Out on the northern stone retaining wall of the turning basin. There, the water swirled in foam-flecked whirlpools five feet deep, Hesta stood on a raised wooden platform braced against the ancient stonework. Her canvas apron was tied tightly over a thick wool pea-coat, her oilskin hood pulled forward to shield her eyes from the stinging sleet. In her right hand she held a weighted brass sighting rule. In her left, an iron-cased signaling lantern fitted with a red glass slide.
“Mark seven on the stonework!” Hesta shouted down the speaking tube. Her voice carried the crisp, authoritative tone she used when directing twelve laundresses at the communal boilers. “The basin is drinking twelve thousand gallons a minute. But the silt is banking up against the lower weir. We have eighteen inches of clearance before the overflow reaches the cattle ramp.”
Across the deep gap, Ada Morland listened through the brass sound chest muscle in the Third Gate control house, her pencil noting the height on her chalk board. “Good sighting, Hesta,” Ada called back. “Keep your eyes on that seventh notch. If the water licks the eighth ring, flash the red slide twice. Don’t wait for the weir to spill.” Hesta wiped river foam from her eyebrows, checked the lamp-wax level in her lantern. Then she braced her boots against the wet timber decking. The first station was anchored in clear, unblinking human watching.
