Discover John Harrison's iconic marine timekeepers

John Harrison's marine timekeepers are arguably the most important ever made. You can see them on display in our Time galleries, at the Royal Observatory Greenwich.

 

The Harrison clocks were revolutionary in their ability to allow ships to determine their longitude at sea. This development drastically reduced the risk of ships and their crews, along with their precious cargoes, being lost at sea. The Harrison clocks were able to keep time at sea, allowing sailors and mariners to determine their longitude. It took John Harrison most of his lifetime to arrive at the design for H4, which was to be his most succesful watch. 

 

The clocks compensate for changes in temperature and, thanks to extensive anti-friction devices, run without any lubrication.

 

When Harrison unveiled H1 in 1735 it was the toast of London. Alongisde the other Harrison clocks, it is one of the great milestones in clock-making history.