Robert Boyle's weather journal for the year 1685

Robert Boyle was one of the most influential natural philosophers of the Enlightenment. Although he recorded fragmentary instrumental meteorological readings in his numerous works, it was generally thought that he did not record observations with the regularity seen in the journals of other late‐seventeenth century philosophers. However, in the Boyle archive at the Royal Society in London is a diary that was recorded while Boyle was living in London and which provides a largely complete record of twice‐daily barometer, thermometer and weather readings from December 1684 to January 1686. As far as I can tell, these data have not been converted to modern units or scrutinised in any systematic manner. In this paper I derive corrections for the instrumental observations and examine the weather descriptions. Although the record is short, it does provide a detailed daily snapshot of weather conditions for this 14‐month period around London. The dry conditions that lasted into early summer 1685 constituted the most prominent feature of the weather during that year. The journal indicates that the winter 1684/1685 was cold and frequent frosts and fog were experienced, although the following winter of 1685/1686 was relatively mild; summer 1685 appears to have been relatively cool. Overall, the data attest to the variety of weather conditions that could be experienced in London during the Late Maunder Minimum