Keck and Tuckman couldn’t say what hazards might lie ahead. According to their instruments, the new Rheinfelden was at roughly the location of the old European cascade, but the approximation was crude, and the white-water rapids that used to run below the falls were either absent or buried under a deeper, slower Rhine. Sullivan saw this as more evidence for a Darwinian that had evolved somehow in parallel with the old Europe, in which the ancient tumble of a single rock might have changed the course of a river, at least within certain limits. Finch put it down to the absence of human intervention. “The old Rhine was fished, locked, navigated, and exploited for more than a thousand years. Naturally it came to follow a different course.” Whereas this Europe was untouched, Edenic.

Guilford reserved his opinion. Either explanation seemed plausible (or equally implausible). He knew only that he was tired: tired of distributing supplies among the crude saddlebags of Erasmus’ snakes; tired of manhandling the big Stone-Galloway boats, whose much touted “lightness” turned out to be a relative thing; tired of pacing the fur snakes and their load as they portaged the Rheinfelden in a miserable drizzle.

They came down at last to a pebble-sharp beach from which the boats could be safely launched. Supplies were divided equally between the waterproof fore-and-aft compartments of the boats and the saddlebags of the fur snakes. Erasmus would herd the animals to their summer pastures at the eastern extremity of Lake Constance and had agreed to meet the expedition there.

Launching the boats would have to wait for morning. There was only enough daylight left to pitch the tents, to nurse fresh aches, to pry open ration tins, and to watch the swollen river, green as a beetle’s back and wide as Boston Bay, as it hurried toward the falls.

Guilford did not wholly trust the boats.

Preston Finch had commissioned and named them: the Perspicacity, the Orinoco, the Camille (after Finch’s late wife), and the Ararat. The motors were prototypes, small but powerful, screws protected from rocks by the skags and the engine compartments from high water by a series of canvas shields. The boats would do well enough, Guilford thought, if the Rhine remained relatively placid as far as Lake Constance. But they would be worse than useless against white water. And their advantage in weight was offset by the need to pack jerricans of gasoline, a stiff load to portage and a waste of potentially useful space.

But the boats would be cached at the Bodensee and would function more than adequately on the return trip, stripped of motors and absent gasoline, with the river current to carry them. And they worked satisfactorily the first day out, though the noise of the engines was deafening and the stink of exhaust obnoxious. Guilford enjoyed being close to the water rather than riding above it — to be a part of the river, resisted by its flow and rocked by its eddies, a small thing in a large land. The rain passed, the day brightened, and the gorge walls were gaudy with vine-like growths and capped with gnarled pagoda trees. Surely we have outpaced Erasmus and his snakes, Guilford thought, and Erasmus might be the only other human being within a hundred square miles, barring a few vagrant Partisans. The land owns us now, Guilford thought. The land, the water, the air.

Camp where a nameless creek enters the Rhine. Pool of calm water, Keck fishing for thorn and blue maddies. Miniature sage-pine among the rocks, foliage almost turquoise, dwarfed by winds a rocky soil.

Postscriptum. The fish are abundant will make a palatable evening meal, though Diggs proclaims his martyrdom as he cleans them. Offal goes into the river — billyflies chase it downstream. (The billyflies will bite if provoked; we sleep under mosquito netting tonight. Other insects not especially common or venomous, although a crablike creature made off with one of Keck’s fish — nabbed it from a wetrock scuttled into the water with it! “Claws like a lobster,” Keck says cheerfully. “Count your toes, gentlemen!”)

The next day they were forced to portage a rocky rapids, a grim task without pack animals. The boats were muscled ashore and the route surveyed; fortunately the pebbled river margin remained fairly broad and there was a ready supply of driftwood — dry, hollow flute logs that had been tumbled against the gorge wall by spring floods — to serve as makeshift rollers. But the portage exhausted everyone and wasted a day; by sundown Guilford was only just able to drag his aching bones under the mosquito netting and sleep.

In the morning he loaded and helped launch the Perspicacity, alongside Sullivan, Gillvany, and Tom Compton. Perspicacity was last in the water; by the time they reached mid-river the lead boat, Finch’s Ararat, was already out of sight beyond the next bend. The river ran fast and shallow here and Guilford sat foremost watching for rocks, ready with an oar to steer the keel away from obstacles.

They were making steady progress against the current when the motor coughed and died.

The sudden silence startled Guilford. He was able to hear the drone of the Camille, a hundred yards ahead, and the lapping of water, and Sullivan swearing quietly as he pulled back the canvas shield and opened the motor compartment.

Without an engine the Perspicacity slowed at once, balanced between momentum and river current. The Rhine gorge was suddenly static. Only water moved. No one spoke.

Then Tom Compton said, “Loose the other oars, Mr. Gillvany. We need to turn and make for shore.”

“Only a little water in the compartment,” Sullivan said. “I can restart the motor. I think.”

But Tom Gillvany, who did not much care for river travel, nodded uneasily and unhooked the oars.

Guilford used his own oar to bring the boat around. He took a moment to wave at Camille, signaling the problem, and Keck waved back acknowledgment and began to turn. But the Camille was already alarmingly far away. And now the shore had begun to reverse, to slip away. The Rhine had taken control of Perspicacity.

The pebbled beach from which they had launched swept past. “Oh, Jesus,” Gillvany moaned, paddling hectically. Sullivan, white-faced, abandoned the engine and took up an oar. “Make a steady pace,” Tom Compton said, his low voice not unlike the rumble of the water. “When we’re close enough I’ll snub the boat. Here, give me the bow line.”

Guilford thought of the rapids. He supposed everyone in the boat had begun to think of the rapids. He could see them now, a line of white into which the river vanished. The shore seemed no closer.

“Steady!” the frontiersman barked. “Dammit, Gillvany, you’re flapping like a fuckin’ bird! Dig the water!”

Gillvany was a small man and chastened by the outburst. He bit his lip and pushed his oar into the river. Guilford worked in silence, arms straining. Sweat drenched his face, a tang of salt when he licked his lips. The day was no longer cool. Darwinian shore birds, like coal-black sparrows, swooped blithely overhead.

The river bottom was jagged now, shark-fin rocks trailing white wakes as Perspicacity neared shore. There was a quick hollow crack from the aft of the boat: “Lost a skag,” Sullivan said breathlessly. “Pull!”

The next snap was the screw, Guilford guessed; it sent a grinding shudder through the boat. Gillvany gasped, but no one spoke. The roar of the water was loud.

The shore became a tumble of boulders, close but forbidding, rushing past perilously quickly. Tom Compton swore and grabbed the bow rope, stood and leaped from the boat. He landed crushingly hard on a slick flat-topped rock, rope unwinding like an angry snake beside him as Guilford paddled vainly against the current. The frontiersman righted himself hastily and snubbed the rope around a granite spur just as Perspicacity drew it taut. The rope sang and whipped from the water. Guilford braced himself as the boat bucked and twisted wildly toward the rocks. Sullivan fell against the motor block. Gillvany, unprepared, rolled over the starboard side into the wash.