A Chemnitzer concertina is a musical instrument of the hand-held bellows-driven free-reed category, sometimes called squeezeboxes. The Chemnitzer concertina is most closely related to the bandoneón (German spelling: Bandonion), more distantly to the other concertinas, and accordions. Physical description It is roughly square in cross-section, with the keyboards consisting of cylindrical buttons on each end arranged in curving rows. Like other concertinas, the buttons are at the sides of the instrument, whereas the keys and buttons of an accordion are at the front. A strap, usually of leather, is fitted at each end to hold the player's palm against the instrument for playing. Compare to the English concertina where the thumb holds a strap, the little finger is held on a rest, and the remaining three fingers press the keys. The instrument is bisonoric, meaning that each button corresponds to two notes: one when the bellows is compressed, and another when it is expanded. On most instruments, two or more (and as many as five) reeds sound for each note. The tones produced are either in octaves, unison, or in some combination thereof. Internal construction is different from other concertinas in that the action more closely resembles that of an accordion, and that the reeds are of steel (rather than brass) and are often fixed in groups of twenty or more to long zinc or aluminum plates, rather than to individual frames. This arrangement resembles that of the Russian accordion, the bayan. History Sources differ whether German inventor Carl Friedrich Uhlig created his first concertina after seeing Charles Wheatstone's instrument of the same name, or whether the two men invented their instruments concurrently and independently. Uhlig's patent dates to 1834, and while Wheatstone patented a related instrument, the symphonium in 1829, he did not patent an instrument under the name "Concertina" until 1844. Types Uhlig's first instrument had five buttons on each side, but the keyboard was quickly expanded and as it did so, it diverged into different lineages. Heinrich Band's was sold under the name Bandonion. Several other German instruments were sold under the name concertina (or konzertina), and their keyboard systems were given names based on their creators, as with Band and Scheffler, or their city of origin, as with the Carlsfelder and Chemnitzer systems. Strictly speaking, the Chemnitzer layout is one of 38, 39, 51 or 52 buttons, or one of the American expanded versions of the