arrangement.
Sometime around 1400, some very clever person realized that if you put the black keys into groups of two and three, (2+3=5) a recognizable visual pattern emerged that allowed a player to easily distinguish each key, white or black.
History does not record who this genius was.
Next, to accomodate the shape of the human hand, the black keys were raised slightly above the level of the white keys, and then came the most revolutionary idea of all: make the black keys shorter than the white, only slightly further away from the player.
But why raise and recess the black keys?
The answer lies in the human hand.
We have five "fingers" but they are not equal in capability at the piano.
The thumb is dominant and yet it is the shortest finger on the hand.
Thus the piano keyboard fits the human hand by making the white keys closer to accommodate the shorter thumb, and the black keys further away to accommodate the longer "non-thumb" fingers.
You can see this by simply putting your hand on a keyboard. Your thumb will comfortably reach the white keys and the other fingers are easily within reach of both the black and white keys.
Name another complex machine from the Renaissance that has survived like the unique design of the piano keyboard.
No other device except perhaps the glove fits the human hand so perfectly.
By John Aschenbrenner Copyright 2012 Walden Pond Press
See also PIANO WARS: EVOLUTION OF THE PIANO IN AMERICA
See also THE GREAT PIANO CRAZE OF 1910
See also THE BALLET OF THE PIANO HANDS