The vaulted stonework of Relief Trunk Three rang like the inside of a foundry boiler. Under the sixty-eight-pound ringing bubbling blast let loose from the High Terrace tower, every lead joint and dressed limestone block in the chamber shook with a fierce, teeth-rattling hum. Scalding droplets of stone water rained from the arch overhead, carrying the sour silt stench of the disturbed river bottom and dusting the crew’s shoulders with gritty gray pipe lime.
Dima Fen didn’t waste a breath complaining about the heat or the noise. Stepping across the wet ash planks of the staging platform, the veteran Lowbank machinist knelt beside Pella Rook and unbuckled the heavy canvas flap of her tool bucket. Inside, wrapped in strips of oiled lambskin to keep the river damp off the ground steel faces, lay four matched pairs of folding machinist’s pry-wedges.
‘We milled these on the big screw-planer at the weavers’ foundry yesterday afternoon from the broken leaf-spring of that Yorkshire lorry,’ Dima shouted over the metal roar of the main channel, laying the steel tapers out on the dry timber brace. ‘High-carbon vanadium alloy, ground to a five-degree included angle and lapped smooth on cast-iron plates with fine emery flour. If you drive two of these in from opposite sides of the pin boss at the exact same speed, they exert pure axial thrust along the centerline of the pin. Zero side-bending moment on the cast-iron ear.’
