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Tag Archives: weather charts

Locke’s swallows

Peter Anstey writes…

John Locke’s commitment to the experimental philosophy was extraordinary. In the 1690s, arguably the busiest decade of his life, Locke continued to make daily detailed records of the prevailing weather conditions at Oates, the house of Francis Masham where he resided from 1691.

Each day he would enter the day of the month, the hour, the temperature, barometric pressure, humidity, wind direction and speed, and the overall weather conditions. Sometimes he recorded three or four sets of data within a single day. Of course, Locke was not the only one in England who was collecting such data. He was merely a small part in a larger loosely connected project that aimed to construct a natural history of the air. The inspiration here was his mentor Robert Boyle whose A General History of the Air Locke had seen through the press in 1692 after Boyle’s death. Indeed Locke included a set of his own weather records from the 1660s in that work and perhaps it was the self-confessed incomplete nature of Boyle’s history that spurred Locke on to resume his weather charts in December 1691 (the very month in which Boyle died). The incompleteness of Boyle’s history is also the explanation of the fact that Locke had his own copy of the work interleaved and began to add new observations on the air.

One particularly interesting set of records is that for the month of September 1694. Here are the readings for the 4th of that month:

Day           Hour       Temp        Barom           Hygrom          Wind          Weather

4 ∙9     5o— 15. 2436 WS  3 covered, a shower at 21
24 1 ∙ 7 29∙10. 2233 very fair

The small dot to the left of the hour indicates that the first reading was made around 9.45am. There was no standard of temperature in Locke’s day, so he provides a relative reading of 5 marks above the zero mark, which was set at temperate rather then freezing. The morning wind from the WSW was evidently quite strong: Locke’s scale is from 0 to 4. And he was up late recording that there was a rain shower at 9pm and taking another set of readings at midnight. (It is interesting to note too that he used a 24-hour clock and records made at midnight are not uncommon.)

After this entry, Locke makes the following observation:

SWALLOWS. No Swallow or Martins this day plying about the house or Moat as they used to be but every now & then 3 or 4 or more appeared & after 2 or 3 turns were gone again out of sight they generally flew very high and seemed to be passengers & to take their course southward as far as I could observe whether they were plying about the house yesterday or not I did not observe.

Then on the 19th of the month he reflects back on the swallows:

SWALLOWS The observation made 4° Sept will need some further experiments to confirm it. It being hard to take notice of their flight so as to be sure they doe not return again. But this I am certain that after that day neither SWALLOWS nor Martins were so many nor so busy as before. But yet some of them though not so frequent were to be seen till the 19th & then I went to London.

Notice the talk of the need for further experiments. Here, within a project for the systematic collection of data for a Baconian natural history, a project that involves the daily use of newly invented meteorological instruments, Locke makes a further observation and conceives of it in terms of the application of the experimental method.

So thorough are Locke’s records that, by his own admission, ‘there seldom happen’d any Rain, Snow, or other remarkable change, which I did not set down’. And what was it all for? He told Hans Sloane that with enough meteorological data ‘many things relating to the Air, Winds, Health, Fruitfulness, &c. might by a sagacious man be collected from them, and several Rules and Observations concerning the extent of Winds and Rains, &c. be in time establish’d to the great advantage of Mankind.’