The Royal Society read Leeuwenhoek's letter of May 14, 1677

May 17, 1677

Birch's History, vol III, p 339:

Mr. OLDENBURG produced a letter to himself from Mr. LEEWENHOECK, dated at Delft, 14th May, 1677, concerning the observations made by him of the carneous fibers of a muscle, and the cortic and medullary part of the brain, as also of moxa and cotton.

Note: Because England had not yet adopted the Gregorian calendar, this letter was read in London 13 days after it was written in Delft, not 3 days, as the dates would imply.