Question

For centuries, transoceanic navigation was a perilous endeavor governed by guesswork. While latitude could be readily determined by measuring the angle of the sun or the North Star above the horizon, calculating longitude presented a far more formidable challenge. The prevailing scientific consensus in the eighteenth century held that the solution lay in astronomy—specifically, mapping the movements of the moon against the stars. The British Parliament’s Longitude Act of 1714 offered a king’s ransom to anyone who could solve the problem. However, the solution came not from the skies, but from the workshop of John Harrison, a self-taught clockmaker. Harrison reasoned that because longitude is directly proportional to time, a navigator could determine their position by comparing local solar time with the time at a reference meridian. To achieve this, a clock had to remain accurate on a rolling ship, resisting temperature fluctuations, humidity, and the physical motion of the sea. Harrison spent decades refining his marine chronometers, culminating in H4, a pocket-watch-sized device that completed a voyage to Jamaica in 1761 with an error of just nine seconds. Despite resistance from the astronomical establishment, Harrison’s mechanical solution revolutionized seafaring, transforming navigation from a hazardous art into an exact science.

Which of the following best describes the primary purpose of the passage?