Period 6 - 1712-1719

July 1, 1712 - December 31, 1719

The 52 letters from the letter of November 8, 1712 (AB 295) through the letter of November 28, 1717 (AB 346).

Of the 46 letters with scientific observations, 22 of them had a total of 144 figures.

Leeuwenhoek published all 46 of these letters, what he called Send-Brieven, in Works IV.

Having matured, its founders dead or aging, the Royal Society entered what some see as a decline from its original vigor and rigor. In 1703, Sir Isaac Newton had become president, and his supporter Edmond Halley resumed the job of editor of Philosophical Transactions, which he had previously held for a few years two decades previously when he edited volume 16.

use? Unfortunately, Edmond Halley replaced Hans Sloane as secretary and Philosophical Transactions editor in 1713. He seems to have followed through on Sloane's commitments because he published van Leeuwenhoek's letter of November 8, 1712, in volume 29 in 1714. But after that, another dry spell. It would be six years until Leeuwenhoek would see another of his letters in Philosophical Transactions.

Over a period of five years, Halley dramatically slowed down the publication schedule and concentrated on articles about astronomy and the physical sciences, as he had with volume 16. Just as he had declined to publish Leeuwenhoek's letters in volume 16 in the late 1680's, so he would again decline three decades later for volume 30.

Knowing this, Leeuwenhoek nevertheless kept addressing letters to the Royal Society. However, he published all 46 letters from this period in his final volume, Send-Brieven (Epistles) and its Latin translation Epistolae Physiologicae (Physiological Letters).

The table below summarizes these eight years of Leeuwenhoek's scientific career, through the end of 1719, which Leeuwenhoek was 87 years old. Edmond Halley served a second stint as editor, taking over from Hans Sloane for volume 29.

Letters in Period 6

	AdB #	# ltrs AdB	# ltrs sci	AvL #	# ltrs w/ figs	# figs	# ltrs RS	# ltrs RS sci	PT vol	PT nos	# arts PT	# ltrs Dutch
1712	295-297	3	2	I-II	2	13	0	0	28	337	0
1713	298-305	8	7	III-IX	2	17	1	1		337	* 1
1714	306-311	6	6	X-XV	3	23	5	5	29	338-342	** 1
1715	312-317	6	5	XVI-XIX	2	7	0	0		343-346	0
1716	318-330	12	11	XX-XXXI	5	48	0	0		347-350	0
1717	331-340	15	15	XXXII-XLI	8	36	7	7	30	351-354	0
1718	346	1	1	XLII-XLVI	0	0	0	0		355-358	0	46
1719		0	0		0	0	0	0		359-363	0
		51	46	46	22	144	13	13			2	46

AdB #: the letter numbering in Alle de Brieven / Collected Letters.
# ltrs AdB: the number of letters written by Leeuwenhoek in Alle de Brieven / Collected Letters.
# ltrs sci: the number of letters with scientific observations.
AvL #: Leeuwenhoek/Cole's letter numbering.
# ltrs w/ figs: the number of letters with figures.
# figs: the total number of figures in all the letters written during that period.
# ltrs RS: the number of letters sent to the Royal Society.
# ltrs RS sci: the number of letters with scientific observations that Leeuwenhoek sent to the Royal Society.
PT vol and no: Philosophical Transactions volume and numbers.
# arts PT: the number of articles by Leeuwenhoek published in Philosophical Transactions.
# ltrs Dutch: the number of letters that Leeuwenhoek published himself in Dutch.

* - The Royal Society dates volume 28 January 1, 1712 and gives it only one number, 337. The title page (right; click to enlarge) says Volume 28 1713. The Contents page says "for the year MDCCXIII", but the date at the bottom says that it was printed for D. Brown in 1714. In it, editor Hans Sloane excerpted Leeuwenhoek's long Letter VII of June 28, 1713, "Some Further Microscopical Observations on the Animalcula Found Upon Duckweed, &c.", the only letter from Send-Brieven also published in Philosophical Transactions. The letters were numbered with Roman numerals, I through XXXIX; Leeuwenhoek's was XVI.

** - In 1714, the earlier letter of November 8, 1712, was published in volume 29, titled "Concerning the Fibres of the Muscles, &c." and dated as October 12, 1713.

*** - The difference between 46 and 51 are these six letters:

1712-11-08    295        Anthonie Heinsius
1713-10-12    304        Hans Sloane
1715-01-11    312        Anthonie Heinsius
1715-11-18    316        Gottfried Leibniz
1716-02-25    318        Anthonie Heinsius
1718-11-28    346        Francisco Cornaro

Only the letters to Leibniz and Cornaro contained scientific observations.

Leeuwenhoek addressed these 46 other letters to 15 different addressees.

Send-Brieven addressed to ...

