Well, we are still not exactly sure! As Lisa Jardine and Robyn Adams wrote in their recent article in Notes of Records of the Royal Society the folio was found under mysterious circumstances. It has been indexed to some extent by Hooke’s posthumous editor William Derham. Based on the original inscription on the cover, Derham suggests that the first hundred pages are extracts from the Journal Books, the official record of meetings, during the period in which Henry Oldenburg was Secretary of the Royal Society. The rest of the manuscript, which runs to 635 pages in total appears to consist of original minutes from the period during which Robert Hooke was Secretary, 1677-1682 with a few additional pages from 1691.
The original minutes of the Royal Society are preserved in the archives, with the exception of the period in which Hooke was Secretary, for which there are binders left empty for the missing pages. It seems, however, that the Royal Society did have some of Hooke’s minutes: in February 1682 the Council demanded that he ‘deliuer up into the hands of either of the Secretary’s all such Books and Papers as any way belong to the society or came to his hands upon the account of his being Secretary’ and later that Spring a committee was appointed to meet in the Repository and correct omissions and mistakes in the journal books. Minutes of a council meeting the next year report having ’stichted paper books of Minutes taken by Mr Hook they begin the 25th of October 1677 and end the 23rd of February 1680/1′. Also in their possession ‘Another bound book of Mr. Hookes minutes, about ¼ full, it begins March 1680/1 and ends July 26 1682′. Finally, the council ‘Resolved that the minutes of the Mr Hooke be written into books suiting with the rest’.
So, the mystery deepens. These council minutes imply that at the original copy of the minutes was in the hands of the Council and, if their instructions were carried out, there would have been an additional copy to be entered in the records. Did Hooke reclaim his notes at some point after this, and if so, for what purpose?