From Classic Encyclopedia 1911
PORTATIVE ORGAN, a small medieval organ carried by the performer, who manipulated the bellows with one hand and fingered the keys with the other. This small instrument was necessarily made as simple as possible. On a small rectangular wind chest or reservoir, fed by means of a single bellows placed at the back, in front, or at the right side, were arranged the pipes - one, two or three to a note - supported by more or less ornamental uprights and an oblique bar. The most primitive style of keyboard consisted merely of sliders pushed in to make the note sound and restored to their normal position by a horn spring; the reverse action was also in use, the keys being furnished with knobs or handles.
Towards the middle of the 13th century the portatives represented in the miniatures of illuminated MSS. first show signs of a real keyboard with balanced keys, as in the 13th century Spanish MS., known as the Cantigas de Santa Maria,' containing four full pages of miniatures of instrumentalists, fifty-one in number. From the position of the performer's thumb it is evident that the keys are pressed down to make the notes sound. There are nine pipes and the same number of keys, sufficient for the diatonic octave of C major with the B flat added. The pipes put into these small organs were flue pipes, their intonation must have been very unstable owing to the irregularity of the wind supply fed by a single bellows, the pressure being at the mercy of the performer's hand. Increased pressure in pipes with fixed mouthpieces, such as organ pipes, produces a rise in pitch. These medieval portative organs, so extensively used during the 14th and 15th centuries, were revivals of those used by the Romans, of which a specimen excavated at Pompeii in 1876 is preserved in the Museum at Naples. The case measures 142 in. by in. and contains nine pipes, of which the longest measures but 9* in.; six of the pipes have oblong holes at a short distance from the top similar to those made in gamba pipes of modern organs to give them their reedy quality, and also to those cut in the bamboo pipes of the Chinese Cheng, which is a primitive organ furnished with free reeds. From the description of these remains by C. F. Abdy Williams, 2 it would seem that a bronze plate 112 in. by 24 in. having 18 rectangular slits arranged in three rows to form vandykes was found inside the case, with three little plates of bronze just wide enough to pass through the slits lying by it; this plate possibly formed part of the mechanism for the sliders of the keys. The small instrument often taken for a syrinx on a contorniate of Sallust in the Cabinet Imperial de France in Paris may be meant for a miniature portative. (K. S.)
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