Adriaen van Assendelft	council member of the city of Delft	V, XIIII
Ewout van Bleswyk		XXXV
Abraham van Bleys-Wyk	medical doctor and City anatomy lecturer; Leeuwenhoek's cousin.	XXVII, XXXII, XXXVI
Herman Boerhaave 1668–1738	botanist, physician Fellow Royal Soc. 1730	XXVIII, XXIX, XXXI, XLI
Antoni Cink	professor, Luvain	IX, XVI, XVII, XXV, XXXVIII
Antonie Heinsius 1641-1720	pensionary of Holland	I, II, VI, VIII
J G Kerkherdere 1673-1738	historian to Emperor Joseph I and King Charles III	XXVI, XXXIX
G W Leibniz 1646 - 1716	member, Royal Society in London, professor in Hanover, librarian of Brunswick	XVIII, XIX, XX, XXIII, XXX
Gerard van Loon		XXII
Jan Meerman	mayor of Delft	III, IV
Members of the Royal Society		VII, X, XI, XII, XIV, XV, XXXIII, XXXIV, XXXVII, XLIII, XLIV, XLV, XLVI
Hubert Poot	poet	XXI
Frederik Adriaan van Rhede		XLIII
Cornelis Spiering 1663-1745	Lord of Spieringshoek, council member and mayor of Delft	XXIV
Adriaan Swalmius		XL

Just as Halley as editor had published 13 of his own articles (and none of van Leeuwenhoek's) in volume 16, in period 6, he published nine of his own articles in volume 29 and five in volume 30.

In Delft

Starting with the letter of Nov 8, 1712, the next forty-six letters through Nov 7, 1717, Leeuwenhoek published himself. Adriaan Beman, in Delft, printed and sold Send-Brieven (Epistles) in 1718, including the two letters published in volumes 28 and 29 of Philosophical Transactions. The following year, he printed the Latin translation, with the same figures, titled Epistolae Physiologicae (Physiological Letters). The letters were translated by Hugo van Rijn.

Thus, between 1712 and 1719, one of the most productive periods of his life, Leeuwenhoek had only two articles published by Philosophical Transactions.

At the end of this phase, according to Cole, over two years from November 20, 1717, to January 1720, Leeuwenhoek wrote no published letters. The other period when Leeuwenhoek wrote no letters, the eighteen months from April 1, 1689, until September 18, 1691, Halley was also editor and not publishing Leeuwenhoek. As another parallel, the 1689-91 letter gap came just after he published Tweede Vervolg / Second Continuation, and this 1717-20 letter gap came just after he published Send-Brieven / Epistles.

Then, when Leeuwenhoek was 87, the Royal Society replaced Halley as editor with James Jurin. Over the final years of his life, he sent another dozen letters to the Royal Society that were published in Philosophical Transactions alone.

Unfortunately, the 19-volume Alles de Briven / Collected Letters project has published only 17 volumes, through 17??, so the only English translations are half a dozen excerpts scattered (and not dated) through Hoole's Selected Letters.

Sources

Year	Author	Title
1720	Heussen, H. van	Oudheden en gestichten van Delft en Delfland
1725	Heussen, H. van	Oudheden en Gestichten van het Rechte Zuid-Holland en van Schieland

What happened?

Date	Event
August 14, 1700	John Chamberlayne wrote to Hans Sloane about whether his Dutch was good enough to translate Leeuwenhoek's letters
June 6, 1701	John Chamberlayne wrote to Hans Sloane about difficulties translating Leeuwenhoek's Dutch, "so abstruse that even his own countrymen cannot explain him"
December 6, 1704	John Chamberlayne wrote to Hans Sloane that even native Dutch speakers have trouble helping him translate Leeuwenhoek's letters
March 3, 1714	Richard Waller wrote Letter L-502 of 3 March 1714 to discuss recent observations about muscles
March 8, 1714	Richard Waller wrote Letter L-503 to Leeuwenhoek on behalf of the Royal Society about recent observations on muscle fibers and numbers of Philosophical Transactions
July 27, 1714	Richard Waller wrote Letter L-506 about Letter L-504 and promised to publish whatever Leeuwenhoek sent
February 28, 1715	Anthonie Heinsius wrote Letter L-515 of 1715-02-28 to thank Leeuwenhoek for the letters sent by him over the years and expects that posterity will be grateful for what he has discovered
August 5, 1715	Gottfried Leibniz wrote about Leeuwenhoek to Louis Bourguet, who was "not persuaded by his hypothesis"
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 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
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
November 4, 1716	Herman Boerhaave wrote Letter L-542 to Leeuwenhoek that his discoveries and thoughts are agreeable to him
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
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
December 15, 1717	Received payment from the city for inspector / wine gauger duties
January 23, 1719	Received payment from the city for inspector / wine gauger duties

Learn more

Learn more about ...
Leeuwenhoek's Cabinet of Wonders

Related letters:

