From her station on the intermediate narrow high walkway, young Edda directed the final clockwork closure of the main cooling water chute with a total, unbending care that brooked no error.
Her left hand, locked still in rigid ash splints and wrapped in greasy linen, rested firmly against the wet spruce handrail to steady her balance. Her index and middle fingers were swollen and blackened from the feeder trap in the nursery five days ago. But the pain was a distant, cold background hum against the sharp focus of her building mind. In her sound right hand, she gripped the heavy three-foot torque wrench that she had modified in the tool shed with an offset extension socket and a welded cross-bar to provide maximum clockwork leverage.
Beside her on the timber staging, three young quarry apprentices held the three forged-iron clamping bands suspended on chain lanyards. These were not light plumbing collars. They were massive, half-round hoops of high-pulling steel, four inches wide and an inch and a quarter thick, forged in the deep pit forge shop and machined with heavy two-inch bolt lugs designed to withstand thirty bar of internal burst pressure.
Edda had spent an hour before the descent calculating the clamping forces on a piece of slate. At six bar of working head, eighty thousand gallons of mountain water exerted over forty tons of outward force against the four-foot channel. If the clamping bands failed to compress the horsehair felt and pitch to a total thickness of…
