On 24 March 2006 HRH The Duke of Edinburgh unveiled a memorial stone for John Harrison. This is near the graves of George Graham and Thomas Tompion, famous clockmakers, in the centre part of the nave. The inscription reads:
"JOHN 'LONGITUDE' HARRISON CLOCKMAKER 1693 1776"
An inlaid brass and stainless steel strip (one of Harrison's inventions – a bimetallic strip) is placed through his name with the longitude for the stone, 000º 7' 35" W, inscribed on it (this was calculated by the National Maritime Museum). Lettering by Gary Breeze.
John was baptised at Foulby in Yorkshire on 31 March 1693, the eldest child of Henry (d.1728) and his wife Elizabeth (Barber). He was a carpenter before he turned to making clocks. In 1718 he married Elizabeth Barrel (d.1726) and secondly in 1726 Elizabeth Scott. Two of his sons, John and William, reached maturity. In 1726 he heard about the Longitude Act, offering a reward to anyone who could find a reliable method of determining longitude at sea. Finding longitude at sea was becoming a major concern to all the seafaring nations as only latitude could be determined with reasonable accuracy at this period. Many ships were wrecked in storms because they did not know their correct location. At sea keeping time involved overcoming the problems of motion and variations in gravity and temperature in different latitudes. It took John thirty years to perfect his prize-winning watch, pioneering the development of the marine chronometer. He died in London on 24 March 1776 and is buried at St John's church, Hampstead.
A photo of the stone can be purchased from Westminster Abbey Library.
"The Quest for Longitude" edited by William J.H.Andrewes, 1998
See the website of the National Maritime Museum, Greenwich