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 1, 1716 Wrote Letter L-525 of some years before 1716 to Frederik Adriaan van Reede about the large number of eggs in the roe of a ling
February 25, 1716 Wrote Letter L-526 of 1716-02-25 to Anthonie Heinsius as a cover letter to "notes" about tendons, muscle fibres, and starch grains
March 3, 1716 Wrote Letter L-527 of 1716-03-13 to Gottfried Leibniz about human twins, trees, birds, size of sperm, number of eggs in fishes' hard roe, structure of tendons and muscle fibres, the heart; does not want to be paid for research or to teach students
March 31, 1716 Gottfried Leibniz wrote Letter L-528 to Leeuwenhoek about membranes, multiple births, and reproduction; he did not mention students
April 3, 1716 Gottfried Leibniz wrote to Louis Bourguet in defense of Leeuwenhoek, "to whom the public owes thanks. ... It is not right to despise him."
May 1, 1716 Cornelis Spiering wrote Letter L-529 in May 1716 to Leeuwenhoek about an accident in which a large carp from his pond died; encloses some scales
May 10, 1716 Wrote Letter L-530 of 1716-05-10 to Hubert Kornelis Poot to thank him for two published panegyrics; the size and origin of little animals; wonder at the smallness of little animals and the largeness of the universe; periwinkle seeds
May 16, 1716 Wrote Letter L-531 of 1716-05-16 to Gerard van Loon about hops from Liege, the structure of hops, its bitter oil, and salt particles from the oil, a comparison with sugar candy, and hop embryos; Leeuwenhoek descended from a family of beer brewers
May 19, 1716 Wrote Letter L-532 of 1716-05-19 to Gottfried Leibniz about muscle and tendon fibers, mammal teats, sperm; did not find eggs in ovaries, Fallopian tube, or womb; cannot imagine how the Fallopian tube could suck sperm; does not know the ovary's function
May 22, 1716 Wrote Letter L-533 of 1716-05-22 to Cornelis Spiering about the scales of a carp that Spiering sent him, using scales to age a fish, eggs in hard roe and sperm in soft roe food for other fishes, shrimp eggs, and the life span of whales and fish
May 24, 1716 Antoni Cink, Ursmer Narez, and Hendrik Jozef Rega, professors in Louvain, wrote Letter L-534 of 1716-05-24 to tell Leeuwenhoek how important they think his work is, well deserving of the accompanying honorary medal and laudatory poem
June 3, 1716 Jacob van den Werf, notary, wrote Letter L-535, the notary act whereby Leeuwenhoek received a medal from the faculty at Louvain
June 12, 1716 Wrote Letter L-536 of 1716-06-12 to thank professors Cink, Narez, and Rega for the honorary medal; barley germination and nutrients; again rejects spontaneous generation
June 22, 1716 Wrote Letter L-537 of 1716-06-22 to Jan Gerard Kerkherdere about how wheat, barley, beans, peas, rice, buckwheat, and maize become food for animals and discusses Leeuwenhoek's techniques for preparing samples
June 25, 1716 Witnessed baptism of great-niece Barbera, who died two weeks later
September 1, 1716 Visited by Hermaan Boerhaave, Frederik Ruysch, and Abraham van Bleiswijk
September 17, 1716 Wrote Letter L-538 of 1716-09-17 to Abraham Cornelis van Bleyswyck about his own intestinal ailment and the roles of chyle, gall (bile), and the diaphragm in the digestive process
September 25, 1716 Gottfried Leibniz wrote Letter L-539 of 28 September 1716 to report that he has forwarded Leeuwenhoek's Letter L-532 about ovaries to two doctors in Leipzig
September 28, 1716 Wrote Letter L-540 of 1716-09-28 to Herman Boerhaave about how trees grow and withstand wind; coconut palm wood and nut; he acknowledges previous errors in his observations of coconut tree trunks
October 1, 1716 Visited again by Joachim Georg Reinerding
October 10, 1716 Herman Boerhaave wrote Letter L-541 to Leeuwenhoek in response to Letter L-540 about coconuts
