John Harrison was convinced that the only way for the sailing ships of his age to get an accurate measure of latitude, was to get an accurate time at your current position with reference to Greenwich Mean Time at Zero degrees latitude. To this end he dedicated his life’s work to creating an accurate time piece that could be used on board ship. His was an up-hill struggle as the Royal Society were convinced that accurate sightings of the moon and stars were the best solution to the problem. Harrison developed several variations of his clock cumulating in the mark H4 watch, which used diamond and ruby bearings to replace the original lignum vitae in his previous designs. Harrison dedicated his life to the development of the accurate time pieces and eventually died at the age of 83 years.