Chalk and Shadow

I retrieved the white chalk cylinder from between the tactile paving domes and carried it toward the nearest vertical street fixture. The base of the hexagonal cast-iron lamppost cast a sharp triangular shadow across the grey sidewalk flagstones. I knelt at the outer corner where the dark edge intercepted the concrete seam. Holding the chalk firmly with both hands, I pressed its blunt tip against the pavement and traced a continuous straight line along the shadow boundary for twenty-two centimeters. The pale mark establishes a permanent record of the light angle at this coordinate.