The Royal Society read the first part of Leeuwenhoek's long Letter L-040 of the previous 9 October about little animals in various waters

February 11, 1677

On February 1 in London (February 11 in Delft), the Royal Society read the first part of Leeuwenhoek's long letter of the previous October 9. They asked that he "communicate his method of observing." This is the third mention of Leeuwenhoek in Birch's History. See vol 3, pp. 332:

There was read part of a very long letter of Mr. Leewenhoeck to Mr. OLDENBURG, dated at Delft, 9th October, 1676, which had not been produced before, because it could not be sooner translated into English out of the Low Dutch language, in which it was written. The contents thereof were a great number of observations made by Mr. Leewenhoeck with his microscope, concerning certain little animals found by him in vast quantities in common water, snow-water, well-water, and such water, wherein several sorts of spices had stood infused, both whole and pounded.

It was ordered, that the sequel of these observations should be read at the next meeting; and that the author be desired to communicate his method of observing.

Oldenburg did so in Letter L-052 of 22 February 1677 (12 February in London).

This is the first time a letter by Leeuwenhoek was read aloud at a meeting of the Royal Society. After that, most, but not all, of Leeuwenhoek's letters were read aloud at a meeting.