November 4, 1716 Abraham van Bleyswijk wrote Letter L-543 to Herman Boerhaave to report on research that he conducted with Leeuwenhoek about rabbit sperm
November 4, 1716 Herman Boerhaave wrote Letter L-542 to Leeuwenhoek that his discoveries and thoughts are agreeable to him
November 5, 1716 Wrote Letter L-544 of 1716-11-05 to Herman Boerhaave about the size of sperm from rams, cod, and ling, little animals from rain water and soil, and blood in arteries and veins
November 17, 1716 Wrote Letter L-545 of 1716-11-17 to Gottfried Leibniz about reproduction, numbers of sperm and seeds, reproductive organs of sheep and ram, fallopian tube too small to let eggs through
November 21, 1716 Wrote Letter L-546 of 1716-11-21 to Herman Boerhaave about ram sperm and details of his experimental methods
January 12, 1717 niece Maria Jans de Molijn's widowed husband Cornelis Haaxman's estate inventoried
January 16, 1717 cousin Maria Maertens Leeuwenhoek buried
March 2, 1717 Wrote Letter L-547 of 1717-03-02 to Abraham van Bleyswyck about the structure of nerves and the associated fat in the spinal cords of cows and sheep
March 6, 1717 Wrote Letter L-548 of 1717-03-06 to the members of the Royal Society tendons and muscle fibres in sheep, flea, ox, honeybee, oyster, and mussel
March 6, 1717 Wrote Letter L-549 of 1717-03-06 to the members of the Royal Society about pig brains, apples, and coconuts; blood circulation nourishes; new technique to examine brains; tea and coffee keep the blood thin
May 6, 1717 Wrote Letter L-550 of 1717-05-06 to Ewout van Bleiswijk about dragonflies' muscle fibres, compound eyes, and corneal facets, flies, lobster, and crab
May 26, 1717 Wrote Letter L-551 of 1717-05-26 to Abraham van Bleyswyck about the structure of nerves and associated blood vessels and membranes, the structure of the spinal cord and brains of a pig, cow, and mouse, and the nerves of a calf, bream, and lamb
June 8, 1717 Named as neighbor in the inventory of Pieter van der Wilt's property
June 15, 1717 Wrote Letter L-552 of 1717-06-15 to the members of the Royal Society about the muscle fibres of an ox and a flea and the reproduction of fleas
July 6, 1717 Wrote Letter L-553 of 1717-07-06 to Antony Cink about how two doctors treated his recent illnesses with saltpeter and opium; saltpeter’s effects on the blood and its efficacy as a drug
July 13, 1717 Wrote Letter L-554 of 1717-07-13 to Jan Gerard Kerkherdere about one of his personal ailments, the consequences for the digestion of eating fatty meat, the particles in his own excrement, and the role of chyle and gall during digestion
August 1, 1717 Adriaan Swalmius wrote Letter L-555 to Leeuwenhoek sometime in August 1717 to ask whether Leeuwenhoek had studied a chicken’s egg shell and the membrane within it
August 18, 1717 Wrote Letter L-556 of 1717-08-19 to Adriaan Swalmius about membranes inside an eggshell, salt crystals from an eggshell, and how birds and oysters produce shells
August 26, 1717 Wrote Letter L-557 of 1717-08-26 to Herman Boerhaave, following up on Letter L-546, about a ram's seed balls, vas deferens, and epididymis, millet grains or mustard seeds as units of measurement, sperm compared smaller little animals, and a sperm’s tail
September 10, 1717 Wrote Letter L-558 of 1717-09-10 to Frederik Adriaan van Reede about haddock intestines, roach and cod, and how scales determine the age of herring, perch, bream, and cod
September 17, 1717 Wrote Letter L-559 of 1717-09-17 to the members of the Royal Society about his own skin's fat globules and sweat ducts, holes in his finger nails, sweat ducts in humans and in cow teats, and how lice and fleas use sweat ducts to obtain their food
October 8, 1717 Wrote Letter L-560 of 1717-10-08 to the members of the Royal Society about Pareira Brava root and the effect of salt particles from it upon blood, starch grains from the membranes of the root, and the roots of “China” and “Irias"
