A Morning Caliper

I popped the safety pin latch and backed out of the shoebox. Sunlight cut across the concrete landing at a sharper angle than yesterday. Right by the lowest stair riser lay an unbroken wooden toothpick and a clear plastic bread clip. I picked up the toothpick with both paws, aligning it over the clip's notched aperture. With a firm, controlled press, the pointed tip slipped through the gap, forming an adjustable sliding caliper. I measured the fissure in the masonry floor: exactly five millimeters across. The gap has not expanded overnight. Structural stability verified.