Thomas Harrison was the mechanical genius who in the 1760's solved the problem of making an accurate timepiece which would enable naivgators to reliably  plot longitude. Before then countless vessels had been lost due to the lack of any workable way to determine their position in the open sea. Very few timepieces were made to Harrison's design which was highly complicated and expensive to produce, however James Cook used one on his third great voyage of exploration and praised it as 'our trusty friend the watch' and as 'our never failing guide'.

Two English makers, John Arnold and Thomas Earnshaw independently carried on experimenting with new ideas and by the 1780's a design incorporating their inventions was established which was so successful that chronometers remained essentially the same for the next 200 years until modern electronics and GPS navigation took over.

English makers dominated the chronometer trade and it is estimated that between 90,000 and 100,000 were made at about 500 per year. In the 19th century it took a full year to make a regulate a chronometer and around Clerkenwell in London there gathered an elite group of craftsmen who produced instruments of outstanding quality and beauty, supplying the navigators of the world. Large ships still carry traditional chronometers as back up and navigators are still using 19th century instruments which if properly maintained will keep time to better that one second per day.

These instruments, particularly older ones are becoming increasingly difficult to find in good original condition and are rapidly increasing in value. Restoration work must be carried out by specialists and can be very expensive, so it is important that when purchasing one you make sure that it has been properly restored.

If you are interested in finding out more about the history and workings of marine chronometers, I have written a book intended for the general reader and collector:

'The Marine Chronometer' John Cronin - The Crowood Press ISBN 978 1 84797 185 2 @ £14.99. It is available from Amazon or direct from me.

All my chronometers are fully restored and guaranteed for five years, they are rated to within two seconds per day.

Please select below for instruments I have available.