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
June 20, 1680 Robert Hooke produced the two letters of 1680-06-14 from Leeuwenhoek at a meeting of the Royal Society
June 27, 1680 The Royal Society read Letter 108 of 1680-06-14 about beer, yeast, a little animals in hermetically sealed tubes
August 9, 1680 Wrote Letter L-109 of 1680-08-09 to Robert Hooke to ask whether the Royal Society received previous letters and to promise further investigations into the formation of blood
August 13, 1680 Constantijn Huygens, jr., called Leeuwenhoek "the great man of the century"
September 28, 1680 Wrote Letter L-110 of 1680-09-28 to Thomas Gale to inquire whether Letter 107 of 1680-06-14 had arrived
November 12, 1680 Wrote Letter L-111 of 1680-11-12 to Robert Hooke about blood globules, lees of wine, globules in rain water, milk vessels, reproduction, little animals in the male seed of animals, and their incomprehensible smallness
November 21, 1680 Robert Hooke read the headings of Letter L-111 of 1680-11-12
December 5, 1680 Francis Aston promised the Royal Society to translate Letter L-111 of 1680-11-12 into English
January 1, 1681 Sat for Cornelis de Man's Anatomy Lesson of Dr. 's Gravezande
January 8, 1681 Appointed curator of the abandoned estate of Willemtie Pieters Touw
January 22, 1681 The Royal Society read Francis Aston's translation of Letter L-111 of 1680-11-12 about the lees of ale and wine
April 29, 1681 cousin Jannitgen Huijchs Leeuwenhoek buried
June 8, 1681 cousin Maria Maertens Leeuwenhoek married Jan den Appel
June 17, 1681 co-worker Daniel Bogaert buried
July 4, 1681 Robert Hooke wrote Letter L-112 of 4 July 1681 to thank Leeuwenhoek for previous letters and to promise to respond more promptly in the future
July 17, 1681 David Gregory wrote Letter L-113 to Leeuwenhoek as cover letter for Letter L-112 from Hooke
August 9, 1681 nephew Anthonij Jans de Molijn married Magdalena van Poelgeest
November 4, 1681 Wrote Letter L-114 of 1681-11-04 to Robert Hooke about hog bristles, shedding hair, blackheads; living little animals in excrement, horse urine, clay, and gout
November 12, 1681 Robert Hooke produced Letter L-114 of 1681-11-04 from Leeuwenhoek
November 19, 1681 Robert Hooke read Letter L-114 of 1681-11-04
November 26, 1681 Members of the Royal Society discussed Leeuwenhoek's observations of hair
December 1, 1681 Robert Hooke wrote Letter L-115 of some time in December 1681 to Leeuwenhoek about his previous letters
December 3, 1681 Members of the Royal Society discussed Leeuwenhoek's microscopes
December 10, 1681 Philosophical Collections number 3 published in London, including Leeuwenhoek's Letter L-111 of 1680-11-12 to Robert Hooke
January 1, 1682 Visited by Cornelis Bontekoe
January 10, 1682 Philosophical Collections number 4 published in London, including Leeuwenhoek's Letter L-114 of 1681-11-04 to Robert Hooke
January 28, 1682 Received fees from new citizens in the name of the city's camerbewaarders and messengers
February 1, 1682 Philosophical Collections number 5 published in London, including Leeuwenhoek's Letter L-116 of 1682-03-03 to Robert Hooke
March 3, 1682 Wrote Letter L-116 of 1682-03-03 to Robert Hooke about muscle fibres, hair, the cell nucleus in the erythrocytes of fishes, the liver of salmons, beards of oysters, and the structure and growth of oyster shell
March 11, 1682 Robert Hooke read the first part of Letter L-116 of 1682-03-03 about striated muscle fibres of mammals and fishes
March 18, 1682 Robert Hooke read part of Letter L-116 of 1682-03-03 about muscle fibers
March 20, 1682 Robert Hooke wrote Letter L-117 to Leeuwenhoek that his observations were well received by the Royal Society
March 26, 1682 Robert Hooke wrote Letter L-118 to Leeuwenhoek that his observations of shellfish muscles were well received by the Royal Society and concurred with his own
April 1, 1682 Philosophical Collections number 7 published in London, including Leeuwenhoek's Letter L-119 of 1682-04-04
April 4, 1682 Wrote Letter L-119 of 1682-04-04 to Robert Hooke about the structure of the muscle tissue of lobsters and shrimps.
