Even though the accordion has piano-like keys (for the melody keys, or right-hand), it is a wind instrument, working on the same acoustic principals as the harmonica, pipe organ, and reed wind instruments. The term "reed" is misleading, as most "reeds" are today made of articifial materials ranging from metals to plastics. Traditionally the "reed" was a small strip cut from reed, fastened on one side, and when blowing across it, it vibrates, causing sound to be heard. Acoustically this is known as the Bernoulli Effect.
The accordion is classified in the genus air, and the sound is created in similar fashion as with other pipe instruments. Abstractly, the according consists of a series of pipes that have different frequencies as outputs. It is thus similar to a panflute, but with reeds attached as modifiers of the pure initial soundwave, while the initiator of the moving air column is not a set of human lungs, but mechanical bellows.
Source: http://www.markkenneth.com/about_the_accordion.htm
In the accordion, instead of puffing air from the lungs over the reeds, airflow is created mechanically by bellows - the squeezebox. Bellows have been used for a long time (at least by 1500 BCE) to increase heat in fire, so it was a known technology by the time the accordion was invented.
The accordion was invented in 1822 by Friedrich Buschmann (Berlin). In 1829 Cyrillus Damian (Vienna) introduced a 10-button accordion with the 7 notes of a major scale. In 1854 Anthony Faas took out a patent for the accordion.
http://soundbible.com/528-Accordion.html
http://www.soundsnap.com/tags/accordion