Royal Navy officers were obliged by the Admiralty to maintain a logbook (sometimes also known as a journal) in which the day's activities on board were carefully recorded. This, as the Admiralty Instructions from 1731 make clear, included attention to the weather

"‘He [ the officer] is, from the Time of his going on board, to keep a Journal…and be careful to note therein all Occurrences, viz. Place where the Ship is at Noon: Changes of Wind and Weather…remarks on unknown Places; and in general, every Circumstance that concerns the Ship…he is to send a Copy of his journal for the said time, to the Secretary of the Admiralty."


The weather observations, which consisted the wind direction, the wind force and general notes on the weather (rain, snow, fog and similar phenomena were all dutifully noted) were made at midday. Before about 1850 few ships carried much in the way of weather instruments such as barometers and thermometers and the observations were made by careful hudgement of the prevailing conditions. For more information on the details of logbook writing and how these data were converted into present-day, sceintific data go to the CLIWOC website at www.ucm.es/info/cliwoc  Upon return to the ship's home port the logbooks were handed to the care of the Admiralty and today over 100,000 of them date from as early as the 1670s until the mid-nineteenth century when logbook formats changed and instrumental data became more commonplace.






With so many such logbooks from the seas and oceans navigated by the ships of the Royal Navy, and each logbook being crammed with such relaible daily data, it is not surprising that scientists are increasingly turning to this rich and largely unexploited resource in their attempts to recover as much information on past climates and to unravel the complexities of predicting what may happen in the not-too-distant future.