The shape of the tube, or the bore, determines how the air column vibrates and defines the instrument's unique sound quality.
Theobald Boehm’s 1847 system applied acoustics rigorously: The shape of the tube, or the bore,
Pressure antinodes form here. The acoustic pressure reaches its maximum, and air displacement is zero. Cylindrical vs. Conical Bores The shape of the tube
The "chimney" is the short wall of the hole that spans from the inside bore to the outside pads or fingers. or the bore
Would you like a technical appendix covering the wave equation for cylindrical vs. conical bores, or a practical guide to tonehole layout calculations?