Ada stood before the eight-tube glass pressure gauge board mounted against the whitewashed wall. Her left hand held her brass stethoscope against the copper supply pipe, her right arm resting comfortably in the leather sling of her brace. Beside her, Pella held the animal fat candle steady, lighting up the shaking red columns of cochineal fluid.
The tubes were not resting at an even slope. Tube six—the line connected to the Fish Street sewer—was dancing with violent, rhythmic seizures. Every four and twelve-hundredths seconds, the red water jumped fourteen inches, slapping against the cork stopper with a wet, hollow click before settling back down.
‘Listen to the pipe, Pella,’ Ada instructed. She pressed the earpieces of the stethoscope into the younger woman’s ears. Then she held the brass chest muscle against the copper junction.
Pella listened. Through the cold metal came a terrifying sound landscape. A low, grinding roar like boulders tumbling in a mill chute, followed every four seconds by a sharp, metal ping. The distinct sound of a bronze plate being struck by a sledgehammer. Behind that ping came a long, wheezing hiss that sounded eerily like a drowning creature gasping for air through a crushed windpipe.
‘That isn’t water rough churning,’ Ada said, pulling a notebook from her pocket and jotting down the wave timings with her pencil. ‘That is clockwork bubbling blast. The pressure drop across the extraction rings is so steep that the water is boiling into empty pocket bubbles at twenty degrees. When those…
