A player piano, also known as a pianola, is a self-playing piano with a pneumatic or electro-mechanical mechanism that operates the piano action using perforated paper or metallic rolls. Modern versions use MIDI. The player piano gained popularity as mass-produced home pianos increased in the late 19th and early 20th centuries. Sales peaked in 1924 and subsequently declined with improvements in electrical phonograph recordings in the mid-1920s. The advent of electrical amplification in home music reproduction, brought by radios, contributed to a decline in popularity, and the stock market crash of 1929 virtually wiped out production.
A restored pneumatic player piano
A player piano performing
Steinway Welte-Mignon reproducing piano (1919)
A player piano roll being played
Pneumatics is a branch of engineering that makes use of gas or pressurized air.
Pneumatic (compressed-air) fireless locomotives like this were often used to haul trains in mines, where steam engines posed a risk of explosion. This one is preserved H.K. Porter, Inc. No. 3290 of 1923.
A pneumatic butterfly valve