Throughout his career, particularly during the 1790s, John Rennie filled many notebooks with information about the works he himself was involved with, and about others which he visited out of professional curiosity. The books are mostly narrow octavos, interleaved with blotting paper. Rennie seems to have carried them with him on his frequent travels and to have filled them in in pencil, rewriting in ink, often on top of the pencil, at some more convenient moment. Ronnie received much of his information orally, and in consequence the spelling of place names is not always accurate, and some places at least cannot be certainly identified. The notebooks also contain addresses, book-lists (especially of the early technological books and medieval chronicles in which he was interested), and notes of expenses for his travels which often make it clear where he went and when. This series of notebooks does not contain those which relate exclusively to subjects represented elsewhere amongst the papers. These have been placed with other relevant material.