Chronology of events:

For some events, the year is certain but the month and day are not. Example: We know only the year for the collections of Leeuwenhoek's letters published in Dutch during his lifetime.

For other events, the season or month are certain but the day is not. Example: Leeuwenhoek mentions that someone visited him "last month".

On the other hand, many events did indeed happen on the first day of a month. Example: public appointments to Delft's city offices took effect on January 1 of each year. Thus:

  • A date of January 1 in a given year may indicate that the year is certain but the month and day are not.
  • A date of 1 in a given month may indicate that the year and month are certain but the day is not.

Unless otherwise indicated, for events in England, the date given is Old Style, 10 days behind the Dutch Republic's New Style until 1700 and then 11 days behind.

Date
August 24, 1674 daughter Maria made a will
September 7, 1674 Wrote letter of 1674-09-07 (AB 10) to Henry Oldenburg
September 7, 1674 Wrote Letter 6 of 1674-09-07 (AB 11) to Henry Oldenburg
October 19, 1674 Wrote Letter 7 of 1674-10-19 (AB 12) to Henry Oldenburg
October 26, 1674 Henry Oldenburg wrote to Leeuwenhoek encouraging him and asking about the kind of salt he was observing
November 12, 1674 The Royal Society read and discussed Leeuwenhoek's letter of June 1, 1674
December 4, 1674 Wrote Letter 8 of 1674-12-04 (AB 13) to Henry Oldenburg
December 21, 1674 Appointed to administer the affairs of sister-in-law Maria de Meij
December 22, 1674 sister-in-law Maria de Meij and Pieter Schepens granted a divorce
December 24, 1674 Henry Oldenburg wrote to Leeuwenhoek about his doubts about globules
December 26, 1674 Wrote letter of 1674-12-26 (AB 14) to Constantijn Huygens
December 31, 1674 sister-in-law Catharina Swalmius buried
January 1, 1675 cousin Maerten Huijchs Leeuwenhoek appointed tax farmer
January 20, 1675 Christiaan Huygens wrote to Henry Oldenburg doubting Leeuwenhoek's observations of globules
January 22, 1675 Wrote Letter 9 of 1675-01-22 (AB 15) to Henry Oldenburg
February 2, 1675 Henry Oldenburg wrote to Christiaan Huygens about doubting Leeuwenhoek's globules
February 11, 1675 Wrote Letter 10 of 1675-02-11 (AB 16) to Henry Oldenburg
February 19, 1675 Henry Oldenburg wrote to Leeuwenhoek in response to his letter of 1675-01-22
March 26, 1675 Wrote Letter 11 of 1675-03-26 (AB 17) to Henry Oldenburg
April 12, 1675 Henry Oldenburg wrote to Leeuwenhoek recommending that he get help from knowledgable people
August 14, 1675 Wrote Letter 12 of 1675-08-14 (AB 18) to Henry Oldenburg
August 22, 1675 Henry Oldenburg wrote to Leeuwenhoek acknowledging reciept of his letters
September 15, 1675 First observed microbes in rain water
December 15, 1675 Jan Vermeer, the painter, buried
December 20, 1675 Wrote Letter 13 of 1675-12-20 (AB 19) to Henry Oldenburg
December 28, 1675 Henry Oldenburg wrote to Leeuwenhoek about the reaction in London to his observations
January 22, 1676 Wrote letter of 1676-01-22 (AB 20) to Henry Oldenburg
January 26, 1676 sister-in-law Maria de Meij buried
February 3, 1676 Henry Oldenburg wrote to Leeuwenhoek requesting that he examine hair
February 22, 1676 Wrote Letter 14 of 1676-02-22 (AB 21) to Henry Oldenburg
April 5, 1676 co-worker Daniel Bogaert married Maria van Rees
April 21, 1676 Wrote Letter 15 of 1676-04-21 (AB 22) to Henry Oldenburg
