Sea of Glory

fleet in the world. Unlike European merchant vessels, which used the Pacific as a thoroughfare from place to place, the whalemen followed the desultory movements of sperm whales across the full width and breadth of the largest ocean in the world. The vast distances they traveled required the whaling captains to look to the islands of Polynesia for provisions. Since few European mariners had reason to visit many of these islands, previous exploring expeditions had neglected to survey a significant number of the islands in any systematic manner. Indeed, there were entire groups, such as the Fijis, that had not yet been properly surveyed at all. Charting hundreds of Pacific islands was a gargantuan, largely thankless, and incredibly time-consuming task, but it was the chief aim of the U.S. Ex. Ex.
    On August 13, after a passage of almost a month, they saw their first Pacific island. Reynolds immediately scampered up the mainmast to the royal yard, where he watched for more than an hour, “entranced with the Singular & picturesque loneliness of that gem of the Ocean.” Before him lay one of the easternmost islands of the Tuamotu Group, the largest collection of coral atolls in the world. The island of Reao, known to Wilkes as Clermont de Tonnere, is less than a dozen miles long with the ringlike shape typical of a coral atoll. “[W]here the white beach terminates there is a beautiful fringe of Trees & Shrubbery,” Reynolds wrote, “hiding from view the Lagoon within, but from aloft, you can look over the quiet lake, the Isles that stud its bosom, and the green strip that encompasses it round about.” How an island comprised of coral, which only grows in shallow water, had come to exist in the middle of a vast and deep ocean was a question that greatly concerned the Expedition’s scientists. “[E]ven in this enlightened age,” Reynolds wrote, “[it] has defied a satisfactory explanation.” By the end of the voyage, with a little help from Charles Darwin, the scientists of the Ex. Ex. would have an answer.
    Wilkes intended to make Reao an object lesson in what were the Expedition’s proper priorities. Surveying, not science, was to be attended to first. All the next day, the scientists watched in indignant disbelief from the decks of the Vincennes, the Peacock, and the Porpoise. After more than a year of anticipation, they were now forced to sit idly by as an island was surveyed, yet remained unexplored. The naturalist Titian Peale called it “a sorry business.” Nevertheless, as all of them would begrudgingly come to acknowledge, there was a magnificent precision in the way that Wilkes and his officers undertook a survey.
    It was essentially the same system he had developed at Georges Bank. Dividing up the four vessels of the squadron into two groups and assigning each group a specific survey area, he was able to reduce the time normally required to survey an island. One of the more interesting—and ear-splitting—aspects of his method was the way he determined the baselines of the survey. The vessels would take up positions along the shore of the island, then begin firing their guns in rapid succession. By noting the time between the gun’s flash and report, the officers were able to calculate the distance between the two vessels. (What effect this day-long display of firepower had on the island’s native population can only be guessed.) In the meantime, other officers used sextants to measure angles between the vessels and points designated on shore. Once these were completed, the vessels changed their positions and eventually worked their way around the island. It wasn’t long before they had roughed out a chart of the island complete with points of “known location along its perimeter.”
    It was now time for the boat-crews to go to work. One of the sailors used the sounding lead to determine the water’s depth while an officer with a sextant measured horizontal angles to known points on land. Each vessel had what was called a deck-board on which the information was recorded, and at the conclusion of the survey, copies of the data were sent to Wilkes along with a diagram to designate all the control points of the survey. Wilkes and his officers then compiled the various surveys to create a finished chart. The system brought a new level of speed and accuracy to the survey of the Pacific, and Reao was the first of 280 islands to be surveyed by the U.S. Ex. Ex.

    But it was punishing work, especially