The Utrecht Psalter

The miniature, illustrating Psalm CL, presents at the centre a double hydraulic organ of exceptional conception. The instrument consists of two side-by-side cisterns and an apparently shared wind chest feeding two identical rows of 5 pipes, with the treble pipes on the right. On the sides cylindrical pumps operated by four attendants are depicted; two organists play simultaneously, each on one series of pipes, with no visible keyboard. A double-frame structure surmounts the pipes, exceeding their height. The ensemble combines technically coherent elements and formal incongruities, suggesting a learned but indirect reconstruction of the instrument, perhaps mediated through literary sources or older models.