Harrison and His Clock
The Man who Solved the Longitude Conundrum
John Harrison - Carpenter, Clockmaker, and Inventor of the Marine Chronometer
P. L. Tassaert 's half-tone print of Thomas King's original 1767 portrait of John Harrison. Located at the Science and Society Picture Library , London
- Born March 1693, in Yorkshire
- Father: Joiner and surveyor
- Self taught
- Made a copy of Cambridge math professor's lectures and tested every theory
- Small Pox as a child. Was given a watch to pass the time to improve his health
Birthplace
Memorial
Tomb
Birthplace
Harrison was born in 1693. A blue plaque marks what may have been his family's home.
Memorial
Located in Westminster Abbey, a memorial to John Harrison can be found on the floor. The stone is inscribed with the longitude for of where it lies, 000º 7' 35" W, (this was calculated by the National Maritime Museum).
Tomb
Upon his death in 1776, Harrison was interred in the church cemetery at Hampstead Parish Church, London. The tomb is engraved with the story of Harrison's life and work.
Harrison built his first clock in 1713. It was a pendulum style clock with a unique wooden design. This clock was accurate to within 1 second per month. He adapted this design to build a clock tower for Sir Charles Pelham at Brocklesby Park which still functions today.
“Harrison’s timekeepers saves countless lives and innumerable ships and cargo, and placed John Harrisons as one of the greatest of the 18th century’s scientific achievements. Indeed, one can also say that H4 was not just the world’s first practical marine timekeeper, it was the first of all truly accurate watches, the ‘father’ of every precision watch which came after.” - Betts, 2006, p.15
The Longitude Act of 1714
Calculating longitude at sea prior to 1714 was dangerous. Sailors had no means to accurately measure their location in terms of longitude, and many ships and crews perished through the years because they didn't know where they were.
After a petition by the Merchants and Seamen, the British Parliament created the Longitude Act of 1714 , which challenged Britains to solve the problem of being able to calculate longitude at sea.
Acceptable solutions had to be "practical and useable". £20,000 was offered to anyone who could prove to be accurate within ½ degree, £15,000 was offered to anyone who could prove accuracy within 2/3 of a degree, and £10,000 was offered for accuracy within 1 degree. It would take 47 years before ½ degree could be proven.
Harrison Enters the Challenge
Harrison's First Entry
Took 20 Years to complete
Weighed 60, and 753 parts
Bimetallic strip
Caged roller bearing (ball bearings)
Circular balance bars linked by metal ribbons
Harrison's Second Entry
Two Year Endeavor
Weight 86 lbs.
Invented the spring remontoire
Never made it to sea
Harrison's Third Entry
Took 20 Years to complete
Weighed 60, and 753 parts
Bimetallic strip
Caged roller bearing (ball bearings)
Circular balance bars linked by metal ribbons
Harrison's Fourth Entry
5 inches across
Weighs 3 pounds
Uses diamonds as bearings to reduce friction
Nevil Maskelyne Rivalry
Nevil Maskelyne was a peer to John Harrison that believed a lunar method to calculating longitude was best. His advocacy for this method eventually led to somewhat of a rivalry between the two men, each trying to prove their longitude solution superior to the others'.
Read their story and ask yourself, was Nevil Maskelyne a supporter to John Harrison, or a villain? What leads you to your conclusion?
Hero or villain? Nevil Maskelyne's posthumous reputation. Presentation by Dr. Rebekah Higgitt, Curator of History of Science and Technology at the Royal Observatory in Greenwich.
Harrison's Legacy
- Harrison's true memorial is his contribution to accurate navigation (shows bi-metal strip)
- Harrison Medal awarded by the Worshipful Company of Clockmakers
- Memorial located in Westminster Abbey
- 230 years later
“John Harrison's invention enabled men to explore the earth with precision and, when most of the earth had been explored, to dare to build navigation systems for voyages to the moon.” - Neil A. Armstrong.
