The Letters
Period 5 - 1693-1714

editors: Richard Waller
and Hans Sloane

This period was the most productive of van Leeuwenhoek's career. He was in his sixties and seventies, a widower for the second time in 1694, living with his devoted and unmarried daughter Maria, presumably with more time than ever for his observations. The situation in London was stable and favorable.

Over these 22 years, almost half of his scientific career, he wrote about 140 published letters, according to Cole. Although the dozen letters from 1713 and 1714 are included in that total, by then Edmond Halley was making the decisions again.

In London

Once Richard Waller got serious about reviving Philosophical Transactions, he set its goals high -- and he began publishing letters from van Leeuwenhoek that had been lying around for twelve years. In 1693, he published letters from April 5, 1680, and May 13, 1680, in volume 17, number 196. He followed that with five letters over a decade old: one from 1683 and two each from 1685 and 1686, all published in volume 17, 1693. The one from 1683, September 11, had already been translated and published a decade earlier by Robert Plot in volume 14. Waller's was shorter, had the figures reversed, and was missing one. In addition, according to Dobell, the translation is not as accurate.

The next year, for volume 18, Waller continued, publishing two of van Leeuwenhoek's letters, from July 10, 1686 and March 7, 1692.

This left a large body of letters that remained untranslated into English until the late 20th century's Alle de Brieven / Collected Letters.

In 1693 Sloane was appointed Secretary of the Royal Society, joining Waller, who had been there for several years. E.S.J. Brooks wrote in Sir Hans Sloane: The Great Collector and His Circle London, (1954, p. 82):

Sloane was the owner and editor of the journal, responsible for obtaining the items to be published. Profits were rare and losses were made up from his assets.

From then, for the next twenty years (excepting only 1710 when John Harris replaced Waller for one year), these two, Waller and Sloane were the two secretaries and Sloane was the editor of Philosophical Transactions. For van Leeuwenhoek, beginning in 1695, the tide turned.

Note: Birch's History stops at the end of 1687, so we do not have as complete an idea of what happened as we did during earlier years.

In Delft

Given the uncertainties in London, van Leeuwenhoek continued publishing his letters is Dutch editions and roughly parallel Latin translations. London was far away and his Dutch printer was literally next door on the Hippolytusbuurt.

While as a fellow of the Royal Society, van Leeuwenhoek never visited London or attended a meeting, in 1700, Hans Sloane visited him. We have no record of that meeting, and we have no reason to think that Sloane spoke Dutch. Two things happened afterwards that were perhaps caused by that meeting:

he started publishing again in London
he stopped self-publishing in Delft

To be specific, from July 1700 until the end of 1712, almost all the 40 letters that van Leeuwenhoek wrote were published by Sloane in volumes 22 through 29.

Compare this to how Sloane treated Halley. After the first year of Sloane's editorship, from 1698 to 1713, volumes 20 - 28, Halley had only 5 articles published while van Leeuwenhoek had 57, half his career total. And then during period 6, Halley was editor and not publishing van Leeuwenhoek. However, he published 13 of his own articles in volume 16.

The table on the left also shows that van Leeuwenhoek had one article in volume 28 of Philosophical Transactions. He also had one article in volume 29, an article that Halley may have inherited from his successor, Hans Sloane, to whom the letter was addressed.

Thus, a dozen letters were published in both Philosophical Transactions and the Sevende Vervolg. However, the bulk of the letters written during this period were not published in Dutch/Latin. Some of them remained in the English translation only until the Alles de Briven / Collected Letters project caught up with them at the end of the 20th century and published the full letters in both Dutch and English.

Unfortunately, the Alles de Briven / Collected Letters project has stopped with volume 15, which ends with the letter of July 25, 1707.

Just as 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, it would be six years until van Leeuwenhoek would see another of his letters in Philosophical Transactions.