The Chromatic Crank-Lock

The smell of heated oil and metallic shavings fills the air of this narrow corridor. At the end stands a heavy bronze door fused with a large vertical gear mechanism. Three metallic pistons (copper, iron, and brass) protrude from the wall at shoulder height. Below them is a small brass plaque and a heavy winding key. Faint ticking vibrations can be felt through the floor, suggesting a massive engine operates behind the stones.