Henry Oldenburg wrote Letter L-013 to Leeuwenhoek, encouraging him to send more observations

August 30, 1674

This letter was written on 20 August in London. It is known only by reference in another letter.

It was probably a reply to Leeuwenhoek's Letter L-011 of 1674-06-01. Leeuwenhoek mentioned it in Letter L-016 of 1674-10-19. Oldenburg relayed a message from Robert Boyle and encourged Leeuwenhoek to continue sending his observations.

This letter is calendared as Letter 2531 in Hall and Hall, The Correspondence of Henry Oldenburg, vol. XI, May 1674–September 1675, p. 71.

Oldenburg’s previous letter to L. is Letter L-010 of 4 May 1674. L. replied with Letter L-011 of 1 June 1674 and Letter L-012 of 6 July 1674, both in Collected Letters, vol. 1. Oldenburg’s next letter is Letter L-017 of 5 November 1674, encouraging him and asking about the kind of salt he was observing.


The manuscript is lost and the letter was never printed.

Letter L-014 of 7 September 1674 to Henry Oldenburg

Your honoured letter of the 20th of last month has reached me today, in proof of which I answer you by return of post. It has been a great pleasure to learn from your letter that both my previous letters reached you, and that my observations, as given in these writings, have been agreeable to the lovers of curiosities; therefore, I find the confidence to continue my speculations on this subject, as will appear from the contents of the enclosed, to which a reference will suffice. I am very much obliged to you and to Mr. Boyle for his undeserved affection towards me.

Letter L-016 of 19 October 1674 to Henry Oldenburg

My previous letter to you was of the 7th of September. I do hope that Your Honour received it, and at the same time I received yours of the 20th August, from which I learned of the undeserved affection of Mr. Boyle and yourself towards me, which leaves me under great obligations.