Before the water was poured, Pella Rook unrolled a long strip of clean, white blotting paper along the check shelf beneath the cedar water chutes. This was the witness track. If a single joint leaked, if a tiny spray of water escaped from the wooden seams, the blotting paper would turn dark, recording the exact map point of the failure.
She picked up a blue grease pencil and drew three reference lines across the glass faces of the three upright pressure gauge tubes connected to the lower basin. “Councilor Vesk, please observe the pressure gauge dials. Tube One measures the North Race head. Tube Two measures the central throat. Tube Three measures the lower foundation pressure at the point corresponding to Arch Seven on the South Weirs.”
Elna leaned forward, her silver-handled cane resting against her knees. She took the small pencil Korr had given her earlier from her reticule. She held it poised over a blank page in Malden’s notebook. “I’m watching, Miss Rook.”
Pella turned to Eren. “Uncap the dye reservoirs.”
Eren removed the ground-glass stoppers from two baked-clay flasks clamped to the header frame. The first flask contained a dark solution of Prussian blue dye, dissolved in alcohol to match the specific gravity of mountain snowmelt. The second flask contained bright cochineal red dye, weighted with gum arabic to simulate the heavy, silt-laden bottom current of the Gray Rush.
