# Longitude 3 - The winner

© National Maritime Museum, Greenwich, London

##### Harrison's famous H1 Sea Clock, his first attempt. It took him five years to design and build. Later he realised that large clocks were not the right way. Smaller watches worked better because the timing movements were much faster than the ship's movement and the two did not interfere. After 30 years he had his final solution and collected the prize.

© National Maritime Museum, Greenwich, London

### Solving the problem- clocks and stars

##### Questions

1. Clocks and pocket watches were made before 1714. What conditions would you expect at sea in a wood sailing ship? Would these be harmful to clocks and watches?

2. Astronomical observations can be used to measure time, for example the timing of the orbits of the moons of Jupiter. Why would making those observations be difficult at sea?

3. In the eighteenth century, ships navigators were highly skilled in mathematics and astronomy. They were also all men. In the modern services are science skills still needed and are women likely to be equal to men in these skills?

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##### John Harrison worked on the problem for over thirty years.

© National Maritime Museum, Greenwich, London

##### Harrison's H4 sea watch

© National Maritime Museum, Greenwich, London

Credit: NASA
##### Today's explorers are also scientists. This is another captain, Samantha Cristoforetti, a Captain in the Italian Air Force, running experiments on board the International Space Station in April 2015.

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