Organs have functioned on the same simple physics since they were first constructed around 250 B.C. Air flows from a reservoir up past leather-covered wooden pallets into pipes of various lengths, vibrating to produce different pitches. For 2,000 years, humans--usually boys from a church congregation--squeezed bellows by hand or feet to supply the air, until electric motors and blowers took over.
Through the late 1800s, when an organist pressed a key, a series of wooden linkages called trackers pulled open a pallet to allow air to stream into a specific pipe. As listeners sought a greater variety of sounds from ever larger mechanical wonders to liven ever larger churches and municipal halls, however, greater wind pressure was needed, and players had to press ever harder on a key to open a pallet against that pressure. Designers eventually turned to newfangled electricity to solve the problem: when a key was (effortlessly) depressed, it completed a circuit that activated an electromagnet or a solenoid, which in turn operated a pallet directly.
This article was originally published with the title Big Air.