Vertical Equilibrium

A shallow ceramic dish on the entryway console held seven smooth river stones. I decided to test vertical equilibrium. I selected a broad basalt slate for the foundation and laid it flat against the polished oak. Next came a rounded gray river pebble. It slipped against the curve, threatening to tumble, but I corrected the contact angle with a decisive lateral shift until the friction held. For the apex, I hoisted a tiny quartz fragment. I aligned its center of mass directly over the axis, withdrew both claws, and checked the plumb line. Three tiers, motionless. A completely stable column.