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Timekeeping
H3 (ZAA0036)
| Object name: |
Marine timekeeper
We
have 4 objects of this type online
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A6263, Marine timekeeper (H3), back and side
© National Maritime Museum, Greenwich, London
About our images
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| Artist/maker: |
John Harrison
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| Date made: |
1757 |
| Place made: |
London, England |
| Materials: |
brass; bronze; steel; glass |
| Measurements: |
Overall display height: 622 mm |
| Credit: |
National Maritime Museum, Greenwich, London, Ministry of Defence Art Collection |
| Collection: |
Chronometers, precision watches and timekeepers
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| Other views: |
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Description:
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Marine timekeeper, H3. Started in 1740, this third timekeeper took Harrison nearly 19 years to build and adjust, although it was not to win him the great longitude prize: he found that he just could not persuade the two large, heavy, circular balances to keep time well enough. Nevertheless, H3 incorporates two extremely important inventions, both relevant today: the bimetallic strip (still in use worldwide in thermostats of all kinds) and the caged roller bearing, a device found in nearly all modern mechanical engineering. See also; ZAA0034 (H1), ZAA0035 (H2) and ZAA0037 (H4).
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Related terms
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Horology
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The foundation of the Royal Observatory, in 1675, was expressly to discover a method for finding longitude, and this astronomical research required the use of very accurate clocks. More…
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