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
January 25, 1663 son Philips Leeuwenhoek (second) baptized, buried three weeks later
April 25, 1663 brother-in-law Adriaan Johannes Swalmius (1631-1667) married Margrieta van der Burch
July 2, 1663 Christiaan Huygens elected member of the Royal Society
August 1, 1663 Christiaan Huygens received letter from Gutschoven about how to grind small lenses
January 1, 1664 cousin Maerten Huijchs Leeuwenhoek appointed tax farmer
February 19, 1664 cousin Sara Maertens Leeuwenhoek (1664-1693) baptized
May 11, 1664 nephew Johannes Adriaans Swalmius (1664-1693) baptized
June 25, 1664 Bought a garden outside the walls of the city
August 19, 1664 son Philips Leeuwenhoek (third) baptized
September 3, 1664 mother Margriete Jacobs van den Berch (1594-1664) buried in Oude Kerk
September 29, 1664 Owed for store goods by the estate of Elizabeth Cornelis
November 25, 1664 Received a legacy from the estate of great-aunt Aaltge Sebastiaans van den Berch
January 1, 1665 Robert Hooke's Micrographia published
March 26, 1665 Christiaan Huygens acquired Hooke's Micrographia
July 13, 1665 Appointed guardian of second cousin Maria van Halmael
January 1, 1666 mentor Reinier de Graaf (1641-1673) moved to Delft
May 28, 1666 cousin Elisabeth Maertens Leeuwenhoek (1666-1743) baptized
June 27, 1666 son Philips Leeuwenhoek (third) buried in Oude Kerk
July 14, 1666 wife Barbara de Meij buried in Oude Kerk
October 10, 1666 Appointed district supervisor (wijkmeester generaal)
January 1, 1667 Dirck van Bleyswyck's Beschryvinge der Stadt Delft, Description of the City of Delft, published
February 5, 1667 mentor Jacob Spoors married Trijntge Jans
March 11, 1667 Presented will after wife Barbara's death
May 2, 1667 brother-in-law Adriaan Johannes Swalmius (1631-1667) buried
May 18, 1667 Appointed curator of estate of Simon de Bourbon
July 15, 1667 Appeared before the Weescamer to begin the process of curating the estate of Simon de Bourbon
September 15, 1667 aunt Cornelia Jacobs van den Berch buried in Oude Kerk
January 1, 1668 Traveled to England
June 13, 1668 grandfather Thonis Phillips Leeuwenhoek's will of 1643 presented
January 1, 1669 cousin Pieter Abrahams Hogenhouck (-1679) appointed mayor in 1669-1673, 1677
February 4, 1669 Certified as a surveyor after passing the oral examination
February 15, 1669 uncle Huijch Thonis Leeuwenhoek buried in Nieuwe Kerk
October 8, 1669 daughter Maria named in will of her aunt Maria de Meij
July 13, 1670 cousin Cornelis Lambrechts Leeuwenhoek (1670-1702) baptized
September 2, 1670 Appointed co-wine gauger to help Dirk Arisz.
January 8, 1671 Testified to marriage conditions with Cornelia Swalmius
January 17, 1671 daughter Maria made a will
January 25, 1671 Married Cornelia Johannes Swalmius
April 14, 1671 Agreed to act as steward for land inherited by second wife Cornelia
May 30, 1671 cousin Anthonij Lambrechts Leeuwenhoek (1653-1671) buried in Oude Kerk
October 15, 1671 wife Cornelia Johannes Swalmius (1634-1694) testified to marriage conditions with Antony
January 10, 1672 sister-in-law Elisabeth Johannes Swalmius married Paulus Marcel
February 17, 1672 Jan Strick was buried
April 9, 1672 Disaster Year: Delft sent troops to help defend against the invading French army
June 12, 1672 mentor Reinier de Graaf married Maria van Dijck
June 29, 1672 Disaster Year: unemployed protestors from Schiedam occupied Delft city hall
July 8, 1672 Prince Willem III wrote to the burgemeesters of Delft that those not cooperating in repelling the enemy will be severely punished
September 10, 1672 Prince Willem III wrote to the burgemeesters of Delft concerning the naming of new regents
September 10, 1672 mentor Dr. Cornelis 's Gravesande appointed to Veertigraad
September 10, 1672 Disaster Year: half of the Veertigraad replaced with pro-Orangist regents
September 21, 1672 daughter Maria made a will
November 7, 1672 nephew Arnold Marcel (1672-1748) baptized in Dordrecht
April 1, 1673 cousin Magdaleentje (Helena) Maertens Leeuwenhoek (1653-1720) married Johannes de Coep
April 28, 1673 Wrote Letter 1 of 1673-04-28 (AB 1) to Henry Oldenburg
May 7, 1673 The Royal Society received Leeuwenhoek's first letter
May 15, 1673 Henry Oldenburg wrote to Reinier de Graaf about the Royal Society's reception of Leeuwenhoek's first letter
May 19, 1673 At age 40, first letter published in Philosophical Transactions
August 8, 1673 mentor Constantijn Huygens wrote to Robert Hooke about Leeuwenhoek
August 15, 1673 Wrote Letter 2 of 1673-08-15 (AB 2) to Henry Oldenburg
August 21, 1673 mentor Reinier de Graaf buried
October 6, 1673 First letter's ten figures published in Philosophical Transactions
October 24, 1673 Leeuwenhoek's family members in 1673
November 8, 1673 Wrote letter of 1673-11-08 (AB 3) to Henry Oldenburg
November 28, 1673 Named as administrator of the estate of Willem Jans Croonenburgh
January 1, 1674 Paid the Familiegeld (estate tax)
February 12, 1674 Constantijn Huygens wrote to Oldenburg about Leeuwenhoek and his own single-lens microscope
March 10, 1674 nieces Margrieta and Maria Jans de Molijn married Arnoldus van den Heuvel and Cornelis Haaxman
March 18, 1674 sister-in-law Maria de Meij married Pieter Schepens
April 5, 1674 Wrote letter of 1674-04-05 (AB 4) to Constantijn Huygens
April 7, 1674 Wrote Letter 3 of 1674-04-07 (AB 5) to Henry Oldenburg
April 16, 1674 Wrote letter of 1674-04-16 (AB 6) to Henry Oldenburg
April 24, 1674 Wrote letter of 1674-04-24 (AB 7) to Constantijn Huygens
April 24, 1674 Appointed curator of the abandoned estate of Bartholomeus Ritmeier
April 24, 1674 Henry Oldenburg wrote to Leeuwenhoek requesting that he examine saliva, chyle, sweat, and sperm
June 1, 1674 Wrote Letter 4 of 1674-06-01 (AB 8) to Henry Oldenburg
July 6, 1674 Wrote Letter 5 of 1674-07-06 (AB 9) to Henry Oldenburg
August 1, 1674 First observed microbes
August 5, 1674 Visited by Holger Jacobæus, the Bartholin brothers, and Arent Seyn; described as "ingenious but illiterate"
August 15, 1674 Visited by Johannes Swammerdam
August 16, 1674 Ordered as curator to hand over the debt books of Bartholomeus Ritmeier
August 20, 1674 Henry Oldenburg wrote to Leeuwenhoek encouraging him to send more observations
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

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