Smithsonian
  • Navigating
    at Sea
    • Challenges of Sea Navigation
    • Navigating Without a Clock
    • The Longitude Problem
    • The U.S. Goes to Sea
    • Navigate at Sea! Activity
  • Navigating
    in the Air
    • Challenges of Air Navigation
    • Early Air Navigators
    • Navigation at War
    • Navigate the Skies! Activity
  • Navigating
    in Space
    • Challenges of Space Navigation
    • Reaching for the Moon
    • Navigating in Deep Space
    • Navigate in Space! Activity
  • Satellite Navigation
    • Challenges of Satellite Navigation
    • Reliable Global Navigation
    • Global Positioning System (GPS)
    • Who Uses Satellite Navigation
  • Navigation
    for Everyone
    • Meet a Professional Navigator
    • Personal Navigation Stories
  • Timeline of Innovation
  • Artifacts
  • Learning Resources
  • Multimedia Gallery
  • Research
  • Visit the Exhibition

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The untold story of getting from here to there.
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  • Navigating at Sea
  • Navigating in the Air
  • Navigating in Space
  • Satellite Navigation
  • Navigation for Everyone
  • Timeline of Innovation
  • Artifacts
  • Learning Resources
  • Multimedia Gallery
  • Research Journal
  • Visit the Exhibition
  • Challenges of Sea Navigation
    • Navigation Gone Wrong: A British Fleet is Lost at Sea
    • Navigate at Sea! Activity
  • Navigating Without a Clock
    • Early Voyages
    • Dead Reckoning
    • Celestial Navigation
  • The Longitude Problem
    • Cash for Creativity
    • Early Sea Clock Experiments
    • Innovations in England
    • Innovations in France
    • The Chronometer
    • Observing the Skies
    • Navigation Gone Wrong: Wreck of the Arniston
  • The U.S. Goes to Sea
    • Early Contributions
      • Meet the Clockmaker: William Cranch Bond
      • Meet the Navigator: Eleanor Creesy
    • Wilkes Expedition
      • Meet the Mapmaker: Charles Wilkes
      • Maps and Charts
      • The "Scientifics"
  • Navigate at Sea! Activity

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Heitiki Ornament »
Arniston Wreck Site »
Navigational Dividers »
Deer »
Marine Timekeeper made by William Cranch Bond, 1812-1818 »

Innovations in England

The loss of the British Fleet in 1707 near the Scilly Isles provoked demands for safer navigation. Parliament passed the Longitude Act of 1714, which created a panel of experts to oversee rewards for solving the problem of finding longitude at sea.

The Longitude Act of 1714 specified levels of clock accuracy in terms of distance:

• 1st prize (£20,000)
For accuracy of 1/2 degree of longitude, or 30 nautical miles.

• 2nd prize (£15,000)
For within 2/3 degree of longitude, or 45 nautical miles.

• 3rd prize (£10,000)
For within 1 degree of longitude, or 60 nautical miles.

One degree of longitude at the equator equals 60 nautical miles (111 kilometers or 69 miles).

A Breakthrough: John Harrison’s Sea Clocks

A stunning technical breakthrough came when English carpenter and clockmaker John Harrison built five prototype sea clocks between 1735 and 1772. This series of specialized timepieces convincingly demonstrated the feasibility of accurate timekeeping at sea.

Because of Harrison’s improvements in technology, his best clock tested at sea—a large, portable, silver-cased watch—kept time with an accuracy of about 1/5th of a second per day.

Shortly before he died, Harrison received nearly the full £20,000 that England had offered to anyone who could solve the longitude problem—but not until King George III himself intervened. Harrison sent his last sea clock to the king’s private observatory in 1772, where George III witnessed its performance and deemed it prize-worthy.

232-sspl_10237505_highres.jpg

John Harrison
Portrait of John Harrison by James King, about 1766.
Credit: Science Museum, Science and Society Picture Library, London

230-shipwreck-a16333_f-ol_small-test_rgb.jpg

"Ships in Distress off a Rocky Coast," 1667
This painting by Ludolf Backhuysen depicts three Dutch cargo ships.
Credit: Ludolf Backhuysen, Ships in Distress off a Rocky Coast, Ailsa Mellon Bruce Fund, Image courtesy of the National Gallery of Art, Washington
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  • Navigating at Sea
    • Challenges of Sea Navigation
    • Navigating Without a Clock
    • The Longitude Problem
      • Cash for Creativity
      • Early Sea Clock Experiments
      • Innovations in England
      • Innovations in France
      • The Chronometer
      • Observing the Skies
      • Navigation Gone Wrong: Wreck of the Arniston
    • The U.S. Goes to Sea
    • Navigate at Sea! Activity
  • Navigating in the Air
    • Challenges of Air Navigation
    • Early Air Navigators
    • Navigation at War
    • Navigate the Skies! Activity
  • Navigating in Space
    • Challenges of Space Navigation
    • Reaching for the Moon
    • Navigating in Deep Space
    • Navigate in Space! Activity
  • Satellite Navigation
    • Challenges of Satellite Navigation
    • Reliable Global Navigation
    • Global Positioning System (GPS)
    • Who Uses Satellite Navigation
  • Navigation for Everyone
    • Meet a Professional Navigator
    • Personal Navigation Stories
  • Timeline of Innovation
  • Artifacts
  • Learning Resources
  • Multimedia Gallery
  • Research
  • Visit the Exhibition
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  • Privacy
  • Contact
  • Sponsors
  • Press
  • Donate
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