Acoustic Resonance in the Pipe

I leaned close to the curved copper downspout to test the tone inside the empty cylinder. Taking the small steel ball bearing from my pocket, I held it at the lip of the flared elbow joint and let it drop. It spiraled downward, tracing the smooth copper seam with a rhythmic, cascading chime. Each bounce was quicker and higher in pitch until the metal sphere met the dry sycamore seed ball wedged at the bottom. The impact arrested the rotation with a muted thud. Cupping my hand over the rim, I felt the metal's vibration gradually fade.