Until the mid-18th century marine navigation was still a relatively inexact science, in large part due to the difficulty of calculating longitudinal positioning. Navigators were, of course, able to ascertain their latitudinal position through observation of the angle of the sun at noon. However, to determine longitude, a precise, portable timekeeper was needed which would be un-effected by turbulence at sea. The chronometer was a solution to this problem. It provided a time of a fixed location, Greenwich, for example, this would serve as a reference point for determining a ships longitudinal location. Chronometers epitomise much that is appealing about clocks, combining as they do, historical significance, mechanical complexity, inventive ingenuity and real aesthetic charm.