April 15, 1682 Robert Hooke read his Letter L-117 of 1682-03-20 and Leeuwenhoek's reply, Letter L-119 of 1682-04-04 about muscles of crabs, lobsters, and shrimp
April 22, 1682 Robert Hooke showed the Royal Society part of a flesh muscle in a microscope, but the rimples mentioned by Leeuwenhoek could not be seen
July 28, 1682 Wrote Letter L-120 of 1682-07-28 to Robert Hooke, now lost, asking whether figures of the anatomy of wood in Letter L-097 of 12 January 1680 will be published in print
November 19, 1682 Sold two bonds from the property of Willem Bolnes to help pay Catherina Bolnes' creditors
January 1, 1683 Visited by Marie-Anne Mancini, Duchess of Bouillon and others
January 1, 1683 Wrote Letter L-121 of some time in 1683 to an unknown "Sir"
January 22, 1683 Wrote Letter L-122 of 1683-01-22 to Christopher Wren about the function of the ovary, muscles of insects, drinking tea and mild beer, erythrocytes, and a theory on the formation of blood
February 8, 1683 Received assistant wine gauger for emergencies
February 17, 1683 The Royal Society read Letter L-122 of 1683-01-22 to Christopher Wren
February 26, 1683 Francis Aston wrote Letter L-123 of 26 February 1683 about problems translating his letters and opposition to his views
March 9, 1683 Wrote Letter L-124 of 1683-03-09 to Francis Aston promising to send observations about generation and colors
March 27, 1683 Francis Aston wrote Letter L-125 to Leeuwenhoek about new Royal Society officers
May 20, 1683 Wrote Letter L-126 of 1683-05-20 to Anthonie Heinsius about generation and about the circulation of the blood, which he intends to communicate in a letter to the Royal Society
June 7, 1683 Anthoinie Heinsius wrote Letter L-127 to Leeuwenhoek about his observations concerning generation and blood circulation
July 16, 1683 Wrote Letter L-128 of 1683-07-16 to Christopher Wren about the procreation of frogs, sperm in fowl's egg, reproduction of rabbits, little animals in frog intestines, a theory about digestion in humans and fish, and blood
July 22, 1683 Wrote Letter L-129 of 1683-07-22 to Anthonie Heinsius about Heinsius's reactions to an earlier letter
July 28, 1683 The Royal Society read Letter L-128 of 1683-07-16 about reproduction, little animals, digestion, and blood
August 4, 1683 The Royal Society discussed Letter L-128 of 1683-07-16 about the male seed in egg yolks
August 27, 1683 Francis Aston wrote Letter L-130 to Leeuwenhoek, thanking him for his recent letter and agreeing to admit two Dutch noblemen to a meeting of the Royal Society
September 1, 1683 Two Dutch noblemen wrote Letter L-131 some time in early September 1683 to Leeuwenhoek about the fear that kept them from attending a meeting of the Royal Society
September 2, 1683 Wrote Letter L-132 of 1683-09-02 to Anthonie Heinsius, requesting his opinion of observations in Letter L-128
September 10, 1683 Anthonie Heinsius wrote Letter L-133 to Leeuwenhoek about recent observations of generation
September 16, 1683 Wrote Letter L-134 of 1683-09-16 to Anthonie Heinsius about whether Heinsius would like a copy of his speculations on the living organisms in mouths and on the structure of the skin
September 17, 1683 Wrote Letter L-135 of 1683-09-17 to Francis Aston about saliva, nasal hairs and blackheads, skin, pores, calluses, and cleaning teeth; the discovery of bacteria in tartar
September 30, 1683 Wrote Letter L-136 of 1683-09-30 to Anthonie Heinsius, a note accompanying a copy of Letter L-135
October 1, 1683 Melchisédech Thévenot wrote Letter L-138 of October 1683 to Leeuwenhoek, a courteous reply
October 1, 1683 Wrote Letter L-137 of October 1683 to Melchisedec Thévenot with some observations
October 8, 1683 Anthonie Heinsius wrote Letter L-139 of 8 October 1683 to Leeuwenhoek that his work was making a positive impression in Paris and that some of his letters would be published in the new Journal de Médecine
October 11, 1683 Francis Aston wrote Letter L-140 to Leeuwenhoek about the translation of a Dutch phrase concerning egg yolks
October 14, 1683 Wrote Letter L-141 of 1683-10-14 to Anthonie Heinsius in reply to his recent Letter L-139
October 18, 1683 Anthonie Heinsius wrote Letter L-142 of in response to Letter L-141
October 26, 1683 Wrote Letter L-143 of 1683-10-26 to Francis Aston in reply to Letter L-140 about egg yolks
November 3, 1683 The Royal Society read and discussed Letter L-135
November 10, 1683 The Royal Society discussed Leeuwenhoek's observations about pores in the skin in Letter L-135
December 28, 1683 Wrote Letter L-144 of 1683-12-28 to Francis Aston about human skin and its diseases, the intestines, the effects of vinegar, the intestinal wall and peristalsis, and an experiment to demonstrate the adsorption of food nutrients in the intestines.
