A Dictionary of Music and Musicians/Arpeggione
ARPEGGIONE, or Guitar Violoncello, a stringed instrument, played with a bow, which was invented by G. Staufer, of Vienna, in 1823, but appears never to have come much into use, and whose very name would probably now be unknown, if it were not for an interesting sonata (in A) for pianoforte and arpeggione by Franz Schubert, written in 1824, and only lately published (Vienna J. P. Gotthardt).
The arpeggione appears to have been of the size of the viol-da-gamba, or a small violoncello; the shape of the body something like that of the guitar. The finger-board had frets, and the six strings were tuned thus—
[ P. D. ]