October 22, 1717 Wrote Letter L-561 of 1717-10-22 to the members of the Royal Society about the brain of a cod, the nerves of cod and haddock, and the spinal cord of haddock
November 20, 1717 Wrote Letter L-562 of 1717-11-20 to the members of the Royal Society about tendons and nerves of sheep, lamb, cow, and ox; his last letter to the Royal Society; expresses his gratitude for being elected a fellow and for Philosophical Transactions
December 8, 1717 Wrote Letter L-563 of 1717-12-08 to Charles VI, Holy Roman emperor, as the dedication for Send-Brieven
December 15, 1717 Received payment from the city for inspector / wine gauger duties
December 23, 1717 Named again as neighbor in the disposition of Pieter van der Wilt's estate
January 1, 1718 Published Send-Brieven (Epistles), Letters I - XLVI
April 1, 1718 cousin Pieter Maartens Leeuwenhoek married Kniertje van der Doe
April 19, 1718 nephew Adriaan Johannes Swalmius married Elisabet van Heering
November 28, 1718 Wrote Letter L-564 of 1718-11-28 to Francesco Corner, a cover letter for Epistolae Physiologicae
December 6, 1718 Named again as a neighbor in final sale of Pieter van der Wilt's property
December 30, 1718 Delft's mayors decided that the camerbewaarder would no longer receive 300 g after the death of Leeuwenhoek
January 1, 1719 Published Epistolae ad Societatem (Letters to the Society), Letters 108 - 146
January 1, 1719 Published Epistolae Physiologicae (Physiological Letters), Letters I - XLVI
January 23, 1719 Received payment from the city for inspector / wine gauger duties
June 26, 1719 Made will with daughter Maria
January 9, 1720 Wrote Letter L-565 of 1720-01-09 to the members of the Royal Society about muscle fibres and membranes of a cow, mites on the flesh of a whale, and the nerves around the muscle fibres and tendons of a cow
April 8, 1720 cousin Magdaleentje (Helena) Maertens Leeuwenhoek buried
April 29, 1720 Received payment from the city for inspector / wine gauger duties
April 29, 1720 Rented the farm in Den Bommel to Johannes Braber
August 3, 1720 Anthonie Heinsius died
November 20, 1720 Wrote Letter L-566 of 1720-11-20 to the members of the Royal Society about bone membrane and the canals in bone, the cell layers and blood vessels in the bone membrane, and bone from the rib of a cow
December 30, 1720 cousin Maarten Pieters Hogenhouck buried
January 11, 1721 Philosophical Transactions, vol. 31, no. 366 published, including Letter L-566
January 15, 1721 Wrote Letter L-567 of 1721-01-15 to members of the Royal Society about the stomata of the leaves of boxwood, the number of them, and the down on the skin of a peach and a quince
January 24, 1721 Wrote Letter L-568 of 1721-01-24 to the members of the Royal Society about vessels in wood from Ambon (Indonesia), oakwood, and pinewood, the muscle fibres of a cow, a whale, and a mouse, and the structure of a red blood cell
April 11, 1721 Wrote Letter L-569 of 1721-04-11 to the members of the Royal Society about how flesh fibers are nourished by the blood vessels, this time in fish
May 1, 1721 At age 88, his 100th publication in Philosophical Transactions
May 11, 1721 Philosophical Transactions, vol. 31, no. 367 published with two letters by Leeuwenhoek, L-565 and L-568
June 27, 1721 Wrote Letter L-570 of 1721-06-27 to the members of the Royal Society about finally discovering the little holes in the membranes of beans and peas and about the little vessels in seed membranes
July 3, 1721 Royal Society ordered Letter L-570 to be translated
September 11, 1721 Philosophical Transactions, vol. 31, no. 368 published with two letters by Leeuwenhoek, L-569 and L-570
November 17, 1721 Made will with daughter Maria
November 26, 1721 Amended will of November 17
