Robert Hooke wrote Letter L-115 of some time in December 1681 to Leeuwenhoek about his previous letters
This letter is known only by reference in other letters.
In this letter, Robert Hooke writes that the members of the Royal Society thank Leeuwenhoek for the observations and reasoning in his two previous letters and will have them published.
All of Leeuwenhoek’s known letters to the Royal Society are accounted for, so it must be Hooke’s reply that is lost. According to Birch, The History of the Royal Society of London, vol. III, pp. 101 and 104, Hooke read Leeuwenhoek’s Letter L-114 of 4 November 1681 to the Royal Society at the meetings of 19 November and 3 December 1681 N.S., so his lost reply would have been written shortly thereafter.
Hooke’s previous known letter to Leeuwenhoek is Letter L-112 of 4 July 1681. By “this and your former”, Hooke means Letter L-114 of 4 November 1681, published in Philosophical Collections, no. 4 of 10 January 1682, and Letter L-116 of 3 March 1682, published in Philosophical Collections, no. 5 of February 1682. These numbers of Philosophical Collections are the two that Hooke sent with his next Letter L-117 of 20 March 1682.
Letter 67 [35] L-116 of 3 March 1682 to Robert Hooke
Having since sent to you a few observations dated November 4th 1681, and having at the same time requested you urgently to send me an answer to a certain cure of the gout, without, however, receiving a reply, I cannot but think that either your missive or mine has been lost.
Letter L-117 of 20 March 1682 from Robert Hooke
Yours of this instant March came safe to my hands as did also that which you sent in November last: but I much wonder to understand that you had not received my answer to it, when you wrote this last. I shall therefore now again acquaint you that I translated both this and your former, and communicated them to the Society at their meeting, who were extreamly well pleased with your excellent discoveries, and ordered me to return you their hearty thanks, as also that I should take care, as soon as might be, to get them published in the Collections: which I have accordingly done, and have herewith also sent them for your perusal.
