The windchests
Positif:
Two key-channel and diatonic windchests, with the low-pitched pipes on both ends, except C1 to F1, located behind the central turret. Some parts are still the original ones built by Dupont, the remaining has been changed by Cavaillé-Coll.
Grand-orgue and Bombarde:
Three key-channel windchests, located at the main case center, behind the case façade. The channels are divided in the middle, with the Grand-orgue’s pallet box at the front; and the Bombarde at the back. The windchests are still the ones of Dupont but have been transformed by Cavaillé-Coll. The central windchest is diatonic for C2 à B2, with low-pitched pipes located in the middle whereas the two lateral windchests are diatonic with low-pitched pipes on both ends.
Récit:
A key-channel windchest by Cavaillé-Coll located above the Grand-orgue’s windchest, and perpendicular to the case façade. Low-pitched pipes are displayed chromatically at the back, where the expressive box is the highest, and higher-pitched pipes at the front. The principals’ and reeds’ pallet boxes are respectively at the right- and left-hand sides. The windchest has been extended by Haerpfer-Erman in order to accommodate the new Plein-jeu stop.
Pédale:
Two diatonic key-channel windchests behind the case façade, on each end at the Grand-orgue’s windchests, with low-pitched pipes located on both ends.
Those windchests were made by Cavaillé-Coll even though they are probably located at the same place as the former’s Dupont ones. They include Dupont Pédale’s stops, ie Flûtes 16’, 8’ et 4’ and also Bombarde 16’ (tin-made), Trompette 8’ and Clairon 4’.
At the back of those two windchests, in parallels, separed by a walkway, stands two key-channel windchests, built by Cavaillé-Coll for the following six stops: Contrebasse and Soubasse 16’, Fourniture (formerly: Violoncelle 8’) and also the three reeds-battery (Contre-basson 16’, Basson 8’ and Baryton 4’).
Finally, two windchests are located at the back against the wall, with an exceptional width, being the one of the Cathedral’s nave. These two windchests are diatonic with low-pitched pipes in the centre.
The first of the two, at the front includes the two Bombardes 32’ et 16’ fir-made, alternatively disposed. The lowest-pitched pipes of the Bombarde 32' are hidden by the expressive box and by the central case’s wooden medallion. The second windchest is located between the first and the back wall, on the second level, and helps to support the Soubasse 32'.
Built without sliders, stops action is made by insertion valve with each pipes having its own, with a downward action system.
Download the positioning of the windchests 
