A device for the gradation of volume in keyboard instruments.
The Swell organ is that manual department of an organ whose chest and/or pipes are enclosed on all sides by a box, one side of which incorporates a device (lid, flap, shutters, sashed panel, etc.) that can be opened and closed by connection with a foot-lever or pedal. A stop or half-stop may be thus enclosed, or several departments (Choir organ, Solo organ) or even the whole organ (Samuel Green, St George's Chapel, Windsor, 1790). The connection from foot-lever to swelling device can be mechanical, pneumatic, electrical, etc. and may be so made that fine gradations in the degree of closure are possible.
Some examples of the small Brustwerk of the 16th century may have had doors that could be opened; most authenticated examples before about 1700, however, have semi-fixed fretwork doors. The idea of foot-operated movable doors or, in chamber organs, flaps, occurred occasionally to builders (T. Mace, Musick's Monument, 1676) but the first Swells of significance are the enclosed Echo boxes of Spanish and later English organs provided with liftable lids or, also later, sliding front panels like sash windows. In Spain (Alcalá, c1680) the Swell box was often put round a stop or two on the main manual chest; only later did it enclose a whole department, usually either on the floor of the organ or tucked away at the top. Single stops were always those for treble solos of an expressive nature (Corneta, Trompeta, Flute); they were often so in England until about 1780 (Hautboy). French and English organs had their Echo stops on their own treble keyboard, the chest placed in the breast of the organ. Abraham Jordan’s advertisement in the Spectator (8 February 1712) for his new Swell in St Magnus the Martyr, London Bridge (‘never … in any organ before’), refers to an organ with four sets of keys; thus the Swell was probably an extra Echo department. The Swell organ soon became regarded as indispensable, and although for the next hundred years it remained a short-compass division, the number of stops and the compass of the keyboard gradually expanded; as early as the 1740s it had ousted the Choir organ as the usual second division.
Despite Burney’s failure to find them, Swell organs were not uncommon in Europe: large departments low in the organ case, with vertical or horizontal shutters (Venice, c1770), little Echo boxes with a solo stop or two (Berlin, 1727; Rostock, 1770), the whole organ in a box (Abbé Vogler, 1784; see Orchestrion (i)), perhaps with a ‘balanced’ Swell pedal-lever (Frankfurt, 1827) not requiring to be notched into place like the ‘nag’s head swell’. Swelling the sound could also be obtained by double or triple touch and by playing free reeds on a higher wind pressure (J. Wilke, 1823).
Important developments took place in England during the 1840s where Hill and Gauntlett introduced full-compass Swells, with complete choruses and a battery of reeds, designed to provide the sort of secondary division then thought to be required by the music of Bach. In the process, Hill made the first ‘English Full Swell’ (i.e. flue chorus capped with a mixture, and reeds at 16', 8' and 4' pitch) for the Great George Street Chapel, Liverpool (1841). Others concentrated on mechanical refinements: of his reconstructed Swell at Gloucester Cathedral (1847) Willis commented, ‘the pianissimo was simply astounding’. He and others began to use balanced swell pedals instead of levers during the 1870s. In France, the Récit expressif of Cavaillé-Coll's organs never challenged the dominance of the Grand orgue, but he deployed harmonic stops, strings and Celestes to maximise its expressive potential.
In both England and America, the first half of the 20th century saw the building of large Swell organs which frequently rivalled the Great in both power and number of registers. In his smaller organs Arthur Harrison often treated the Swell and Great as parts of a single division: the Great provided the chorus work, the Swell provided powerful reeds and refined accompanimental stops for supporting the voices of the choir. This trend attained its logical conclusion (and a musical dead end) in an instrument such as that built for Wakefield Cathedral in 1952 by the John Compton Organ Co., in which four of the five manual departments were enclosed in expression chambers.
The recovery of classical principles and a return to earlier models has led inevitably to a re-thinking of the relevance of the Swell organ. Some builders have compromised by enclosing the Oberwerk or placing doors in front of the Brustwerk. In England and America the Swell is still found useful for both concert and liturgical work, and Swells of a 19th-century type are regularly appearing in new organs (Meyerson Symphony Center, Dallas, 1992; St John's College, Cambridge, 1994).
In addition to the machine stop (see Machine stop (1)), two kinds of device for producing crescendo effects were applied to English harpsichords (and occasionally to pianos) in the second half of the 18th century. In the earlier of these, the ‘lid swell’ or ‘nag’s head swell’, depressing a pedal gradually raised a hinged section at the right side of the harpsichord’s lid. With the second type, the ‘Venetian swell’, the entire area of the soundboard was covered by an inner lid fitted with pivoted louvres like those of a Venetian blind, which could be opened by depressing a pedal. The lid swell is first mentioned in the patent specification of Roger Plenius’s Lyrachord (1755) and seems to have begun to be applied to harpsichords in the early 1760s. From about 1775 square pianos were fairly often made with a pedal to raise the portion of the lid to the right of the keyboard, over the soundboard. The Venetian swell was patented by Burkat Shudi in 1769 and appears to have been an improvement only to the extent that the operation of its louvres is visually less obtrusive than the flapping of a large section of the instrument’s lid.
Both types of swell have two important disadvantages. When they are closed in order to reduce the harpsichord’s volume, they severely muffle its tone as well, and even when they are entirely open, they rob the instrument of some of its volume and brilliance. In addition, most of the crescendo that is produced occurs with the first opening of the swell, which is also accompanied by an abrupt brightening of the instrument’s tone. Despite these disadvantages, the swells do increase the range of crescendo effects beyond those available with only a machine stop. By providing a lower level of pianissimo when closed, they increase the instrument’s overall dynamic range, and they also permit the player to achieve crescendos and decrescendos when only one or two registers are in use.
Harpsichords were first fitted with swells at about the same time that the piano was beginning to achieve great popularity. The swell should not necessarily be viewed as a reaction to the piano but rather as a parallel response to fundamental musical conditions. Along with the machine stop it helped the harpsichord to coexist, even to prosper, alongside the piano until nearly the end of the century.
For bibliography see Harpsichord, Pianoforte and Organ; for illustration see Harpsichord §4(ii), fig.12.
PETER WILLIAMS/NICHOLAS THISTLETHWAITE (1), EDWIN M. RIPIN/JOHN KOSTER (2)