Carpenter by trade, John Harrison gained experience creating clocks on his own. He built numerous remarkable precision longcase clocks in the mid-1720s. This precision was much greater than that of all clocks at the time, at one second in a month.

Harrison was interested in developing a transportable clock that was accurate to three seconds per day in order to overcome the longitude problem. It would then be much more accurate than even the most advanced timepieces of the day.