A Dictionary of Music and Musicians/Swell (Harpsichord)
SWELL (HARPSICHORD). The desire for a power of increase and decrease on keyboard instruments like the harpsichord and organ, so as to emulate the bow instruments, and even the human voice, in that flow and ebb which are at the foundation of form no less than of expression, has led to the contrivance of mechanical swells as the only possible approach to it. A swell was first attempted on the Organ; the harpsichord swell was introduced by Robert Plenius in a sostenente variety of the instrument, named by him 'Lyrichord,' and is described (in 1755) as the raising of a portion of the lid or cover of the instrument by means of a pedal. Kirkman adopted this very simple swell, and we find it also in many small square pianos of the last century. About 1765 Shudi introduced the Venetian swell, and patented it in 1769. This beautiful piece of joinery is a framing of louvres which open or close gradually by means of a pedal (the right foot one) and thus cause a swell, which may be as gradual as the performer pleases. Shudi bequeathed this patent to John Broadwood, who inherited it on the death of Shudi in 1773. When the patent expired, Kirkman and others adopted it, and it was fitted to many old harpsichords, and even to pianos, but was soon proved unnecessary in an instrument where power of nuance was the very first principle.
The English organ-builders perceived the great advantage of Shudi's Venetian swell over the rude contrivance they had been using [see Organ, vol. ii. p. 596a], and it became generally adopted for organs, and has since been constantly retained in them as an important means of effect.