While much research remains to be done for the beginning of this period, especially on developments in German organs of the area Mainz–Nuremberg–Innsbruck–Basle, a provisional historical sketch can be derived from Henri Arnaut’s treatise and from certain documents relating to church contracts concerning organs of about 1450. From the 17th century onwards much more complete documentation is available.
1. The treatise of Henri Arnaut de Zwolle.
2. Developments, 1450–1500.
3. Arnolt Schlick’s ‘Spiegel der Orgelmacher’.
4. The new potential of the 16th century.
5. Structural developments c1600.
6. The Werkprinzip organ.
7. The French classical organ.
8. The English organ.
9. The Baroque organ in the Iberian Peninsula and Latin America.
10. The 18th-century Italian organ.
11. The organ of J.S. Bach.
12. Splendours of Europe, 1650–1800.
13. Organs in the Americas.
Organ, §V: 1450–1800
1. The treatise of Henri Arnaut de Zwolle.
Although concerned primarily with small organs, Arnaut’s treatise (F-Pn lat.7295; ed. and facs. in Le Cerf and Labande, B1932) throws much light on the potential which organs were seen to have by 1450. The treatise was written in Dijon between 1436 and 1454, partly by Arnaut, a Dutch polymath at the Burgundian court of Philip the Good, and partly by two other authors or scribes. It reflects a lively cultural exchange between Burgundy, Paris and the Low Countries. Arnaut’s remarks are more practical than those of any treatise since the 11th century. His description of an organ pipe is empirical and systematic; details suggest a scale some ten semitones narrower than Normalmensur at bass B but some seven semitones wider than Normalmensur at a hypothetical treble b''. The mouth width is about a quarter of the circumference (2/7 for bigger-toned pipes), the cut-up a quarter of the mouth width; the foot-hole diameter of a quarter of the pipe width was large, though easily reducible. From the measurements it is unclear whether Arnaut was working from two pitches of a' = c395 and a' = c435 or from a mean tonus cori of a' = c415. Two portative or positive chests (‘ciste portivorum’) are drawn and described. In one, a single rank of pipes for the compass b–g'''a''' is arranged ‘ad modum mitre episcopalis’ (i.e. like a bishop's mitre, tallest pipes in the middle); in the other, a rank for the compass b–f''' is arranged in the chromatic manner, tallest to left, shortest to right (‘ciste communis’ or ‘the usual chest’). Arnaut also drew the front of a standard larger organ of the Sion type, probably the instrument at Salins (Salin, formerly in Burgundy), whose 4' Blockwerk he later specified as B (6 ranks)–f'' (21 ranks).
On f.127 of Arnaut’s manuscript occurs the first incontrovertible reference in organ building to reed stops. On a page of scarcely 20 words (and ten figures) apropos the ‘scales … of the pipes in the church of the Dei custodientes’ occurs the phrase ‘l’anche de F’, which apparently refers to the reed and block of a reed pipe. Arnaut seems to be saying that a rank of such pipes from B to b' needs eight different sizes of block but gives no other details.
Of the organ of about 1350 in Notre Dame, Dijon, Arnaut noted that the pipes (B–a'') are already old and corroded; the pipe mouths were generally about half an octave too narrow, in his opinion. The Fourniture is mentioned, apparently the only separable part of the plenum. The total number of pipes in the organ was 768; the leather bellows (?c1350, ?c1440) had three folds and measured c160 cm by c70 cm. Arnaut also gave in tabular form the disposition of four different Blockwerke, one of F (8 ranks)–e''' (21 ranks), two of B'–f'' (6 to 21 and 6 to 15 ranks respectively) and one of B'(10 ranks)–a'b' (26 ranks). The first has three categories (Principal, Cymbale, Fourniture), suggesting ‘stops’ made to play separately by two manuals or perhaps by some mechanical device (possibly a divided chest operated by a Sperrventil). The Principal 8' has four ranks at the top and the Fourniture 14 (making 126.96.36.199/3.51/188.8.131.52.184.108.40.206.4.4); the Cymbale is nothing less than a three-rank Terzzimbel, indeed the first documented mixture containing a Tierce rank. The Cymbale repeats (i.e. breaks back to lower pitches), 29.31.33 at B, 8.10.15 at e'''.
One of the other three organs was apparently that at Salins, which had a long-compass 4' Blockwerk of:Even more important, perhaps, is that Arnaut’s Fourniture is not an accumulative Blockwerk but a Mixture that breaks back to lower pitches in the upper octaves.
Arnaut referred also to the 12 ‘fistula[e] tenoris’ at St Cyr (probably Nevers Cathedral), i.e. 12 Trompes or bass pipes, half as long again as the lowest ranks of the chorus. Unlike the other Principal pipes, these pipes had no accompanying Fourniture pipes of their own, and were thus presumably played from a separate keyboard and chests. At the church of the Cordeliers (?Dijon), the ten ‘subdupla tenoris’ pipes had a separate keyboard which could couple with that of the chorus, thus affording three effects: the usual chorus, the chorus + tenor or Bourdon pipes, or tenor pipes played by the left hand while the right hand played the chorus or discantus. It is unclear what Arnaut meant by ‘double Principals’ (‘duplicia principalia’); did this mean that only the 8' stop was doubled (two open ranks, or one open and one stopped rank), or that all ranks of the principal chorus were doubled? The reference to ‘double principals’ in the 1519 contract at All Hallows, Barking-by-the-Tower, London, is similarly obscure, although the recent discovery of two early 16th-century English soundboard fragments (analysed in BicknellH), strongly suggests the latter. If this is so, then ‘Principal’ in this context simply meant chorus or plenum – a hold-over from the earlier period when it referred to the Blockwerk (as at St Sebaldus, Nuremberg) – but with the exception of the ‘bassys or diapasons’ (corresponding to Arnaut's tenor, or the Flemish Trompes). The ‘simplicia principalia’ of the Dijon court chapel organ was described by Arnaut as ‘in duo divisa’, which may mean either one halved rank (with treble and bass stops) or the usual paired Principals separated off, perhaps by a slider. Two quints and an octave gave the organ a total of five registers, possibly with five push–pull slider-ends.
Further light is thrown on Chair organs (‘tergali positivo’). Arnaut described one with 195 pipes, FG–f'' at 4' pitch and a four- to seven-rank Blockwerk of octave ranks only. The front pipes were of tin, the others of lead; the measurements of neither the mouths nor the foot-holes were systematic or regular in the particular Chair organ Arnaut was referring to, and he was puzzled as to why it nevertheless sounded well.
Though never completed, and although it appears to be more indebted to earlier writings than was previously thought, Arnaut’s draft treatise stands as something unique in organ building, not least in its description of certain Blockwerk or plein jeu choruses. During the whole of the next century no source was to describe in such detail how an organ builder could plan his chorus. Contemporary documents, like modern histories, prefer to dwell on the new colour stops and other, essentially secondary, effects.