Yan Zhiqiu stood at the outer threshold of the writing hall. There, the massive dark rock archway met the lead-sealed drop-gate track of Entry hall 480. She placed her flat palm against the cold bronze leaf of the heavy blast door. Right away, a fine, nonstop tremor passed through the metal into the bones of her forearm. A high-hum shaking that hummed at forty-two shakes per second, with a rhythmic, dull percussion that sounded like a huge iron piston striking bedrock three leagues away.
“The void-borers,” she whispered, her brow furrowing behind her glasses. Her training as a royal scroll-keeper had taught her to parse clockwork sounds. She had cataloged the working logs of high-pressure pumps, mine augers, and siege rams across three dynasties. This sound was not the natural settling of underground rock. It was the deliberate, rhythmic hammering of air-powered diamond-tipped drills shattering load-bearing granite.
She drew her bronze sounding rod from her satchel, holding its sharpened tip against the doorframe while resting the ivory handle knob against her mastoid bone. Through the bone heat flow, the sound swelled into a terrifying sound profile: the roar of escaping high-pressure cold air, the metal shriek of rotating cutter-heads, and behind it all, the deep, hollow gurgle of rushing salt water.
