The great oak floorboards of the Old Ferry warehouse were cleared across a thirty-foot square, lit up by shafts of pale autumn sunlight cutting through the high eastern high window row. On four heavy timber frame stands, Eren Tal and Korr Var had assembled the main framework of Hal Rook’s scale high-pressure testing rig. The scent of fresh-planed cedar, boiled linseed oil, river mud, and pipe lime filled the cavernous space. It mixed with the bitter silt stench from the boat ramp outside.
The model consisted of three large sixty-gallon oak wine casks, scrubbed clean of wine tartar and mounted on stepped platforms to represent the three river valleys converging on Lathmere: the Gray Rush, the Black Tine, and the High Sike. Connecting the barrels was a fine, detailed network of slotted cedar troughs, carved to match the exact deep-water curve of the lower harbor channels. A pot of boiled tea sat on a tool chest beside a plate of sourdough crust. There, Tavi was sharpening scrapers.
Senior Surveyor Korr Var stood over the central trough, a brass sliding rule in his hand, checking the slope of the water chutes against a water level. “Froude scale similitude, Eren. In an open-channel model, sharp-angled scale is one to forty-eight. But the speed scale must be proportional to the square root of the depth: one to seven. If we pour water too fast, water’s skin will dominate the flow and distort the rough churning profile.”
