Chronology of events: 1673--1679

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
April 1, 1673 cousin Magdaleentje (Helena) Maertens Leeuwenhoek (1653-1720) married Johannes de Coep
April 28, 1673 Wrote Letter L-001 of 1673-04-28 to Henry Oldenburg about mould and a bee's stinger and eye
May 17, 1673 The Royal Society received Leeuwenhoek's first letter
May 19, 1673 At age 40, first letter published in Philosophical Transactions
May 25, 1673 Henry Oldenburg wrote to Reinier de Graaf about the Royal Society's reception of Leeuwenhoek's first letter
August 8, 1673 mentor Constantijn Huygens wrote to Robert Hooke about Leeuwenhoek as "exceedingly curious and industrious"
August 15, 1673 Wrote Letter L-002 of 1673-08-15 to Henry Oldenburg about the bee, the movement of liquids in wood and food in a louse, and the composition of air
August 21, 1673 mentor Reinier de Graaf buried
October 16, 1673 First letter's ten figures published in Philosophical Transactions
October 24, 1673 Leeuwenhoek's family members in 1673
November 8, 1673 Wrote Letter L-003 of 1673-11-08 to Henry Oldenburg about globules in milk and in blood and his theory on the structure and growth of hair and of tumours
November 28, 1673 Named as administrator of the estate of Willem Jans Croonenburgh
January 1, 1674 Paid the Familiegeld (estate tax)
February 1, 1674 Constantijn Huygens wrote Letter L-004 to Leeuwenhoek, enclosing an extract of a letter from Oldenburg that asked Huygens to encourage L.’s nature study
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 L-005 of 1674-04-05 to Constantijn Huygens about globules in milk and blood and the growth of hair; first mention of red blood corpuscles
April 7, 1674 Wrote Letter L-006 of 1674-04-07 to Henry Oldenburg about globules in milk and blood, the growth of hair and nails, and the anatomy of a louse
April 11, 1674 Constantijn Huygens wrote Letter L-007 to Leeuwenhoek about sending his observations to son Christiaan in Paris
April 16, 1674 Wrote Letter L-008 of 1674-04-16 to Henry Oldenburg about the delivery of his letters and asking Oldenburg to befriend van Conincxbrugh
April 24, 1674 Appointed curator of the abandoned estate of Bartholomeus Ritmeier
April 24, 1674 Wrote Letter L-009 of 1674-04-24 to Constantijn Huygens about his further observations about blood, bones, teeth, and salt
May 4, 1674 Henry Oldenburg wrote Letter L-010 to Leeuwenhoek requesting that he examine saliva, chyle, and sweat
June 1, 1674 Wrote Letter L-011 of 1674-06-01 to Henry Oldenburg about movement of liquid in capillary tubes, structure of body parts, growth of skin, and the size of red blood cells
July 6, 1674 Wrote Letter L-012 of 1674-07-06 to Henry Oldenburg bout sweat, hair, fat, tears, and improved capillary tubes
August 1, 1674 First observed little animals in water
August 11, 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 24, 1674 daughter Maria made a will
August 30, 1674 Henry Oldenburg wrote Letter L-013 to Leeuwenhoek, encouraging him to send more observations
September 7, 1674 Wrote Letter L-014 of 1674-09-07 to Henry Oldenburg, stating that he will send further observations
September 7, 1674 Wrote Letter L-015 of 1674-09-07 to Henry Oldenburg about the anatomy of the eye and optic nerve of a cow, minerals eg. salt, clay, English and Flemish earth; first mention of protozoa in stagnant water
October 19, 1674 Wrote Letter L-016 of 1674-10-19 to Henry Oldenburg about eggs in the bile of cow, sheep, rabbits and poultry, the structure of metals, skin, and the bladder, and theories about the sense of taste.
