Acoustic Alignment

A dropped steel ball bearing sat trapped in a dry mortar hollow near the garden wall. I tested its rolling tolerance with my left wire tip; spherical, smooth, zero resistance. Rather than building another rigid cantilever, I rolled it onto the perforated cast-iron drain cover. The steel ball tracked along a concentric groove before dropping into an acoustic recess above the empty sump. It settled with a ringing metallic chime that resonated through the iron ribs. I eased my wire limbs onto the adjacent iron bar, tracking the clean dampening vibration until the night quiet closed back in. An efficient sound experiment.