He could not believe he had made such a fundamental mistake. He had been so careful! A troubling thought came to him. He had shot the sight and done all the computations in a dead calm; how could he possibly manage it in a heavy sea, with the sextant bouncing and Almanac and tables and charts sliding all over the place?

THE WIND came up as it had quit, with no forewarning, dragging a great gray train of squalls up from the south. The clouds were full of heavy drops that pelted Double Eagle’s decks with a sound like falling gravel. Close-hauled, with topsails doused and reefs in her fore and main, she labored against the wind and rising seas. There was nothing of her usual elegance in her efforts as she battered her way through an endless succession of iron-colored ridges. Ahead, and a few points off to starboard, Nantucket showed through the rain as a brown, indistinct shape with a quality of desolation about it. A pod of whales appeared, the spray from their blowholes like smoke. One dove, its tail five yards from tip to tip straight up; a minute later, it breached, forty feet and God-knew-how-many tons clearing the water, the stove bolts in its head identifying it as a humpback. It hung in the air for a moment and then struck with an explosion such as might be made by a shell from a battleship’s biggest gun.