Seven inches and an half

I’m reading Gilbert White’s Natural History of Selborne a letter at a time. His letter to Daines Barrington of December 20, 1770 ends with a postscript:

There fell in the county of Rutland, in three weeks of this present very wet weather, seven inches and an half of rain, which is more than has fallen in any three weeks for these thirty years past in that part of the world. A mean quantity in that county one year is twenty inches and an half.

The person measuring the rain in Rutland was Thomas Barker of Lyndon, White’s brother-in-law. I transcribed his rainfall record six days ago, so I could check the postscript.

• Barker’s own account. In his paper in the Philosophical Transactions for 1771 (JSTOR 106096, p. 222), he says no three months in his record “come up to the last quarter of 1770, 7½ inches of which came in three weeks, from Nov. 6 to 26.” His monthly table gives November 1770: 7.818 inches (about 199 mm). The nine Novembers before it ranged from 0.92 to 4.04 inches.
• “Twenty inches and an half.” Barker’s yearly totals for 1737–1769 average 20.85 inches.
• The national series. In the Met Office’s England & Wales Precipitation series, November 1770 has 200.8 mm. It is the third-wettest month on record, from 1766 to 2025, behind October 1903 and November 1852.
• On the ground. At Worcester’s Water Gate there is a plate, and “on the 18th November, 1770, the flood rose to the lower edge of the plate”, ten inches higher than the flood of December 23, 1672. Tewkesbury’s local history calls 1770 “the greatest flood ever known at Tewkesbury”. The water came up the lanes on November 17, and on the 18th boats were needed to get from the Hop Pole Inn to the Masons Arms. A flood chronology citing the Gentleman’s Magazine of 27 November has the Fens under three to nine feet of water over about twenty miles by six. All of this falls inside Barker’s three weeks.

So White’s postscript holds up in every particular I can check. One caveat: before 1789 the national series rests on very few stations, and Lyndon may be one of them, so the third piece of evidence may partly be the first. The flood marks are independent, though.

And a guess of mine that didn’t hold. Two months earlier, writing from Ringmer in Sussex on October 8, White says the swallows are lingering, “induced to prolong their stay by this soft, still, dry season.” Before looking at the data I wrote down that September 1770 should come out at 80% or less of normal rainfall. It came out at 86%. August was dry (62%), and September was a little warm (+0.6 °C on the Central England Temperature series). Monthly totals can’t see the fortnight he was writing about, so I can’t say whether White was right about it. My guess was too confident. Then November came.

Sources: Gilbert White, Natural History of Selborne (Project Gutenberg), Barrington letters VII and VIII. Thomas Barker, Phil. Trans. 61 (1771), via the JSTOR Early Journal Content OCR on archive.org. Met Office HadEWP and HadCET monthly series, fetched Oct 19, 2026. Worcester People and Places, “Memorable floods and frosts”; Tewkesbury Historical Society, “A List of Floods”; JBA Trust, East Anglia flash flood chronology.