Philosophical Collections

Henry Oldenburg was the founding editor of the Royal Society's Philosophical Transactions. He paid for its printing out of his own pocket, in numbered pamphlets and yearly volumes until he died in 1677, having published almost 136 numbers since 1665 and completing half of volume 12. Unfortunately, no other member of the Royal Society had Oldenburg's time, interest, financial resources, or international network of correspondents.

Robert Hooke, the Society's unofficial (until 1682, then officially until 1702) curator of experiments, replaced Oldenburg as one of the Society's secretaries. He was not interested in continuing Philosophical Transactions on his own, nor could he afford to pay for it himself. Fortunately, the Society's other secretary, Nehemiah Grew, was willing to finish the final six numbers (137 - 142) of volume 12. During 1678, he published the final six numbers of volume 12, including letters by Leeuwenhoek in number 140 and 142. After that, the journal did not resume until 1683 with volume 13.

The time between published letters in Philosophical Transactions was a little more than four years, from early 1679 to March 1683.

Meanwhile, in 1678 Hooke published two of Leeuwenhoek's letters in his Lectures and Collections of 1678, the second part of which, Microscopium, began with the Leeuwenhoek letters and Hooke's even longer response to Leeuwenhoek's experiments.

• Letter 21 of 5 October 1677 to Henry Oldenburg
• Letter 23 of 14 January 1678 to Robert Hooke

In 1679, Hooke started his own journal, Philosophical Collections. In Birch's History of the Royal Society (vol. III, p. 491, 514, and 518), the minutes of the meeting of July 3, 1679 notes that:

Mr. Hooke be desired to publish (as he hath now declared he is ready to do) a sheet or two every fortnight of such philosophical matters, as he shall meet with from his correspondents; not making use of any thing contained in the Register-books of tbe Society without the leave of the council and author.

That November of 1679 , Hooke published the first number. At the meeting of December 8, the members spent some time trying to give some structure to their meetings.

Later that meeting, they turned to Hooke:

A week or so later, at the meeting of December 17, "Mr. Hooke was desired to continue the Philosophical Collections."

Hooke waited almost two years, then quickly in the winter/spring of 1681-1682, published seven numbers, not of the next volume of Philosophical Transactions, but of more numbers of Philosophical Collections. Five of them had letters by Leeuwenhoek, as shown on the table below. Hooke could not afford to pay for the printing of as many copies as Oldenburg had, so few libraries have a complete set.

The first of these letters, Leeuwenhoek's Letter 28 of 25 April 1679, was addressed to Nehemiah Grew. The rest were addressed to Robert Hooke. The manuscript versions of the letters have a total of 19 figures. Hooke published all except the one with the concentric circles to show proportion; he also omitted the calculations that it illustrated.