By noon, the sprawling staging area behind the Iron Dragon Gap looked like a vast outdoor machine shop rather than a military encampment.
Across three miles of sheltered terrace, rows of forge fires burned with intense, smokeless heat fed by bellows operated by teams of four mortal quarrymen. Long wooden frame stand tables were covered in glittering, freshly burnished copper plates, each two feet in width and concave to a curve of exactly three inches at the center. Master smiths from the Azure Basin used fine foam-stone and sheep fat to polish the copper until each mirror gleamed with the bright glare of liquid gold. He reflected the sky like liquid metal.
Lin Tao walked the line of tables. His brass measured tongs in hand, checking the tolerances of every batch.
Beside him walked Tie Shan and Elder Chen, the master of the Southern Water-Clock Guild. Chen carried a large wooden case containing eighty matching sound water-droppers, each designed to release a uniform bead of salt water every forty-one point six seven split seconds, matching the deepest heartbeat of the realm.
“The curve of each plate is critical, Master Zhang,” Lin Tao said, inspecting a newly polished mirror. “If the bowl is too shallow, the reflected beam will scatter across twenty paces and lose its photonic thickness. If it’s too deep, the focal point will fall short of the barrier’s sensor sky-slits. We need a packed beam four inches wide at a distance of three hundred paces.”