January 1, 1684 Daniel Gaesbeeck wrote Letter L-145 of 1684-01-01 to Leeuwenhoek about why he was publishing his letters
January 1, 1684 Published Eyerstok (Ovary), Letters 37, 39 (L-122, L-135)
January 1, 1684 Published Humor Cristallinus (Crystalline Humor), Letter 41 (L-147)
January 1, 1684 Published Onsigtbare Geschapene Waarheden (Invisible Creation Truths), Letters 32, 33, 39 (L-108, L-111, L-135)
January 1, 1684 Published Schobbens in de Mond (Scales in the Mouth), Letter 40 (L-144)
January 6, 1684 Authorized as curator to inspect estate of Willemtie Pieters Touw by her heir
February 23, 1684 The Royal Society read Letter L-144 of 1683-12-28 to Francis Aston
March 7, 1684 Francis Aston wrote Letter L-146 to Leeuwenhoek about the importance of his work
April 2, 1684 cousin Margrieta Maertens Leeuwenhoek married Michiel Reijniers van Hasseld
April 14, 1684 Wrote Letter L-147 of 1684-04-14 to Francis Aston about lenses and corneas, the function of eye-lids, the involuntariness of blinking, the optic nerve, and the skin of Moors
May 24, 1684 The Royal Society read the first part of Letter L-147 about the crystalline humour of the eye
May 26, 1684 William Molyneux demonstrated blood flow in a newt to the Dublin Philosophical Society
May 31, 1684 The Royal Society discussed Leeuwenhoek's observations in Letter L-147 about the crystalline humour of the eye
June 7, 1684 Francis Aston wrote Letter L-148 to Leeuwenhoek to thank him for his letter with observations of the lens of the eye, which was read to the Royal Society and was well-received by them
June 14, 1684 The Royal Society read the latter part of Letter L-147 about the crystalline humour of bird and fish eyes, the vitreous humour, the cornea tunica, and the colour of a Blackamore
June 15, 1684 Visited Christiaan Huygens in Den Haag with the Durven brothers
July 24, 1684 Daniel van Gaesbeeck wrote Letter L-149 about why he was publishing more of Leeuwenhoek's “mutilated”, “mistranslated”, and “misunderstood” letters
July 25, 1684 Wrote Letter L-150 of 1684-07-25 to Members of the Royal Society about parts of the brain of several animals, chalk stones of gout, leprosy, and the scales of eels
July 27, 1684 Christiaan Huygens gossiped about Maria Duyst in a letter to his brother Constantijn Huygens
September 15, 1684 Francis Aston wrote Letter L-151 to Leeuwenhoek that Letter L-150 had not been read by the Royal Society
December 13, 1684 sister Catharina Philips Leeuwenhoek received legacy from great uncle Johan Sebastiaans van den Berch
December 13, 1684 The Royal Society read the first part of Letter L-150 about the brain of several animals, chalk stones of gout, leprosy, and scales of eels
December 20, 1684 cousin Geertruijt Huijchs Leeuwenhoek buried
January 1, 1685 cousin Maerten Huijchs Leeuwenhoek appointed tax farmer
January 1, 1685 Published Anatomia et Contemplatio (Anatomy and Contemplation), Letters 43, 42, 38 (L-128, L-150, L-152)
January 1, 1685 Published Onsigtbare Verborgentheden (Invisible Mysteries), Letters 38, 42, 43 (L-152, L-150, L-128)
January 1, 1685 Published Sout-figuren (Salt figures), Letters 44, 45 (L-154, L-157)
January 1, 1685 Published Zaden van Boomen (Seeds of Trees), Letters 46, 47 (L-160, L-166)
January 5, 1685 Wrote Letter L-152 of 1685-01-05 to Members of the Royal Society about salts in wine and vinegar and in the stomach, the eye, the need for food and water, Descartes's theory on smallest water particles, and a theory of taste - salt, sour and sweet
January 17, 1685 The Royal Society read the latter part of Letter L-150 about the brain of an ox and a sparrow, moxa, chalk from gout, leprosy, and eels, in which he discovered both scales and fins
January 20, 1685 Francis Aston wrote Letter L-153 to inform Leeuwenhoek that his recent letter about wine was favorably received at the Royal Society
January 23, 1685 Wrote Letter L-154 of 1685-01-23 to Members of the Royal Society about salts and their crystals and his theory about the causes of taste
January 31, 1685 The Royal Society read the former part of Letter L-152 about salts in vinegar and wine, vinegar eels, and salts found in vinegar mixed with crabs eyes and chalk
February 5, 1685 Visited by Thomas Molyneux on behalf of the Royal Society
February 7, 1685 The Royal Society read and discussed the latter part of Letter L-152 salt in various wines, mixtures of tartar, crabs eyes, or chalk with wine, and the difference between salts in wines and salts in chalk stones of gout
