Meeting Recap - John Harrison: Longitude, the Precision Watch and Pendulum Clock

John Harrison's H1 Marine Chronometer

John Harrison's H1 Marine Chronometer

Rory McEvoy - Curator of Horology at the Royal Observatory, Greenwich, UK
April 4, 2016

The guest speaker at the April 4th meeting of the HSNY was Rory McEvoy from the Royal Observatory in Greenwich, England. Held at our new meeting place, the General Society library, a large audience heard him discuss the contributions to horology by the famous scientist and inventor, John Harrison. Many clocks made by Harrison are at the museum, which displays the H4 chronometer, the first accurate timepiece made to calculate longitude at sea. Mr. McEvoy related some interesting details about how Harrison produced this smaller chronometer.

At an early age Harrison was a bell ringer; he observed the rhythmic swinging of bells giving him the idea to utilize the horizontal pendulum in his first attempt to win the prize for longitude. Two more version over many years were not successful. Utilizing a mainspring and not depending on gravity was the solution; a highly precise type of pocket watch, which could be handled more easily at sea, instead of a cumbersome clock, was the answer. Harrison formulated special alloys and sought the advise of famous watchmakers to achieve a final accuracy of one half degree, adequate for navigation. In fact some "copies" of H4 were ordered by the British Admiralty and made by Kendall or Jeffries. History records that one was used on the famous ship "Bounty."

Our thanks to Mr. McEvoy for this informative presentation. The story of John Harrison is fascinating and inspiring.

Submitted by Walter Pangretitsch, Recording Secretary, HSNY