| RefNo | Title | Date |
| EC/1830/10 | Knowles, Sir Francis Charles: certificate of election to the Royal Society | |
| NLB/6/312 | Copy letter from Herbert Rix, to Miss M J T Knowles, care of Miss E Jennings, St Stephen's Green, Hampstead | 11 April 1892 |
| NLB/4/386 | Copy letter from Herbert Rix, to Sir Francis Charles Knowles, 24 Oxford Terrace, Hyde Park | 9 May 1890 |
| NLB/4/1017 | Copy letter from Herbert Rix, to Sir Francis Charles Knowles, Fellow of the Royal Society, Mayfield, Ryde | 22 December 1890 |
| MC/15/115 | Letter from Francis Charles Knowles, Mayfield, Ryde, to the President and Council of the Royal Society | 29 November 1890 |
| MC/15 | Volume 15 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1889-1892 |
| HS/11/64 | Letter, from Francis Charles Knowles to Sir John Herschel, dated at Beaumont St. | 5 April 1849 |
| HS/11/65 | Letter, from Francis Charles Knowles to Sir John Herschel, dated at Belvedere House, Ryde | 9 October 1856 |
| HS/11/66 | Letter, from Francis Charles Knowles to Sir John Herschel, dated at Belvedere House, Ryde | 5 December 1856 |
| HS/24/153 | Copy letter, from Sir John Herschel to Francis Charles Knowles, dated at Collingwood | 23 April 1866 |
| HS/23/182 | Copy letter, from Sir John Herschel to Francis Charles Knowles, dated at Collingwood | 16 October 1856 |
| HS/11/68 | Letter, from Francis Charles Knowles to Sir John Herschel, dated at Belvedere House, Ryde | 17 April 1866 |
| HS/11/67 | Copy letter, from Sir John Herschel to Francis Charles Knowles, dated at Collingwood | 6 December 1856 |