February 13, 1685 Thomas Molyneaux wrote Letter L-155 of 1685-02-13 to Francis Aston about his visit to Leeuwenhoek's house
February 19, 1685 Francis Aston wrote Letter L-156 to inform Leeuwenhoek that his Letter L-154 about salts was received but had not been read to the Society
February 23, 1685 At age 52, his 25th article in Philosophical Transactions
March 30, 1685 Wrote Letter L-157 of 1685-03-30 to Members of the Royal Society about sperm, the uterus of a bitch, sheep embryos, ovaries in young animals and apples, and his claims that sperm are the life-carriers and that there are male and female sperm
April 4, 1685 The Royal Society read the former part of Letter L-154 about salts in wormwood, alum, and other substances
April 20, 1685 At age 52, his 25th letter in Philosophical Transactions
May 9, 1685 The Royal Society read part of Letter L-154 about oil of tartar, potash, and camphor
May 16, 1685 The Royal Society read the latter part of Letter L-154 about salts in ashes, lime, soda, and sal armoniac
May 28, 1685 The Dublin Philosophical Society asked the Royal Society for a copy of Letter L-154 about salts of wine and vinegar
May 31, 1685 Maria Duyst van Voorhout married Frederik Adriaan van Reede van Renswoude
June 20, 1685 The Royal Society read part of Letter L-157 about the role of eggs and male sperm in a female dog
June 22, 1685 Visited by John Locke
June 27, 1685 Francis Aston wrote Letter L-158 of 1685-06-27 to pass along the recommendation by John Hoskyns that Leeuwenhoek examine silkworm eggs
June 27, 1685 The Royal Society read the latter part of Letter L-157 about sperm and eggs in sheep and rabbits
July 2, 1685 sister Catharina Leeuwenhoek appointed as tax collector for three years
July 11, 1685 cousin Adriaen Lambrechts Leeuwenhoek appointed curator
July 13, 1685 Wrote Letter L-159 of 1685-07-13 to members of the Royal Society about reproduction of trees, transfer of nutrients, male and female trees, hazelnut, comparing reproduction of mammals with reproduction of plants, cross-breeding, and germination
July 22, 1685 Royal Society published Letter L-154, titled, “An abstract of a letter from Mr. Leewenheock, to the R. S. Dated Jan. 23rd, 1685; concerning the various figures of the salts contained in several substances”
August 3, 1685 Anthonie Heinsius wrote Letter L-160 to Leeuwenhoek about Robert Boyle's reaction to the letter about cochineal
August 9, 1685 Francis Aston wrote Letter L-161 of some time between August and October 1685 to inform Leeuwenhoek that Letter L-159 had been received but not yet read
August 10, 1685 Wrote Letter L-162 of 1685-08-10 to Anthonie Heinsius about cochineal
August 27, 1685 editor Edmond Halley did not publish any letters by Leeuwenhoek in Philosophical Transactions from 1685 to 1693
August 31, 1685 Anthonie Heinsius wrote Letter L-163 of 1685-08-31 about Boyle's idea about the origin of cochineal
September 21, 1685 Wrote Letter L-164 of 1685-09-21 to Anthonie Heinsius about cochineal
October 1, 1685 Visited by Karl von Hessen-Kassel and Willem Meester sometime in October
October 2, 1685 Karel von Hessen-Kassel wrote Letter L-165 to thank Leeuwenhoek for the visit to his house
October 12, 1685 Wrote Letter L-166 of 1685-10-12 to members of the Royal Society about the beginning of plants in seeds; chyle, sweat, about skin, optic nerve, and bile of fish; salts in beer vinegar and lemon juice; and spirits mixed with blood and wine vinegar
November 5, 1685 Constantijn Huygens Jr. wrote to his brother Christiaan about Leeuwenhoek's character and the visit by Hessen-Kassel and Meester
November 14, 1685 The Royal Society read and discussed Letter L-159 about reproduction of trees, comparison of reproduction of mammals with the reproduction of plants, and cross-breeding
December 1, 1685 Visited by De Saingermain, who later called Leeuwenhoek a "Magus"
December 17, 1685 Constantijn Huygens wrote Letter L-167 to Leeuwenhoek about root trees
December 19, 1685 Francis Aston and Tancred Robinson abruptly resigned as the secretaries of the Royal Society, just a week after they had been reelected
December 25, 1685 cousin Elisabeth Maertens Leeuwenhoek married Dirck van Schie
January 1, 1686 Published Cinnaber Naturalis (Natural Cinnabar), Letters 48 - 52
January 1, 1686 Published Levende Dierkens (Living Animals), Letters 28 - 31, 34 - 36

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