October 25, 1674 The Royal Society began requiring an oath of secrecy from the members who attended meetings
November 5, 1674 Henry Oldenburg wrote Letter L-017 to Leeuwenhoek encouraging him and asking about the kind of salt he was observing
November 22, 1674 The Royal Society asked Olderburg to produce Leeuwenhoek's Letter L-011 of 1 June 1674
December 4, 1674 Wrote Letter L-018 of 1674-12-04 to Henry Oldenburg about optic nerves and sight; enclosed specimen of cow's optic nerve
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 26, 1674 Wrote Letter L-019 of 1674-12-26 to Constantijn Huygens, enclosing a drawing of the optic nerve and excerpts from two recent letters
December 31, 1674 sister-in-law Catharina Swalmius buried
January 1, 1675 cousin Maerten Huijchs Leeuwenhoek appointed tax farmer
January 3, 1675 Henry Oldenburg wrote Letter L-020 to Leeuwenhoek about his doubts about globules
January 20, 1675 Christiaan Huygens wrote to Henry Oldenburg doubting Leeuwenhoek's observations of globules
January 22, 1675 Wrote Letter L-021 of 1675-01-22 to Henry Oldenburg about a new technique for observing blood and sectioned brain tissue; optic nerve, smoke, gunpowder, and scorpions
February 11, 1675 Wrote Letter L-022 of 1675-02-11 to Henry Oldenburg about crystals, vinegar, soap, spices, cod, louse, and oak leaf.
February 12, 1675 Henry Oldenburg wrote to Christiaan Huygens about doubting Leeuwenhoek's globules
March 1, 1675 Henry Oldenburg wrote Letter L-023 to Leeuwenhoek in response to his Letter L-021 of 1675-01-22
March 26, 1675 Wrote Letter L-024 of 1675-03-26 to Henry Oldenburg about meals, seeds, and pearls; transparency; movement of fluids in plants and animals
April 22, 1675 Henry Oldenburg wrote Letter L-025 to Leeuwenhoek recommending that he get help from knowledgable people
August 14, 1675 Wrote Letter L-026 of 1675-08-14 to Henry Oldenburg about blood, taste of saps, sugar, and salt, and the mechanics of taste and digestion
August 22, 1675 Henry Oldenburg wrote Letter L-027 to Leeuwenhoek acknowledging reciept of his letters
September 15, 1675 First observed little animals in rain water
September 20, 1675 Appointed curator of estate of Henricus van Zuijlen
December 15, 1675 Jan Vermeer, the painter, buried
December 20, 1675 Wrote Letter L-028 of 1675-12-20 to Henry Oldenburg about various omissions in previous letters, small animals in water, his theory of “globules”, and the aerometer he devised
January 1, 1676 Wrote Letter L-029 of some time in 1676 to Theodore Craanen about gold and mercury
January 7, 1676 Henry Oldenburg wrote Letter L-030 to Leeuwenhoek about the reaction in London to his observations
January 22, 1676 Wrote Letter L-031 of 1676-01-22 to Henry Oldenburg about forwarding his mail and about sending his observations of little animals in water
January 26, 1676 sister-in-law Maria de Meij buried
February 13, 1676 Henry Oldenburg wrote Letter L-032 to Leeuwenhoek requesting that he examine hair
February 20, 1676 Henry Oldenburg wrote Letter L-033 to Leeuwenhoek and pre-paid the postage
February 22, 1676 Wrote Letter L-034 of 1676-02-22 to Henry Oldenburg about hair, cow skin, horn, and bone, inviting Hooke's response
April 5, 1676 co-worker Daniel Bogaert married Maria van Rees
April 21, 1676 Wrote Letter L-035 of 1676-04-21 to Henry Oldenburg about movement of liquid in ash and other trees, little animals in wine, and cinnamon and taste
April 24, 1676 Began series of experiments to observe little animals in spice infusions
April 26, 1676 Began Pepper 2 experiment
May 1, 1676 Constantijn Huygens wrote to Oldenburg that Leeuwenhoek gave him an issue of Philosophical Transactions
May 14, 1676 Henry Oldenburg wrote Letter L-036 to Leeuwenhoek about Hooke's and Grew's reactions to recent observations
