The discussion revolves around the exhibit of John Harrison's clocks at the Mystic Seaport Museum, its historical significance in maritime navigation, and inquiries about the future location of the exhibit. The conversation touches on both historical context and the technical challenges of determining longitude at sea.
Participants generally agree on the significance of John Harrison's work in navigation, but there are varying levels of detail and emphasis on the technical challenges of longitude determination. The future location of the exhibit remains uncertain, with multiple suggestions presented.
The discussion includes assumptions about the historical context of navigation and the technical specifications of timekeeping devices, which are not fully resolved or detailed.
historicallywhy was longitude a harder problem to solve for navigators than latitudejedishrfu said:Thanks for sharing. John Harrison's legacy really revolutionized maritime navigation. It's hard to imagine what we'd be doing today without it.
https://en.wikipedia.org/wiki/John_Harrison
https://en.wikipedia.org/wiki/Longitude_(book)
and NOVA did show on his work based on the Sobel's book Longitude.
Why was longitude determination such a difficult problem compared with finding latitude? A very basic answer is that latitude is measured north or south and so is independent of the Earth's east-west rotation, whereas longitude's determination by celestial means is affected by that rotation. Latitude can be found, in principle, from angular measures alone—say the angle of the midday sun above the horizon—but longitude requires knowledge of time. Thus if a mariner had a clock keeping Greenwich time and found that it read 2 p.m. when the sun was at its maximum angle above the horizon—the local noon—he would know that his longitude was two hours west of Greenwich. The whole problem lay in finding a clock that would keep time with sufficient accuracy over the long voyages of the 17th and 18th centuries. The best timekeepers of the age were pendulum clocks, but these were useless on the heaving deck of a small ship, whereas spring-wound clocks were relatively crude and hopelessly inaccurate for voyages over many weeks or months.
Sydney, Australia Then back to EnglandAstronuc said:http://www.mysticseaport.org/ships-clocks-stars/
Exhibition produced by the National Maritime Museum, London
I wish that I had known about it. Where will the exhibit go from there?