Carrying the hardened True-Sight Verdigris Needle from the cool water chutes, Qiao Ming and Yan Zhiqiu entered Entry hall 724: The Metrological Calibration Lab. This was a long, vaulted hall built from massive stone slabs of grey and white banded marble, designed by the First Mapmakers to test and certify their deep-sea instruments under controlled sound and earth-magnet conditions.
Arranged along the centerline of the hall were twelve testing piers of solid granite, each six arm-lengths square and five arm-lengths high. Embedded in the face of each pier was an ancient fine-tuning standard. A split crystal of sight white spar-stone, a polished sphere of pure bismuth, and an underground sounding well dropping through the bedrock to a known depth.
Qiao Ming walked to the first testing pier, his bare calloused feet gripping the cool marble floor flags. The air in this hall was clean and still, holding a faint, dry stone aroma that reminded him of the high scroll halls of Entry hall 003. He drew the newly forged needle from its leather harness sheath, feeling the smooth, weightless balance of the four-sided steel across his fingertips.
Behind him, Yan Zhiqiu set the Broken Slate upon the watching desk, lighting up the testing protocols with her horn lantern. She looked at the needle in his hand. She watched the faint, rainbow-bright green rust patina shimmer with delicate shades of malachite and cyan under the amber flame.
