The instrument was already over a hundred years old by the time Beethoven was writing his last sonatas, around the time when it ousted the harpsichord as the standard keyboard instrument.
The Age of the PianoFrom 1790 to the mid 1800s, piano technology and sound was greatly improved due to the inventions of the Industrial Revolution, such as: the new high quality steel called piano wire, and the ability to precisely cast iron frames. The tonal range of the piano increased from the five octaves of the pianoforte to the seven and more octaves found on modern pianos.
Upright PianoAround 1780, the upright piano was created by Johann Schmidt of Salzburg, Austria and later improved in 1802 by Thomas Loud of London whose upright piano had strings that ran diagonally.
Player PianoIn 1881, an early patent for a piano player was issued to John McTammany of Cambridge, Mass. John McTammany described his invention as a "mechanical musical instrument." It worked using narrow sheets of perforated flexible paper which triggered the notes.
A later automatic piano player was the Angelus patented by Edward H. Leveaux of England on 27 February 1879, and described as an "apparatus for storing and transmitting motive power." John McTammany's invention was actually the earlier one invented (1876), however, the patents dates are in the opposite order due to filing procedures.
On March 28, 1889, William Fleming received a patent for a player piano using electricity.