A message from Clocktime's Creator Good morning As you may well know, John Harrison is my hero, so I’m delighted to be giving a talk about his inventive genius at the Annual Convention for the National Association of Watch and Clock Collectors (NAWCC), taking place in Pennsylvania USA next month. I’m also pleased that my friend Roger W Smith will be giving the keynote speech there. John Harrison made the first marine chronometers that could stand the rigors of a sailing ship in the tropics and the polar regions. These were accurate enough to find longitude at sea. His masterstroke was that he miniaturised his inventions and also improved the accuracy of his creations, as demonstrated by his iconic H4, completed in 1759. At the time, the H4 was the most accurate timekeeper in the world, thanks to his innovative use of diamond pallets - a hard-wearing, low-friction material that he used in its escapement. Harrison was the first to use bi-metal to compensate for the temperature variations in his clocks. This culminated in the design of the gridiron pendulum for his wooden regulator in 1726. He used this design for his H3 sea clock, started in 1740. He then applied these principles to the design of his two later marine chronometers, the H4 and the H5, made in 1759 and around 1770 respectively. (H4 is at the Royal Museum Greenwich and H5 is at the Clockmakers’ Museum within the Science Museum). I first came across bi-metal in my father’s workshop in 1945, when I was just nine years old. I’ve been fascinated ever since. I spent my entire business life designing thermostats, temperature safety cutouts, motor protectors and kettle controls. All of these utilise the very bimetal that Harrison invented. Dr John C Taylor OBE FREng
