Period 6 - 1712-1719

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
# ltrs
AvL # # ltrs
w/ figs
# ltrs
# ltrs
RS sci
# arts
# ltrs
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
botanist, physician
Fellow Royal Soc. 1730
Antoni Cink professor, Luvain IX, XVI, XVII, XXV, XXXVIII
Antonie Heinsius
pensionary of Holland I, II, VI, VIII
J G Kerkherdere
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
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.