Organistrum

In other examples a player pushed levers forward to create the notes. The word organistrum is derived from organum and instrumentum; the former term was applied to the primitive harmonies, consisting of octaves accompanied by fourths or fifths, first practised by Hucbald in the 10th century. This explanation allows tolerable certainty about the period of its invention, at the end of the 10th or beginning of the 11th century. It also explains its construction. A stringed instrument of the period — such as a guitar fiddle, a rotta or oval vielle — was used as a model, while the proportions were increased for the convenience of holding the instrument and of dividing the performance between two persons (this happened in early models). Inside the body was the wheel, rosined like the bow of a violin, to create friction in its 3 melodic strings. The three strings resting on the wheel and supported on a bridge of the same height sounded together as the wheel revolved. In the earliest examples the wooden tangents took the place of fingers on the frets and acted upon all three strings at once, thus producing the harmony known as organum.