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 nearest allied to geometry; that they are first sketches and occasional notes, the Author always intending afterwards to compose from them complete treatises.” He adds further, “that they are written backwards from right to left, in the manner of the oriental writers, probably with intention that the curious should not rob him of his discoveries. The spirit of geometry guided him throughout, whether it were in the art of analysing a subject in the connexion of the discourse, or the care of always generalizing his ideas. As to natural philosophy, he never was satisfied on any proposition if he had not proved it by experiment.” From the extracts given from these manuscripts by Venturi himself, and which he has ranged under the different heads mentioned in the note, the contents of these volumes appear to be extremely miscellaneous; and it is evident, as Venturi has marked by references where each extract is to be found in the original, that Rh