The contents are as follows. (i) Correspondence and papers of George Rennie, engineer, 1821-1863 (folio 1); (ii) Papers relating to the sale in 1850 of John Rennie's library by his sons, including annotated sale catalogues etc. (folio 186); (iii) Copy, 1893, of George Rennie's marriage certificate, 1828 (folio 240); (iv) Letters to James Watt junior, passed on to George Rennie, on the subject of John Rennie's life and work, 1821 (folio 241).