May 29, 1676 Wrote Letter L-037 of 1676-05-29 to Henry Oldenburg about disagreements with Grew about the structure of wood and a further account of the vessels, fibres, and medullary rays of wood
July 1, 1676 Visited by Christiaan Huygens during the summer; he saw the little animals in Leeuwenhoek's infusions
July 28, 1676 Wrote Letter L-038 of 1676-07-28 to Henry Oldenburg; now lost
July 28, 1676 Wrote Letter L-039 of 1676-07-28 to Robert Boyle about the effects of air on ammonia and copper
September 30, 1676 Appointed curator of estate of Catherine Bolnes, Vermeer's widow
October 9, 1676 Wrote Letter L-040 of 1676-10-09 to Henry Oldenburg about little animals in various waters and spice infusions, the relationship of their shape to taste, and whether there were little animals in the air
October 18, 1676 Henry Oldenburg wrote Letter L-041 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 Letter L-042 to Leeuwenhoek acknowledging receipt of the letter of 1676-10-09
October 30, 1676 Wrote Letter L-043 of 1676-10-30 to Henry Oldenburg about his discussions with Grew and Boyle as well as the unreliability of the postal system
October 31, 1676 Constantijn Huygens wrote Letter L-044 to Leeuwenhoek about his son Christiaan's translating Letter L-040
November 7, 1676 Wrote Letter L-045 of 1676-11-07 to Constantijn Huygens summarizing the observations of little animals in Letter L-040
November 12, 1676 Henry Oldenburg wrote Letter L-046 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 L-047 of 1676-11-27 to Henry Oldenburg, now lost
January 1, 1677 Theodore Craanen wrote Letter L-048 to Leeuwenhoek, some time in 1677, requesting that his relative Johan Ham be allowed to visit
January 1, 1677 Wrote Letter L-049 of some time in 1677 to Robert Boyle, now lost
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 Buitenwatersloot 214
February 2, 1677 Recovered twenty-six paintings from Jannetje Stevens to help pay Catherine Bolnes' creditors
February 9, 1677 Christiaan Huygens wrote Letter L-050 of 1677-02-09 to Leeuwenhoek that his observations of little animals in spice infusions were well received in France
February 11, 1677 The Royal Society read the first part of Leeuwenhoek's long Letter L-040 of the previous 9 October about little animals in various waters
February 15, 1677 Wrote Letter L-051 of 1677-02-15 to Christiaan Huygens to thank him for translating a letter into French
February 18, 1677 The Royal Society read the second part of Leeuwenhoek's long letter of 9 October 1676
February 22, 1677 Henry Oldenburg wrote Letter L-052 to Leeuwenhoek for more details about his method for observing little animals
March 4, 1677 Henry Oldenburg wrote Letter L-053 to Leeuwenhoek requesting that he examine muscle fibers and brains
March 8, 1677 Named quartermaster of the 2nd quarter
March 8, 1677 The Royal Society read the third part of Leeuwenhoek's long letter of 9 October 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 L-054 of 1677-03-23 to Henry Oldenburg about the quantity of little creatures in one drop of water
March 25, 1677 The Royal Society published Michael Butterfield's letter about melting glass to make spherical lenses
March 25, 1677 The Royal Society published part of Leeuwenhoek's Letter L-040 of 9 October 1676 reporting little animals in infusions
April 15, 1677 The Royal Society read Leeuwenhoek's Letter L-054 of 23 March 1677 and assigned Grew to replicate his results
April 20, 1677 Henry Oldenburg wrote Letter L-055 to Leeuwenhoek relaying the compliments of the members of the Royal Society
May 14, 1677 Wrote Letter L-056 of 1677-05-14 to Henry Oldenburg about muscles, blood, the movement of fluids in fruit, moxa, and cotton
