Map Showing Recorded Dates of Influenza Epidemic in 1889 and 1890

From Report on the Influenza Epidemic of 1889–90 by Dr. Henry Parsons (1846–1913), London : Printed for Her Majesty's Stationery Office by Eyre & Spottiswoode, 1891.

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(courtesy Wellcome Collection, attribution 4.0 International (CC BY 4.0))