John Harrison

John HarrisonHarrison is the classical example of a workman becoming a master without any formal training. He was born in Wragby, Yorkshire, the son of a carpenter and moved to Barrow where he pursued the trade of carpenter. From an early age he showed a great interest in the improvement of clocks. He made clocks with wooden wheels. (The Guildhall Museum has an example with wooden wheels, except from the escape wheel).

He was encouraged to produce a timekeeper sufficiently accurate to determine longitude at sea by an Act of Parliament of 1714 offering £20,000 as a reward for such an instrument. In 1728, Harrison journeyed to London to demonstrate a compensated pendulum he had invented. This pendulum was made of nine rods, five of steel and four of brass, the length of each kind being 100 to 60, that being the ratio of expansion of the two metals. This pendulum, called a gridiron pendulum, was to be widely employed and most satisfactory.

It was also to show his timekeeper that Harrison made his journey and he hoped that the Board of Longitude would consider his proposed timekeeper. George Graham was asked to report on his work and it was at this meeting that Graham lent Harrison a substantial sum of money so that he might continue with his work. Only after many trials of his various timepieces did Harrison finally get his reward for producing the first chronometer to meet with approval. He died in 1776.

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