The modern piano is an amazingly complex wooden machine with over 5 thousand parts, myriad felt covered wooden pieces and 220 to 250 strings, all built inside an iron structure that sustains an average of 20 tons of tension. That's 40 thousand pounds, the weight of an average house!!

Three centuries ago an Italian harpsichord builder named Bartolomeo Cristofori produced a big technological advance, a new mechanism for the harpsichord giving it the ability to be played with dynamics, or variations in the loudness of individual notes. This touch-sensitive invention was called in Italian: “Gravicembalo Col Piano E Forte,” ... “Harpsichord With Soft And Loud.”

Since the 1400s, there have been two keyboard instruments that were widely used. The clavichord and the harpsichord had their own strengths, and were popular for specific venues and music styles. They eventually led to the invention of the piano.

Clavichords are constructed with "bichord" or double strings that are struck by brass hammers called "tangents" attached to the end of each key. As a key is depressed, the tangent struck its two strings and remaining in contact would act as a fret, causing the note to play. It set the string in motion at its correct speaking length. Varying of the pressure on the key would create vibrato. Dynamic expression was also possible on the clavichord, but the range of volume was limited to the mezzo-piano level, or about as loud as an acoustic guitar. However they were extremely popular in domestic use and remained so for 400 years.

Harpsichords date from about 1505, was popular during the same period and had its own followers. Harpsichord strings are plucked by a quill or plectrum. A felt damper rises off the string, allowing the string to vibrate freely when plucked. Volume could be altered for all notes at once by adjusting parameters of quill alignment and coupling with multiple sets of keys, so the harpsichord had a higher volume than the clavichord. This made it especially popular in churches as it could be played with organ and singers and still be heard.

A third instrument, also a forerunner of the piano had no keyboard. The dulcimer, a multi-stringed instrument is struck with hand held padded hammers. In 1690, German player and showman Pantaleon Hebenstreit designed a special one. It was four times the normal size, nine feet long with a giant soundboard. He made special tow-sided hammers for striking the strings, one side for soft and the other for loud. This was a great success for Hebenstreit, but required his high-level unique skills to play. It did not develop commercially, yet provided another link for the piano.

Bartolemeo Cristofori finally developed a keyboard that could satisfy composers with an instrument having a broad dynamic range. He was an accomplished harpsichord maker, and more importantly a key musical expert in the Medici court. Having their considerable capital behind him, was able to produce the great invention, the “Gravicembalo Col Piano E Forte” in 1700. It was the first successful keyboard instrument which used hammers to hit the strings. There are only three surviving Cristofori piano-fortes: a 1720 is in the Metropolitan Museum in New York City; a 1722 in the Museo Degli Strumenti Musicali in Rome; and a 1726 model in Leipzig, Germany.

For this new instrument’s hammers, he combined a small roll of parchment glued to a pad of leather fitted into a wood molding. His “escapement” invention allowed the hammer to hit the string yet escape rather than stay touching the string. This action, unlike the clavichord, allowed strings to vibrate freely. Years passed before the invention was made public, but in 1709 an Italian journalist named Scipione Maffei visited Cristofori, and published drawings of the design two years later. Instrument builder Gottlieb Silbermann saw the drawings and built his own version. J.S. Bach praised Silbermann’s work, and endorsed it in the 1740s.

A separate and distinct English style of action arrived in 1766. In the next 20 years there were two schools of piano making, the Viennese, and the English. By then Maffei’s article had been translated into several languages and many builders experimented the with Cristofori’s action. The Viennese instruments had lighter weighted and simpler mechanisms. Composers such as Wolfgang Amadeus Mozart were excited by their great responsiveness musical expression. In 1777, Mozart wrote to his father praising Johann Andreas Stein who perfected the Viennese action. This style of action was popular until 1905. The English builders increased volume to the sound by adding iron bars to the wooden framework. Strings could now be made heavier. Still, these action designs, while satisfying the need for greater volume, were limited in repetition.

From the late 1700s to early 1800s, instrument builders in both schools continued to improve the mechanics and the structures of their products. But no one had the impact of Cristofori until a Parisian named Sebastian Erard invented the “double escapement” or repetition mechanism. This revolutionary idea, patented in 1821, made it possible for a hammer to hit the string again before the key was returned to its original position, making rapid repetition possible. By then, composers such as Franz Liszt were writing music with greater speed, power and expressiveness.

Larger venues and concert halls brought about louder orchestras. Instrument builders throughout the late 1700s and early 1800s continued the quest for more volume and dynamics. Strings became heavier, adding tension to the frame. Iron bars were added to the wooden timbers of the cases, the whole structure becoming stronger and heavier. In 1825, a quantum change occurred with the American piano make, Alpheus Babcock, who patented the full cast iron plate for the square piano, completely removing the tension from the wooden case. Boston's Jonas Chickering further developed Babcock’s idea with the full iron frame for the grand piano. The innovations came fast and furious.

Mechanized factories were under way in Europe and America. Piano styles ranged from rectangular boxes to wing-shaped grands and uprights. They incorporated improvements in structural integrity, strength and volume. Having all the strings running parallel was still a limitation. In 1859, Steinway produced the first overstrung grand piano where the bass strings cross over the other strings, creating an even bigger sound. By 1870 they were close to what we know today. Since 1885, the piano has not changed significantly. From just a few thousand in 1850, sales rose to well over 300,000 by 1909.