The Letters
Period 7 - 1720 -1723

editor: James Jurin

Van Leeuwenhoek not only survived through the lean years when Halley was editor. He kept living -- and reporting his observations -- until he was 91. This gave him the opportunity to enjoy a couple of years at the end of his life when he was again published regularly in London.

In London

After Halley was replaced as editor by James Jurin, he and the other secretary, the astronomer and mathematician John Machin, shifted the direction of Philosophical Transactions. It wasn't until mid-century, 1753, that it finally became an official publication of the Society, as opposed to the personal project and sole responsibility of Henry Oldenburg and whoever followed him as editor.

In the ongoing struggle between the physical sciences and the biological sciences, Jurin was with the former, as, of course, were Machin and the Society's president during this period, Isaac Newton.

In 1726, Jurin wrote about Newton in the final volume of Philosophical Transactions that he edited (italics in original):

That Great Man was sensible, that something more than knowing the Names, the Shape and obvious Qualities of an Insect, a Pebble, a Plant, or a Shell, was requisite to form a Philosopher, even of the lowest rank. ... We all of us remember that Saying so frequently in his Mouth, That Natural History might indeed furnish Materials for Natural Philosophy; but, however, Natural History was not Natural Philosophy. ...

It was not that he despised so useful a Branch of Learning as Natural History; he was too wise to do so: But still he judged that this humble Handmaid to Philosophy, though she might well be employed in amassing Implements and Materials for the Service of her Mistress, yet must very much forget her self, and the Meaness of her Station, if ever she should presume to claim the Throne, and arrogate to her self the Title of Queen of the Sciences.

Jurin was not, however, as focused as Halley. And van Leeuwenhoek wasn't claiming royalty; he just wanted to get his observations published.

Van Leeuwenhoek's final fifteen letters, as listed by Cole, were all addressed to the Royal Society and were all published in volumes 31 and 32. This included the final two, dictated on his death bed in August 1723 to Johan Hoogvliet and translated into Latin before Hoogvliet sent them. Jurin published them the following year, in Latin.

In Delft

After the Send-Brieven / Epistles of 1718, van Leeuwenhoek published no more volumes on his own. Of the final fifteen letters that he wrote to the Royal Society, half of them were translated into Latin before he sent them, including the final five.

As with the Send-Brieven / Epistles, the elderly van Leeuwenhoek was not looking at things that needed the strongest lens, or we presume, the strongest eyes. They were almost all sections or otherwise flattened on glass presumably so that he could use transmitted light passing through the specimen.

From the titles of the articles in Philosophical Transactions, van Leeuwenhoek studied:

bones and periosteum seeds of plants vessels in several sorts of wood calluses on the hands and feet foetus and reproductive organs of a sheep (images on the left)

magnetic quality of iron muscular fibres of different animals and fish particles of fat (image on the right) membranes enclosing the fasciculi of fibres

Dual Thrones

The concerns expressed by Newton and Jurin above were not resolved at the Royal Society until 1887, when Philosophical Transactions was split into two parts, A and B.

According to the Royal Society Publishing web site, Philosophical Transactions A is devoted to a specific area of the mathematical, physical and engineering sciences.

Astronomy and astrophysics
Chemistry
Earth Sciences

Philosophical Transactions B is divided into four cluster areas:

Cell and Development
Health and Disease
Environment and Evolution
Neuroscience and Cognition