rigole

CONT: Dans les instruments, il faut, bien entendu, fixer [l']anche quelque part. Dans l'orgue, on l'adapte sur la rigole [...] Pour l'accorder, on fait glisser un fil de fer, la rasette qui appuie sur l'anche et raccourcit ou allonge la partie vibrante, ce qui fait monter ou baisser le son.

CONT: Many of the pipes in a good organ work in an entirely different way .... Hidden inside the pipe foot is a metal reed, usually made of brass. The tuning wire is springy and holds part of the reed firmly against the open side of the air channel called the shallot, leaving enough free to have the desired vibration frequency.
CONT: the shallot ... is roughly cylindrical in shape with its lower end closed and the upper end open.