The Pianola was a trademark of the Aeolian Corporation (filed in 1898), referring to a its "Piano Player," a device that could be pushed up to the keyboard of any piano, and would play the keys of that pianos using rolls. It was a pneumatic machine, with pedal operated pump and mechanism. The trade name "Pianola" was adopted by the public and later used to refer to any player piano.
These wooden "fingers" in the back of the instrument fit over the keys of the piano. The range was 65 notes, or a little over five octaves.
Pressing each pedal in turn filled the bellows that operated the complex machinery inside.
The holes in the player roll allowed outside air to close a valve, causing a small bellows to inflate and play the corresponding key.