Admiral Robert Fitzroy devised this form of barometer to help anticipate bad weather for people working at sea or in coastal villages. Atmospheric presure - the weight of air - is indicated by the fluctuating levels of mercury in an upended sealed tube in a barometer. Fitzroy was the captain of the 'Beagle' during Darwin's voyages and was later made the first head of what was to become the UK Meteorological Office and introduced the first published daily weather forecasts in The Times in 1860. Fitzroy also devised a system of signals appropriate for use by day or night which would be hoisted above a harbour to warn shipping of imminent storms, effectively the precursor of the modern shipping forecast broadcast on the radio.
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