Blast From The Past Sunday: John Harrison.

John Harrison was an 18th century self-taught English clockmaker who is most recognized for his achievement of finding a way to accurately measure latitude and longitude. It took Mr. Harrison fourty years to build and perfect his marine chronometer (a ship clock accurate enough for navigation). It is important to note that previous to the invention of his ship clocks, celestial navigation was the only way of calculating maritime distance and location. This method was a less than precise practice and led to many lost ships and lives.  John Harrison's marine chronometer is seen as one of the most significant inventions of the 18th century.  The technology we enjoy today relies on the 300 year old contributions of John Harrison.  So, the next time you get lost and look to the G.P.S. (Global positioning System) for guidance, be sure to thank Mr. Harrison.  Another significant contribution of Harrison was his Grasshopper Escapement (invented in 1722).
The Grasshopper Escapement is a low-friction escapement for pendulum type clocks. Perhaps one of the most interesting modern examples of John Harrison's Grasshopper escapement is on display at Cambridge. The clock is called the Corpus Clock or Chronophage (Time Eater).

-JKS