Through the chilled brass eyepiece of the refractor, the red three-sided flag dropped.
Ivara Quill watched the vermilion sheet slide down its bronze guide wires and vanish into the cedar housing beneath the quarry low roof wall. A split second later, the two parallel white slats of the double-bar snapped upward into the harsh glare of the coal-gas lanterns, their polished copper bands flashing across three miles of dark basin like twin sparks struck from a cold flint.
RESUME DISCHARGE, the white bars declared. THE SINK IS CLEAR.
Ivara didn’t permit herself a celebratory word or a loosened shoulder. Relief in a high-pressure gallery was a form of skilled fault. An worker who relaxed after clearing a blockage was a worker who missed the backup bubbling blast spike that followed the clearing. She had spent thirty years surveying high-pressure under-road drains and deep adits across the province. The cardinal rule of high-pressure building was that the moment a blocked path clears is the moment the pipes experience their highest volume surge.
She pulled her face back from the telescope, her right thumb catching the brass index lever of the side telegraph. She hauled the lever backward forty-five degrees and slammed it home into the brass detent.
