The water beneath the iron arch of the old Millcreek aqueduct was five feet deep and perpetually dark. Even on sunny summer afternoons, the light from the canal surface barely penetrated more than two feet into the gloom, leaving the stone foundations in near-total blackness. For Bramble, however, darkness was not a barrier.
His whiskers—twenty-four long, rigid tactile hairs arranged on either side of his muzzle—were fine-tuned acoustic sensors that mapped the underwater environment in exquisite detail. He could feel the shape of the stone wall four feet away by the way the water current rebounded from the dressed granite.
He could detect the outline of an old iron chain lying on the canal bed by the subtle turbulence it created in the lower flow.
As he dived deeper into the intake flume beneath the mill arch, Bramble kept his forepaws tucked close to his ribs, using his webbed hind feet and long, muscular tail to propel himself through the cold water. Ten feet below the surface, the water pressure increased noticeably. Here, at the mouth of the illegal siphon pipe, the water was being sucked into a narrow cast-iron throat with terrifying force.
Bramble felt the pull on his belly fur before he even saw the iron grating. He flexed his powerful tail, bringing himself to a complete halt two feet from the siphon intake, his claws gripping the rough mortar between two foundation stones. The siphon valve assembly was massive.
The outer housing was forged from dark grey iron, held in place by four heavy steel anchor bolts driven into the bed of the canal. Inside the housing, a large brass disc—the main flow pallet—was held open at a thirty-degree angle by a heavy mechanical ratchet mechanism. Every three seconds, a brass gear tooth engaged with the ratchet bar with a loud, underwater clack that sent shockwaves through the water.
Bramble approached the valve assembly cautiously, his whiskers vibrating wildly in the turbulent intake current. He needed to understand how the mechanism worked. If the brass ratchet could be disengaged, the heavy lead counterweight on the upper lever would fall, slamming the brass pallet shut against the iron seat and sealing the siphon completely.
He circled the housing twice, staying eighteen inches clear of the suction zone. The current was cold, carrying bits of charred coal and industrial grit that stung his nostrils. Near the base of the frame, he discovered a small iron lever connected to a heavy coil spring.
This was the secondary safety release—a mechanism designed to allow engineers to drop the counterweight in an emergency. If he could apply enough force to that lever, the main ratchet pin would slip, and the heavy lead weight would do the rest. He swam closer, testing the spring tension with his forepaw.
The spring was stiff, coated in sea-salt crust and old graphite grease, but it had a fraction of an inch of play. He knew that if he could find an object to jam under the release arm, the continuous pressure of the water would do the rest. The stone walls of the aqueduct flume were built of massive granite blocks weighing two tons each.
They had been set in place by stone masons using wooden derricks and hand-winches during the height of the canal boom. Over eighty years, the water had worn smooth grooves into the stone where the iron barge keels had scraped along the sides. Bramble used these underwater grooves as hand-holds, jamming his curved claws into the deep scratches to anchor himself against the six-knot current.
He could feel the cold river water pressing against his ribcage like a heavy iron weight. His heart rate slowed automatically—a natural otter diving reflex that allowed him to stay underwater for up to five minutes without taking a breath. He kept his eyes open, his nictitating membranes—clear inner eyelids—protecting his eyes from the suspension of coal dust in the water.
Through the murky green gloom, the brass teeth of the siphon valve glowed like sinister golden eyes. The granite foundation stones of the aqueduct had been laid underwater by divers wearing heavy brass helmets and lead-soled boots. Bramble could still see the marks of their iron chisels on the submerged stone faces.
He paddled quietly around the intake grate, feeling the cold, dark water swirling past his flanks. The current was carrying a fine suspension of river sand that tickled his nose. He knew that if he could break the main ratchet pin, the immense hydraulic pressure of the river itself would help seal the valve shut.