 While the Lunar Distances method would complement and rival the marine chronometer initially, the chronometer would overtake it in the 19th century.The more accurate Harrison timekeeping device led to the much-needed precise calculation of longitude, making the device a fundamental key to the modern age.Following Harrison, the marine timekeeper was reinvented yet again by John Arnold who while basing his design on Harrison's most important principles, at the same time simplified it enough for him to produce equally accurate but far less costly marine chronometers in quantity from around 1783.