May 18, 1677 Benedict Haan and Henry Cordes wrote to the Royal Society attesting to the number of little animals in Leeuwenhoek's infusions
May 27, 1677 The Royal Society read Leeuwenhoek's Letter L-056 of 14 May 1677
June 2, 1677 Robbert Gordon wrote to the Royal Society attesting to the number of little animals in Leeuwenhoek's infusions
August 7, 1677 Henry Oldenburg wrote Letter L-057 to Leeuwenhoek, asking him to examine the skin of Moors and enclosing Philosophical Transactions no. 136
August 13, 1677 Aldert Hodenpijl wrote to the Royal Society attesting to the number of little animals in Leeuwenhoek's infusions
August 21, 1677 Johannes Boogert, Robert Poitevin, and W. van der Burch wrote to the Royal Society attesting to the number of little animals in Leeuwenhoek's infusions
August 30, 1677 Alex Petrie wrote to the Royal Society attesting to the number of little animals in Leeuwenhoek's infusions
September 5, 1677 mentor Henry Oldenburg died in London
September 11, 1677 Visited by Hennig Brand, the Hamburg merchant who discovered phosphorus
October 1, 1677 Denis de Dodart wrote to Christiaan Huygens about his admiration for Leeuwenhoek: "people of this merit should be pensioned as external academicians"
October 5, 1677 Wrote Letter L-058 of 1677-10-05 to Henry Oldenburg about skin, eels, fleas, and measuring and counting the little animals; enclosed testimonials
October 16, 1677 Wrote Letter L-059 of 1677-10-16 to William Brouncker; he is sending some observations and a Latin translation
October 25, 1677 The Royal Society requested that Robert Hooke try to replicate Leeuwenhoek's observations
November 9, 1677 Wrote Letter L-060 of 1677-11-09 to William Brouncker about sperm and their movements in fresh human semen
November 11, 1677 Robert Hooke failed to demonstrate "minute animals" in pump water. The Royal Society read the testimonials from people in Delft.
November 15, 1677 Bought land near Berkelse Meer
November 18, 1677 Robert Hooke again failed, using an improved microscope
November 25, 1677 Robert Hooke finally succeeded in replicating Leeuwenhoek's observations of little animals
December 2, 1677 Wrote Letter L-061 of 1677-12-02 to William Brouncker; now lost
December 8, 1677 Constantijn Huygens wrote Letter L-062 to Leeuwenhoek about his observations of sperm
December 10, 1677 Robert Hooke wrote Letter L-063 to Leeuwenhoek to acknowledge the receipt of Letter L-060 of November 1677 to describing sperm in human semen
December 16, 1677 Robert Hooke demonstrated the superiority of single-lens over double-lens microscopes
January 1, 1678 Robert Hooke's Lectures and Collections: Cometa, Microscopium published
January 1, 1678 Wrote Letter L-064 of some time in 1678 to Robert Boyle; now lost
January 11, 1678 Nehemiah Grew and Robert Hooke wrote Letter L-065 to Leeuwenhoek asking him to further observe sperm
January 11, 1678 Nehemiah Grew wrote Letter L-066 of 1678-01-11 to Leeuwenhoek about comparisons of the size and shape of sperm from a variety of animals, the role of sperm in reproduction, and vessels in semen
January 14, 1678 Wrote Letter L-067 of 1678-01-14 to Robert Hooke about human blood, blood transfusions, flea larvae, and little animals in pepper water
January 27, 1678 Robert Hooke read Letter L-067 of 1678-01-14 at a meeting of the Royal Society
February 1, 1678 Empowered a Gouda notary to sell Vermeer's property to help pay Catherine Bolnes's creditors
February 3, 1678 Robert Hooke produced two experiments on blood and milk and read the latter part of the Letter L-067 of 1678-01-14 about phlegm and little animals in pepper water
February 11, 1678 Robert Hooke wrote Letter L-068 to Leeuwenhoek about how he verified Leeuwenhoek’s observations of little animals in a pepper infusion

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