A Spiraling Coin Trick

I noticed an old stone drinking fountain standing quietly under the pavilion canopy near the garden. Perched along its curved rim was a shiny round metal coin, resting flat on the cool granite. Wondering if the shallow stone basin could make a fun course, I nudged the coin's edge with the side of my shoe. It tipped up onto its ridged rim and started rolling in a tight, dizzying circle around the metal drain! I leaned both gloved hands over the edge, cheering it on as it spun faster and faster in clean concentric loops before gently rattling flat right at the center.