April 24, 1676 Began series of experiments to observe microbes
April 26, 1676 Began Pepper 2 experiment
May 4, 1676 Henry Oldenburg wrote to Leeuwenhoek about Hooke's and Grew's reactions to recent observations
May 29, 1676 Wrote Letter 16 of 1676-05-29 (AB 23) to Henry Oldenburg
July 1, 1676 Visited by Christiaan Huygens during the summer; he saw the microbes in Leeuwenhoek's infusions
July 28, 1676 Wrote letter of 1676-07-28 (AB 24) to Henry Oldenburg
July 28, 1676 Wrote Letter 17 of 1676-07-28 (AB 25) to Robert Boyle
September 30, 1676 Appointed curator of estate of Catherine Bolnes, Vermeer's widow
October 9, 1676 Wrote Letter 18 of 1676-10-09 (AB 26) to Henry Oldenburg
October 18, 1676 Henry Oldenburg wrote to Leeuwenhoek; sent Philosophical Transactions no. 127
October 23, 1676 mentor Cornelis 's Gravesande lent money to Sijmons Decker
October 26, 1676 Henry Oldenburg wrote to Leeuwenhoek acknowledging receipt of the letter of 1676-10-09
October 30, 1676 Wrote letter of 1676-10-30 (AB 27) to Henry Oldenburg
November 7, 1676 Wrote letter of 1676-11-07 (AB 28) to Constantijn Huygens
November 12, 1676 Henry Oldenburg wrote to Leeuwenhoek that he would write at greater length soon
November 18, 1676 Visited by Gottfried Leibniz
November 25, 1676 Magistrates approved payment by Maria Thins so Leeuwenhoek could pay Vermeer's creditors
November 27, 1676 Wrote letter of 1676-11-27 (AB 29) to Henry Oldenburg
January 22, 1677 mentor Jacob Spoors buried
January 26, 1677 Constantijn Huygens wrote to Oldenburg about Leeuwenhoek, a "painstaking man" who should be "cherished"
January 30, 1677 cousin Lambrecht Huijchs Leeuwenhoek (1624-1701) bought A0129 Buitenwatersloot 214
February 2, 1677 Recovered twenty-six paintings from Jannetje Stevens to help pay Catherine Bolnes' creditors
February 11, 1677 The Royal Society read the first part of Leeuwenhoek's long letter of the previous October 9
February 15, 1677 Wrote letter of 1677-02-15 (AB 30) to Christiaan Huygens
February 18, 1677 The Royal Society read the second part of Leeuwenhoek's long letter of October 9, 1676
February 22, 1677 Henry Oldenburg wrote to Leeuwenhoek for more details about his method for observing little animals
March 4, 1677 Henry Oldenburg wrote to Leeuwenhoek requesting that he examine muscle fibers and brains
March 8, 1677 The Royal Society read the third part of Leeuwenhoek's long letter of October 9, 1676.
March 12, 1677 Maria Thins filed a legal action to prevent Leeuwenhoek from selling The Art of Painting
March 15, 1677 Organized the auction of Vermeer's remaining paintings
March 23, 1677 Wrote Letter 19 of 1677-03-23 (AB 31) to Henry Oldenburg
March 25, 1677 The Royal Society published Leeuwenhoek's letter of October 9, 1676, reporting microbes in infusions
March 29, 1677 The Royal Society read Leeuwenhoek's letter of March 23, 1677
April 20, 1677 Henry Oldenburg wrote to Leeuwenhoek relaying the compliments of the members of the Royal Society
May 14, 1677 Wrote Letter 20 of 1677-05-14 (AB 32) to Henry Oldenburg
May 18, 1677 Benedict Haan and Henry Cordes wrote to the Royal Society attesting to microbes in Leeuwenhoek's infusions
May 27, 1677 The Royal Society read Leeuwenhoek's letter of May 14, 1677
June 2, 1677 Robbert Gordon wrote to the Royal Society attesting to microbes in Leeuwenhoek's infusions

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