In the cellar entry of the Old Ferry warehouse. There, the flat stone slabs met the rough-hewn granite footing of the museum party wall, Imran Bell paused to unclip his clockwork draft tube. The air here was ten degrees warmer than the washroom, heavy with the choking reek of wet stonework, decaying river snails. The sharp, vinegar-like bite of stone acid.
Pella Rook stood two paces behind him. She held the braided flax safety tether on its notched wooden spool. She didn’t hover, and she didn’t offer unsolicited advice. She kept four feet of slack in the line, her fingers resting lightly on the cord. She felt the tiny shakes sent through the fibers.
‘The draft is pulling inward toward the high water chute,’ Imran observed. He watched the five goose feathers inside the glass metal tube. Four of the feathers were bent forty degrees toward the western foundation. Meanwhile, the fifth shivered erratically in a swirling boundary eddy. ‘Your Grand Master’s second witness line has created a negative pressure pocket in the sub-basement. It’s sucking cellar air through the stonework joints.’
‘Because the second return line is running at seventy pounds of head,’ Pella explained, her voice muffled slightly behind her three-ply linen mask. ‘The high-speed flow creates a venturi effect in the drainage under-road drains, drawing damp air out of the museum vaults and heating it against the bronze pipe jackets.’
