Maarten Etienne van Velden wrote Letter L-313 to Leeuwenhoek about receiving Sesde Vervolg der Brieven
This letter is known only by reference in Leeuwenhoek’s reply.
In this letter, Van Velden writes that he has received the booklet that Leeuwenhoek sent, which includes Leeuwenhoek’s ideas about the rotation of Earth, which had caused Van Velden to be suspended as a professor.
The booklet that Leeuwenhoek sent is either Sesde Vervolg der Brieven, geschreven aan verscheide Hooge Standspersonen en Geleerde Luijden (Sixth continuation of the letters, written to various high-standing persons and scholars), published in 1697, which included Letter L-294 of 10 July 1696 to Nicolaas Witsen, or a separate printed copy of that letter. In it, Leeuwenhoek refers to van Velden:
Now last year I was visited by a certain professor (from another province), who complained that his thesis on the motion of Earth, which he had committed to paper and published, had caused such a stir among other scholars or the authorities that his statements had to be recanted.
As we live in a country where we are allowed to express frankly our ideas on the motion of Earth, I often thought of the complaints of the said professor and at last decided to commit to paper this my thesis, with which some years ago I tried to explain the matter to my satisfaction.
For a detailed review of the controversy involving van Velden, see Stevart, Copernic & Galilee devant Universite de Louvain: Process de Martin-Etienne van Velden.
Van Velden’s previous letter to Leeuwenhoek is Letter L-256 of 30 May 1695. Leeuwenhoek replied with two letters. Letter L-261 of 12 July 1695 discussed the metamorphosis of caterpillars and the necessity that each of them individually forms a cocoon for this. Letter L-306 of 26 October 1696 was a cover letter accompanying a presentation copy of Leeuwenhoek’s printed letters, Sesde Vervolg Der Brieven.
The present letter is the last known letter that van Velden wrote to Leeuwenhoek, who replied to it with Letter L-314 of 12 February 1697 about his regrets that van Velden, owing to his defence of the Copernican world-picture, has encountered difficulties. In support of van Velden’s standpoint, Leeuwenhoek enclosed a copy of a letter from a professor in Brabant, whose Copernicanism was confirmed by Leeuwenhoek’s arguments.
Letter 181 L-314 of 12 February 1697 to Maarten Etienne van Velden
From your very welcome letter of the 4th of February I see that you have received my booklet and further that you take pleasure in the matters dealt with therein, which I was pleased to learn. Furthermore, I had not imagined that your theory of the motion of Earth would have caused such a commotion as I now see.