What Leeuwenhoek wrote ...
Wrote Letter L-488 of 1712-11-08 to Anthonie Heinsius, a cover letter for Letter L-489
Wrote Letter L-489 of 1712-11-08 to Anthonie Heinsius about the muscle fibres of a whale
Wrote Letter L-490 of 1712-12-17 to Anthonie Heinsius about salts in the blood of a shrimp and the muscle fibres and enveloping membranes of cod, shrimp, flounder, and perch
Wrote Letter L-492 of 1713-02-28 to Jan Meerman about wheat and barley grains, beans, peas, and chestnuts, vessels and membranes in coconut rind, and the embryo in an apple pip and in a coconut
Wrote Letter L-493 of 1713-03-14 to Jan Meerman about the eye of a whale, the lens, and the cornea and calculations of the pressure on a whale's eye at great depth
Wrote Letter L-494 of 1713-03-25 to Adriaen van Assendelft about little hairs of a mouse, mole, cat, and rabbit all have the same shape; thick, dark bear hair, composition and color of hair, hair of deer and elk
Wrote Letter L-495 of 1713-03-29 to Anthonie Heinsius about the muscles of cows, muscle fibers of mice thinner than whales, fat particles, muscle fibers of sheep same size as of mice and oxen, though the animals differ greatly in size
Wrote Letter L-496 of 1713-06-28 to the members of the Royal Society about little animals on duckweed, muscle fiber membranes, and a list of unanswered letters; little animals in his mouth come from rinsing glasses with pond water
Wrote Letter L-497 of 1713-06-30 to Anthonie Heinsius about the composition of crabs’ eyes and lobster and crab shells, ring-shaped structures in lobster pincer shell, compared to annual rings of woody vegetation, and the lobster's muscle fiber membrane
Wrote Letter L-499 of 1713-10-12 to Hans Sloane as a cover letter for a copy of Letter L-489 on muscle fibres of a whale and a request for new numbers of Philosophical Transactions and a list of fellows of the Society to be sent to relatives in Rotterdam
Wrote Letter L-501 of 1713-10-24 to Antony Cinck refuting, as requested, Kircher's ideas about poisonous little animals on sage leaves and spontaneous generation
Wrote Letter L-504 of 1714-06-22 to the members of the Royal Society to acknowledge Letter L-503 and numbers of Philosophical Transactions and to query why figures of the muscle fibres of whales were not published
Wrote Letter L-507 of 1714-08-21 to the members of the Royal Society about the muscle fibres of cow, chicken, mouse, honeybee, flea, ant, and whale and the blood vessels in the leg of a fly; thanks for recent numbers of Philosophical Transactions
Wrote Letter L-509 of 1714-10-26 to the members of the Royal Society about muscle fibres and enclosing membranes in the legs of a mosquito, rose chafer, fly, crane fly, honeybee and cow; rectifying earlier opinion, the contractions in a muscle are spiral
Wrote Letter L-510 of 1714-11-04 to Adriaen van Assendelft, comparison between muscle fibres and a tightened rope; the shorter the rope, the quicker it can shrink; application of this comparison on the size of muscle fibres of a cow and of a mouse
Wrote Letter L-512 of 1714-11-09 to the members of the Royal Society about the muscles of an ox, sheep, chicken, mouse, and hare
Wrote Letter L-513 of 1714-11-20 to the members of the Royal Society about muscle fibres and tendons from a mouse leg, a duck wing, a honeybee, a polecat leg, and between the ribs of a mouse; a theory about the structure and action of tendons
Wrote Letter L-514 of 1715-01-11 to Anthonie Heinsius, a cover letter for a copy of a recent letter on muscle fibres
Wrote Letter L-516 of 1715-03-26 to Antony Cinck about the structure and action of muscle fibres and tendons from the leg of a mouse and the head of cod and a wire model of spiral contraction
Wrote Letter L-518 of 1715-07-07 to Antony Cinck about contracting and stretching of muscle fibres and tendons; their connection in lobster and crab; no observed nerves between muscle fibres and membranes; cannot confirm that nerves are hollow
Wrote Letter L-521 of 1715-09-28 to Gottfried Leibniz about scholars who do not agree with Leeuwenhoek; sperm the same size in different animals; the pulse; posthumous letters; muscle fibers, tendons, and nerves; Hartsoeker; why he won't train students
Wrote Letter L-524 of 1715-11-18 to Gottfried Leibniz about vessels in the flesh of fruit and in the seeds of various strains of pears, a pear's embryo and the structure of a pear's skin, and spiral vessels in tea-leaves
Wrote Letter L-526 of 1716-02-25 to Anthonie Heinsius as a cover letter to "notes" about tendons, muscle fibres, and starch grains
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
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
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
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
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
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
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
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
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
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
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
Wrote Letter L-546 of 1716-11-21 to Herman Boerhaave about ram sperm and details of his experimental methods
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
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
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
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
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
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
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
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
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
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
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
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
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"
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
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