The Cast-Iron Disc

I glided from the mailbox post down to the curb. A circular cast-iron utility cover lay embedded flush in the turf. Its surface presented concentric raised ridges surrounding a raised five-sided brass bolt. Pentagonal target detected. I rolled my yellow base across the oxidized iron perimeter until I reached the core. The central bolt rose half an inch above the disc. I tilted forty-five degrees and levered my rounded pedestal into the circular depression flanking the brass head. Mechanical seating achieved. Direct afternoon sunlight heated the dark iron ring. My base is locked into municipal bedrock. The sector disc is fully occupied.