ORGANISTRUM  , the

medieval Latin name for the earliest known form of the hurdy-gurdy (q.v.) . The organistrum was large enough to rest on the knees of two performers sitting side by side, one of whom turned the crank setting the wheel in motion, while the other, the artist, manipulated the keys . The word organistrum is derived from organum and instrument um; the former term was applied to the primitive harmonies, consisting of octaves accompanied by fourths or fifths, first practised by Hucbald in the loth century . This explanation enables us to fix with tolerable certainty the date of the invention of the organistrum, at the end of the loth or beginning of the 11th century, and also to understand the construction of the instrument . A stringed instrument of the period—such as a guitar-fiddle, a rotta or oval vielle—being used as model, the proportions were increased for the convenience of holding the instrument and of dividing' the performance between two persons . Inside the body was the wheel, having a tire of leather well rosined, and working easily through an aperture in the sound-board . The three strings resting on the wheel and supported besides on a bridge of the same height all sounded at once as the wheel revolved, and in the earliest examples the wooden tangents taking the place of fingers on the frets of the neck acted upon all three strings at once, thus producing the harmony known as organum . The organistrum appears on a bas-relief from the abbey of St Georges de Boscherville (11th cent.), now preserved in the museum of Rouen, where it is played by a royal lady, her maid turning the crank . It has the place of honour in the centre of the band of musicians representing the twenty-four elders of the Apocalypse in the tympanum of the Gate of Glory of the cathedral of Santiago da Compostella (12th cent.) . There is also a fine example in a miniature of a psalter of English workmanship (12th cent.), forming part of the Hunterian collection in Glasgow University; this was shown at the Exhibition of Illuminated MSS. at the Burlington Fine Arts Club in 1908 . (K . S.) 6 See also for other organs with sliders being drawn out, A .

Haseloff, Eine Sachsischthidringische Malerschule

urn die Wende des XIII . Jahrh., pl. xxvi . No . 57, part of Studien zu der Kunsigeschichte; the same is reproduced in Gbri's Thesaurus diptychorum, Bd. iii . Tab . 16, where it is falsely ascribed to the 9th century . 6 Praetorius mentions the Halberstadt and Erfurt organs as having been built 600 years before his time (1618), and still bearing on them the date inscribed . See op. cit . •p . 93 . 7 See A . J .

Hipkins,

History of the Pianoforte (London, 1896) . Brit . Mus . Colton MSS . Tiberius A vii. foL 1o4b . 14th century . Brit . Mus . Add . MS . 26602, fol . 6 .

14th century .