| RefNo | Title | Date |
| EC/1900/11 | Muir, Sir Thomas: certificate of election to the Royal Society | |
| NLB/26/672 | Copy letter from Robert William Frederick Harrison to, Dr Thomas Muir, Fellow of the Royal Society, Cape Town | 8 May 1903 |
| NLB/25/166 | Copy letter from [A H White], to Dr Thomas Muir, Fellow of the Royal Society | 5 September 1902 |
| NLB/26/511 | Copy letter from Robert William Frederick Harrison to, Dr Thomas Muir, Fellow of the Royal Society | 3 April 1903 |
| NLB/25/324 | Copy letter from Robert William Frederick Harrison, to Dr Thomas Muir, Fellow of the Royal Society | 17 October 1902 |
| NLB/25/372 | Copy letter from Robert William Frederick Harrison, to Dr Thomas Muir, Fellow of the Royal Society, Department of Public Education, Cape Town | 24 October 1902 |
| NLB/25/708 | Copy letter from Robert William Frederick Harrison, to Thomas Muir, Fellow of the Royal Society, Department of Public Education, Cape of Good Hope | 12 December 1902 |
| NLB/25/836 | Copy letter from Robert William Frederick Harrison, to Dr Thomas Muir, Fellow of the Royal Society | 9 January 1903 |
| NLB/32/5 | Copy letter from Robert William Frederick Harrison, to Dr Thomas Muir | 11 December 1905 |
| NLB/46/685 | Copy letter from Robert William Frederick Harrison, to Thomas Muir, Fellow of the Royal Society | 16 October 1912 |
| NLB/46/794 | Copy letter from Robert William Frederick Harrison, to Dr Thomas Muir, Fellow of the Royal Society | 4 November 1912 |
| NLB/56/516 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Sir Thomas Muir, FRS; Elmcote, Sandown Road, Rondebosch | 27 February 1919 |
| NLB/64/739 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to R.H. Dick, Esq. M.A.; Boys' High School, South Africa | 12 June 1923 |
| MC/18 | Volume 18 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1903 |
| NLB/53/593 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Sir Alfred [Bray] Kempe, Treasurer of the Royal Society | 06 November 1916 |
| MC/18/175 | Letter from [Thomas] Muir, Department of Public Education, Cape Town, South Africa, to the Royal Society | 18 March 1903 |
| MC/18/174 | Letter from [Thomas] Muir, Education Office, Cape Town, to the Royal Society | 11 March 1903 |
| MC/17 | Volume 17 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1897-1899 |