p until the 17th century, sailors braved the ocean by sheer grit, line of sight, compass and, in many instances, a bit of sheer luck. By 1731, British Mathematician John Hadley changed the game, developing an improved version of the reflecting telescope (and grandfather of the sextant) for the purpose of using the celestial bodies to calculate one’s position at sea. For centuries, boaters might have thought it couldn’t get any better than this—until the year 2000, when the military released GPS for
