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On this floor, the collection of marine chronometers is on display. Used since the 18th century to determine longitude (the angular distance from the prime meridian of Greenwich, measurable by comparing the time at the port of origin with local time: 1 hour equals 15 degrees of longitude).
Chronometers: the marine chronometer was designed by the craftsman, mechanic, and carpenter John Harrison (1693–1776), who spent roughly 60 years refining the device. Harrison never received the full amount of the prize offered by the British Parliament, which downplayed his work simply because he was not an academic scientist.
The museum houses 50 chronometers from the 19th and 20th centuries of Swiss, German, English, and French manufacture.
The chronometer is housed in a brass case suspended inside a mahogany box and protected by glass for reading the dial. It was wound with a special key by turning it 8 to 10 times. Ships always carried 2 or 3 chronometers on board for safety in case one failed.
Sundials: portable sundials that indicate solar time through the shadow cast by the gnomon onto the dial. The items on display date from between the late 17th and early 19th centuries, made of ivory and painted wood from various origins (including Chinese). Notable among these are shepherd's dials, characterized by their typical cylindrical shape.
Astrolabe: an ancient astronomical instrument used to calculate the altitude of the Sun or a star above the horizon and to determine local time (knowing the latitude). It reached Europe from Persia via Spain during the Arab occupation in the 10th century. The three examples on display are brass alloy reproductions of ancient models, made between the 19th and 20th centuries.
Planetarium: an instrument used to realistically reproduce the Solar System. The item on display was made in Berlin in 1870.
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