Clue from nature AD 1800 📍 Seesen, Harz, Germany (beech forest)

Beech seed crops at Seesen (Harz, Germany), scored every year 1685-1875: Picardy sweat years follow a big crop only weakly, and just as much precede one

scripts/sweat_mast.py, tests set before looking. Mast score (1 to 5) in the year before outbreak years minus other years: +0.35 (all France, shuffle p 0.04, shift p 0.05) and +0.33 (Hirsch's north-east strip, p 0.06 / 0.04). But the year after an outbreak shows the same rise (+0.39, p 0.05), which a cause cannot do, and with outbreak years shuffled only within 20-year blocks the signal falls to p 0.08-0.11. 16 of 23 big crops (score 4-5) were followed by an outbreak somewhere in France the next year, against about 51% by chance (p 0.06). The largest outbreak years (1849: 15 departments, 1854: 12, 1855: 10) did not follow big crops at Seesen. Seesen is 500-800 km from the outbreak areas, so a French mast record would be a fairer test; none was found before 1858. Also: Dijon April-August temperature (grape harvests) and English June-August temperature two years before outbreaks were slightly cooler, not warmer (p 0.72-0.95), confirming the earlier negative result with two more temperature records.

How it connects

This clue from nature supports this hunch Sweating sickness followed seed-boom years, as modern European hantavirus does direct mast record: weak, not specific to the year before

This clue from nature is a clue for English sweating sickness: what was it?

This clue from nature we read it in Ascoli et al. 2017, Two centuries of masting data for European beech and Norway spruce across the European continent, Ecology 98: 1473 (data file in the Cambridge repository); Seesen (Harz) series from Beling 1877

This clue from nature we read it in Chuine et al. 2004/2005, Burgundy Pinot Noir grape harvest dates and Dijon April-August temperature reconstruction, 1370-2003 (NOAA Paleoclimatology)

This clue from nature we read it in Central England Temperature, monthly, 1659 to today (Manley 1974; Parker et al. 1992), Met Office Hadley Centre

This clue from nature we read it in Hirsch 1883, Handbook of Geographical and Historical Pathology, vol. 1 (English translation), chronological table of miliary fever (Picardy sweat) epidemics in France 1718 to 1879; outbreak years extracted to sources/picardy_sweat_years.json

This clue from nature came from this step Checked the Picardy sweat against a real beech seed record and against today's hantavirus map