“I’d say two fifty-one was wrong. That’s the reading off the outer scale, the true north scale. You steer by the inner scale, the magnetic north scale. Two sixty-six, because the declination is fifteen degrees west. That’s kid stuff. My dad taught me that last year. Were you trying to trick me?”

“Merely testing the level of your aptitude.” Will lightly penciled a line across some seventy miles of water. “So, if we had been blinded by fog and for any reason had to put into Gloucester, we could have done so, just as confidently as Nathaniel Bowditch put into Salem in days of yore. A good Christian who takes good sights has no fear of fog. Next kid-stuff question. Why did I shoot those stars at four instead of at two or three?”

The rising sun reddened the rocks of Paradise Cliffs, and Thacher’s Island, with its twin lighthouses, looked like a picture Drew had seen in a book of a Muhammadan mosque.… Eastern Point appeared, its light flashing welcome, welcome, welcome in the dawn.… Passing Ten Pound Island, Double Eagle slipped into the inner harbor and toward the forest of masts rising above the wharves.… Drew stepped off the boat onto land, blessed, motionless land.…

“Still with me?” asked Will.

“What?”

“Why did I take my sights at four this morning instead of at two or three?”

“Because a sextant measures the angle between a heavenly body and the horizon,” he answered, parroting his father’s lesson, word for word. “It had to be light enough for you to see the horizon.”

“Thus endeth the kid stuff. Now you’re going to take a sun sight and we’ll figure out where we are at this moment.”

“We can see where we are,” said Eliot, looking up from his letter.

“It’s for purposes of instruction,” Will informed him, and took his sextant on deck, where Nathaniel stood at the wheel, yawning.

“Don’t think we’ve gone half a mile since that breeze quit,” he said, motioning at the dark wall of Siasconset Head in the distance.

He had been looking at it from the same angle for almost an hour now, and was growing irritated as well as bored. Double Eagle had logged an astonishing one hundred and seventy-four miles in her first twenty-four hours, inspiring Nathaniel to make some optimistic mental calculations—at that rate, they would get to Key West in nine more days. As if to rebuke him for such presumptuousness, the wind stopped, and the schooner began to wallow, on long, gentle swells, across the mouth of Nantucket Sound.