November 30, 1721 Presented will of November 17 to notary Jan de Bries
December 19, 1721 grand-nephew Jan Cornelis Haaxman buried
January 1, 1722 Published Arcana Naturae Detecta (Nature's Mysteries Disclosed), Letters 32, 33, 37, 39 - 41, 61 - 92 (2nd)
January 1, 1722 Published Continuatio Arcanorum Naturae detectorum (Continuation of Nature's Mysteries Disclosed), Letters 93 - 107 (2nd)
January 1, 1722 Published Opera Omnia, seu Arcana Naturae Microscopiorum (The Works, or Nature's Microscopical Mysteries), 25 Letters from 28 - 60 (4th)
January 11, 1722 Philosophical Transactions, vol. 31, no. 369 published, containing Letter L-567
January 22, 1722 Royal Society read Letter L-566 about bone membranes
February 22, 1722 James Jurin wrote Letter L-571 to Leeuwenhoek summarizing and praising his life's work
April 21, 1722 Wrote Letter L-572 of 1722-04-21 to the members of the Royal Society about the muscular fibres of different animals and whether iron becomes magnetic over time
May 1, 1722 Wrote Letter L-573 of 1722-05-01 to the members of the Royal Society about the structure of fat particles in sheep, lamb, flatfish, and perch
May 1, 1722 Wrote Letter L-574 of 1722-05-01 to James Jurin, a cover letter to Letter L-573, asking for support for his observations of hermaphroditic animals
May 15, 1722 Received payment from the city for inspector / wine gauger duties
May 21, 1722 Royal Society read Letter L-572 about muscle fibers and iron
May 26, 1722 James Jurin wrote Letter L-575 asking Leeuwenhoek to send Latin translations of his letters and passing along Hans Sloane's request for Leeuwenhoek to investigate smallpox pustules for insects
June 11, 1722 Philosophical Transactions, vol. 31, no. 371 published, containing Letter L-572
June 13, 1722 Wrote Letter L-576 of 1722-06-13 to the members of the Royal Society about the reproductive organs of a ewe and a fetus from it
June 13, 1722 Wrote Letter L-577 of 1722-06-13 to James Jurin, a cover letter for Letter L-576, expressing doubts that inoculations protect against smallpox
July 2, 1722 Royal Society read Letter L-573 about fat particles
July 7, 1722 Wrote Letter L-578 of 1722-07-07 to the members of the Royal Society about calluses on human skin
July 7, 1722 Wrote Letter L-579 of 1722-07-07 to James Jurin, a cover letter to Letter L-578, that no little animals are to be found in smallpox pustules; again opposes a proponent of spontaneous generation
July 13, 1722 Received payment from the city for inspector / wine gauger duties
September 11, 1722 Philosophical Transactions, vol. 32, no. 372 published, containing Letter L-573
October 12, 1722 James Jurin wrote Letter L-580 to Leeuwenhoek, saying that his ideas about pocks are acceptable to the Royal Society
November 11, 1722 Philosophical Transactions, vol. 32, no. 373 published with two letters by Leeuwenhoek, L-576 and L-578
November 20, 1722 Wrote Letter L-581 of 1722-11-20 to James Jurin about the miscroscopic structure of diamonds and rock crystal
January 4, 1723 James Jurin wrote Letter L-582 to Leeuwenhoek about how to measure his microscopic observations
January 11, 1723 Philosophical Transactions, vol. 32, no. 374 published, containing Letter L-581
March 19, 1723 Wrote Letter L-583 of 1723-03-19 to the members of the Royal Society about blood, now lost
March 19, 1723 Wrote Letter L-584 of 1723-03-19 to James Jurin about blood, the size of blood globules, the state of his health, and the role of the ovary in reproduction
April 1, 1723 Royal Society read Letter L-570 of 27 June 1721, two years after it was written, about beans and peas
May 31, 1723 Wrote Letter L-585 of 1723-05-31 to the members of the Royal Society about the structure and texture of the diaphragm, the source of his most severe ailment
June 8, 1723 Royal Society read Letter L-584 about blood, Leeuwenhoek's health, and his position on ovaries
