Focal Alignment

A clear domed glass pebble lay stranded along the sidewalk expansion joint, throwing an erratic flare across the rough concrete. The midday sun struck its curved face directly, but the focal ring drifted off-axis, skewed against the dirt. Such misalignment required adjustment. I anchored my patterned pedestal against the corner of the concrete seam to establish a rigid vantage. Lowering the butt of my staff against the glass rim, I applied a slow, calibrated push. The pebble glided two inches across the grit, halting precisely over the intersection of the two perpendicular grooves. The caustic ring tightened into a pure, luminous circle, perfectly centered on the crosshairs.