July 6, 1723 James Jurin wrote Letter L-586 to introduce Matthew Raper to Leeuwenhoek and continue the discussion about blood globules and generation
July 11, 1723 Philosophical Transactions, vol. 32, no. 377 published, containing Letter L-584
July 15, 1723 Visited by Matthew Raper
August 1, 1723 Wrote Letter L-587 of sometime in August to James Jurin about the similarities between globules in blood and in the lees of wine to argue against Jurin’s hope to discover how blood globules are made
August 1, 1723 Wrote Letter L-588 of 1723-08-00 to James Jurin about his spermist view of the generation of animals and palpitations of his diaphragm, his final letter
August 25, 1723 Requested on his deathbed that his friend Johannes Hoogvliet translate his final two letters into Latin
August 26, 1723 Died in his Hippolytusbuurt home, 90 years old
August 27, 1723 Delft newspaper published notice of Leeuwenhoek's death
August 29, 1723 pastor Petrus Gribius wrote Letter L-589 to James Jurin announcing Leeuwenhoek's death
August 31, 1723 Buried in Oude Kerk
September 4, 1723 Johannes Hoogvliet wrote Letter L-590 to James Jurin accompanying his Latin translation of Leeuwenhoek's last two letters
September 4, 1723 Replaced as wine gauger by Lambert the Greek
October 4, 1723 daughter Maria wrote Letter L-591 as a cover letter for the cabinet with 26 magnifying glasses to the Royal Society (AB 381)
October 4, 1723 pastor Petrus Gribius wrote Letter L-592 to James Jurin about Leeuwenhoek's methods
October 12, 1723 James Jurin wrote Letter L-593 to Peter Gribius about Leeuwenhoek's death
October 20, 1723 Arnout van den Berch wrote Letter L-594 to the Royal Society that Abraham Edens will deliver the cabinet of magnifying glasses to the Royal Society
November 2, 1723 translator John Chamberlayne died
November 11, 1723 Philosophical Transactions, vol. 32, no. 379 published, containing Letter L-585
November 18, 1723 Isaac Newton wrote Letter L-595 to Abraham Edens, a receipt for the cabinet with 26 magnifying glasses
November 18, 1723 Abraham Edens presented a cabinet sent by Maria van Leeuwenhoek with 26 of her father's magnifying glasses to the Royal Society;
November 29, 1723 James Jurin wrote Letter L-596 to Maria van Leeuwenhoek thanking her for sending the cabinet with 26 magnifying glasses
November 29, 1723 James Jurin wrote Letter L-597 to Arnoud van den Berch about the cabinet of microscopes
November 29, 1723 James Jurin wrote Letter L-598 to Petrus Gribius thanking him for the safe delivery of the cabinet with Leeuwenhoek's magnifying glasses
December 2, 1723 Royal Society read Leeuwenhoek's Letter L-587 and Letter L-588 of August 1723, the final time they would read a letter by Leeuwenhoek, and Letter L-592 from Petrus Gribius
December 17, 1723 James Jurin wrote to Peter Gribius in thanks for the cabinet full of "precious treasures"
January 11, 1724 Martin Folkes's article, Letter L-599, about Leeuwenhoek's cabinet of microscopes published in Philosophical Transactions
January 11, 1724 Philosophical Transactions, vol. 32, no. 380 published with final two letters by Leeuwenhoek, L-587 and L-588, and Martin Folkes's article about the bequest of 26 microscopes
June 2, 1724 James Jurin wrote Letter L-600 to Arnoud van den Berch about delivering the Royal Society's gifts to Maria van Leeuwenhoek
June 2, 1724 James Jurin wrote Letter L-601 to Maria van Leeuwenhoek, presenting her with two volumes of Philosophical Transactions and a silver bowl
January 1, 1729 Reinier Boitet's Beschryving der Stadt Delft published; first biography of Leeuwenhoek
April 16, 1729 nephew Anthonij Jans de Molijn buried
January 1, 1730 Published Continuatio Epistolarum (Continuation of the Letters), Letters 53-60 (4th)

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